Proceedings of ARCH 2019

Due to the large number of masonry bridges in the European Infrastructural network, the maintenance and retrofitting of this kind of bridges is an up-to-date issue of Structural Engineering. In this paper, the Mechanics of masonry bridges is discussed starting from the definition of load carrying structure, which is much wider than the arch itself. Once proper similarity criteria for reduced scale laboratory testing are discussed, the results of some tests are used to outline the basic features of the mechanical response of masonry bridges. Arch-Fill interaction turns out to be crucial for the l.c.c. of the bridge since it is responsible also for the span of the structural arch. The concept of Limit Load is discussed, which is not so trivial to be defined as usually assumed since it does not correspond to the Ultimate Load that activates a collapse mechanism. Once the basic issues of the dynamic and seismic response of masonry bridges are discussed, showing unexpected good seismic performances of these massive bridges, new trends in retrofitting of the bridges are discussed.

This work presents some arch bridges constructed in Portugal since the Roman Empire period to recent times. For some masonry. Steel and concrete bridges construction details are also presented. Bridges and all constructions requires permanent maintenance. Some old bridges presents a reduced deck width requiring its enlargement. Live loads increased along time requiring strengthening interventions in existing bridges. The most severe action that led to some bridge destruction is river flooding and foundation infraescavation.Some examples of interventions are presented in the paper.

For 2000 years, the basic material to build a bridge was wood or stone. The typical shape of stone bridges was the semi-circular arch. The first bridges made of metal were again arch bridges where the internal forces are essentially compression forces. The industrial revolution and the progress of the theoretical knowledge in the field of structural mechanics made it possible to design bridges with different shapes. Bridges with large spans were mainly suspended and also arch bridges. Today, the arched bridges are probably very well suited for crossing very deep valleys or rivers in an area without relief.

As one of the most formidable challenges on long-span bridges, recent development of arch bridges have been presented in the aspects of static stability, dynamic characteristics and aerodynamic performance. Concrete, steel and concrete-filled-steel-tube arch bridges have been numerically analyzed to evaluate elastic structural buckling instability and plastic material yielding instability. Concrete arch bridges may result in plastic material yielding instability during construction, especially under strong winds, although completed bridges have quite high safety factor. Most long span bridges show good dynamic characteristics, and have higher structural stiffness and natural frequency than those of cable-stayed bridges with same span length. Steel box rib arch bridges have been found with some aerodynamic problems due to very bluff cross section, especially in vortex-induced vibration, but the increase in span length of arch bridges should not be influenced by aerodynamic performance.

Arch bridges were very popular in Italy in the last century, mainly employing reinforced concrete. Arturo Danusso, Eugenio Miozzi, Giulio Krall were amongst the famous “authors” that gave a huge impulse to the Structural Art in arch bridges design. However, the role of Riccardo Morandi was quite exceptional, due to his innovative design criteria very well represented, for example, in the Storms River bridge in South Africa and in the Fiumarella Bridge in Catanzaro.

Hopefully, this paper will help to contribute to the awareness and knowledge of old bridges in the territory of Bragança, which can and should be understood as key elements of the landscape, regarded as heritage landscape units, under permanent transformation. One tries to look at those different types of existing old bridges, like parts of this palimpsest in human interactions with the environment, which one calls culture.The analysis proposed in this paper is focused not only on the old bridges themselves, acting as isolated objects, but mostly on the old road networks in which they were included, distinguishing the different types of roads that one can identify in Bragança nowadays, as a natural outcome of the social, cultural and economic background over the centuries and millennia. Ultimately, this paper will contribute to the enhancement of public policies to rehabilitate the old road systems in Bragança, in a coherent and integrated way.

The conservation of a structure with cultural value, such as the Bridge of Arco, is necessary for the purpose of preserving and safeguarding any monument, but it can also be an activity that causes disturbances and changes in a place or in its construction. However, the need to transmit these medieval arch bridges from generation to generation is conditioned by the erosion of the elements and by the action of men, which during their life course are causing changes that compromise the stability of this type of structures, their construction rationality and the context in which they are inserted, determining the need for a project, that ensures their safeguard through conservation and valorisation actions. These actions are determined through a conservation methodology, that defines strategies and project criteria appropriate to the heritage, which respects their values and meanings, using tried and tested repair methods compatible with these stone masonry structures in a manner that does not damage the historical materials and their cultural significance. This is done not only with the minimum of invasive means, but also verifying the relationship that he established with the territory in which it is inserted, as a repository of identity and authenticity of the heritage itself that is added to it. The article reports a concrete case study, approaching the conservation methodology, that was used to define the strategies and project criteria carried out in the Bridge of Arco conservation. It does not aspire to find a standard solution for the safeguard of medieval arch bridges conservation, but rather to test a methodology as a key to understanding, debating and sharing knowledge in the heritage conservation.

This paper reports on modelling strategies used to represent the structural behaviour of a multispan masonry bridge under railway loading. The bridge structural behaviour is simulated by a 3D finite element model, in which the different bridge components are represented by homogeneous materials. The masonry and infill nonlinear behaviour are simulated using the Drucker-Prager model. The response of the bridge is evaluated for different passages of a freight train considering its dynamic effects and using a simplified methodology.

This paper reports on the numerical simulation of the structural response of a single span stone arch railway bridge under incremental static loading representing real trains. The study aimed at identifying adequate numerical modelling strategies to simulate the bridge structural behaviour by means of computational resources, based on the Finite Element Method (FEM) and Distinct Element Method (DEM), taking into account the nonlinear behaviour of the bridge materials and suitable conditions for the geometrical discretization. The bridge modelling was supported by experimental data gathered from in situ and lab testing obtained within the framework of the StonArcRail project.

The soil-steel arch bridges typically range from 3 to 25 m, and they can be applied as an effective alternative for bridges with short spans. They are able to meet the design and safety requirements as for traditional bridges more rapidly and at a lower cost. Seismic excitations are completely different in comparison to the static and dynamic loads. Therefore, during the design of soil-steel bridges on the seismic areas, the appropriate structural solutions should be found to avoid an increase of the internal forces acting in such bridges. The paper presents the results of the numerical study of the soil-steel arch bridge under seismic excitation applying four models (1–4). The soil-steel arch bridge with span of 17.67 m and height of 6.05 m was selected for the numerical analysis. Calculations were conducted using the DIANA program based on a finite element method. The non-linear models with seismic excitation of El Centro form 1940 and Time-History analysis were applied. The conclusions from the study can be useful in making a decision regarding the design of the steel-soil bridges located in seismic zones.

The parabolic three-pinned arches are commonly used in structural engineering; however, its in-plane nonlinear buckling is not explored in the available publications. This paper investigates the closed-form solutions of in-plane nonlinear elastic buckling of the parabolic three-pinned arches. The equilibrium differential equations of in-plane nonlinear elastic buckling are derived based on the membrane and bending strain in the Cartesian coordinate system and the virtual work principle, and the equilibrium equation of nonlinear buckling are obtained by the integration of the membrane strain along the span. Comparisons with finite element results show that the nonlinear elastic buckling predictions of proposed method have sufficient accuracy in a large parameter range.

The paper presents a problem of a simplified modelling of masonry arch bridges utilising a linear elastic material model. Although, such approach provides significant time and labour savings, it may lead to dangerous overestimation of the load carrying capacity of evaluated structures. Theoretical bases for this effect are being explained and illustrated by means of a comparison of two essentially different approaches to analysis of masonry arch bridges. Both of them are using Finite Element Method, however each with different material model for the arch barrel. One of them is based on an advanced nonlinear non-tensile-resistant constitutive model most properly representing masonry, while the other one is a linear-elastic model with unlimited compressive as well as tensile strength. In a parametric study of bridges with various geometries and mechanical properties all differences depending on the applied material model in the structures’ response to typical loading scenario are presented. Clear measures enabling numerical comparison of the approaches are given. Some diagrams are provided to describe and explain effectively the essence and causes of the appearing differences (including distribution of internal forces or cracking development) originating from the chosen material modelling techniques. General conclusions coming from the study are drawn.

Tied arch bridges, among other types of arch bridges, are the most delightful bridges that have been ever shaped on the earth. Analysis and design of tied arch bridge is further intricate especially when the bridge is skewed. In this research paper, the behavior of skewed concrete tied arch bridge is presented. Numerical investigation through three-dimensional finite element models was performed to examine the behavior of skewed concrete tied arch bridge. The study involved five concrete tied arch bridges with five different span lengths of 30, 35, 40, 45, and 50 m, and different skew angles ranging from 0°-to-60°. Linear static analysis was conducted for the nominated bridges. The effect of skew angle, and the aspect ratio (span length/width), on the response of the global and the main supporting structural elements and on the deck flooring system of the bridge was examined. The results showed that an increase of the skew angle will alter the bridge behavior. Deflections, reactions, and straining actions of the main supporting elements and floor system were significantly influenced when the skew angle increased.

Based on the prototype of a fly-bird type concrete-filled steel tube (CFST) truss arch bridge, the analysis on the effect of different debonding length and debonding locations on the mechanical performance of CFST arch bridge is carried out. The results show that the axial force of chord steel tube increases and the axial force of core concrete decreases due to debonding, regardless of the debonding length or the debonding locations, but debonding hardly affect the total axial force of each chord. The bending moments of the steel tube, the core concrete and the total bending moments of each chord at the debonded locations are not uniform. The longer of deboning length is, the greater of the maximum deflection is, and the smaller of the ultimate bearing capacity is. The stiffness and ultimate bearing capacity of truss arch ribs largely decrease when whole debonding is occurred, and the maximum deflection increase by 88% and the ultimate bearing capacity decrease by 24% compared with the completely bonding situation.

In this paper, a novel modelling approach based on the discrete element method for the simulation of backfill material in masonry arch bridges has been proposed. According to the method, bricks in the barrel vault are represented as an assembly of distinct blocks separated by zero thickness interfaces at each mortar joint while backfill is represented as an assemblage of densely packed discrete irregular deformable particles. A series of computational models were developed and their results are compared against full scale experimental test results. A good agreement between the experimental and the numerical results was obtained which demonstrates the huge potential of this novel modelling approach proposed. One of the major advantages of this approach is the potential to simulate the initiation and propagation of cracking in the backfill and arch ring as a result of the application of the external load.

