Concrete Composite Bridges Research Articles

Performance of grouped stud connectors in precast steel-UHPC composite bridges under combined shear and tension loads

Ultra-high performance concrete (UHPC) becomes an innovative resolution for facilitating the construction and structural performance of prefabricated bridges. Head stud shear connectors are commonly applied in prefabricated steel–concrete composite bridges and can withstand uplift forces as well as shear forces. In this paper, six standard push-out tests (SP-Test) and ten modified push-out tests (MP-Test) are prepared and tested. In the MP-Test, stud connectors are subjected to shear and tensile forces simultaneously. The stud diameter, stud aspect ratio and the ratio of tension to shear are considered for their effects on shear resistance, shear stiffness and ductility. Besides, the finite element (FE) analysis and parametric analysis are conducted to further investigate the behavior of stud connectors under combined loads. The formulas for predicting the shear-tension interaction strength and shear resistance of stud connectors in UHPC under combined loads are proposed. The results show that the stud connectors exhibit both shear and tension failure characteristics under combined loads. The lower ratio of tension to shear has less effect on the shear resistance and ductility. Meanwhile, the stud aspect ratio is positively related to shear resistance and ductility but has no effect on shear stiffness under combined loads. As the ratio of tension to shear increases, a considerable reduction is observed in the shear resistance and relative slip as well as shear stiffness of stud connectors. However, the attenuation effect of tensile stress on the shear strength of studs can be neglected when the tensile shear ratio is less than 0.17. The unevenness of the force on single stud in stud connectors can be ignored and excessive strength of UHPC has limited effect on improving the strength of studs under combined shear and tension loads. The proposed shear strength reduction factor takes into account the ratio of tension to shear and gives more reasonable predictions of shear resistance under combined loads. Besides, compared with other available equations, the proposed shear-tension interaction model predicts the interaction strength more accurately.

Experiment Analysis on Crack Resistance in Negative Moment Zone of Steel–Concrete Composite Continuous Girder Improved by Interfacial Slip

Due to the strong interface effect of continuous steel-concrete composite beams with conventional shear connectors, the efficiency of applying pre-stress in the negative moment zone is greatly reduced, which leads to a difficulty of anti-cracking design in the negative moment zone of pre-stressed steel-concrete composite box girder. In order to study the feasibility and the working mechanism of improving the crack resistance of continuous steel-concrete composite bridges by releasing the interfacial slip effect within the negative bending moment region, two groups of model tests were carried out in the paper. Two steel-concrete composite beams were used for model test, one of them using the conventional stud shear connectors, another one using the new shear connectors, named uplift-restricted and slip-permitted shear connectors. The results show that, compared with the composite beam with conventional shear studs, the composite beams with uplift-restricted and slip-permitted shear connectors have a higher pre-stress application efficiency, and the new connector could release the interface slip, which can make the tensile stress distribution in concrete slab more uniform within the negative moment zone, thus increasing the cracking load of concrete slab and reducing the subsequent crack width effectively. This study is helpful to understand the relationship between the interface slip and the anti-crack characteristics in negative moment zones, and a new anti-crack design method is proposed for the design of continuous composite girder.

Fatigue behavior evaluation of full-scale OSD-UHPC composite bridge deck system

To investigate the fatigue performance and fatigue damage process of the Orthotropic Steel Deck (OSD) - Ultra-High Performance Concrete (UHPC) composite bridge deck, a two-span continuous full-scale specimen was designed and tested under cyclic loading. Test results showed that the fatigue cracks firstly initiated near the lower part of the weld toe of the rib-to-cross beam welded joint, and then cracks along the weld length of the U-rib butt-welded joint developed. These observations followed by the OSD-UHPC interface debonding. The U-rib bolted joint exhibited better fatigue resistance than the U-rib butt-welded joint. The S-N curves of the rib-to-cross beam welded joint, the U-rib butt-welded joint and the U-rib bolted joint were established based on existing fatigue test data, and were compared with provisions in design codes. The S-N curves from the beam test for the short-headed stud connectors were compared with that from the push-out test. And the established S-N curves with 95% survival probability from the push-out test could be used to assess the global fatigue performance of the composite deck. Considering the durability-based critical crack width of UHPC, the established tensile S-N curve regarding critical UHPC crack width of 0.05 mm could be used to evaluate the anti-fatigue cracking ability of the UHPC layer in the composite deck system.

Saleyard Bridge, UK – an improved approach to precasting steel–concrete composite bridge decks

Saleyard Bridge carries the A465 Heads of the Valleys Road over the River Clydach near Gilwern, Monmouthshire, UK. It comprises a 67 m single-span steel–concrete composite multi-girder superstructure made integral with the abutments. A full-depth precast deck was chosen to tackle site constraints and improve constructability. The alternative precast panel connection detail developed used straight laps to overcome the problems that can arise from using typical U-bar loop type connections between precast deck panels. The successful use of the precast panels proved that a deck design with straight laps was a practical alternative. The ability to increase the multi-beam centres and avoid cantilever edge formwork created a more economical solution with savings estimated at £500 000. The paper examines the detailed design and construction planning needed to realise the savings and speed up construction as well as improving site safety. The lessons learnt are also applicable to the wider use of precast panels as an alternative to in situ concreting.

