8th International Conference on Advanced Composite Materials in Bridges and Structures

Bridge footing plays an important role in transferring the load from the bridge superstructure to the soil underneath. It might need structural strengthening due to insufficient flexural or shear capacity, while in most cases punching shear failure is the dominant failure mode. The most commonly applied retrofit strategy is to enlarge the dimensions of the footings, where dowel splice connections are installed to connect additional concrete to the existing footing. However, the splice connection is not practical. In this paper, a series of upgraded enlarging footing retrofit methods for spread footing using FRP systems are proposed, including an active strengthening system and three passive strengthening systems. For all systems, the connection at the interface is achieved by composite action, instead of dowel connection. Thus, the new connection type is simple and effective. In the active system, circular external prestressing strands were installed. While in the passive systems, the exterior surface of the retrofitted footing was wrapped with different materials including CFRP, BFRP, and steel. A total of Eighteen footings were simulated using Abaqus CAE, and the punching shear capacity of each model was calculated. The results of this investigation suggest that both the active and the passive retrofit systems can significantly improve the punching shear capacity of the spread footing.

In this paper, an experimental investigation into the shear strengthening of damaged rectangular reinforced concrete (RC) beams using two near-surface mounted (NSM) fiber reinforced polymer (FRP) bar systems is presented. In addition to the epoxy adhesive, which is typically used to bond the FRP bars to the RC, in this study a novel mortar-based adhesive was tested. The parameters investigated in this study include (a) adhesive used (epoxy or mortar) and (b) level of damage (no damage, first shear crack, or 70% of maximum theoretical load). For this endeavor, seven 2 m-long RC beams were cast and tested in three-point bending. From the results, it was observed that (a) both strengthening systems were able to overcome the effects of the damage and provide substantial increases to the beams’ shear capacity; (b) both systems were able to restore the damaged beams’ stiffness to their original values; (c) the mortar-mounted bars were less effective compared to their epoxy-mounted counterparts.

Carbon fiber reinforced polymer (CFRP) rod panels (CRPs) are a recently developed retrofit system for concrete and steel structures. CRPs consist of multiple, small diameter (typically 1–5 mm) CFRP rods attached to a fiberglass mesh used to secure the rods in place and facilitate panel installation. One of the main advantages of CRPs, in addition to the well-known favorable properties of FRP material, is the splicing of panels through a finger joint mechanism. Splicing reduces labor and equipment costs in retrofit of long-span members or those with limited access. In this study, the bond between CRPs and the concrete substrate is studied analytically and a model is developed based on the shear-lag theory. Analytical terms were established for key variables of the CRP-concrete joint, namely shear stress, slip, and strain. The analytical model is validated with experimental results from a series of double-lap shear tests of concrete prisms bonded on two opposite sides to CRPs. The strains derived from the analytical models were compared very well with the ones from gauges placed along the panel length in the experimental study. The development length predicted by the analytical model for panels with 2 mm or 4 mm rods was less than 100 mm. The CRP panel width was found to have negligible effects on the development length.

High-density polyethylene (HDPE) pipes have been introduced in various infrastructure sectors as cost-effective pipes due to their physicochemical and mechanical properties. The HDPE pipes have corrosion, chemical resistance, good flexibility and low maintenance costs. However, as compared to HDPE pipes made with recycled resins, using these pipes from virgin resins will lead to increased costs as well as environmental impacts. Therefore, using the pipes from recycled resins is essential. The HDPE pipes need to be manufactured from recycled resins but must ensure the properties and strength from virgin resins. The objectives of this work are to determine the short-term properties as well as to compare the performance of HDPE pipes manufactured from virgin resins and recycled resins. The HDPE pipes are collected from one company to analyze important material properties affecting the pipe durability, such as tensile strength, density, softening point, thermal stability and carbon black content. These physical properties were tested by MTS Universal Testing Machines, Thermogravimetric analysis (TGA), Thermomechanical analysis (TMA) and Dynamic mechanical analysis (DMA). The results of these short-term tests can be used to estimate a lot of information about the long-term material serviceability.

This study presents the fatigue durability of a cantilevered deck slab strengthened by Near-Surface-Mounted (NSM) method using Carbon Fiber Reinforced Polymer (CFRP) rods. The CFRP rod manufactured by PULTRUSION method has ultra-high modulus of 450 GPa. The study used a polymer-cementitious mortar of ultra-high-early strength as a filling material for CFRP rod while the rod is generally embedded in epoxy-resin mortar/adhesive. The ultra-high-early strength mortar can contribute to shortening the construction term for strengthening upper-deck slabs. The CFRP rod has little shear-resistance ribs, so the bond performance in concrete is significantly low. In this study, Glass Fiber Reinforced Polymer (GFRP) ribs were attached to CFRP rods to improve the bond performance. To examine the fatigue durability, the study conducted a moving-wheel load test for a cantilevered deck slab embedding the bond-improved CFRP rods. The test shows that the cantilevered deck slab strengthened with the bond-improved CFRP rods had the excellent fatigue durability even to 150% higher wheel load than the load in Japanese design code.

In this study, the flexural properties of sandwich panels with flax fiber-reinforced polymer (FFRP) faces and polyisocyanurate foam cores are examined. Three large-scale 1220 mm by 1220 mm sandwich panels with thicknesses of approximately 80 mm were fabricated and two have been tested. A balanced bidirectional flax fabric with a nominal areal mass of 400 g/m2 and an epoxy resin with a bio-content of approximately 30% were used to make the faces and a 76 mm thick polyisocyanurate foam with a nominal density of 96 kg/m3 was used as the core material. Each panel was tested under a concentrated load at the center and the test span in each direction was 1120 mm. During the tests, the load, center deflection, and face strains in the fiber directions were measured at a sampling rate of 10 Hz. The main parameter of the tests was the effect of facing thickness: one (approximately 1.5 mm thick), two (approximately 2.5 mm thick) or three (approximately 3.5 mm thick) layers of FFRP on the structural behavior of the panels. It was shown that doubling the number of face layers increased the strength by 68% and the stiffness by 48%. This is an on-going study and more results will be available at the time of the conference.

In this study, the flexural behavior of hollow ± 55° GFRP tubes is examined experimentally. A total of 15 tubes were tested under four-point bending: three identical tube specimens for five different tube types. The main test parameter was the effect of the tube inner diameter (76.2 mm and 203.2 mm) and the nominal pressure rating (350 kPa, 700 kPa, and 1050 kPa) which is correlated to the tube wall thickness. For each test, the load was measured using a 250 kN load cell, the deflection was measured using a string potentiometer and the strains in the extreme tension and compression fibers were measured using strain gauges with a gauge length of 6 mm. All measurements were recorded at a sample rate of 10 Hz. The results of the tests show that the ultimate moment increased with both tube diameter and wall thickness and that the tubes all exhibited the same failure mechanism: a progressive tensile weakening in the bottom of the tube until an ultimate failure in compression at the top. The mechanical behavior of these tubes is important to understand in order to effectively use them in structural systems, such as concrete-filled FRP tubes.

