Proceedings of the 1st Conference of the European Association on Quality Control of Bridges and Structures

Inhaltsverzeichnis

1. Frontmatter

2. Quantification of Uncertainties for Geodetic Observations in the Context of Bridge Surveillance

   Matthias Haslbeck, Thorsten Strübing, Thomas Braml

   Abstract

   Ageing infrastructure and the pursuit of minimal life cycle costs provide a basis for a wide range of surveillance and recalculation techniques such as structural health monitoring and model updating. For many of these applications, the accompanying uncertainties in the measurement of structural reactions are key to the success of these methodologies. In this context, geodetic surveillance represents one of the most widely used methods for the measurement of deformations.

   This paper will explain and quantify the uncertainties inherent to geodetic observations of bridge structures based upon measurements conducted in Roding (Bavaria) with the objective to update a Finite-Element-Model via Bayes´ theorem. In this project, both a tachymeter and a lasertracker were used for data gathering.

   After providing an overview on the theoretical background on uncertainty quantification according to the GUM, the measurement uncertainties of both devices are evaluated and compared to the manufacturer’s specifications.

   The determination of the stochastic parameters` variances will follow from the statistical analysis of the empirical test data, e.g. by bootstrapping. Finally, this results in statistical models for the surveying uncertainties of both devices.

3. A Survey of Bridge Condition Rating Systems

   Chiara Iacovino, Zehra Irem Turksezer, Pier Francesco Giordano, Maria Pina Limongelli

   Abstract

   Starting from the results of a bridge inspection, a set of indicators can be obtained to define or calculate the so-called condition rating, which indicates the global state of the infrastructure. Rating the condition or functionality of bridges or individual bridge components is essential to take necessary actions at the right time and to prioritize the maintenance or replacement projects within bridge inventory, with respect to the economical most effective and cost-saving solution. A bridge condition index (BCI) is often used for this aim. In some countries, a qualitative method is used to define the BCI, in others a formula is developed to integrate the condition ratings of components in an overall BCI. Various aspects of damage (e.g., degree, extent, importance, and urgency) are considered to derive a BCI defined by numbers, letters, or their combinations. The present paper provides a critical comparison of existing bridge condition rating systems adopted in different countries worldwide.

4. Structural Health Monitoring at the Heart of the Decision-Making Process for Structural Asset Management

   Patrice M. Pelletier, François-Baptiste Cartiaux, Valeria Fort

   Abstract

   The structural health monitoring (SHM) of buildings, infrastructures, and civil engineering & industrial equipment is in full expansion. One of the key drivers behind the ever-increasing need for SHM is that a major part of the infrastructures has been built during the last century with life-limited materials and processes.

   With the development of digital sensing technologies, telecommunications and the algorithmic processing of data in real time, it is today possible to complement the visual inspections with continuous real-time structural health monitoring. It is imperative that inspection and monitoring be considered as complementary activities to improve the safety and the on-time maintenance of infrastructures, when and where it is deemed required. An innovative process is presented that proposes the integration of such key activities through the life cycle of the structural asset into the decision-making process.

   The solution presented proposes the enhancement of the management of the structural asset knowledge by knowing the state, the behavior and sustainability (health) of the works, and to monitor them continuously and in real time to improve safety and enhance longevity of structures.

5. Cost Oriented Object-Related Damage Analysis with the Ultrasonic Method for Small Steel Bridges

   Thomas Krausche, Hartmut Pasternak

   Abstract

   The aging of the existing infrastructure engineering structures like bridges challenges the state authorities and the society as a whole. The maintenance or the replacement of critical connections between points of interest in combination with the increasing volume of traffic is critical to meet the essential economic needs of a region. In Germany the Federal Highway Research Institute (Bast) provides regulations for the construction and maintenance of bridges and civil engineering on federal highways for the practical engineers. Thereby the guidelines for the monitoring of the bridges are precise and frequently to categorize the stability, road safety and durability. The purpose is to recognize occurring defects and damage as early as possible to take action. Beyond the regular inspection there is also the possibility of an audit from special occasion when necessary. A detailed recording of the damage images enables the progress over time to be observed and can be maintained in the next audit.

   For the type of bridges where the initial damage is not immediately visible or can only suspected an object-related damage analysis can be obtained. A specific analysis is usually very time-consuming and costly and will not be very economic for small bridges. In the case study a simply tool using ultrasonic method to verify the steel plate thickness and calculations can provide the lifetime extension of bridges.