The demand for high speed trains has significantly been increasing globally for the past two decades. High speed trains have great impact on bridges. Therefore, investigation of bridge performance under moving trains with high speeds is crucial. In this paper, the behavior of concrete railway tied arch bridge under moving loads is presented. Numerical study through detailed three-dimensional finite element models were developed to examine the dynamic characteristics behavior of railway tied arch bridges. Three railway concrete tied arch bridges with span lengths of 36 m, 50 m and 60 m were nominated for the study. The dynamic parameters that influence the dynamic response which include; the number of coaches, damping, and train speeds were considered. Dynamic characteristics behaviors, such as mode shapes, dynamic amplification factor, resonance and its cancellation phenomenon were evaluated. Subsequently, both resonance and cancellation speeds were determined, and the optimal bridge span length that suppresses the response at resonance was also proposed.

The paper presents a complex analysis of an old railway backfilled concrete arch bridge located in Rybnik, Poland. The study includes experimental and numerical assessment of the structure aimed at evaluation of precise functional conditions for the bridge further exploitation since all the previous analyses indicated its deficient load carrying capacity and operating speed. It is related to increased requirements for the predicted traffic collated with a very poor technical condition of the bridge. Specific features of the considered structure are very narrow and long arch spans exceeding 30 m, unreinforced concrete material and intensive cracking of the superstructure in numerous sections.Scope of works includes numerical analysis of the bridge by means of both 2D and 3D Finite Element (FE) models as well as experimental in situ testing of the structure response to railway traffic loads. The obtained results enable evaluation of the structure performance and validation of the numerical models which then are used for assessment of the load carrying capacity of the bridge. A special attention is paid to influence of temperature variation on the behaviour of so large arch spans and its potential influence on the visible extensive cracks. The study may be useful at assessment of similar backfilled arch structures (including masonry arch bridges) subjected to intensive exploitation and advanced degradation.

Historically, medium span bridges were generally composed of arch structures made of stones, masonry, and concrete or of metal construction. Despites the inherent efficiency of the form, modern traffic development in combination with the evolution of materials, arches were gradually replaced by frames and girder structures. Now in the UK, the most commonly road and rail bridge solution for medium spans (range between 30 m to 80 m) is the steel-concrete composite deck type with conventional plate girders connected to reinforced concrete deck slabs. This form of construction has dominated the UK construction market for the past 25 years. However, tomorrow construction challenges for our modern societies depends on delivering sustainable designs with consideration for resources efficiency. Arches and shells are “form-active” providing higher degrees of structural efficiency than the girder system. Could this be a new opportunity for arch bridges to become more competitive? This study compares the efficiency of a recently constructed 50 m span flat arch road bridge with a selection of alternatives in forms and in materials. Each option is presented considering the quantities of material, the estimated construction costs, the estimated duration of site works, the whole life cost aspects and consideration for the risk assessment factor. The efficiency ratio of each option is then compared to the flat arch bridge solution.

Assessment of masonry railway arch bridges are typically conducted using static loads. To account for the increase in structural response due to the dynamic application of loads, amplification factors are prescribed by the codes. These amplification factors have been derived from extensive large-scale laboratory testing on model concrete and steel bridges, carried out in the 1970s. Analytical solutions to the dynamic response of an undamped simply supported beam to moving loads demonstrate general agreement with these tests, and form the basis of the formulae used to determine dynamic amplification factors. This paper investigates the suitability of applying the dynamic amplification formulae to masonry arches. In particular, the critical role of determinant length and the chosen vibration mode and frequency is considered. To achieve this, the dynamic response of a damped two-hinged circular arch due to a moving point load is evaluated using Galerkin’s method. Solutions are compared to classical solutions and finite element analysis results for an instrumented single span arch, to highlight the limitations of codified formulae.

In the presented work the mechanical behavior of a masonry arch bridge of a single-track railway is analyzed numerically. The 3D discrete element model contains the arch barrel, the backfill and the spandrel walls as well. Every voussoir is represented by a discrete element, while the backfill is modelled as an elasto-plastic continuum. Between the elements zero-thickness nonlinear interfaces can be found where mechanical interaction can take place. Static analysis has been carried out to investigate the effects of spandrel walls on load bearing capacity and structural stiffness. Failure modes of spandrels due to the excessive lateral displacement of the backfill are identified.

The article discusses the overall optimization of the tied arch bridge. The parabolic arch is hardly never the best shape of arch. The optimum height which gives the minimum volume of the load-bearing structure is solved mathematically in the article. The span length relation to arch height l/h = 2,309 gives the minimum load bearing material amount. Practical examples are calculated numerically by using iteration, based on geometric vector algebra solution in finding the arch thrust line. The iteration is performed so that the weight of the arch is in the correct position and has the correct size during each iteration round. The geometry changes after each calculation round. The area of the cross-section is determined by the axial force along the arch. The comparison calculations are made for the selected tied arch bridge for four different heights.The arch structure is a concrete filled steel tube. The assumption is that the concrete is cast into the tube when the arch is still supported by the temporary structures. The optimum rise relation l/h, for the example bridge is 2,55. The bridge has a span of 250 m, and the weight of superstructure is 200 kN/m. Calculations are based on permanent loads, selected stress level and unit prices. The calculation takes into account the weights of the tie member and the hangers. The cost increase related to the arch height is estimated. An example calculation produces an optimal rise relation of l/h = 3,2.The calculations are prepared only for permanent gravity loading. Stability of the arch in lateral direction is not discussed in the paper. Stability in the plane of tied arch will not be decisive problem. It is not handled in the paper. The article does not take opinion on the bridge aesthetics.

In this paper the effects of live loads will be analysed. The loads are movable, but have characteristic of static passes. The results of strain measurements with relatively dense layout located around the periphery of the corrugated steel structure are used to calculate its deformations. Due to this, the solution includes the interaction of all elements of the structure i.e.: corrugated steel sheets, backfill material, road superstructure (real rules of interaction) between these elements. Thus, there is faithfully (exactly) mapping the geometry and physical characteristics of the structure, equipment and the loads in structure 3D layout. Convenience of the algorithm is that the function of displacement is determined with use of a scheme of the peripheral strip of the shell in the form of a beam element with the cross-section of the steel shell in the 2D model (without the other, the aforementioned elements of the object).In previous studies of soil-steel bridges, the difference of the courses of the displacement functions during the primary and secondary passages was observed. A characteristic feature of these test results (strains) and calculated geometrical effects (displacement) is the formation of a hysteresis loop. As proposed in this paper the two-part terms of solutions, can be seen that the deformation of the structure comes from two equivalent bending and compression components of the corrugated steel shell. On this basis the behaviour of the contact layer between the backfill and the steel shell in such a hysteresis loop is assessed.In this paper using dense strain gauges’ layout any direction of the structure displacement can be calculated based on the changes of the strains in the analysed circumferential strip (part) of the structure. To implement such calculation is sufficient to use the simplest FE models. The effectiveness of the algorithm was verified by comparing displacements obtained from different measurement technics i.e.: induction (sensors) and geodetic (3d laser scanning).

A characteristic feature of soil-steel structures is that, unlike in typical bridges, the backfill and the carriageway pavement with its foundation play a major role in bearing loads. In the soil-steel structure model one can distinguish two structural subsystems: the shell made of corrugated plates and the backfill with the pavement layers. The interactions between the subsystems are modelled as interfacial interactions, i.e. forces normal and tangent to the surface of the shell. This is a static condition of the consistency of the mutual interactions between the surrounding earth and the shell, considering that slip can arise at the interface between the subsystems. This paper presents an algorithm for determining the internal forces in the shell on the basis of the unit strains in the corrugated plates and subsequently, the interfacial interactions. The effects of loads arising during the construction of a soil-steel bridge when, e.g., construction machines drive over the structure, are taken into account in the analysis of the internal forces in the shell and in the surrounding earth. During construction the forces in the shell are usually many times greater than the ones generated by service loads. Thus the analytical results presented in this paper provide the basis for predicting the behaviour of the soil medium under operational loads.

The article presents experiences and recent developments in design and construction of net-arch bridges, using cold-bent hot-rolled HD sections. Gained experience and positive economical footprint is leading to increase in popularity of the solution, together with much better recognition of the technology in the market. The first net-arch bridges, using cold-bent HD profiles were built in Poland about 10 years ago. While the first bridges had shorter spans of about 60–75 m, a recently built bridge has a span length of 120 m. Several other bridges are in design phase, in particular, the first railway net arch bridge with nine independent decks and the largest span of 116 m length. Current design codes do not provide guidance on fatigue behavior of butt weld joints of heavy HD profiles. When the thickness of the steel shape requires access holes, its influence on the fatigue behavior is not familiar in common design. Moreover, the stress concentrations and possible weld defects near the weld toe, result in a short fatigue crack initiation period. Experimental and numerical investigations are envisaged and could fulfill the gap of knowledge in this field. The experimental part consists in the evaluation of the residual stresses of a butt weld beam splice. The numerical simulations are made using Abaqus software and comprise the calibration of the experimental test and optimization of the access hole geometry, considering fatigue loading.To conclude, the aim of the paper is to familiarize the developed technical solution together with the economical background and design recommendations

This paper presents an approach for stiffness identification of node joints of a large-scale truss bridge (Nam O Bridge in Vietnam) based on vibration measurements and model updating. Vibrations are recorded under ambient conditions using piezoelectric sensors. Excitation is due to wind, micro-tremors, or train passage. From these vibrations, modal parameters are extracted. Modal analysis is also performed using a finite element model created in MATLAB. Afterwards, model updating is applied to minimize the discrepancy between numerical and experimental modal analysis results. Evolutionary algorithm such as particle swarm optimization (PSO) based on a global search technique is employed. Three scenarios of boundary conditions of truss joints (pin, rigid, and semi-rigid) are considered. The result of model updating shows that semi-rigid (using rotational springs) joint conditions represents correctly the dynamic behavior of the considered bridge.