A hollow fibre composite reinforcing system (CRS) has been designed and developed to create a void and a shear connector in reinforced concrete structures and, at the same time, provide an additional reinforcement to the structures including dry walls, slabs and bridge decks. This presentation will focus on the results of an experimental investigation on the flexural behaviour of precast concrete slabs with hollow CRS and glass fibre reinforced polymer bars. Four full-scale concrete slabs, i.e. solid slab, slab with a hollow-core, slab reinforced with GFRP bars and CRS and slab reinforced with steel bars and CRS were cast and tested up to failure under four-point static bending. The failure behaviour, load–deflection behaviour and failure load of these slab systems were evaluated and compared. The results showed that the CRS enhanced the structural performance of hollow core concrete slabs. The slab with three CRS increased the stiffness of the slab by 33%, reduced the loss of stiffness after concrete cracking by 24%, increased the load-carrying capacity by 45% and significantly increased the deformability by 117%. The hollow composite system also prevented vertical flexural cracks starting from bottom and propagating up to the top layer of concrete, this resulted in ductile flexural failure. From these results, it was clearly demonstrated the effectiveness of CRS in concrete slabs indicating that a thinner concrete slab with CRS is possible to achieve the same strength and stiffness of solid and hollow slab resulting in a more lightweight and economical structure.

Glass fibre reinforced polymer (GFRP) bars are now accepted as longitudinal reinforcements for concrete columns. However, code recommendations for designing and analysing concrete columns with GFRP bars are still ignoring their contribution to carrying the axial loads due to the limited understanding of its behaviour under compression, while in some cases; the compressive strength is calculated as a percentage of the tensile strength. This is due to the limited understanding on the compressive behaviour of GFRP bars and the lack of standard testing methodology to characterise the compressive behaviour of the GFRP bars. In this paper, a novel testing methodology is introduced to fulfil the gap in the knowledge on characterising the compressive behaviour of GFRP bars. In the specimen preparation, both ends of the GFRP bars were embedded in hollow steel caps filled with a cementitious grout to facilitate compressive tests and minimise premature failure due to stress concentration at the ends. The effect of the bar diameter (9.5, 15.9, and 19.1 mm) and the slenderness (Lu/db) ratio (2, 4, 8, and 16) were also investigated. The failure mechanisms showed that an increase in the micro-fibre buckling and decrease in the compressive-to-tensile strength ratio could be achieved when the diameter of GFRP bar increases. Furthermore, the compressive strength and mode of failure are highly affected by (Lu/db) ratio. Simplified theoretical equations were also proposed to reliably describe the compressive behaviour of GFRP bars with different bar diameters and slenderness ratios.

This case study presents the use of carbon-fiber reinforced polymer (CFRP) prestressed concrete (PC) soldier-piles coupled with glass-FRP reinforced concrete (RC) precast panels, for a combined bridge bearing abutment and retaining wall system. The application of FRP prestressing and reinforcing on the US 41 Highway Bridge over North Creek in Sarasota County was promoted by the Florida Department of Transportation under their Transportation Innovation Challenge initiative. Soldier-pile retaining walls are a commonly used system in southeastern US coastal states, but the incorporation of innovative materials such as CFRP-prestressing for piles and GFRP-reinforcing for concrete panels is not yet widespread. In addition to describing the preferred FRP-PC/RC solution adopted for this project, a comparison is provided to a recently completed adjacent bridge that utilized a traditional carbon-steel PC soldier-pile and RC precast panel wall system. A further comparison is presented for the design and cost of the wall system based on the project design criteria (ACI 440.1R, ACI 440.4R, and 2009 AASHTO LRFD Bridge Design Guide Specifications for GFRP-Reinforced Concrete, 1st Edition) with the refinements and savings possible under the newer editions. Finally, the life-cycle cost, durability and environmental benefits from the use of the innovative CFRP and GFRP reinforcing systems in this type of traditional wall system will be identified for typical urban coastal areas with extremely aggressive conditions, congested access, and challenging environmental constraints.

The critical slenderness ratio of concrete columns reinforced using fiber-reinforced polymer (FRP) bars in ACI 440.1R is based on a deterministic approach and a failure criterion of 5% drop in axial capacity. There is an urging need to quantify the safety associated with the recommended slenderness ratio for the purpose of optimizing the design of FRP reinforced columns. A research program developed by the authors is currently underway to develop a novel reliability-based approach to recommend slenderness ratios for possible inclusion in ACI 440.1R. In the proposed approach, recommended slenderness ratios are formulated based on achieving a predefined target reliability index as opposed to the current deterministic approach of setting a failure criterion of 5% drop in axial capacity. The approach is aligned with the general philosophy of limit state design adopted by North American codes and standards in which failure limit states are established based on reliability principles and not deterministically. In this paper, some aspects of the proposed approach are described while limited preliminary analysis results are included. The preliminary results showed a range of 3.59–3.95 reliability indices for slenderness ratios ranging between 17 and 22 based on the limited parameters considered in this study. Considerable future research is needed to complete the proposed approach and bring it to a level suitable for application in calibrating code slenderness ratio limits.

A powerful method of strengthening existing structures is to use fiber-reinforced polymer (FRP) wraps particularly for columns. Wrapping provides columns with confinement and increases their strength and performance. During the past decades, numerous researches have been performed on the characterization of concrete columns wrapped with FRPs. Therefore, a large experimental database is available that assists in determining the behavior of FRP-wrapped concrete columns. From the designer's point of view, both for analysis and for design, having failure criteria for FRP-wrapped concrete columns is crucial. There have been many proposed stress–strain models for concrete columns confined with FRPs. The majority of the proposed formulas were derived based on a statistic approach. Only a few formulas were derived based on mechanics-based methods such as plasticity-based approaches. The presence of a database, with almost 800 data points, on the behavior of FRP wrapped concrete columns with different FRP strength and modulus, thicknesses, number of layers, and diverse concrete properties was the motivation for conducting a research on developing new equations for the prediction of the confined concrete strength of circular concrete columns wrapped with FRPs. In this study, Hoek–Brown and Drucker-Prager models were used, and new equations for predicting the strength of confined concrete were introduced.

In this paper, an experimental program was undertaken to investigate the splitting-tensile strength and the direct-tensile strength of geopolymer concrete reinforced with glass fibers (GCGF). The compressive strength, splitting-tensile strength and direct-tensile strength of plain geopolymer concrete (GC) and GCGF at 28 days were determined. Test results highlighted that the incorporation of glass fibers into geopolymer concrete decreased the compressive strength by approximately 4.3%. On the other hand, the splitting-tensile strength and the direct-tensile strength of geopolymer concrete increased by approximately 5.6% and 7.7%, respectively, with the incorporation of glass fibers. The splitting-tensile strength and the direct-tensile strength of both GC and GCGF were on average 7.9% and 5.3% of their compressive strengths, respectively.

A new application of a buried secant-pile GFRP reinforced auger-cast wall was constructed along 1.5 km of Florida’s coastline, protecting State Highway A1A (SR-A1A) north of Flagler Beach, Florida, USA. Repeated destruction from tropical Hurricanes, especially in the last 20 years, has resulted in continual damage and sometimes temporary closure of SR-A1A, which is a critical access route for emergency evacuation, response and recovery efforts. The uniqueness of this application involved the use of Glass Fiber-Reinforced Polymer (GFRP) reinforcing for the structural concrete elements and the elimination of any scour protection, to avoid impacts on the natural functioning of the beach dunes during normal weather conditions. The lack of scour protection resulted in a demanding free-standing height condition that had to be met by the retaining system in the aftermath of a major Hurricane and for a specified time period, until beach restoration and sand re-nourishment can be accomplished. In addition to describing the as-built GFRP-RC solution adopted for this project, a brief Life-Cycle Cost Analysis (LCCA) methodology for SR-A1A GFRP-RC Seawall/Bulkhead project is provided with estimated percentage and/or unit cost savings over alternative construction means via black steel. Furthermore, an update to the second edition of the AASHTO Bridge Design Guide Specifications for GFRP-RC, including GFRP-RC Design Provisions, Parameters and Resistance Factors is provided herein. Finally, GFRP-RC Member Design Provisions and implications on the state-of-the-practice will complete this research effort, by comparing the project design criteria (ACI 440.1R and ASHTO LRFD Bridge Design Guide Specifications for GFRP-Reinforced Concrete, first edition) verses the refinements and alternatives possible under the 2018 AASHTO second edition updates.