Experimental and Numerical Study on UHPC–RC Decks within Hogging Moment Region

Steel–concrete composite continuous bridges can take full advantage of concrete and steel, but in regions with hogging moments, cracking of the concrete deck is a big issue affecting the durability of bridges. In order to solve cracking problems within the hogging moment region, this study proposes a composite deck method using ultra-high-performance concrete (UHPC) and regular concrete (RC). In this way, the layers of UHPC and RC are composited to take advantage of the high tensile strength of UHPC materials to improve the anti-crack performance of the concrete deck within the hogging moment region. Four different specimens were designed to account for different layer thickness of UHPC. Bending experiments of the UHPC–RC composite deck were undertaken and a corresponding finite element model was established to study the behavior of the UHPC–RC composite deck. The regularity of crack development in different UHPC layer thicknesses was revealed, and the load-displacement results were compared to investigate the ultimate capacity of a steel–concrete composite bridge structure using a UHPC–RC composite deck. Finally, with consideration of material cost, a reasonable UHPC layer thickness suitable for the composite deck was obtained to provide a reference for the design of a UHPC–RC composite deck.

Fatigue performance of prefabricated coarse aggregate ultrahigh-performance concrete deck subjected to negative bending moment

The concrete deck of a steel–concrete composite bridge is vulnerable to cracking under negative bending moments of fatigue loads. Thus, this work performed fatigue tests on the prefabricated decks to study the influences of the curing method and stress level on the fatigue behavior of the prefabricated ultrahigh-performance concrete (UHPC) deck in an assembled steel–UHPC composite beam under negative bending moments. A numerical simulation was further conducted to investigate the behavior of the decks with joints. The results indicate that the effect of the curing method on the fatigue performance of reinforced UHPC decks is not as pronounced as that on their static performance. The prefabricated UHPC decks exhibit excellent fatigue performance, and fatigue cracks do not form until 13 million loading cycles when the upper fatigue limit is near the breaking load. On the other hand, the deck with a joint has a substantially lower fatigue cracking resistance than the prefabricated ones. The maximum fatigue crack width of the deck with a joint is 0.08 mm at low stress amplitudes. As a result, even though the UHPC has high fatigue performance, further joint reinforcing is recommended.

Optimal design of steel–concrete composite bridge based on a transfer function discrete swarm intelligence algorithm

Bridge optimization can be complex because of the large number of variables involved in the problem. In this paper, two box-girder steel–concrete composite bridge single objective optimizations have been carried out considering cost and CO_{2} emissions as objective functions. Taking CO_{2} emissions as an objective function allows to add sustainable criteria to compare the results with cost. SAMO2, SCA, and Jaya metaheuristics have been applied to reach this goal. Transfer functions have been implemented to fit SCA and Jaya to the discontinuous nature of the bridge optimization problem. Furthermore, a Design of Experiments has been carried out to tune the algorithm to set its parameters. Consequently, it has been observed that SCA shows similar values for objective cost function as SAMO2 but improves computational time by 18% while also getting lower values for the objective function result deviation. From a cost and CO_{2} optimization analysis, it has been observed that a reduction of 2.51 kg CO_{2} is obtained by each euro reduced using metaheuristic techniques. Moreover, for both optimization objectives, it is observed that adding cells to bridge cross-sections improves not only the section behavior but also the optimization results. Finally, it is observed that the proposed design of double composite action in the supports allows to remove continuous longitudinal stiffeners in the bottom flange in this study.

Dynamic real-time reliability prediction of bridge structures based on Copula–BHDLM and measured stress data

This study presents a novel dynamic real-time reliability prediction method by considering the time-varying correlation among the data at multiple measurement points. The Bayesian Hilbert dynamic linear model (BHDLM) is developed to predict the stress response, and the dynamic real-time reliability is then predicted by using the Pair-Copula theory. To illustrate the feasibility of the proposed method, the dynamic real-time reliability of a steel–concrete composite girder bridge based on the simulated stress data due to a single vehicle with various weights and random traffic flow load is predicted. Finally, the dynamic reliability of a real bridge based on the monitoring stress data is predicted. The results show that the proposed BHDLM is effective for predicting coupled stresses, and the dynamic real-time reliability can be predicted. In addition, the predicted dynamic reliability of the real bridge demonstrates that the influence of the data correlation should be considered.