Structural analysis can be performed with assumed geometric shapes. However, using actual field shapes can improve results. A close-range photogrammetric method was used to obtain these shapes during the study of a stone bridge in the USA. In this presentation, the method is described, followed the use of the resulting data in a structural analysis.

The geometric information of 20 steel arch bridges was collected and used to investigate the correlation between proportions and behaviour. The sample bridges are deck arches, half-through arches, and suspended arches from existing provincial steel arch bridges in Ontario, Canada and other steel arch bridges familiar to the authors.The empirical trends of flatness (span-to-rise ratio), arch depth and girder depth, bending stiffness, slenderness, and shallowness were computed and plotted versus span length. These trends can be used for validating steel arch bridge designs for evaluating feasibility, initial proportioning of a steel arch bridge, or for assessing the efficiency of a proposed bridge through the effective stiffness depth and system slenderness. This study was inspired by research on concrete arch bridges [1].

Stone and masonry arches characterize the structure of a large number of existing bridges, built in the past and still in service under more and more increasing traffic loads. The evaluation of safety of such bridges is therefore of interest for the bridge owners and responsible and quick and reliable procedures of analysis are certainly useful, at least for a preliminary approach. The mechanism method certainly satisfies these requirements. The main hypothesis is that stone arches fail by forming pin joints, as demonstrated by old but also by recent experimental studies. Furthermore, the assumption of masonry with no tensile strength and infinite compressive strength was done. This last hypothesis was removed in a previous paper, by assuming a rigid-perfect plastic behavior in compression. The load factor and the corresponding collapse mechanism are found by using an iteration procedure. In this paper, this model is used for the case of a two-span arch bridge, so that the collapse mechanism involves plastic hinges in the two arches and the pier.

This work deals with the seismic reliability analysis of an existing single-span open spandrel RC arch bridge, aiming to assess its seismic structural safety. In general, the seismic reliability analysis is a powerful tool able to combine the seismic hazard and the structural fragility for computing the probability of failure of a specific damage state of interest. The present work wants to apply this consolidated procedure to the specific case study of an open spandrel RC arch bridge located in Vicenza (IT), adopting as suitable engineering demand parameter the inter-story drift ratio of the columns between the RC arches and the RC beams grillage.

Limit analysis provides a simple yet powerful and effective means of verifying the safety of masonry arch bridges. However, a disadvantage of traditional rigid block limit analysis methods is that any soil fill surrounding the arch barrel in a bridge cannot readily be modelled directly, since the locations of potential failure planes in the soil are not known in advance. Also, it will seldom be feasible to model every individual unit in the masonry parts of a bridge with a rigid block. In this contribution discontinuity layout optimization (DLO) is used to extend the scope of the traditional rigid block analysis method, enabling direct modelling of both masonry and soil elements. DLO involves discretizing a solid body using nodes, and then interconnecting pairs of nodes with potential failure plane discontinuities. Optimization can then be used to identify the critical subset of discontinuities at failure which defines the geometry of the critical failure mechanism. In this contribution DLO is applied to both soil and masonry problems before being applied to a number of representative masonry arch bridge problems.

Masonry arch bridges continue to form a vital part of the transport networks of the UK and other countries around the world, where most masonry arch bridges have typically been in service for well over 100 years. To verify that they can safely carry modern traffic they need to be regularly assessed; however, assessment is not always straightforward, due to the wide range of geometrical configurations encountered and the many variables that influence structural behaviour. Specifically, whereas research in recent years has predominantly focused on the behaviour of arch bridges containing soil backfill, much less attention has been paid to bridges containing internal spandrel walls, which have different performance characteristics. In the present study the discontinuity layout optimization (DLO) numerical limit analysis technique is applied to bridges incorporating internal and/or external spandrel walls. DLO is an upper bound method capable of modelling both soil and masonry elements, enabling comparisons to be drawn between the behaviour of bridges containing soil fill and internal spandrels. After first validating numerical results against laboratory masonry arch bridge tests, the method is applied to a field bridge containing internal spandrel walls.

Limit analysis has been used for many years to rapidly estimate the ultimate load-carrying of masonry arch bridges. However, often only masonry elements are modelled directly, with the surrounding soil backfill modelled in a simplified, indirect, manner. Due to the importance of the soil backfill, this may lead to inaccurate predictions of the load-carrying capacity of a bridge. In this contribution, a soil backfill model based on lower-bound (stress field) theory is proposed, similar to that used to compute the bearing capacity of shallow foundations. In the model the Mohr-Coulomb criterion is strictly obeyed in the stress fields in the soil fill surrounding the masonry elements of bridge. The model is applied to backfilled masonry arch bridges, with results compared with the upper-bound (failure mechanism) solutions obtained using the discontinuity layout optimization (DLO) numerical limit analysis procedure.

Structural reassessments of existing older German road bridges based on current German standards often uncover substantial deficits especially in terms of the required shear reinforcement in the main girders in longitudinal direction. These shear deficits are only partly due to increases of traffic loads. Most of it is attributed to the evolution of structural shear capacity calculation models and especially due to disregarding a substantial concrete contribution to shear capacity. As a result of these imprecise calculation models, unnecessary cost-intensive strengthening measures might have been executed in many cases.In order to gain more information about the shear load bearing capacity of prestressed continuous concrete beams, large-scale experiments have been executed. The overall aim was to verify an analytical arching model to offer a more precise shear reassessment approach for existing bridge structures. The basic idea of the model is to add the vertical component of the inclined compressive force at beams with parallel chords to the truss model according to DIN EN 1992-2/NA in order to provide additional shear load bearing capacity.

In compliance with the Italian law OPCM 3274/2003 (Ordinance of Presidency of the Council of Ministers No. 3274, 2003) the seismic vulnerability of about 5600 bridges is currently being assessed by RFI (Italian Infrastructure Manager). Masonry arch bridges represent a significant part of the railway bridge population. From 1830 to 1920 all Italian railway bridges were built with this project solution. This work presents the mitigation of the seismic risk process about masonry arch bridges of the Italian railway network. The process includes an initial phase of geotechnical and structural investigations, used to evaluate the minimum risk indicator among all the possible collapse mechanisms of each bridge, by specific analyses. In particular, the structural capacity is assessed by kinematic analyses for simple single span bridges otherwise by pushover analyses applied to 3D FEM models. After that, for those structures that show a lower structural capacity than the seismic demand defined by the Italian standards, the seismic improvement intervention is designed, considering the usage requirements of the Infrastructure.

In the Kinematic Method applied to arch-type structures, Heyman computed the virtual work of the external applied forces using “any system of bending moments” balancing the forces themselves [1]. Similarly, the Consecutive Plastic Hinges theorem [2] considers “any thrust line”, balancing the forces themselves, in order to obtain the virtual work through the moments of the forces applied to an arch with respect to the plastic hinges, without computing the virtual displacements. If the thrust line runs through three of the four hinges of the arch, the virtual work of all the vertical and horizontal forces applied to the arch can be written as a simple single product. In many load cases, such an approach makes easier and much more user-friendly the estimate of the load multiplier, that is needed when analyzing an existing bridge and designing its retrofitting. The paper shows how the automatic construction of thrust lines allows to calculate not only the static multiplier (as is usually done) but also the kinematic multiplier of multi-span bridges, thus detecting the range that includes the collapse multiplier for the given model. This approach is applied to a real case in order to show how this computational tool may be of great help for retrofitting a masonry arch bridge.

Network arch bridges are arch bridges where hangers intersect each other at least twice. Although these innovative bridges present several advantages in terms of cost and structural performance with respect to the conventional tied-arch bridges, they remain vulnerable under certain loading condition. Indeed, due to the large compressive force that may arise in steel arches of the bridge under service, they are prone to deflect out of his plane resulting in the degradation of the aesthetic aspect often praised of bridges of this type and later its service disablement. For this reason, the lateral behaviour of such kind of bridges should be investigated carefully. In this study, lateral structural response of network arch bridges against traffic loads has been analyzed through extensive non-linear analyses. Firstly, a calibration is useful to validate the numerical model. Then, initial geometric imperfections are assigned to the arch member before the analysis in order to take into consideration defects from the manufacturing process. Finally, non-linear analyses are performed on a full 3D numerical model to capture the behaviour of the arch bridge. The results showed that the lateral displacement of the arch member increase with the increase of the traffic loads up to a certain value. In addition, it is observed that the lateral arch’s bracing changes the development of plastic hinges in the arch.

Concrete filled steel tubular (CFST) structures have a wide range of applications in buildings and bridges due to the high bearing capacity. This beneficial composite action could be weakened even destroyed by debonding. In this paper, the debonding of circular CFST long columns subjected to axial load was investigated experimentally, taking the slenderness ratios and steel ratio as parameters. The simulation method of debonding by using soft PVC sheet was proposed, which can be pulled out after 7-days of concrete curing to avoid the inaccurate pull-out time which may lead to the failure of debonding simulation. The results of non-debonding and debonding CFST long columns were compared. The failure modes of the specimens show that the specimens under axial load are subjected to bending failure. The flexure curvatures of the non-debonding specimens are larger than the corresponding debonding specimens. Compared with the non-debonding specimens, the debonding specimens experience a strong concrete crushing during the loading process. The ultimate load-bearing capacity of debonding specimens is less than that of non-debonding specimens. With the increase of steel ratio or the decrease of slenderness ratio, the ultimate load-bearing capacity of the specimens increases. With the increase of steel ratio or slenderness ratio, the influence of debonding on the ultimate load-bearing capacity decreases. The lateral deflection of debonding specimens is less than that of non-debonding specimens. With the increase of steel ratio or slenderness ratio, the influence of debonding on the lateral deflection increases.

Experiment study on dumbbell-shaped CFST X-shaped arches subjected to spatial loads under non-directional loads is carried out. The mechanical behavior and failure mechanism of the arch model under spatial loads are revealed. Test results show that the failure mode of the arch model is the extreme point instability, and the arch model has a low initial geometric imperfection sensitivity. The arch model is mainly bearing compression and out-of-plane bending moment under spatial loads, and the out-of-plane bending moment is the main control factor of the ultimate stability bearing capacity of the arch model.