This paper investigates the effects of the natural fiber reinforced polymer (FRP) confinement of concrete cylinders on axial compressive strength. Jute and hemp were used as natural cellulosic FRP confinement. Results were compared with the mineral fiber-based basalt fiber reinforced polymer (BFRP) confinement on concrete cylinders. Sixteen concrete cylinders of 100 mm diameter and 200 mm height were cast and tested. The parameters considered were the type of FRP and the number of layers. The effect of confinement on the axial compressive strength of the tested specimens was ascertained and discussed. It was observed that jute and hemp FRP confinement resulted in a small increase in the axial compressive strength as compared to the BFRP confinement. The results demonstrated that the natural mineral fiber-based FRP, i.e. Basalt FRP confinement showed a superior performance as compared to the natural cellulosic fiber-based FRP, i.e. jute and hemp FRP confinement.

Aging buildings and ever evolving design codes imply the need of implementing retrofit techniques to ensure the safety and functionality of buildings under current operating loads as well as extreme hazard events. Fiber reinforced polymer (FRP) composites are being implemented in practice to retrofit existing buildings as a popular retrofit system because of their high strength, lightweight properties, minimal profile, and versatile application. There are standards that help the engineer implement an FRP retrofit of a building (e.g., ACI 440.2R). However, the current performance-based seismic design standards such as ASCE/SEI 41-17 do not provide guidance on modeling parameters and acceptance criteria of reinforced concrete retrofitted components including beams, columns, and shear walls. This study develops a database of experimental tests of FRP retrofitted reinforced concrete (RC) shear walls, which contains over 200 test specimens from test programs performed across the globe. The database is organized to present the most important parameters and details in an accessible format. The database is an essential means to fill in missing gaps of information for the practicing engineer by analyzing the responses of the walls and determining backbone curves and modeling parameters relevant to retrofitted shear walls.

In this study, the effect of confining concrete with flax fiber-reinforced polymers (FFRPs) is examined. A total of six concrete specimens were tested under uniaxial compression. Each specimen had a diameter of 101.6 mm and a height of 203.2 mm. The main parameter of the tests was the effect of FFRP thickness on specimen behaviour. Two specimens were used as control specimens and tested without an FFRP wrap. The second and third sets of specimens were wrapped with an FFRP such that the ratio of confinement pressure (fl) to concrete compressive strength (f’c) was 0.08 and 0.16 respectively. Each specimen was fitted with a yoke fixture to measure the lateral and longitudinal deflection using four linear potentiometer displacement gauges. Each test was performed at a displacement rate of 0.6 mm/min and the data were sampled at a rate of 10 Hz. The strength of concrete confined with six layers of FFRP wrap was found to be approximately double that of the plain concrete specimens. The results indicate that FFRPs can effectively confine concrete and have the potential for use in the rehabilitation of existing structures.

Trenchless pipe repair can offer time and cost savings over traditional excavation and replacement of damaged pipes. Conventional repair methods using prefabricated steel liners are not effective due to significant loss of discharge capacity, especially for non-circular cross-sections. The objective of this paper is to introduce a novel layered sandwich system composed of fibre-reinforced polymer (FRP) composites. Concrete pipes with a length of 0.5 m and inner diameter of 380 mm are stressed to simulate damage; cracks at the crown and invert are produced by loading via the three-edge-bearing test setup (ASTM C497). The damaged pipes are repaired with multiple layers of FRPs sandwiching a layer of a syntactic foam core. The sandwich system will save FRP materials and provides the required stiffness based on the mechanics of sandwich composites. The sandwich system is applied with epoxy resin to the entire length of the inner diameter of the pipes. The repaired specimens are then loaded to failure via the three-edge-bearing test. Normalised loads and strains are analysed to compare performance between the repaired specimens and a control group. Initial results show hybrid sandwich structures composed of GFRP (Glass Fibre Reinforced Polymer), syntactic foam and CFRP (Carbon Fibre Reinforced Polymer) outperforming GFRP liners, and GFRP sandwich liners.

Squat walls with a ratio of height-to-length of less than two are important structural components in many commercial buildings and safety-related nuclear structures. Given their low aspect ratio, squat walls have shorter fundamental periods (of order of 0.20–0.50 s.) than high-rise ones. Therefore, for any ground shaking of a given duration, they would have a higher potential damage. Recently, the seismic design of structures has been evolved towards a performance-based approach, where the need for robust structural systems with higher damage tolerance and reduced permanent deformations is paramount. The previous research on mid-rise and squat shear walls reinforced with glass fiber-reinforced polymer (GFRP) bars has demonstrated their ability to achieve a high lateral drift ratio with no strength degradation and minimal residual deformations. The current study examines the effect of the axial load ratio on the lateral load response of two GFRP-reinforced squat walls with an aspect ratio of 1.14. The test results indicated that the axial load has a significant effect on the cracking pattern, failure mode, and lateral load-displacement hysteretic response of the GFRP-reinforced squat walls.

For an earthquake-resistant structure, the inelastic response which provides ductility is the important aspect of maintaining the strength of the structure under seismic loads. To ensure ductile behavior, the column should have adequate confinement reinforcement in the region of the plastic hinge. The available design codes specify the special confinement ratio for the moment-resisting structure in the region of the plastic hinge. However, there is a lack of information concerning the performance of Fiber Reinforced Polymer (FRP)-reinforced concrete columns subjected to lateral reversal loads. Thus, this paper presents the results of an experimental study on the Glass FRP (GFRP)-reinforced concrete column under simulated seismic load. The investigation includes testing of two full-scale rectangular columns of 400 mm X 400 mm cross-sectional dimension with an effective height of 1650 mm with different spacing of the transverse reinforcement (100 mm and 150 mm). The two columns were tested under quasi-static reversed cyclic loading with constant compression axial load until failure which was indicated by the crushing of longitudinal reinforcement in compression and damage to core concrete. The confinement behavior of the GFRP spirals and ties was analyzed from the hysteresis response which clearly shows the acceptable level of deformation with no strength degradation for the well-confined column.

The unique properties of concrete-filled fiber reinforced polymer (FRP) tube (CFFT) makes it an efficient system for use in the construction industry. It can provide confinement, improve the axial load carrying capacity, and can be used as a formwork for casting concrete. A task group was formed by ACI 440-0J to develop a detailed design procedure for CFFTs for building applications. A reduction factor of 0.65 was proposed by the task group based on ACI 440 reduction factor for FRP confined concrete columns. In this research, a reliability analysis was conducted using Monte Carlo (MC) simulation and first order second moment (FOSM) method to calculate the reliability index associated with the proposed reduction factor of 0.65 and to compare it with established target reliability indices. The CFFT statistical parameters were based on 45 experimental tests found in the literature. The reliability analysis showed that the FOSM and MC methods yield comparable results with a reliability index of 3.5 corresponding to a reduction factor of 0.65. It is recommended to conduct further tests to increase the confidence level of the safety evaluation.