6. Rapid Repair of Damaged RC Columns Through CFRCM Confinement

   Klajdi Toska, Flora Faleschini, Mariano Angelo Zanini, Lorenzo Hofer, Carlo Pellegrino

   Abstract

   This paper presents the results of an experimental campaign aimed to investigate the behavior of pre-damaged reinforced concrete (RC) columns, repaired through confinement with Carbon fiber reinforced cementitious matrix (CFRCM). The analyzed samples differ by the shape of the cross-section (circular or square) and inner steel stirrups, while confinement was realized with 2 CFRCM layers for all cases. The experimental behavior was characterized in terms of axial stress-strain response, and hoop strains development. During the test, strains were monitored both in the carbon fiber layers and in the inner steel stirrups. The study aims to investigate the effectiveness of CFRCM jackets when applied to RC elements with pre-existing damage and their capability to restore the initial compressive strength and ductility. Results showed that the effectiveness of CFRCM confinement system was able to restore the initial capacity of the damaged columns. In addition, an important influence on the confinement effectiveness of the cross-section shape and of the configuration of the internal transverse reinforcement was observed.

7. Monitoring of Reinforced Concrete Structures by Distributed Optical Fiber Sensors

   Mattia Francesco Bado, Joan R. Casas

   Abstract

   Distributed Optical Fiber Sensors (DOFS) are modern-day cutting-edge monitoring tools that are quickly acquiring relevance in the Structural Health Monitoring engineering. Their most ambitious use is embedded inside plain or reinforced concrete (RC) structures with the scope of comprehending their inner-workings and long-term performance. Yet, multiple studies have shown that the bonding technique with which the DOFS are bonded to the reinforcement bars has a significant role on the quality of the extracted strain data. Whilst this influence has been studied for externally bonded DOFS, it hasn’t been done for embedded ones. The present work is set on performing such study by monitoring the strain measurement quality as sampled by DOFS bonded to multiple rebars with different techniques and adhesives. These instrumented rebars are used to produce differently sized RC ties later tested in tension. The discussion of the test outputs highlights the quasi-optimal performance of a DOFS/rebar bonding technique.

8. Methodology for the Study of Prestressed Concrete Bridges Affected by Alkali-Silica Reaction

   Ismael Carpintero, Eduardo López, Jorge Rueda, Víctor Lanza

   Abstract

   The alkali-silica reaction occurs when the alkaline solution in the pores of concrete and the siliceous minerals of some aggregates react to form a gel that significantly increases its volume by absorbing water. It is typical of massive concrete elements exposed to high humidity environments. However, in recent years there have been numerous cases of prestressed bridge decks that have developed alkali-silica reactions in not particularly humid environments.

   The influence of this pathology on the structural behaviour of the bridge is determined by the decrease in the mechanical properties of the concrete and the reduction of the deck stiffness due to the intense cracking. This work presents a multidisciplinary study methodology that allows to estimate the degree of structural affection, and to determine the most likely cause and the expected evolution of these damages.

   A series of physico-chemical tests on samples of the bridge materials is pro-posed to confirm the alkali-silica reaction and to assess the remaining reactive potential. The influence on the structural behaviour is evaluated by mechanical tests of concrete cores that allow to quantify the loss of capacity of the material. The stiffness and modal characteristic of the deck is estimated by means of dynamic tests. The global response measured is compared with that expected according to finite element models.

   With these data, some numerical calculation checks are carried out to evaluate the influence on structural safety of the loss of mechanical properties of the concrete, and to quantify the deck stiffness loss associated with the cracking.

9. Evaluation of Post Tensioned Bridges’ Tendon Ducts by NDT and Minor Invasive Measures

   Guy Rapaport

   Abstract

   This paper introduces the author’s accumulated experience in applying state of the art NDT methods (ultrasound tomography and Impact-Echo) for post tensioned bridges’ grout injection evaluation together with minor invasive investigations for validating NDT results and for evaluation of prestressing system condition including duct’s grout injection and prestressing steel corrosion.

   The injection grout has a crucial role in protecting the prestressing steel against corrosion and it is important for intermediating the prestressing forces to the concrete structure. Therefore, successful grout injection is critical for the correct structural functionality of a post tensioned bridge.

   There are thousands of aging post-tensioned bridges, frequently on critical transportation routes. Occasionally, construction faults and environment stresses pose significant functionality and durability problems to the prestressing system. The consequences may possibly affect the safe usage of bridges. Faults and damages in prestressing systems are hidden from the eyes. Therefore the severity of the situation is unknown and may result in extreme cases even in sudden collapse of bridges - as witnessed in the 2018 collapse of the Morandi Bridge in Genoa, Italy where apparently, according to publications, a post tensioned main structural part failed.

   Especially the condition of old bridges should be assessed. “Traditional” inspection techniques do not provide information on the internal prestressing system which has a crucial role in the bridge load carrying capacity. The abovementioned NDT methods combined with invasive investigations enable this critical evaluation task.