A 1:5 scaled segmental model test of a sunflower arch bridge was performed to explore the stress and displacement responses of this new type of arch bridge. Displacement and stress at key sections of the model were measured. The measured stresses of the concrete showed that the maximum tensile stress under a dead load at the end of the spandrel arch was larger than the tensile strength of the concrete, which means cracks will occur in these regions. To avoid cracks an optimized design of the joint was proposed in which I-section steel beams were used to replace the concrete at the end of the spandrel arch. Through a comprehensive parametric analysis using the experiment verified finite element model, effect of number, length and flange thickness of I-section steel beams on the displacement and stress responses of the model were obtained. Finally, optimized geometrical dimensions, number and length of the I-section steel beams were suggested.

For their aesthetic values, both arches and stress-ribbon decks are widely used in design of pedestrian bridges. The combination of the two systems provides the solution of a self-anchored structure. In the current paper, the dynamic characteristics of a short-span stress ribbon and butterfly arch bridge are investigated by means of operational modal analysis. Ambient vibration of the bridge is recorded by using several highly-synchronous three-axial wireless accelerometers deployed on the bridge deck. Modal parameters, including natural frequencies, mode shapes and damping ratios are extracted from the measurements. By comparing the experimental modal results to their numerical counterparts obtained from a preliminary finite element model, interesting results are found both related to the flexibility of the whole system and the stiffness contribution of the non-structural elements. The findings also serve as the basis of the serviceability assessment of the pedestrian bridge.

Several concrete-filled steel tube (CFT) arch bridges have been built over the past few years around the world. Current design codes do not address the design of CFT arch bridges, particularly with consideration of concrete creep effects, which can be very important. This paper presents experimental results from tests conducted on 7 specimens to evaluate the creep behavior of CFT eccentric compression members. The results from experiment indicate that the creep development of CFT eccentric compression members is the same to axial load member, which is increasing faster in the early 60 days and then slower after that. Creep strain is smaller with the higher of strength grade of concrete. The earlier the loading age of concrete, the larger the creep strain. The difference is that when the eccentric creep is stable, the deformation is earlier than the axial compression creep. An experimental database is compiled using results from this paper and 16 additional tests from the literature. The comprehensive database is used to evaluate six commonly used creep models for predicting short-term (up to 250 days) creep strains of the concrete infill in CFT eccentric compression members. The selected models are the CEB-FIP MC78 model, CEB-FIP MC90 model, fib MC2010 model, ACI 209R-92 model, GL2000 model and the B3 model. Analytical results indicate that fib MC2010 model, CEB-FIP MC90 model and ACI 209R-92 model have a most prediction accuracy for the creep strain of CFT eccentric compression members.

Settlements represent one of the main causes of collapse in arched structures. The stiffness degradation and strength reduction associated with these slow long-term movements are reflected in changes of the dynamic properties of the system (frequencies, mode shapes and damping ratios). The correct dynamic characterization of the nonlinear behaviour of masonry arches undergoing supports settlements is therefore fundamental to timely detect the occurrence of serious damage mechanisms and prevent unexpected failures.This paper aims to investigate the dynamic behaviour of a segmental masonry arch subjected to stepwise horizontal displacements of one support. To this end, output-only dynamic identification techniques are first used to estimate the experimental dynamic properties of the system under progressive damage scenarios. Then, a numerical procedure coupling linear perturbation and modal analysis is applied to evaluate frequencies and mode shapes of the arch, taking into account the actual crack distribution induced by the settlements. The combination of experimental and numerical investigations allows to explore in detail the dynamics of the settled masonry arch as well as its potential collapse mechanism.

Marsh Lane viaduct is a typical example of a 19th century brick masonry railway arch in the UK. It frequently carries passenger trains to and from Leeds Station. This paper broadly discusses the sensing techniques and associated analysis procedures used to (i) identify the reasons for existing damage, (ii) quantify their impact on the dynamic response of the structure and (iii) measure degradation of the response over a period of one year. To identify existing damage, distortions in geometry of the structure are examined with new point cloud processing techniques. With the aid of limit analyses, these distortions are interpreted, and past support movements which may have caused the distortions are identified. Then, to measure the dynamic response of the bridge, quasi-distributed fibre optic strain sensing and digital image correlation displacement measurement techniques are used. These highlight the increased dynamic response around locations of existing damage, and point out to the global mechanisms of response that could propagate damage. Continuous fibre optic strain measurements between November 2017 and 2018 are then discussed to investigate the ongoing deterioration.

The purpose of this paper is to present realization of two university initiatives: “Zwierzyniecki Bridge Copy – Paste” and “Students’ Steel Bridge Competition”. Events were co-organised by members of a student scientific group “Young Bridge Builders” at Wrocław University of Science and Technology in Poland. The first initiative has been held as a part of the program “Bridges” organised by “Wrocław – European Capital of Culture 2016”. Project concerned design, construction and transport of a model of the Zwierzyniecki Bridge (steel arch bridge – one of the oldest and the most charming bridges in Wrocław) built in scale 1:4. Whole process of realization starting from concept, through calculations, choice of materials, construction and transport to the final destination will be described. The second event “Students’ Steel Bridge Competition” is being organised for seven yearsat Wrocław University of Science and Technology. The main topic of the 5th edition were “Arch Bridges”. The main competition principle is to be as much as possible similar to bridges investment process – from design, through construction, to proof-load tests. Five person students’ teams should calculate in advanced FEM programs, then built and test projects of 2.5 m long arch bridge models. In conclusion of this paper scientific benefits of organisation and participation in the university initiatives will be presented, as well as advantages of alternative methods used in young’s engineer education.

An extensive monitoring installation of a skewed masonry arch railway bridge is presented, where a range of technologies were used to measure the strain and displacement response of the bridge under train loading. Fibre-Bragg Gratings, videogrammetry, vibrating wire strain gauges, crack sensors utilizing potentiometers, and a laser distometer are employed. The objective of the study is to evaluate techniques for measuring the behavior of masonry arch bridges in order to facilitate future monitoring decisions by asset owners. Characteristics and practicalities of each technique are compared, as well as specific monitoring data. While the monitoring data from most methods agrees reasonably well, disagreements do exist due to error or measurement limitations, and the implications of this disagreement for asset owners are discussed. In general, the work also exemplifies the potential of structural health monitoring technologies to provide insight into the dynamic behaviour of masonry arched structures, and in particular heritage structures which may have a complicated history of damage, the progression of which is of interest to their owners.

The development of efficient vibration-based Structural Health Monitoring (SHM) methodologies, capable to timely detecting the onset of anomalies and damages in the structures, is still a challenging task for Civil Engineering community. Most of SHM strategies are based on automated operational modal analysis (OMA, i.e. the extraction of the modal parameters from the signals collected in operational conditions) and often on the monitoring of resonant frequencies. Alternatively, when a well distributed measurement grid is available on the structure, a further strategy for damage assessment should rely on evaluating the mode shape changes. Within this context, the paper is focused on a damage detection strategy based on the variation in time of mode shape (using MAC) and mode complexity (using MPC and/or MPC). The reliability of this approach is exemplified using a short period of monitoring of the San Michele bridge in which the structure was subjected to extreme environmental conditions. The analysis was carried out through a fully automated procedure based on the interpretation of the stabilization diagrams (provided by SSI-Cov technique) and adaptable thresholds in the modal tracking process.

The Olla bridge is a multi-span masonry arch bridge dating back to the second part of the 19th century. The structure, 117 m long, includes five arches of different span and crosses the Stura river close to the small town of Gaiola, about 16 km far from Cuneo (Piedmont, Northern Italy). The central span of the bridge was destroyed during the 2nd World War and rebuilt in 1945. Recently, damages (i.e., the opening of some cracks) have been reported on two arches and the structural assessment of the structure is ongoing.So far, no original drawings of the bridge have been found in the archives and a multidisciplinary research program started, including direct visual inspection, geomatic survey, ambient vibration tests, minor destructive tests, numerical simulations and full-scale load tests.The paper summarizes the experimental results obtained from direct inspection, geometric survey and dynamic tests as well as the development of a simplified numerical model.

The numerical analysis of masonry arch bridges requires detailed information about the geometry and mechanical properties of all the bridge components. As for the geometry, masonry bridges present complex shapes, being the characterization of the inner geometry (e.g. arch thickness or presence of backing) still a relevant challenge. As for mechanical properties, which are hardly measurable, they are essential for a reliable definition of the load carrying capacity. This paper presents a multidisciplinary approach based on the use of non-destructive testing techniques and describes critically its application to a medieval masonry arch bridge. The geometric characterization is based on a detailed laser scanning and ground penetrating radar survey, allowing determining the external and inner geometry of the bridge. Regarding material properties, indirect sonic tests were conducted on piers and spandrels to obtain the dynamic elastic modulus of stones. In addition, a dynamic identification test was carried out to characterize the dynamic properties of the bridge.

Numerical and experimental load test results of the road arch bridge located in Rabka Zdroj town in Poland will be presented in this paper. The bridge under consideration is designed as a reinforced concrete open-spandrel deck arch structure, of a 40 m long effective span between its springing lines, having both arches fixed in abutments. The whole bridge comprises two parallel arch superstructures, which are tied together by a top slab and joint abutments but having separate sets of vertical wide column systems. The structure was analysed using three numerical distinctive FE models, of different levels of details in order to properly assess the sensitivity of numerical results and accurately determine its realistic structural behaviour. The scope of further investigation to validate its structural behaviour included both static (2 cases) and dynamic (6 cases) proof-load testing undertaken on site. As the result, the bridge is considered to be a very interesting research case as it was identified during the site testing, specifically in terms of its intriguing structural behaviour due to thermal effects. The developed numerical models were used for further static and dynamic simulation. In the paper, the results of both numerical analysis and site proof-load testing are thoroughly reported and concluded.