There has been a considerable number of studies related to optimizing the use of fiber reinforced polymer (FRP) in strengthening existing structures based on reliability methods. These studies are not augmented with current design codes, standards, and the typical methods utilized by practicing engineers in evaluating and designing FRP strengthening of existing concrete structures. This represents a major challenge that hinders the wide-spread use of FRP in strengthening existing structures in Canada. In this research, a novel approach is outlined to present reliability-based optimization of existing concrete columns strengthened using FRP (i.e. the optimum number of layers) in terms of the well-known parameter “utilization ratio”. The utilization ratio refers to the ratio of the factored loads to factored resistance, where the factored loads are calculated as per Part 4 of Division B of the National Building Code of Canada (NBCC 2015) and the factored resistance is calculated as per the concrete standard (CSA A23.1/A23.2-14) and the FRP building design standard (CSA S806-12). The reliability method utilized in this research accounts for the load history experienced by the existing columns, the degree of redundancy in the floor system supported by the columns, and the ratio of the design dead-to-live load. Sample user-friendly design aids were generated based on the proposed reliability method to relate the standard utilization ratio to the number of FRP layers required to strengthen concrete columns deficient in axial load. The proposed method typically yields one-third a smaller number of layers as compared with the direct application of the NBCC 2015 and CSA S806 load and material resistance factors.

The purpose of this paper is to present the results of non-destructive testing (NDT) on CFRP-structural systems applied to RC (reinforced concrete) highway bridges in North Macedonia on the M2 and one bridge in Slovenia on the E57. The NDT procedure performed impact tests on CFRP plates applied to bridge structural members to determine CFRP-concrete bond performance: bonded vs de-bonded. Using the impact-echo technique, the NDT machine produced acoustic emissions with specific frequencies and sinusoidal waveforms indicating the CFRP-concrete bond condition. The NDT procedure used for the field investigation in Oct 2019, on 12 of the 17 CFRP-retrofitted bridges, confirmed the CFRP systems applied in 2001 remain fully bonded to the bridge structural members. The bridge section tested in Slovenia found the CFRP plates fully bonded 21 years after installation.

In recent decades, FRP reinforcing bars have been widely used in construction applications as internal reinforcement in concrete members. However, the feasibility of using FRP bars as internal reinforcement in seismically active regions has become called into question. Moreover, CSA S806-12 and ACI 440.1R-15 do not include any requirements concerning the strength, stiffness, or drift capacity of flat-plate structures under seismic load. This study aims to assess the effect of increasing the gravity shear on the strength and stiffness of the FRP-RC slab-column connections under lateral cyclic loading. Two full-scale interior slab-column connections were constructed and tested under combined gravity and quasi-static revered lateral cyclic loading until failure. The slabs measured 2500 × 2500, with a thickness of 200 mm. A square column of 300 mm extended from the center of the slab surfaces by 700 mm. The performance of connections was evaluated based on the experimentally recorded moment lateral drift hysteretic relationships, connection stiffness, and energy dissipation. The test results revealed that increasing the slab gravity-load intensity and subsequent punching shear level at the interior connection had a considerable effect on punching shear performance. The unbalanced moment and the lateral-drift capacities decreased by 16 and 22%. Moreover, the specimen, which was subjected to a higher gravity load, displayed higher connection stiffness degradation.

This paper investigates the performance of a full-scale reinforced concrete bridge deck subjected to cyclic loads. The purpose of this study was to compare the performance of a GFRP-reinforced bridge deck using traditional pulsating loads against the newer method of rolling loads. A slab-on-girder type bridge deck was constructed with dimensions 15.24 m × 3.89 m × 0.21 m and a girder spacing of 3.05 m. The bridge deck was reinforced with top and bottom grids of glass fiber reinforced polymer (GFRP) rebar in accordance with the empirical method presented in the Canadian Highway Bridge Design Code. One section of the deck was subjected to 3000 cycles of fixed pulsating loads using a hydraulic actuator. Another section was subjected to 3000 cycles of rolling loads using a novel Rolling Load Simulator (ROLLS), the first machine of its kind in Canada. Throughout cycling, monotonic load tests were performed to monitor the reinforcement strains and the stiffness degradation behaviour of each section. The results showed that the section subjected to rolling loads experienced a greater overall change in flexural stiffness. Further cycles should be performed to assess the behaviour of each section over its full fatigue life.

The addition of steel fibers improves the tensile and flexural strengths of plain concrete. However, steel fibers are prone to corrosion, affecting the performance of steel fiber reinforced concrete. This study investigates the mechanical properties of concrete reinforced with 1.5% alkali-resistant glass fibers (AR-GF) and 0.15% polypropylene fibers (PF) by volume of concrete. Ready-mix concrete was used to cast the concrete specimens. The concrete specimens were tested at the age of 28 days to determine the compressive, split tensile and flexural strengths of the alkali-resistant-glass fiber reinforced concrete (AR-GFRC) and polypropylene fiber reinforced concrete (PFRC) as compared to plain concrete (PC). Based on the results of the experimental program, the compressive strengths of the AR-GFRC and PFRC decreased, while the flexural strengths increased as compared to PC. The split tensile strength of AR-GFRC decreased, while the split tensile strength of PFRC increased as compared to PC.

This paper presents an experimental study on the development length of small diameter basalt fiber reinforced polymer (BFRP) bars embedded in normal strength concrete. Small diameter bars have been used as ties and connectors in concrete sandwich panels. The beam bending method was used to provide realistic conditions, where concrete is in tension, as opposed to the pull-out method. Results are compared to predicted values from current design standards. One set of 15 beam specimens using 35 MPa concrete reinforced by BFRP bars measuring 4, 6, and 8 mm in diameter was tested. BFRP bars were embedded at lengths ranging from 10 to 75 db, where db denotes the bar diameter. The beams were tested in flexure under four-point bending and failed by BFRP bar pullout, concrete splitting, or rupture of the bar. The theoretical development lengths were calculated using the ACI 440.1R-15 Design and CAN/CSA S806-12 and compared to experimental results. It is concluded that current design equations are adequate for the use with the BFRP small diameter bars tested in this study.

This paper presents an update to the GFRP Slab Top Mat Reinforcement for Prestressed Concrete I-Girders (IGFRP) bridge standard issued by the Texas Department of Transportation (TxDOT) in June 2015 and revised in August 2017. The 2019 update aligns the IGFRP bridge deck standard with current AASHTO provisions and makes the GFRP reinforcement layout in the top mat more efficient. Four (4) design locations are considered: (a) interior bay at center of span; (b) overhang at center of span; (c) interior bay at thickened end slab; and (d) overhang at thickened end slab. For each location, top mat reinforcement is designed in the primary and secondary directions for a potential of eight (8) different reinforcement layouts per girder spacing. The traditional design of IGFRP-17 considers four (4) different girder spacing: 2.3, 2.6, 2.9, and 3.0 m, for a total of thirty-two (32) possible reinforcement layouts. The 2019 update specifies one (1) layout for the secondary reinforcement and four different (4) layouts for the primary reinforcement with positive implications in terms of simplicity and efficiency. The update reduces the required amount of GFRP reinforcement by approximately 30%.

Concrete beams reinforced by fibre reinforced polymer (FRP) bars are known as an attractive option for the construction of buildings and bridges, where corrosion of traditional steel reinforcement is a major concern. Among various structural aspects of FRP-reinforced concrete (FRP-RC) beams, shear performance has been a subject of research in recent years. This is based on the fact that the conventional sum of concrete plus stirrup contributions to shear strength, though generally adopted for steel-RC beams, may not be simply generalized to FRP-RC beams due to major differences between FRP and steel bars. Thereby, there is an attempt to provide shear design equations, which are specific to FRP-RC beams. In this paper, the Eurocode 2 approach for the shear design of steel-RC beams is modified through a reliability analysis in order to apply it to the case of FRP-RC beams. In doing so, the load factors used in Canadian standards are taken into account and first-order second-moment (FOSM) method is employed. The model errors are evaluated on the basis of a large set of experiments on shear-failed FRP-RC beams assembled from the literature. The calibration is aimed at modifying the resistance reduction factor in addition to altering the characteristic value to achieve the target reliability index.