10. Model Calibration of a Historic Masonry Arch Bridge Using a Probabilistic Approach

    B. Barros, B. Conde, L. J. Sánchez-Aparicio, M. Cabaleiro, O. Bouzas, B. Riveiro

    Abstract

    Masonry arch bridges are one of the most important structures built through time which have allowed overcoming the important transportation difficulties associated with the irregular ground topology. Many of these ancient constructions are still in use and in many cases subjected to heavier traffic loads. For a rigorous structural safety assessment, accurate numerical models are essential. However, this is not a trivial task due to the intrinsic complexity of the structural system, the inhomogeneity of the constituent materials, the existence of damage, etc. Therefore, calibration procedures supported on experimental data of the structure are a desirable tool to obtain a model that sufficiently replicates the real mechanical behavior. In this sense, in recent years, the use of model updating strategies based on deterministic approaches, such as optimization strategies, has acquired widespread use. In contrast, the use of other appealing approaches, such as probabilistic-based methods has received little attention. Thus, in this work, a probabilistic approach aimed at the calibration of numerical models of masonry arch bridges is presented. A case study located in Ávila (Spain) is considered for the implementation of the proposed methodology.

11. Metamodel-Based Reliability Assessment of Reinforced Concrete Beams Under Fatigue Loads

    Silvia J. Sarmiento Nova, Jaime Gonzalez-Libreros, Gabriel Sas, Lennart Elfgren, Ibrahim Coric, Ola Enoksson

    Abstract

    It is well-known that highway bridges are frequently under cyclic load; therefore, deterioration due to fatigue is one of the most important phenomena to be analyzed when determining a bridge safety margin. This paper studies how uncertainties related to fatigue models for concrete structures affect reinforced concrete element’s reliability, and the critical parameters in fatigue damage are investigated. To this end, a metamodel-based method is described and used to calculate the probability of failure and reliability index values of an application example. Metamodel-based methods have become an essential and efficient tool to determine structural safety as the possibility to decrease the computational cost and couple the reliability approach with nonlinear finite element analysis (NLFEA) allows a better estimation of structural reliability. Results show how the proposed method can reduce the computational cost of traditional reliability simulation methods, maintaining a good accuracy.

12. Diagnostics and Evaluation of Bridge Structures on Cogwheel Railway

    Peter Koteš, Martin Vavruš, Martin Moravčík

    Abstract

    The paper is focused on diagnostics and calculation of load-carrying capacity of the two bridge objects on cog railway (cogwheel railway) Tatranská Štrba – Štrbské Pleso in Slovakia. The bridges are situated in the north part of Slovakia in the mountains of the High Tatras and bypass the road way. The bridge objects were built during 1968–1969, so, they are 52 years old bridges. The bridges are made from precast prestressed post-tensioned beams of three single spans. In the transverse direction, the beams are not coupled by a slab, but act as a “curtain slab”. The peculiarity is that these are prefabricated beams intended for road bridges. In 2020, the Department of Structures and Bridges, the Faculty of Civil Engineering, University of Žilina, was asked to carry out the technical survey and diagnostics of the above-mentioned bridge. The visual inspection, diagnostics, verifying real dimensions and material characteristics were requested. After that, calculation of the load-carrying capacity was done. For determining the load-carrying capacity, the standard approach given in Eurocodes was used according to provisions, which take into account the modified (lower) reliability levels and their adequate partial safety factors according to Eurocodes.

13. Masonry Arch Bridges in Long-Term Operation on Slovak Railway Network

    Patrik Kotula, Ondrej Kridla

    Abstract

    Masonry arch bridges., in addition to the numerous predominance of traditional bridge structures, form an integral part of the railway infrastructure They are among the oldest types of railway bridges, which despite their advanced age (more than 100 years), still reliably serve their purpose with the increased demands of current railway operations. Many of them currently belong to technical monuments and therefore when choosing the maintenance of masonry arches, emphasis should be placed on the method of their repair, reconstruction and possible strengthening. The presented paper maps the current state of these types of bridges in the Slovak Railway network (ŽSR). The selected representative arch bridge is subjected to numerical analysis (LimitState Ring) with emphasis on taking into account the influence of degradation of material elements and local defects on its resulting load-carrying capacity.

14. Condition Assessment of a First Generation Precast Prestressed Bridges in Slovakia

    Petra Bujňáková, Martin Moravčík, Jakub Kraľovanec

    Abstract

    Diagnostic surveys and structural analyses conducted by the Department of Structures and Bridges have shown the growing number of a first generation precast prestressed structures with deterioration signs. The consequences of a deficient conceptual design and inadequate maintenance will be shown using practical examples of three precast bridges under emergency condition close to collapse state. These bridges were built in the 1960s. Fortunately, the early closure of those bridges has prevented fatal consequences. On the other hand, this state has been offered the opportunity to analyze those bridges step by step. The paper summarizes some findings from visual inspection, diagnostic survey, in-situ and laboratory testing. The results can help to assess the functionality of similar bridge structures and show how important is a visual routine inspection combined with quantitative information from detailed structural analysis.