The truss model as defined by DIN EN 1992-2/NA is largely based on the assessment of shear force experiments carried out on untensioned reinforced single-span concrete beams. Hence, this model does not take into sufficient account the specific structural behavior characteristics of large prestressed continuous concrete beams. Additionally, concrete beams provide a significant concrete contribution to the shear load bearing capacity due to arching effects, which is of particular interest at prestressed concrete beams. This compressive membrane action is not taken into account for bridge design according to DIN EN 1992-2 and the corresponding German National Annex.As part of several research programs experimental investigations into the shear load bearing behavior of prestressed continuous concrete beams had been carried out at the Chair of Concrete Structures at TU Dortmund University. The overall target was to analyze the extremely favorable arching effects which are also of huge importance at prestressed concrete beams with parallel chords. Such arching effects provide significant relief from shear forces and could be measured, visualized and documented using suitable measurement technique.

This paper presents the results of the dynamic tests conducted on a historical reinforced concrete arch bridge located in the Tuscan-Emilian Apennines, in the province of Parma (Italy). The design of the sensors location was determined in order to investigate the possible separation into bodies operated by the joints between the different spans. The ambient vibration data allowed the dynamic characterization of the 3-span arch bridge with the total length of 146 m and 18 m in width. The interpretation of the main global modes, distinctly detected through time domain identification methods, indicates that the horizontal response is governed by the deformability of the joints. The results show that the obtained modal features provide a reliable reference for the subsequent updating of the bridge FE model.

The actual load carrying structure of a masonry bridge is not just the arch but a complex structure consisting of the arch, the fill and the spandrels. The interaction between the arch and the backfill is responsible for a span of the structural arch shorter than its geometric appearance. Starting from this observation, the selective injection of the fill may be a low-invasive retrofitting technique for increasing the load carrying capacity of a masonry bridge. Since injection can be performed rather easily from the spandrels, it does not need the traffic to be stopped, thus turning out to be quite cheap. Experimental tests on reduced scale models show that this technique may increase by 2/3 the l.c.c. of a masonry bridge. The similarity conditions for reduced scale models to be tested are discussed in advance. The results of the tests show also that the distribution of the load through fill is not as wide as usually assumed and does not account for a relevant contribution to the l.c.c. of the bridge.

Results of the tests of aerodynamic stability of arched bridge in specialized wind tunnel are presented in this work. Atmospheric boundary layer properties were modeled in Landscape Wind tunnel of Krylov State Research Center to take into account wind characteristics – changing of mean wind velocity with height, turbulence intensity and spectrums. Present work includes two parts: visualization of flow structures behind the bridge deck and wind tunnel tests of modifications of original geometry to minimize oscillations due to vortex shedding. Tests with different modifications show that amplitudes were reduced at 50% on average or shifted in a region of high velocities.

This paper describes the dynamic and quasi-static tests performed in a multispan masonry arch bridge, under railway traffic actions. The dynamic forced vibration tests performed under train loading allowed to characterize the dynamic response of the bridge in terms of accelerations in the deck and piers. The quasi-static tests were performed using two in service freight train passages circulating at reduced speed and allowed monitoring particularly deformations in the arch. The main objective of this work is to use these experimental results for validation of the numerical model of Durrães bridge for dynamic and static analysis.

This paper outlines the design, analysis and construction of Taplow Footbridge. The paper considers the challenges faced when designing the distinctive slender arch and deck, and how they were overcome. This paper considers the challenges posed by the constrained site and details how most works were achieved from a floating pontoon on a flowing river. The bridge steelwork was moved into position in a single operation from a floating pontoon. This paper also considers the implications on the design of using flat plate hangers, as well as a discussion on the appropriateness of Eurocode rules for dynamic behavior of slender structures.

Recent research and engineering applications of arch bridges are discussed in this paper. About 19 stone arch bridges with spans greater than 100 m have been built in China. A research program on Ultra-High Performance Mortar (UHPM) for use in stone arch bridges is currently being conducted. The woven timber arch bridge is a unique structure consisting of two longitudinal polygonal arch rib systems, research on woven timber arch bridge have been conducted to understand the structural behavior of these arch bridges. For concrete arch bridges, the current record span of 445 m belongs to the Beipanjiang Bridge. Furthermore, the design and model tests of an Ultra-High-Performance Concrete (UHPC) arch bridge are presented. The applications of steel and Concrete-Filled Steel Tube (CFST) arch bridges in China are discussed. Finally, new types of steel-concrete hybrid arch bridges are briefly introduced.

The Hoang Van Thu Bridge is located in Haiphong, Vietnam. It is the first fly-bird-type concrete filled steel tube (CFST) arch bridge in Vietnam, with the span arrangements of 45 m + 120 m + 45 m. The structural design and construction method of Hoang Van Thu Bridge are mainly introduced in this paper. The main span of the bridge is a half-through CFST truss rib arch, and the two side spans are cantilever steel-shelled concrete half arches. Both the arch axis of the middle span and the two side spans are catenary. Steel-concrete composite structure was employed as the bridge deck systems. The main span CFST arch ribs were divided three segments, the two segments near arch abutments were erected by scaffolding method, and the rest segment was hoisted by crane. The two side spans concrete arch ribs were constructed by scaffolding method. The construction of Hoang Van Thu Bridge is expected to serve as an example for the promotion and application of CFST arch bridge in Vietnam.

The Hejiang Yangtze River Highway Bridge is located in Hejiang County, Luzhou City, Sichuan Province, China, whose main bridge will be the largest span of fly-bird CFST arch bridge in the world, with the span arrangement of 80.5 m + 507 m + 80.5 m, which is currently under construction. The arch rib for middle span is a half-through concrete-filled steel tube truss rid arch, and the arch ribs for side span are half-arches of concrete cantilever with concrete-filled steel tube skeleton inside. This paper mainly introduces the structures and design features of the main arch rib and side arch ribs of the bridge, its construction method, especially, the vacuum assisted pumping-up pouring method is also introduced. It is hoped to provide reference for the design of other such type arch bridges.

To support this paper, the under-construction Wang’anshi Fuhe Bridge (main span 168 m), a mid-through tied arch bridge with concrete-filled steel tube (CFST), is taken as the research object, to discuss the advantages and disadvantages of the two construction procedures of the first-arch-then-girder, and the first-girder-then-arch. In account of construction difficulty, environmental influence, construction period and economy, the advantages and disadvantages of each construction method is revealed from construction methods including tower crane, gantry crane, and island building, which puts forward the optimal construction method and main control points of CFST tied arch bridge in shallow water channel.

Based on Wang’Anshi bridge under construction (CFST arch bridge, the suspender cross-girder made of Steel-Concrete composite girder, the main span 168 m) as the research object, by monitoring the process of construction, this paper discusses the advantages brought by Steel-Concrete composite girder in concrete-filled steel tube bowstring arch bridge, from such aspects as the construction cost, construction difficulty, in-process structural stress control, maintenance in later period.The results show that steel-concrete composite girders are highly industrialized and effectively reduce site construction difficulties; avoid the cracking problem of concrete cross girder and the maintenance cost is effectively reduced. In conclusion, the steel-concrete composite suspender girders are remarkably better than the prestressed concrete suspender girder.

When using traditional techniques, the following problems may appear during the construction of large-span CFST arch bridges: (1) high construction cost of traditional towers and long construction period; (2) large friction in traditional steering cable saddles and severe abrasion of fastening stay; (3) large pipe diameter and great perfusion volume, which make it difficult to guarantee concrete compactness in the pipes; (4) large span and a great number of arch rib erection segments, which affect the linear construction precision. This study focuses on the Matan Hongshui River Super-large Bridge, which is a half-through CFST arch bridge with a main span of 336 m. Specifically, the installation of arch rib cable-stayed fastening stay system, self-compacting non-shrinking concretes and intelligent load regulation for fastening cables during the construction process were investigated in depth. Moreover, some novel devices including distributed cable steering saddle and heavy steel tube tower were proposed and adopted. The present study can provide a new approach for the construction of large-span CFST arch bridges and insightful reference for same type of large-span bridges.

In 2007 the City of St. Gallen, Switzerland, has announced a public competition for a new bridge across the Tamina Canyon. The new road bypasses the village of Pfäfers in the northwest and leads into the district of Bofel. From Bofel to the district of Berg on the other side of the Tamina valley (Fig. 1) a 400 m long bridge was built, crossing at the gorge at about 200 m height, becoming the most important and outstanding bridge construction in Switzerland of the last years. This paper presents the winning design, and gives an overview of the most important design and construction aspects. The Tamina Canyon Crossing has already received the Supreme Award for Structural Engineering Excellence 2018 by the Institution of Structural Engineers. Fig. 1. Tamina valley, view from North-West © Tiefbauamt St. Gallen

The Podilskyi Arch bridge is crossing the river Dnieper in center of Kiev and is part of a 7.4 km long link which connects the center of Kiev with the “sleeping district” on the left bank of the river. The bridge has a main span of 344 m intended for six lanes of vehicles in the top level and two metro lines in the bottom level plus large diameter water pipes. The bridge is of steel, except of the reinforced concrete bases of the lower parts of the arches. The draft design works began in 1991 and in 2005 parallel design and construction work started. Due to the financial crisis in the Ukraine, the work was interrupted for several years but construction recommenced in 2018 and the bridge shall be completed at the end of 2020.

Construction of arches has hundreds of years, from execution using stone to the latest construction methods.Estructuras y Montaje de Prefabricados (from now on Estructuras), subsidiary of Grupo Puentes, has developed several construction methods for arches, thorough its own history, considering needs of viaducts, environmental requirements, structural determining or even the search of the beauty of the bridge.Estructuras is the company in Spain that has developed the latest technology for folding or lowered arches, and as well, has got the highest number of arches executed using this method in Europe. Although this paper is going to focus on a representative method, folding arches, the following lines will be a summary of the evolution or arch construction using some examples hold by our company: scaffolding supported on the ground, cantilever segments (precast and on site segments), lifted arches and folding arches. This evolution has gone along with the own evolution of construction methods in Civil Engineering during last 20 years.