This paper presents a simple and cost-effective method to detect and measure debonding in reinforced concrete (RC) structures retrofitted with externally bonded fiber-reinforced polymer (FRP) sheets. Debonding is a phenomenon that occurs when the FRP sheet separates or delaminates from the concrete substrate. Digital image correlation has been used extensively in the past to measure displacement, strain, and crack fields over the surface of a structural element. In this study, a tool is developed in the freely-available image analysis software ImPro Stereo to allow for the measurement of the out-of-plane displacement field over the surface of a structural element. This tool is then applied to detect areas over the surface of a structural element where FRP-concrete debonding has occurred. Validation of the developed tool in ImPro Stereo in a controlled laboratory environment demonstrates that it provides a non-destructive, non-contact, and cost-effective solution to measure FRP-concrete debonding. The results show great potential for its application in structural condition assessment and structural health monitoring of civil structures.

This paper presents the experimental results of two full-scale circular reinforced concrete (RC) columns. The column specimens had a diameter of 350 mm and a shear span of 1,750 mm. Both specimens were reinforced longitudinally and transversely with GFRP reinforcement. The GFRP transverse reinforcement was provided in the form of spirals for one specimen and circular hoops, with lap splice length equals to 40 times its cross-sectional diameter, for the other specimen. The transverse reinforcement had a pitch of 85 mm, satisfying a specific requirement of the Canadian code for FRP-RC columns of one-fourth the column’s gross diameter. Longitudinal reinforcement of the columns was provided as six No. 16 GFRP bars. All specimens were tested under a combination of simulated seismic loading and constant axial loading (equal to 20% of axial load carrying capacity of the GFRP-RC column). The results showed that the specimen reinforced with GFRP circular hoops achieved similar lateral load resistance to the spirally reinforced specimen. However, limited deformability was provided by GFRP circular hoops due to its insufficient lap splice length.

The differences in the mechanical properties between steel and glass fibre-reinforced polymer (GFRP) reinforcement, in terms of tensile strength, compressive strength, and stress–strain relationship, necessitate developing independent code provisions for the design of FRP-reinforced concrete (RC) structures. Moreover, due to the lack of experimental data on GFRP-RC circular columns in general and those constructed with high-strength concrete (HSC), in particular, the design provisions remain in need of further research and development. In this study, three full-scale HSC columns with 60 MPa concrete compressive strength were constructed and tested to failure under eccentric loading. One specimen was reinforced with steel as a control specimen, while the other two were constructed using GFRP longitudinal and spiral reinforcement. The test variable was the pitch of the spiral reinforcement, which varied between 50 and 85 mm. The specimens had a diameter of 350 mm, a length of 1,750 mm, and 1.23% longitudinal reinforcement ratio. The results showed that a spiral pitch of 85 mm was adequate to confine the concrete core of the column under eccentric load.

This study aims to develop a fundamental test for the detection of a surface crack in the concrete covered with fiber reinforcement polymer (FRP) sheets. For this purpose, the study focuses on the electrical impedance variation and phase transition. It can be assumed that the concrete exhibits inductive and resistive properties. The study prepared some FRP-covered concrete specimens with an artificial crack and examined the frequency characteristics of impedance and phase angle under AC voltage with frequencies ranging from 1 kHz to 8 MHz. The frequency characteristics were examined using an impedance analyzer which was controlled by a computer. The impedance and phase were measured using a probe with two electrode terminals. The test results confirmed that the capacitive phase property of cracked concrete was altered to exhibit inductive characteristics at approximately 3–4 MHz. The paper reported that a surface crack can be detected by measuring a frequency at the impedance local maximum value and the phase transition property of the FRP-covered concrete.

This study presents an experimental investigation to evaluate the behavior of circular geopolymer concrete columns reinforced with Glass Fiber Reinforced Polymer (GFRP) bars and helices under axial compression. Four circular geopolymer concrete columns of 160 mm diameter and 640 mm height were tested under concentric and eccentric axial loading. Two columns were reinforced with longitudinal steel bars and steel helices and two columns were reinforced with longitudinal GFRP bars and GFRP helices. The influence of the type of internal reinforcement and the axial loading eccentricity were investigated. The GFRP bar reinforced columns achieved lower axial load-carrying capacity than the steel bar reinforced columns under both concentric and 35 mm eccentric axial loadings. The axial load carrying capacity of concentrically loaded GFRP bar reinforced column was 15% less than the axial load carrying capacity of steel bar reinforced column. However, the axial load carrying capacity of eccentrically loaded GFRP bar reinforced column was only 5% less than the axial load carrying capacity of steel bar reinforced column. The ductility of concentric and 35 mm eccentric axially loaded GFRP bar reinforced columns were about 42% and 7% less, respectively than the ductility of their steel counterpart.

Many research studies have shown that the internal flexural reinforcement has a significant influence on increasing the shear capacity of reinforced concrete deep beams. This study investigates the potential of using externally bonded FRP reinforcement for the shear strength enhancement of RC deep beams. Experiments include serval RC deep beams with a rectangular cross section and a shear span to depth ratio (a/h) equal to 1.5. The deep beams were tested under symmetric three-point bending monotonically until failure. One beam specimen was a control test with no strengthening. The remaining beams were strengthened with three composite systems namely; 0° unidirectional CFRP, 0/90° bidirectional CFRP and ±45° bidirectional GFRP. The bidirectional GFRP composite system was applied at different orientations and locations of the beam using epoxy adhesives for shear strength enhancement evaluation. The behavior of the tested deep beams is discussed in terms of their levels of ultimate shear strength, mid-span deflection, FRP reinforcement strain, strut angle, and by their type of failure. The behavior of the tested deep beam specimens is compared to each other experimentally. Test results show different modes of failure and gain in the ultimate shear strength over the control beam depending on the orientation of the GFRP sheets.

The behavior and shear strength of lightweight self-consolidating concrete (LWSCC) beams reinforced with basalt fiber-reinforced polymer (BFRP) bars were investigated. A total of four large-scale reinforced concrete beams without stirrups were constructed. Tests were carried out on three rectangular beam specimens using LWSCC; the remaining one, serving as a reference beam, was cast of normal weight concrete (NWC). The beams measured 3100 mm in length, 200 mm in width, and 400 mm in depth. All beams were tested in four-point bending up to failure. The test variables included the concrete type, the longitudinal reinforcement ratio, and the reinforcement type. The experimental results of these tests are presented in terms of crack patterns, load–deflection behavior, and failure modes. In addition, the experimental results are compared to the predicted shear strength according to the CSA/S806-12 (2012) code. A reduction factor is found to be required for predicting the shear strength when LWSCC is used with BFRP bars and hence a reduction factor should be addressed for LWSCC.

Unreinforced masonry (URM) walls are prone to a brittle failure when subjected to out-of-plane and in-plane forces caused by seismic events. Fiber Reinforced Polymer (FRP) materials offer an economical and viable solution for the seismic retrofit of URM to increase their resistance to in-plane and out-of-plane forces. This paper presents the results of an experimental program that aimed to determine the in-plane shear performance of unreinforced concrete masonry walls strengthened with different levels of externally applied Carbon and Glass FRP composites. All the wall specimens were tested under in-plane cyclic loading with increasing intensity. The test set-up configuration consisted of double-height walls loaded at the mid-height. A total of five specimens (one control, two carbon, and two glass) were tested with increasing amounts of FRP and different layouts. The FRP was applied to one face of the walls to simulate field conditions where access to only one face of the wall is possible. The ultimate shear strength, lateral deformation, and peak load were compared for all tested walls. In most cases, failure occurred in either the masonry or the epoxy and in no case did the FRP reach its ultimate capacity. The experimental results demonstrated that a significant increase in the in-plane shear capacity of masonry can be achieved for walls retrofitted with Glass and Carbon FRP. Ultimate shear strengths of the walls were compared with those determined using the design model in ACI 440.7R for predicting the in-plane shear capacity of CMU walls. A good correlation between experimental results and theoretical predictions was observed.