15. Prolonging the Lifetime of Existing Reinforced Concrete Infrastructures with Thermal Sprayed Zinc Coating Anodes

    M. C. van Leeuwen, P. M. Gagné, B. Duran, F. Prenger

    Abstract

    Metallic zinc coatings protect steel from corrosion by acting first as a barrier coating and more importantly as a sacrificial anode. Zinc will provide galvanic protection to the steel. As such, concrete structures reinforced with plain or black steel showing signs of distress can be galvanically protected with external zinc anodes. Thermal sprayed metallic zinc coatings on the exposed surface of the concrete can be electrically connected to the steel reinforcement and provide corrosion protection to the steel.

    Infrastructure constructions which are exposed to a high degree of chloride contamination, from proximity to the seacoast, or due to the use of de-icing salts can experience chloride induced corrosion of the reinforcing steel. Typical reinforced concrete constructions where thermal sprayed zinc coatings are applied as anodes for passive or active cathodic protection are parking houses, piers and bridges.

    Thermal sprayed zinc coatings were successfully tested as anodes in cathodic protection systems for reinforced concrete structures in the United States. Subsequent installations were made on numerous structures, including three historic reinforced concrete bridges in the state of Oregon. The 25-plus-year performance confirms that the service life of reinforced concrete structures can be significantly and economically extended by using metallic zinc anodes to protect the plain steel reinforcement from further corrosion.

16. Development of Damage Detection Methodologies in Bridges Using Drive-by Methods and Machine Learning Algorithms: A Systematic Review of the Literature

    E. F. Souza, T. N. Bittencourt, D. Ribeiro, H. Carvalho

    Abstract

    This paper is aimed at presenting a systematic literature review of damage detection methodologies in bridges using drive-by methods and machine learning algorithms. In order to emphasize the main aspects of the state of the art in this topic and present an insight on its trends, a Scientometric approach is used for identifying high impact research, as well as VOSviewer® for clustering of terms and authors. For the case of railway bridges, the combined results of this dedicated research revealed significant advances in the last decade with a considerable number of impactful publications. Even so, some challenges still need to be overcome particularly the extension of the application of drive-by methods to the damage identification in high-speed railway bridges is revealed to be a prominent and very promising research field.

17. Application of the Non-destructive Methods to the Determination of Discontinuities Between the Bridge Steel Box Girder and Concrete

    Dalibor Sekulić, Maria Grozdanić, Karla Ille

    Abstract

    Assessment of the condition of building structures is carried out for the purpose of maintenance planning, for old and damaged structures or for new structures assessment in case of doubt about the quality of performed works. When assessing the condition of building structures, priority must have non-destructive testing methods. So, it is necessary to apply, effective and accurate non-destructive methods for finding and characterization of different types of damages. This paper presents an innovative application of the impact-echo method to the specific problem of determining the discontinuity between the steel plate and concrete. Namely, during concrete pouring in the steel box girder of the bridge, there was a suspicion that there were discontinuities between the steel structure and the installed concrete because the concreting took too long and shrinkage of concrete was not tested. Several non - destructive methods were considered, between which ultrasonic wave reflection and impact-echo methods were selected as potential candidates. These two methods are commonly used for the determination of the thickness of structural elements and searching for delaminations, cavities, inhomogeneities, interruptions of concreting, etc., but a review of the literature did not find their application to our problem. Although the ultrasonic wave reflection method did not give good results, but by the impact-echo method, discontinuities and places of reduced adhesion of concrete to the steel structure was successfully determined.

18. Amplitude Dependency Effects in the Structural Identification of Historic Masonry Buildings

    Panagiotis Martakis, Yves Reuland, Eleni Chatzi

    Abstract

    Masonry buildings form a significant part of the central-European building stock. Despite significant efforts to standardize the seismic evaluation of such buildings, uncertainties pertaining to material properties and modeling assumptions introduce significant ambiguity. Operational modal analysis tools have been exploited to infer global structural stiffness properties, under the assumption of linear elastic behavior. However, measurements on real structures demonstrate nonlinear structural responses in the range of small strains, typically attributed to material cracking or to the soil. This work reports analysis of dynamic measurements on three real buildings at various amplitude levels, due to vibrations that are arbitrarily induced by construction works preceding planned demolition. The results show transient frequency drops that are attributed to increasing excitation amplitude, while the response remains in the commonly assumed linear elastic regime. This amplitude dependency remains poorly investigated, as vibrational data of higher amplitude for real masonry buildings are scarce. The evaluation of the impact of amplitude dependency on the, commonly assumed, linear elastic stiffness properties bears notable impact both in terms of model updating, as well as in terms of data-driven damage detection after disastrous events.