This case study paper concentrates on the construction method adopted with associated temporary works for a recently completed steel-concrete composite flat arch bridge in the city of Northampton (UK). The new road alignment over the navigation channel of the river Nene imposed an arch with span to rise ratio of 13.9. The 50 m span alternative tender design was led by the site constraints with limited access for heavy construction plants due to the presence of a significant numbers of existing buried utilities. The mobile crane lifting arrangement is discussed together with the related restricted crane platforms and temporary supports. The stability verification during erection of the steel arch is presented with discussion on the details for the temporary bracing that was required prior installation of the cross girders. The stage by stage construction is described including the design details that needed to allow for geometrical tolerance in the installation of the steel structure within pre-set reinforced concrete thrust blocks as part of the buttressed abutments.

The Railway road bridge in Novi Sad is situated on the international railroad Belgrade-Budapest. The bridge is designed for two railway tracks (with design speed of 160 km/h), two road lanes and two footpaths. The bridge structure consists of four structures: two approach composite bridges at the banks and two steel tied network arch bridges over the river and transition structure between two arches. The spans are 27.0 + 177.0 + 3.0 + 219.0 + 48.0 m, totally 474.0 m in length. The rises of arches are 34.0 m and 42.0 m respectively. The width of the bridge is 31.44 m. The arches and ties, as well as the girders of the approach spans, are steel box girders. The decks of all bridge structures are the composite reinforced concrete slabs with thickness of 300 mm, locally 400 mm.The launching was very complex, in both analysis and construction. The arch bridges were fully assembled on the banks and launched by skids over the bank and by pontoons over the river, to the final position on piers. The bridge was designed fully according to European standards and additionally – according to requirements of Deutsche Bahn Richtlinie 804, Edition 2003.The bridge was opened to traffic in 2018.

The presented footbridge connects the centre of Poznań with Ostrów Tumski Island and the campus of the Poznań University of Technology.The bridge consists of two parts: an object over the Warta River and an object over the Cybina (the Warta Canal). The paper describes in detail the part located on the Warta River, which has an arched structure. It is a steel structure with the following span lengths: 28.50 + 17.00 + 60.00 + 40.00 + 6.50 m. The elevation of arches is equal to 23.00 and 19.00 m. The design attached a lot of attention to the symbolism of the object. The result is an interesting structure with great aesthetic and functional qualities. The paper will present the construction of the object and its architectural values.

Good engineering design and aesthetics are synonymous. Arches have been used throughout the ages as structural elements and considered to be one of the most competitive options from aesthetic perspective. Five examples of bridges from India highlight the effectiveness of engineering design simplicity in the remote hilly region of North East India. The working season in such areas is less than six months in a year. The velocity of flow is also very large. Providing intermediate pier supports has created problems like tilting of piers, including foundations, due to erosion at many locations in such areas. Site specific structural design and aesthetic solutions using arch bridges have been worked out for following bridges: 1. Tharia Bridge over river Wahrew, Meghalaya, Steel Arch span 165 m 2. Tlawng Bridge on NH 44A, Mizoram, Steel Arch span 100 m 3. Sanjenthong Bridge at Imphal, Steel Bow String Girder Span 56 m 4. Wahjapuh Bridge, Meghalaya, RCC Arch Span 62 m 5. Kalipai Bridge, Meghlaya, RCC Span 79 m In all the above bridges, proportion, order and symmetry are well applied and the structures so produced have aesthetic value. A steel intensive scheme for the arch superstructure has been adopted for Wahrew, Tlawng and Sanjenthong Bridges to solve site constraints of less working season and very high velocity of flow, to improve the aesthetics and to take advantage of the lightness of the structure whilst erecting and improving seismic performance of the structure. Wahjapuh and Kalipai are designed as RCC Arch Bridges.Design Criteria for preserving existing landscape, complementing and even enhancing the settings have been given weightage. Various components are designed to work together and complement each other visually with aesthetics integral to the design. Five important aspects such as form, character, detail, scale and proportion have been considered from first principles. The bridges should stand as proud inheritor of Indian tradition of bridge design and construction.

Singular structures require singular and innovative design, construction and supervising methods. The authors present their experiences on two different arch bridges, from the perspective of the construction process. Construction Management on site during construction by means of a team of technicians that can bridge the gap between the Project and the actual necessities during the construction phase, carrying out detailed designs and the supervision of the parameters that are involved in the construction process, such as availability of materials or construction methods, cranes, materials and parameters like deflections, stresses, temperature, inclination and the like.The uncontrollable factors to deal with during the construction of singular structures such as temperature, wind, erection process, magnitude of the loads require exhaustive controls of all the elements involved in the project. The use of robotic surveying system together with a profuse structural monitoring system can provide the design and construction team a wide range of information about the construction process which can be analyzed in real-time to allow the designer to control the process.The role of technical offices on site for this kind of projects is a fundamental part of the proper development of the project, requiring professionals with deep understanding of the structural phenomena and on-site experience.

The main bridge of the new highway connecting the cities of Santos and Guarujá, in São Paulo state, Brazil, will comprise three arch bridges spanning 335 m, 400 m and 335 m respectively. The arches will be constructed over the 1.000 m wide Santos Port channel, the largest port in Latin America, with pre-assembled steel trusses bolted together in a balanced cantilever sequence to form three steel arches, which, after concrete placing, will form the steel reinforcement of the concrete arches. Concrete columns will be erected over the arches and two prestressed concrete box girders, one for each traffic way, will be incrementally launched from both edges of the arches. Foundation of the arches is designed as 2 m diameter drilled shafts with 7 m rock socket. Access spans to the main bridge will be built with balanced cantilever box girders and precast I girders.

The footbridge located at the new north bypass in Morelia, Mexico is very useful for thousands of pedestrians who use it daily. Not having a footbridge, both in the construction process of the bypass and already completed, would cause great problems as it is the only pedestrian passage in 3 km, leaving several colonies without communication. Leaving the pedestrian bridge to function during the construction process of the release will facilitate the works, as the flow of pedestrians will not be affected by excavations and the use of heavy machinery. The change of the substructure type is planned in order to never close the pedestrian passage on the bridge, as well as to hinder or interfere in the works that are carried out in the construction of the northern bypass.The structure of the arch shall be used to support the pedestrian bridge and thus to eliminate the central column formed by a tower of 4 steel beams type I.The important part of this work is the transmission of the forces that will be transferred to the arch when the central column is cut, and all the dead load of the bridge is left over the new substructure.

Arch bridges are part of the cultural heritage of all cultures of humanity. However, the tied-arch bridges are a relatively recent creation and their structural behaviour is not obvious for those who do not know the basic principles of structural engineering. However, despite this difficulty in interpreting the flow of forces, the tied-arches also have a strong symbolic significance for the Public. This visual or symbolic force, together with its inherent resistant advantages, such as the slenderness of the deck or their independence from the foundation conditions, make the tied-arches a very suitable solution when it comes to building a bridge in an urban context. In the present paper, several small-scale bow-string arches are presented, all of them built in urban or peri-urban areas. These bridges are characterized by the rational use of resources and by a formalization of the structural elements that make them modest examples of how structural engineering can serve, not only to fulfil a purely functional and resistant purpose, but also to contribute to ennobling the area in which a bridge is built. The examples presented here are: the Najera bridges in La Rioja, the bridge over the Genil river in Granada, the bridge over the Guadalquivir river in Montoro (Córdoba) and the Roquetas Bridge all built in Spain.

Hongqili Bridge in Nansha Port Railway located at an offshore cyclone affected district is composed of a flexible arch bridge of steel truss girder, with a main span of 2 × 360 m. It has the longest span and largest scale of construction among similar bridges so far. The Bridge has the characteristics of complex structure and difficult construction, which is a great challenge for design and erection. Structure deformation and its stiffness are the critical considerations of the working safety and comfort of railway Bridges. For a large span flexible arch bridge of steel truss girder, the structure stability is the key study item in the design. Based on the introduction to the design and the construction technology of Hongqili Bridge, structure stiffness and its stability analysis is applied in the study. The analysis conclusion shows that the combined structure of rigid truss girder and flexible arch rib has high stiffness, good bearing capacity, stable performance meeting the design requirements and enough safety margin.

The viaduct over the Genil River is a road bridge built as part of the new Granada bypass. The total length of the viaduct is 110 m, divided into three spans 15 + 80 + 15 m long, respectively. Span configuration of the viaduct has been highly restricted due to some particular project features, such as the minimum vertical clearance to the river and the drainage requirements. Both conditions have been solved by implementing an 80 m long span over the river with a 1,50 m depth below the grade. The motorway has two carriageways with 3 lanes each one, with a total width of 34 m. Although the lateral view of the bridge appears as a classical tied arch type, actually the central span is made up by three concrete tied arches with different sags and inclinations. The central arch, with a sag of 16,6 m, remains in a vertical position while the lateral arches at both sides are sloped towards the inside of the deck, 7° with respect to the vertical. Hanger arrangement are also different, being triangular in the central arch are and vertical in the lateral arches. The arches are made of reinforced concrete and the deck consists in three longitudinal post-tensioned concrete girders, placed below each one of the arches. The slab directly under the traffic lanes consists in a reinforced concrete slab. The viaduct is placed in a highly risk seismic zone.

Construction methods of arch bridge can be classified mainly by the type of arch bridge, supporting and erecting methods. Typical construction methods are summarized in a table as six groups by supporting and erecting methods. Methods of using temporary support, using cable stay to hold arch rib, swing arch rib horizontally or vertically, launching whole arch bridge horizontally, lifting whole arch bridge vertically over water and other methods such as casting precast concrete arch rib in laying down posture, and steel tube encased in concrete are included. For the long span arch bridge, using steel tube can be economical option for arch rib. Each erection method can be selected depending on the site condition, and if a proper construction method is selected, the construction cost can be reduced significantly.

The high-speed rail line between Madrid and Extremadura, crosses over River Almonte with a great 384 m arch made of high-performance concrete. The exceptional dimensions of the arch and the specific considerations of high-speed rail bridges, required using an innovative structural scheme in HSR arch viaducts, using two separate sections in foundations that join in an octagonal one in the central part of the arch.The construction of the structure has already come to an end, and nowadays the final steps are being undertaken. One of these features, includes the installation of a service monitoring system, that will allow the control of the structure’s behavior during the service life of the viaduct, and its comparison with the theoretical deflections obtained during its structural analyses.