Improvements in state-of-the-art GFRP rebar materials have demonstrated higher durability in accelerated environmental corrosion resistance testing, higher creep rupture and fatigue endurance limits. Case studies of bridge rehabilitation projects have demonstrated the value of glass fiber-reinforced polymer (GFRP) in building longer-lasting, maintenance-free reinforced concrete (RC) infrastructure. The recent ACI Strategic Development Council (SDC) durability study sampled core extractions from eleven 15 to 20-year GFRP-RC bridge structures. The analysis confirmed the GFRP exceeded the implications of accelerated durability tests from AASHTO and ACI standards with less than a 0.15% reduction in strength per year. Based on this study, if the estimated strength reduction due to aging was less than 15% over a period of 100 years assuming linear degradation, then the 0.7 strength reduction factor (CE) adopted by most design guides to account for environment degradation appears overly conservative (Nanni et al., Durability study of GFRP bars extracted from bridges with 15 to 20 years of service life, Report for strategic development council of the American Concrete Institute, Farmington Hills, MI, June 2019, p 732019). The environment strength reduction factor is under evaluation for refinement. Recent improvements in state-of-the-art GFRP rebars have demonstrated higher sustained load creep rupture and fatigue endurance limits. This paper examines the ACI 440.3R-B.8 creep rupture strength data from state-of-the-art GFRP rebar supporting higher endurance limits for the industry. In RC bridge design, the cyclic fatigue load limit often controls near the contraflexure for bending inflection along continuous spans (Nolan S, Perez J, Hartman D, Ellis K, 2019, Bakers haulover cut bridge: seawall-bulkhead rehabilitation and new GFRP-RC solutions, Transportation research board, paper 19-05552R1, Washington DC, January 2019, pp 7–8). The AASHTO LRFD “Design Guide Specification for GFRP-Reinforced Concrete Bridge Decks and Traffic Railings” (BDGS-1) was recently expanded to include all RC members under the 2nd edition (BDGS-2). As part of the BDGS-2 specifications, owners may require manufacturers to certify that their products meet endurance limits based on testing, if they propose using a higher limit (AASHTO, 2018, LRFD bridge design guide specification for GFRP reinforced concrete, 2nd edn., AASHTO committee bridges and structures, December 2018, Burlington, VT.). The ASTM D7957-17 “Standard Specification for Solid Round Glass Fiber Reinforced Polymer Bars for Concrete Reinforcement” (ASTM International, 2017, Standard specification for solid round GFRP bars for concrete reinforcement, ASTM D7957/D7957M-17. July 2017, West Conshohocken, PA) does not provide test methods or acceptance criteria for creep rupture or cyclic fatigue. Industrywide endurance limit characterization curves would allow manufacturers to assure that a product meets the established limits through simple short duration verification testing. Refinements in endurance design limit should be linked to creep rupture at 75, 100, and a maximum time up to 150-year service life, or based on fatigue at 2, 3, or 4 million cycles, as appropriate for GFRP-RC bridge design specification and consistent with pending AASHTO Service Life Design Guide expectations proposed in the NCHRP project 12–108 (NCHRP, 2019, Guide specification for the service life design of highway bridges: project 12–108”, Modjesky & Masters for National Cooperative Highway Research Program, October 2019, Washington DC). This paper shares testing of improved GFRP rebar conforming to ASTM D7957-17 specification, using a corrosion resistant vinyl ester resin with corrosion reistant E-CR glass at higher fiber content, enabling a 60 GPa tensile elastic modulus that safely resists higher sustained load.

As part of a comprehensive study on the effects of climate change on the performance of structures containing internal or external FRP reinforcement, tensile tests were performed on FRP specimens under different loading and temperature conditions representing different field scenarios. For steady state temperature testing, specimens were heated to the desired temperature and subsequently loaded to failure. Tensile tests were also conducted on specimens subjected to sustained load or sustained deformation and increasing temperature conditions until failure. A significant difference in the results was observed for the two loading scenarios. For the GFRP bars, steady state temperature tests were conducted up to 250 °C and sustained stress levels varied from 40 to 90% of the bar strength at room temperature. Results showed that GFRP bars experienced about a 60% reduction in strength as the steady state temperature increased to 250 °C. The bars were subjected to a 40% stress level and then exposed to an increasing temperature at a fire rate sustaining the load for about 50 min. Similarly, for the GFRP sheets, steady state temperature tests were conducted up to 150 °C and transient temperature specimens were tested at 40%, 65% and 85% of the GFRP sheet strength at room temperature. The results indicated a sudden drop in the mechanical properties of the GFRP sheets around the glass transition temperature ‘Tg’ in both scenarios. However, beyond glass transition temperature, the specimens were able to retain almost 40% of the strength at room temperature.

A huge inventory of concrete structures exists in many parts of the world that have been made deficient due to steel corrosion. The columns damaged by steel corrosion in these structures are especially vulnerable to events such as an earthquake. In this research, the use of GFRP bars in full-scale columns has been investigated as an alternative to steel reinforcement for sustainable construction. As columns containing GFRP longitudinal and lateral reinforcements display softer responses with lower shear and flexural capacity, the behaviour of columns with lateral GFRP reinforcement but steel longitudinal bars was investigated. The experimental program involved testing of eight full-scale, 508 mm diameter, concrete columns under simulated seismic loading. Variables included level of axial load, amount of confining reinforcement and spacing of transverse reinforcement. The columns performed in an excellent manner and the GFRP spirals were found to provide increasing confining pressure to the large concrete core with increased deformations until either their rupture or crushing of the concrete. Results from selected specimens from this and earlier test programs are presented to highlight the effects of different variables and establish the feasibility of using GFRP spirals for seismic resistance of columns.

Seismic fragility analysis is deemed to be a functional tool for evaluating the performance of bridges subjected to natural hazards such as earthquakes. Although there have been many studies on developing fragility curves for generic bridges, few have focused on the existing bridges (particularly long-span bridges). Moreover, the majority of studies have been conducted using as-built bridge parameters, whereas the seismic performance assessment of retrofitted bridges has not been investigated to the same extent. This study aims to develop fragility curves for the original as-built configuration of an existing bridge and its constitutive components and then compare them with those developed for the current retrofitted bridge. The employed retrofit technique in this study is seismic isolation of the superstructure utilizing a novel type of isolation system known as Unbonded Fiber Reinforced Elastomeric Isolators (U-FREI). A comprehensive three-dimensional model of an existing bridge is generated in OpenSees. Incremental Dynamic Analysis (IDA) is performed to monitor the seismic performance of the bridge components under a range of earthquake intensities. Derived fragility curves show that isolating the superstructure using U-FREI can effectively reduce the seismic demand by allowing the deck to have larger displacements and avoiding the formation of plastic hinges in the columns.

Steel-reinforced one-way slab thickness is usually determined using a simple formula based on span and support conditions. This allows designers to skip deflection calculations and simplifies design. This formula does not apply to GFRP-reinforced slabs since they are usually governed by serviceability limits (e.g. deflection, crack control). This complicates GFRP-reinforced slab design as there is not an easy method of assuming a slab thickness. To simplify GFRP-reinforced slab design, charts and instructions based on the most recent ACI 440 provisions were developed. These charts give designers a quick reference to select slab thickness, bar diameter, and bar spacing for typical GFRP-reinforced one-way slabs. Parameters include support condition (simple, fixed), span (2–10 m), bar diameter (12–22 mm), live loads (1.9–7.2 kPa), and sustained load percentage. The charts give insight into governing design criteria. Longer spans (> 5 m in simple slabs, > 8 m in fixed-fixed slabs), are governed by long-term deflections, intermediate spans are governed by crack control, and short spans (<3 m) are governed by temperature and shrinkage requirements. Though some slabs were almost shear-critical, moment resistance was not a concern for any of the considered slab designs.

Insulated wall panels are comprised of two concrete layers that surround rigid insulation. Glass Fibre Reinforced Polymer (GFRP) often connects the concrete layers since it has better thermal resistance than steel. The structural response of these panels is heavily dependant on the load-slip response of the connectors. A connector system consisting of two GFRP bars arranged in an X-shape is investigated. This arrangement resists slip via truss action and is more efficient than dowel-type connectors. The load-slip response of six arrangements was evaluated using 18 push-through tests. Parameters included connector size (9.5, 12.7, 16.0 mm) and insulation bond quality. Connector stiffness increased with connector area but had diminishing returns as diameter increased. Peak load increased 70% when connector size increased from 9.5 to 12.5 mm but only increased 13% between 12.7 and 16.0 mm connectors because the failure mode changed from GFRP compression failure to concrete crushing. Stiffness and strength were higher in specimens with active insulation bond but this effect was minimal with larger connectors. The 12.7 mm connectors had the best performance and have a similar shear flow to other high-stiffness systems that use GFRP shear grids.

This paper presents a numerical investigation of the shear creep behaviour of the adhesive joint in the case of a concrete structure strengthened by externally bonded FRP composites. Based on experimental data collected in a previous study (Houhou (2012) Durabilité des interfaces collées béton/renforts composites: développement d’une méthodologie d’étude basée sur un dispositif de fluage innovant conçu pour être couplé à un vieillissement hygrothermique. PhD thesis, Université Paris-Est, France (in French). https://tel.archives-ouvertes.fr/tel-00765147 ; Houhou et al. (2014) Analysis of the nonlinear creep behaviour of concrete/FRP-bonded assemblies. J Adhes Sci Technol 28(14–15):1345–1366), creep constitutive equations were developed for the adhesive layer and implemented in a finite element code. The proposed model extends the classical one-dimensional formulation of the Burgers creep model to a fully 3D model and also introduces the non-linearity of the model parameters observed by Houhou et al. The creep behaviour of a double lap shear test specimen is then simulated with this numerical approach. A major result is that creep induces a redistribution of the interfacial shear stress along with the concrete/CFRP lap joint, leading both to a reduction in the peak stress near the loaded end of the adhesive joint and an increase in the effective transfer length.

Modal-based damage assessment methods are efficient tools to identify location and magnitude of damage associated with change of modal properties (natural frequencies, modal damping ratios and mode shapes). However, while numerous applications of these methods to simple structural systems (i.e. simple shape structure made of homogeneous material, submitted to well-known boundary conditions…) have proved their efficiency, quite a few studies have been conducted to complex civil engineering structures. This paper presents then the experimental modal analysis applied to reinforced concrete beam-column joint. During tests, a full-scale specimen was subjected to cyclic loading to introduce damage. After each loading phase, specimens were excited with an impact hammer to determine the current modal parameters. The main objective of is to identify from the after-impact responses, the changes occurred in the modal parameters due to damage induced by loading. Structural tests and model used to interpret the experimental result are presented. The capability of the proposed approach to detect small level damage as well as the impact of the measurement errors are then discussed.

In this paper, an AFRP-reinforced concrete (AFRP-RC) column is designed to dissipate energy through rocking when subjected to cyclic loads. The AFRP-RC column rocks via unbonded energy dissipaters that act as replaceable structural fuses (25.4, 32.25, and 38.1 mm) fabricated out of plain Grade 50 mild steel bars. Six columns (350 × 350 × 1524 mm) are subjected to a predetermined drift up to 4%, and loaded until failure to examine the overall column responses and effectiveness of the external dissipaters. This numerical study accounts for the material, geometry, and interaction among elements of the system. Failure of the rocking AFRP columns occur at higher drifts (>3%) as a result of the yielding of the steel dissipaters with minimal strains noted in the internal AFRP reinforcement. In addition, there are noticeable ductility and energy dissipation gains of 70% and 200%, respectively, in the rocking AFRP-RC columns compared to the conventional RC column.

The current study presents the results of a collaborative research project between Quebec’s Ministry of Transportation and the University of Sherbrooke to develop a new test methodology for evaluating the tensile strength of Glass Fiber-Reinforced-Polymer (GFRP) bent bars at the bends. The proposed testing procedure aims at facilitating the in-site examination of the bent bars’ strength for quality control. The testing allows for examining the tensile strength and the strength reduction factor of a wide variety of GFRP shapes within a maximum of three days. The procedure involved embedding a single L-shape GFRP bar in a concrete block and applying tensile force on the straight portion of the bar until failure. Fast-setting self-consolidated concrete (SCC) capable of achieving a concrete compressive strength of 48 MPa after 36 h was used to cast the concrete block. Another set of concrete blocks was prepared using normal-strength concrete (NSC) and compared to that cast using SCC. The tensile test results were validated against that obtained by the typical B.5 testing recommended by the ASTM D7914 (2017) and CSA S807 (2015). GFRP bent bars of size #5 (15.9 mm) produced by two different manufacturers were used in the validation. The comparison resulted in a 4 to 7% difference in the tensile strength at the bends between the two methods using NSC or SCC.

Concrete-filled FRP tube (CFFT) is a composite member, having many applications in construction such as in bridge columns and marine piles. The fiber reinforced polymer (FRP) tube provides a permeant formwork, strength and stiffness, and confinement to the concrete core. Type and laminate structure of the tube can significantly affect the structural response of CFFT. A nonlinear response has been observed in FRP coupon tests, in hollow FRP tube tests, and in CFFT tests, for tubes having angle-ply structures where the laminates are oriented at ±θ° from the longitudinal axis. Although some general hypotheses have been given, a sound theory of the cause of this nonlinearity is still needed. In this study, three different finite element (FE) formulations were developed to examine the behavior of ±55° glass-FRP (GFRP) tube under axial and bending loads, in single tube or CFFT tests. The formulations chosen were (a) ANSYS software, using Orthotropic Elastic material, (b) ANSYS software, using Anisotropic Hill Plasticity material, and (c) LS DYNA software using “MAT_LAMINATED_COMPOSITE_FABRIC (Mat 058)” material. ANSYS models were able to capture the ultimate load of coupon tests, hollow tube tests, and the load–deflection response of CFFTs tested in bending. Only LS-DYNA models were able to fully simulate the nonlinear behavior of the tube in axial tension, including the softening and flat plateau. For CFFTs in bending, the FE models showed that the cause of nonlinear behavior is the progressive matrix cracking in the tube.

The main objective of the research project reported in this paper is to develop a new type of high-performance light beam that will increase the performance of usual beams (timber steel or RC beams) by combining Fibers Reinforced Polymer rebars cast in a Ultra-High-Performance Concrete with Short Fibre Reinforcement (UHPC-SFR). The beam is obtained to get a light beam with a high compressive and tensile capacity to sustain high bending moment and to be also shear resistant. The hybrid beams thus obtained are light and have higher ultimate load capacity. Fatigue and static tests are done to enhance the use of such structure under fatigue loading. The load–displacement relationships are analysed based on results obtained from 5 large scales specimens. In order to confirm the fatigue test done on UHPC material, fatigue tests are done on beams. According to the fatigue test, if tensile stress is lower than 7 MPa in the shear area or tension zone, the fatigue effect may be neglected. The results show good results and illustrate the potential interest of such composite beam configurations for civil engineering structures.