A new arch bridge has been designed in the Khada Valley (Georgia) by IDOM and Arenas & Asociados. This has been a challenging project, which has simultaneously achieved a high-quality result for erection process and service life of the bridge, in a high-seismicity area.

Namhangang Railway Bridge is a series of arches, and 480 m long with 5 spans. It consists of three normal and two underslung arches. By putting normal and underslung arch in serial and giving variable rise ratio, ‘wave’ impression and similarity with famous monuments has been derived. The 1st, center and 5th span is 100 m, 120 m and 100 m, respectively, while the underslung span is 80 m in between. Height of arch is taken as 18.0 m for 100 m span and 25.5 m for 120 m span, respectively. Hangers with 7.5 m spacing are given positioned in radial direction. Depth of underslung arch is 8.0 m, where diagonal strut is provided. As result of detailed rail structure interaction study, a proper dimensioning of substructure has been made. From dynamic performance analysis, satisfactory performance has been verified. Erection of arch has been done by block by block on temporary trestle and completed in 2018.

Reinforced concrete box-ribbed arch bridge by suspending crane cantilever casting method has unique advantages in the construction of bridge in mountainous areas. However, with the increase of bridge spans, it not only puts forward higher requirements on the safe and efficient operation of construction equipment, but also increases the difficulty of the internal force control of the arch ring. In order to solve these problems, this paper takes the ShaTuo Bridge of Guizhou Province as an example and illustrates main technical solutions focusing on these three core contents: the suspending crane system, the anchoring system and the internal force control during construction of the main arch ring of the mountain arch bridge by cantilever casting method. The suspending crane adopts the structure of upside-down triangle suspending crane with divided principal truss, and the walking hanger is separated from the anchoring rod to realize the light weight and modularization of the suspending crane structure. Using the automatic correction system for real-time collection of the buckle tower offset information to rectify the deviation of the buckle tower in real time to ensure the safety of the anchoring system. The internal force of the arch ring is effectively controlled by providing temporary prestressing tendons in the arch box and the practice shows that the new technical means and methods used in subtilized control of the whole process of the construction ensures the safety of the main arch ring and the temporary construction structure, and also makes the internal force meets the design requirements both in arch box construction process and the completion state, which has a good reference value on the construction of similar arch bridges.

In the past 30 years, China’s concrete-filled steel tube (CFST) arch bridges have developed rapidly, and more than 450 CFST arch bridges have been built so far. With construction of the 1st Hejiang Yangtze River Bridge with 530 m main span, the construction of Hejiang Yangtze River Highway Bridge in Sichuan (span combination 80.5 + 507 + 80.5 m) and the 3rd Pingnan Bridge in Guangxi (main span 575 m), the span of CFST arch bridges has reached main span larger than 500 m.In order to solve a series of technical problems of CFST arch bridges, Chinese scholars have carried out a number of theoretical studies and technical practices, and formed a series of technical achievements of long-span CFST arch bridges: new structural system of main arch has been developed, new technology of main arch using composite structure with full steel tube has been put forward, and independent unit system of main arch has been developed. New structures such as composite main arch transverse brace, rectangular arch rib inner diaphragm, wind-resistant and vibration-reducing series cables and long-term cable anticorrosive suspension system have been established. The unified theory and constitutive relationship of CFST capacity have been established. The non-linear stability analysis of long-span CFST arch bridge has been put forward. The series technical achievements have established a solid foundation for the development of large span CFST arch bridges and reinforced concrete arch bridges with rigid skeleton.

Before the estuary of Plentzia, within one of the last meanders of the Butron river, the unique medieval castle of Butron can be found. It is located in the municipality of Gatika, in the Historical Territory of Biscay. The ancient masonry bridge connecting the castle and the opposite bank of the river, apart from being a hydraulic obstacle favouring the flooding of the alluvial plain in the area, presented a high risk of collapse, due to the scour of its right abutment. The local administration decides to reconstruct the ancient bridge, building a reinforced concrete deck arch bridge, with a single span of 23 m and a rise-to-span ratio of 1/6.57. This structural typology was chosen because of its ability for ensuring hydraulic section, and as a reminiscence of the ancient bridge. This humpback profiled structure is an example of an arch solving, in our days, a clearance in the range of very short spans.

There are several types of reinforce arch bridges and their construction method is highly influenced by its design. The aim of this article is to present the construction method of two singular concrete arch bridges: Don Enrique Bridge, in Oporto, Portugal; and the Almonte Bridge, in Caceres, Spain. Both case studies are already constructed. The construction methods in both cases are different since it was the result of the combination of design of the bridge and boundary conditions and restrains present on construction site.However, in both cases the construction method is based on the balance cantilever bridge construction, applied to arch concrete typologies.It is important to highlight that in arch bridges typologies, the construction methods are more complex than the rest of bridge types, because of the need of controlling deflection, geometry variability and launching processes.Almonte traveler was designed as underslung structure while Don Henrique as upper structure (composed by 2 independent structures). In both cases, the formwork structures were designed, manufactured and supervised by Rubrica.

This paper summarizes the highlights of rehabilitation design and construction of a reinforced concrete arch bridge. The bridge consists of five open-spandrel arch spans and nine closed-spandrel arch spans, with a total structure length of 420 m and an out-to-out width of 24.4 m. The bridge was originally constructed in 1913 and has exhibited deteriorations in many structural members, including the arch ribs, spandrel columns, arch barrels, and concrete floorbeams. Load rating analyses were conducted to determine the capacity of the bridge for the current design loadings based on the as-inspected condition. Additional analyses were also conducted for staged construction, temperature effects, and additional defects during reconstruction due to construction. The load rating analyses for the arches and spandrel columns are based on strain compatibility (P-M capacity interaction curves). The floorbeams exhibited concrete spalls and exposed reinforcing rebars at the midspan. The lap lengths of the reinforcing steels were determined to be insufficient, which resulted in low ratings of the floorbeams based on the as-inspected condition. The floorbeams were therefore needed to be replaced.

The topic of bridge asset management has taken particular relevance in the later part of the 20th Century when the advancements in the knowledge of reinforced concrete behaviour made the structural engineering community aware of the fact reinforced concrete and pre-stressed structures designed and built in the 1960’s were unlikely to last the 100 years they had been designed to. The United Kingdom, with most of its motorway network having been built during the 1960s, is a typical example of this.This paper focuses on the inspection and detailed structural assessment that Mott Macdonald’s A3M (Advanced Analysis for Asset Management) team was commissioned to undertake on this rather unique reinforced concrete arch bridge. With a total span of circa 50 m and built in 1968, this arch bridge is located in an area of outstanding natural beauty in South Wales and presently owned and managed by a Water Company.Aspects relating to the inspection and survey techniques employed, such as point cloud surveys derived from site laser scans and live load monitoring using wireless strain gauges are covered in detail in the first part of the paper. The second part of the paper focus on the aspects related to the static and dynamic modelling of the structural behaviour of the bridge using the finite element method emphasizing some of the techniques developed by the authors to establish comparisons between the experimental and numerical results.The paper finishes with a summary of the fundamental conclusions and some reflections on the future of asset management in the 21st Century.

The Grade II listed Silver Jubilee Bridge is a two-pinned steel arch bridge with continuous side spans spanning the River Mersey and Manchester Ship Canal. With a main span of 330 m, it is one of the largest steel arch bridges in the world. Since construction in 1961, Mott MacDonald has been employed on numerous refurbishment and strengthening commissions on the bridge to the various bridge maintainers, currently Halton Borough Council. The bridge is currently closed undergoing major refurbishment works with traffic using the recently opened Mersey Gateway Bridge 2 km upstream. Silver Jubilee Bridge is planned to reopen late 2019.This paper presents a case study highlighting the challenges in maintaining an ionic long-span arch bridge. Recent refurbishment works described include new maintenance gantries, cathodic protection, maintenance of the locked coil cables and the challenge of maintenance painting.

The continued use of many UK highway and railway masonry arch bridges is dependent upon maintaining robustness as the materials deteriorate over time. A common failure in multi-ring brickwork arches subject to fatigue, is ring separation.This paper offers some early results from an investigation of a ring separation repair technique involving radial pinning. Triplet testing is used to establish and compare the structural behavior of two types of shear reinforcement, which are validated by finite element modelling. Conclusions are drawn which are potentially of significant practical interest to masonry arch bridge owners and assessors.

There has been a lot of research works to develop damage detection methods using the change of vibration characteristics for bridge structures. However, the change can occur due to not only the structural damages but also other factors. Furthermore, it is well known that function of bearings is prone to deterioration and it has an influence on the vibration characteristics of bridge structures. In this study, in order to clarify the influence of temperature and bearing condition on the vibration characteristics of the whole bridge structure, monitoring of vertical acceleration, temperature, and axial displacement at movable support of the girder was carried out in a steel arch bridge, and correlation analysis using the measured data was performed. As a result, a negative correlation was found between the natural frequencies and the bridge temperature in the estimated vibration modes, and a positive correlation was confirmed between the axial displacement and the temperature of the bridge. It was also confirmed that the behavior of axial displacement when rising in temperature is different from that when dropping in temperature.

With the increase of traffic volume and load, the carrying capacity of the early constructed reinforced concrete multi-ribbed arch bridges are obviously lower, it is necessary to take various measures to strengthen them and enhance bearing capacity of these bridges. This paper proposes a reinforcement method by adding cable tower at the two ends abutments of the arch bridges and the inclined cables to improve behavior of the multi-rib arch bridge. The main idea is that additional bridge towers are set on both sides of the single span ribbed arch bridge abutment to hang stayed cables. Taking a typical reinforced concrete multi-rib arch bridge-Baibu Bridge as engineering background, the design of strengthening project was given. The analysis and field load test of the bridge were finished. The comparison between spatial finite element analysis results and field bridge test values of strengthened bridge has good agreement. It shows the validity of the proposed strengthening method for the rib arch bridge and improves effectively the bearing capacity of arch bridges.

This paper deals with a simplified full-probabilistic methodology for the safety assessment of existing masonry arch bridges. The proposed framework aims to determine the ultimate load-carrying capacity (Ultimate Limit State) of a bridge subject to environmental deterioration, and to establish the influence on the structural reliability.

A number of vibration-based Structural Health Monitoring (SHM) algorithms have been developed in the last two decades with the purpose of extracting reliable structural features from recorded dynamic signals. By using a mix of techniques the identified frequencies gain a statistical evidence, as in the procedure used in the validation of the Pontelungo bridge natural frequency set. The Pontelungo Bridge is an historic masonry bridge crossing the Reno River, firstly built in the medieval age and updated several times in its life, resulting so in a very complex geometry and behaviour. A numerical model able to reproduce the experimental frequencies has been obtained through a suitable calibration procedure, based on several iteration steps and FE models of different complexity. The updated model can then be used in checking hypotheses of potential damage scenarios that can emerge as frequency shifts in the bridge monitoring phase. However, in order to have a sound set of frequency values, a long-term monitoring period is needed. This activity has started recently but with consistent results that validate the worked out model.

There is a large stock of masonry arch bridges built more than 100 years ago that are still in use in the world roadway and railway network. The restoration and conservation of this type of structures has become one of the main challenges of bridge engineering. As a first step, any intervention strategy requires an early stage consisting in the assessment of the structural safety (in the actual condition) of the masonry bridge. Only after that stage is performed, it is possible to design, if required, optimal repair interventions to bring the bridge to adequate safety level. In the first part of this paper, the seismic vulnerability assessment of a slender multi-span masonry arch bridge is presented. Results show that it is required to increase the flexural capacity of the structure. In the second part, an innovative intervention technique intended to increase the capacity of masonry arches is discussed. The proposed intervention technique consists on applying a layer of steel fiber reinforced mortar (SFRM) on the arch intrados. The behavior of a masonry arch strengthened with this technique is discussed by means of experimental and analytical results.

Maintenance and upgrading are the urging needs of the European infrastructural network that, for masonry bridges, mainly mean: (i) widening of the deck; (ii) installation of the safety barriers; (iii) seismic safety, for seismic-prone areas. The common approach to the first two issues makes use of r.c. slabs, often lied down on the spandrels, and some other procedure somehow derived from r.c. construction. The outcomes may be serious damages to the bridges: the load distribution on the bridge is completely changed from the original design and damage may be induced in the arch barrel. In this paper, a case study is discussed to introduce a new technique for widening the bridge deck and setting the safety barriers is discussed: a r.c. slab, lied down onto the fill and separate from the spandrels, with lateral cantilevers, is used to widen the deck and so restrain the safety barriers. Large concrete blocks connected to the bedrock by means of piles have been built behind the skewbacks as horizontal restraints to the slab in case of seismic actions. In this way horizontal actions on the slab and the impact load of vehicles on the barriers are directly sustained by new structures and not by the old bridge. Such an approach is also cheap and does not necessarily ask for interrupting the bridge service.

Masonry arch bridges form an integral part of the railway infrastructure worldwide. It is estimated that there are over 200.000 masonry arch bridges and culverts in the European railways network that represent more than 50% of the total bridge stock in Europe with an inestimable asset value. Most of these bridges are over 100 years old and would be considered to have reached the end of their theoretical service lives if compared against current design codes.Masonry arch bridges have however stood the test of time and proved to be long-lasting structures with considerable reserve capacity and resilience. Appropriate maintenance and management are key to maintaining the bridge stock in a safe and serviceable condition.To maintain the safety of their operation it is thus necessary to confirm with appropriate assessment and testing methods that the load carrying capacity of the arches is sufficient for the current and foreseeable applied loads without accelerated deterioration, and therefore that arches remain serviceable and sustainable.The paper introduces some of the results of an international project entitled “Assessment of Masonry Arch Bridges”. The project was organised by the International Union of Railways (UIC) and the University of Pécs with the participation of several railway administrations and consultant institutions. The principle objective of the project was to develop tools that help optimise life-cycle management of masonry arch bridges by providing advancement in understanding of the deterioration process in masonry arches and develop assessment tools that enable bridge owners to determine the safe working load and residual life of arches.

An innovative approach, defined by the term “Active Monitoring”, has been designed and implemented by the Company ARCOS Engineering for a steel suspended arch bridge, starting from its design phases, for the sake of structural control and maintenance operations. The structure has a span of 250 m with a central arch that supports the runway through steel tendons. The bridge deck consists of a central beam and cantilevered lanes. The bridge has been instrumented with load cells at suspension cables, high precision servo inclinometers, steel surface temperature, differential pressure and humidity sensors, triaxial accelerometers. Data from sensors are the input of a finite element computational engine that evaluates derived quantities. Then, the coherence between the acquired and computed quantities is verified. Warning signals are provided if this check is not met. In this manner, a real-time structural assessment is carried out in a fully automated way, highlighting potential anomalies without human interaction. Therefore, this strategy becomes a valuable support for management and maintenance planning of infrastructure assets. The paper illustrates the layout and implementation of the system as well as some of the results that have been attained.

This paper reports on the application of the Quality Control framework suggested in the COST TU1406 to masonry arch bridges. A case study of a single span stone arch bridge built in Portugal is addressed based on real data available from visual inspections performed by the Portuguese public concessionaire and manager for the national road and railway, IP - Infraestruturas de Portugal. The results of the suggested methodology are discussed considering two maintenance scenarios and confronted with the results of the IP assessment.

Bridges play a crucial role as they are critical elements in several road networks. Recent trends in condition state assessment require to evaluate not only the seismic vulnerability and the load carrying capacity for increased traffic loads, but also the damage state due to decay and environmental effects. in order to evaluate the structural reliability of the bridge and define priority lists for interventions on the network. In the framework of a series of inspections carried out at a municipality level for the above mentioned aims, a numerical and experimental analysis was carried out on a historical steel deck arch bridge, called Paleocapa bridge, located in the historic city centre of Padova (Italy). Paleocapa bridge is composed by six arches and is highly vulnerable to traffic load, due to a widespread and advanced corrosion state.In order to study the effects of both internal and external boundaries and the loss of mass and stiffness due to steel corrosion a parametric modal analysis was implemented. The steel material was characterized through uniaxial tensile test and metallographic and chemical analysis, while a dynamic identification test of the bridge was performed in order to extract modal parameters, i.e. natural frequencies, damping ratios and mode shapes.Modal analysis pointed out a decoupled behaviour of arches and deck, and among the same arches, with a consequent significant decrease in load-bearing capacity. The calibrated FE model of the bridge was used to assess the seismic and static capacity of the structure. In particular, the latter was very critical; therefore, it was necessary to limit the transitable load on the deck, in agreement with the public authority.

The paper describes a technique for the consolidation of masonry arches, through the placement of post-tensioned steel cables, either at the extrados of the arch or at the intrados.Small scale experimental tests were conducted to measure the improvement obtained with the adoption of the “Reinforced Arch Method” (RAM).An experimental campaign was conducted, testing 117 arches, in order to evaluate the effect of the RAM Method in case of horizontal loads, simulating seismic actions along the principal axis of the arch.A proposal for the strengthening of multiple interconnected arches is presented, referring to “Arsenale Repubblicano” of Pisa.

This paper focuses on survey methodologies and structural repair interventions on stone masonry arch bridges, stemming from the experience and knowledge gathered by the Nucleus of Rehabilitation of the Institute of Construction of the Faculty of Engineering of University of Porto, through a large number of surveys in heritage structures in general and masonry arch bridges in particular. Besides a brief discussion on structural survey and intervention methodologies, a practical example of structural intervention is presented, the case of Esmoriz bridge, for which the main objective was to preserve its structural safety, authenticity and integrity.

When it comes to the construction and maintenance of bridges, integral constructions have many economic advantages. The abutment areas of conventional integral bridges with lengths over 70 m often cause problems due to the length variations caused by temperature changes of the concrete in particular. A new bridge construction technology has been developed at the Institute for Structural Engineering of TU Wien to make the construction of very long integral bridges possible. The new construction method is based on the positive behavior of arch constructions. By using arches, which are situated between two fixed abutments, the temperature changes as well as length variations caused by creep and shrinkage are translated into a raise and a lowering of the tops of the arches. This “breathing” of the arches makes the construction of integral bridges of arbitrary length possible since all longitudinal strains are eliminated. Tendons, which connect the springers of the arches, enable the bridge construction in stages without temporary bracings, despite of slender piers. Further advantages are the reduction of bending moments of the arches and the piers for traffic loads positioned in a single span as well as the redundancy of the entire structure. To test the new technology under real conditions a 30 m long prototype, representing a segment of a very long integral bridge was built.

Examples of solutions for arch bridges recently developed in Poland are presented. The content of the paper was limited to two issues. First: Construction of spans of concrete arched bridges from various types of prefabricated elements. Second: Construction of steel or hybrid arch bridges in which the arches were made of cold bended steel sections. The presented solutions are characterized by low material consumption and low construction costs.

The present paper describes the relevance of the arch on the new modular bridge solution developed by MBSbyBERD to reach a new range of spans. Modular Steel Bridges are commonly used for the rapid reestablishment of interrupted roads and to a range of spans up to 60 m, and rarely for spans up to 90 m. In this last case there are few solutions available on the market and no longer than 90 m.Designed to be pre-assembled and containerized in order to minimize assembly time, a long modular bridge LMB-120 has been developed to cover spans from 80 m up to 120 m.The comparative analysis between solutions with or without the arch are introduced in this paper. Ultimate and service limits states were considered for launching and service phases.

Three pedestrian bridges, which prestressed concrete deck is suspended on outwardly inclined arches, are described in terms of their architectural and structural solution. The first one was completed in 2017 in Salem, Oregon, USA, the other two, which were awarded by first prizes in architecture-structural competitions are being designed.

The present article intends to divulge an innovative concept for large span bridges with articulated slender arch and thin deck. Definitive prestressed ties, connected between the arch and the foundations, are used to stabilize the hinged arch, mobilizing external reactions. The ties are prestressed in order to remain tensioned under the effect of external actions, ensuring effective addition of stiffness both in tension and in relative compression. The prestressed ties are true pillars for the traffic variable actions, for which the arch has not anti-funicular shape. The viability of the solution is demonstrated with a practical example for a railway bridge with span L = 400 m.