This paper presents the results of 2 tests of slab/wall connections reinforced with composite materials. The full-scale tests are carried on X-shaped connections. Joint connects RC wall and RC continuous floors. Design approach (geometry and steel rebars) is carried out in accordance with European standard. Reinforcement are made using CFRP, GFRP and carbon anchors. In order to study the mechanical behaviour of the joint, displacement sensor, load cells, strain gauge and digital image correlation are put in place. After analysis of the results, composite reinforcement increase the bond strength by 80% and the ductility by 70%. Failure mode is modified (bending failure to shearing failure). Strengthening increase the energy dissipation of the connection by 400%. Results show that composite reinforcement is a good solution for making structures safe from seismic actions.

This paper discusses the mechanical behaviour of the textile/matrix interface of Textile Reinforced Cementitious Matrix Composites (TRCMC) subjected to tensile loading. This behaviour is obtained by the experimental identification of the shear stress distribution at the interface level. For this purpose, optical fibre strain sensors are embedded in the core of the TRCMCs to measure the normal strain of the two TRCMC components. Given the millimetric spatial resolution of these sensors, the strain distribution of the TRCMC in the direction of the applied load is obtained, thus allowing the identification of the crack location, the load transfer length as well as the behaviour of the matrix and the textile at all points. From these experimental results and based on a mechanical analysis, the evolution of the shear stress at the textile/matrix interface is deduced. Two reinforcement ratios were studied: a specimen reinforced with a single layer of textile, and a second one reinforced with three layers of textile. A relationship was established between the interface stress, load transfer length, matrix behaviour and reinforcement ratio. This study allows, on the one hand, a better understanding of the cracking behaviour of this type of composite, and on the other hand, improve existing analytical models by implementing the obtained experimental results.

It is evident that the deterioration of traditional mechanical expansion joints in simply supported spans is one of the major factors affecting the durability of bridge structures. In the previous study by the writers, a flexible and ductile fiber reinforced polymer (FRP) reinforced engineered cementitious composite (ECC) link slab was proposed, which can be used to address the problems of deterioration of expansion joints by eliminating those joints in bridge deck systems. To extend the understanding of the structural behavior of FRP reinforced ECC link slabs in bridge decks, a series of ECC link slabs in full-scale bridge decks were constructed and tested under monotonic cyclic loadings. The experimental variables were reinforcing materials and FRP reinforcement percentage, which aims to study the influence of reinforcement on the behavior of link slabs. The performance of link slab was discussed and presented based on the load-deformation response with particular emphasis on the load and crack development. The test results revealed that the stiffness of reinforcing materials had a strong effect on the behavior of ECC link slabs and the combination of ECC and FRP bars resulted in more flexible and ductile link slabs.

An important objective of sustainable development applied to bridge infrastructure is to develop and deploy effective strengthening solutions, with a view to increasing the service life of existing structures. Steel bridges are prone to fatigue and their remaining service life can be evaluated after careful diagnosis of induced structural damages. However, it is generally difficult to assess the extend of damage caused by fatigue at an early stage before crack initiation. Besides, old structures are particularly vulnerable to fatigue as old steels exhibit a rather brittle behavior, but most design codes did not take into account fatigue effects before the 1970s. To address these issues, an assessment method and a preventive strengthening solution based on the use of adhesively bonded UHM (Ultra-High Modulus) CFRP (Carbon Fiber Reinforced Polymer) plates were developed and applied to an existing bridge for validation (Jarama bridge owned by the Community of Madrid in Spain). Strain measurement collected during load tests was analyzed to verify that the reinforcement works according to theoretical expectations, and different parameters were studied such as the influence of low traffic during CFRP installation. In the end, this field demonstration provided clear evidence of the efficiency of the developed solution.

The increasing rate of the world natural disasters increased the importance of the aftermath rapid mobility. This led to the necessity of using effective deployable bridge systems in terms of weight to capacity ratio. A composite bridge deck possesses a remarkable share of a bridge superstructure’s weight. The objective of this study is to produce CFRP webbed core sandwich decks that are effective in strength to areal weight ratio compared to the military Composite Assault Bridge (CAB) deck system. Another aim of the study is to achieve the target capacity performance while not using a special expensive matrix formulation. Two potential CFRP sandwich deck configurations are considered. The buckling capacity of the core webs is enhanced using different structural shapes of the CFRP construction. The common configuration of the cores consists of several honeycomb polyisocyanurate foam beams placed parallel to each other. The honeycomb foam beams are placed between two upper and lower carbon/epoxy skins to hold the whole core together. The experimental program included coupon testing to quantify the mechanical properties of the used carbon/epoxy material, a flatwise compression test, three-point loading test, and finally a microscopic analysis to estimate the fiber volume fraction of the manufactured webbed core samples and to verify the adequacy of the used manufactured technique and infusion strategy. The test results showed promising values of shear and compression strength to areal weight ratio at least by 1.5 times and 0.99 times, respectively, compared to the CAB deck system. The configuration that showed the promising results for ultimate strength capacities is chosen as a candidate for further parametric analysis and design with the deployable bridge tread-way.

This research study investigates the feasibility of using fiber-reinforced polymer bars as internal reinforcement in concrete arch slabs. Five arch slabs were constructed with 0.5 m width, 0.975 m maximum height, and 3.92 m span. The thickness of the arch slabs varied from 100 mm at the middle to 175 mm at the ends. Test parameters included the type of reinforcing bars (Steel, Glass FRP, and Caron FRP) and reinforcement ratio. All arches were pin supported at both ends and were tested under two concentrated loads. Measurements included cracking, mode of failure, ultimate capacity, deflections, and strains in reinforcement. All tested arches showed good capacities ranging between 154kN and more than 250kN. The ultimate capacity of the steel-RC arch was slightly higher (16%) than the ultimate capacity of the GFRP-RC arch with the same reinforcement ratio, whereas the CFRP-RC arch showed higher capacity compared to the steel-RC arch. Increasing the GFRP reinforcement ratio from 0.63% to 0.95% and 1.27% enhanced the ultimate capacity by 26% and 61%, respectively. The test results showed that FRP bars can be used as a reinforcing material in arch slabs in corrosive areas as they showed comparable behavior to steel-RC arches.

In recent years, fiber reinforced polymer (FRP) bars have become one of the promising reinforcing materials in concrete structures, however, elevated temperatures can severely affect their performance. Within this study, different types of FRP bars were subjected to elevated temperatures (100–300 °C) and then tested in flexure to investigate their flexure strength and tensile modulus. One type of carbon FRP (CFRP) bars and three types of glass FRP (GFRP) bars were tested in this study. The bars were tested using two testing scenarios. In the first scenario, the bars were tested immediately after exposure to temperature. In the second testing scenario, the specimens were kept to cool down before testing. Test results showed that significant reductions in the flexural strength and modulus were recorded at temperature levels higher than the glass transition temperature (Tg). The flexural strength and modulus decreased as the temperature level increased. The results also revealed that larger diameter bars showed lower residual flexure strength and modulus than smaller diameter bars after exposure to elevated temperatures. The immediately tested specimens showed higher losses compared to bars tested after cooling. All types of GFRP bars showed comparable results. The flexural strength losses ranged between 29 and 37% after exposure to 200 and ranged between 39 and 60% after exposure to 300 ℃. The tested CFRP bars showed similar flexural strengths compared to the tested GFRP bars; however, they showed lower residual flexural modulus.