Dynamic Analysis of a Steel–Concrete Composite Box-Girder Bridge–Train Coupling System Considering Slip, Shear-Lag and Time-Dependent Effects

A dynamic computational program considering slip, shear-lag and time-dependent effects of composite box-girder bridge–train coupling system is firstly proposed based on the authors’ previous studies. In the program, the long-term vertical displacement of a composite bridge is firstly calculated. The calculated vertical displacement is then superimposed on the existing uneven track as the new excitation of the composite box-girder bridge–train coupling system to obtain the dynamic responses of the bridge–train coupling system. A 3 × 40 m simply supported steel–concrete composite box-girder bridge is selected to investigate the influence of its time-dependent behavior on its dynamic responses. The results showed that the time-dependent effect will amplify the dynamic characteristics of the composite box-girder bridge and the high-speed train. The maximum vertical displacement and acceleration of the composite bridge increase by 8.82% and 13.64%, and the maximum vertical acceleration of the train body increases by 144.78%. Additionally, the slip and shear-lag effects have an impact on the dynamic responses of the composite box-girder bridge–train coupling system at different operation times. The dynamic responses of the coupling system strengthen with the decrease in shear connection stiffness. The dynamic responses of the system may be underestimated when the shear-lag effect is not neglected. Therefore, these conclusions should be given sufficient attention in the design, construction and operation of high-speed railway composite bridges.

Structural performance of steel–concrete composite beams with UHPC overlays under hogging moment

This paper investigates the usage of a thin layer of Ultra-high performance concrete (UHPC) reinforcing the concrete decks at the hogging moment region of steel–concrete composite beam bridges. An integrated experimental and numerical study was conducted to assess the influence of several parameters, such as the type of overlay concrete, arrangement of interfacial shear steel rebars, and presence of wire meshes, on the structural performance of the retrofitted composite beams. In the experimental program, five steel–concrete composite beams, including one normal concrete (NC)-strengthened composite beam and four UHPC-strengthened composite beams, were fabricated and tested. Experimental results indicate that the application of UHPC overlays significantly improved the structural performance of the retrofitted composite beams, and providing wire meshes in UHPC overlays restricted crack propagation of combined UHPC-NC decks. The bending stiffness and cracking resistance of the UHPC-strengthened composite beams were 25.2% and 368.7%, respectively higher than those of the NC-strengthened composite beams. As expected, the shear steel rebars can avoid sliding and uplifting at the substrate-to-overlay interface, and the utilization of shear steel rebars by a ratio of 0.28% magnified the bending stiffness and cracking resistance of the retrofitted beams by 9.7% and 5.1%, respectively, as compared to those without the rebars. In the numerical simulation, a three-dimensional finite element (FE) analysis of the composite beams was carried out, and the simulation results were validated with the experimental data. It is shown that the retrofitted beams under hogging moment finally failed due to fracture of the longitudinal steel reinforcements in the original decks, regardless of the presence of bonded overlays. Moreover, an analytical model for the combined UHPC-NC deck was developed to provide reliable predictions for the composite beams with UHPC overlays under hogging moment.

Innovative design of long-span steel–concrete composite bridge using multi-material topology optimization

This paper proposes a novel bridge design approach based on multi-material topology optimization, which realizes the process from conceptual design to detailed design, and an innovative bridge form is obtained with the proposed approach. In the present study, the multi-material bi-directional evolutionary structural optimization (MBESO) method, which is developed from the bi-directional evolutionary structural optimization (BESO) method, is used as the algorithm which can effectively handle topology optimization problems involving multiple materials. Since the method assigns two different materials to the tension and compression members in a structure, it is particularly suitable for designing bridge structures composed of steel and concrete. A three-span bridge with a main span of 350 m is used as an example to apply the MBESO method for the topology optimization design, and a set of techniques are introduced, such as the variation of the design domain, the utilization of symmetry, the selection of the non-design domain and the consideration of multiple load cases, to obtain multiple optimization results. By comprehensively studying the functionality, ease of construction, and aesthetic properties, a competitive result is selected as the proposed conceptual design for the bridge, and then a detailed design, including an implementable construction process, is achieved and verified by finite element analysis. The comparison between the proposed bridge and other typical bridge types based on technical and economic indicators clearly shows the obvious advantages of the new type of bridge design. This research work realizes the whole process to obtain the detailed design of a new bridge type from the form-finding with the MBESO method, revealing the considerable value of applying multi-material topology optimization to the design of practical long-span bridges.

An efficient model for simulation of temperature field of steel-concrete composite beam bridges

Thermal performance between steel and concrete differs significantly and leads to the complexity of the temperature field and effect of steel–concrete composite bridges. Refined numerical models and accurately calibrated thermal parameters can solve the transient analysis of complex temperature fields. However, the method is inefficient and difficult to apply to analyzing massive historical data in calculating design temperature loads. In this paper, a vertical discrete and dimensionality-reduced model of the steel–concrete composite bridge is deduced and established for rapid temperature load calculation. A MATLAB-based state equation solving method is proposed to implement the one-dimensional efficient numerical model. Besides, an outdoor sunshine experiment is conducted to study the temperature field. The outdoor sunshine experiment measurements and refined model simulations verify the efficient numerical model. The computational efficiency of the efficient model is nearly 1000 times higher than that of the refined model, achieving rapid calculation of the composite bridge temperature field. The efficient thermal model proposed in this paper provides a powerful tool for analyzing the temperature field and effect and calculating the design temperature load of the composite bridge.

Steel-alkali activated cement based ultra-high performance concrete lightweight composite bridge decks: Flexural behavior

The production energy consumption and carbon dioxide emissions of alkali activated cement-based material (AAM) are low which make it environmentally friendly. At the same time, alkali activated cement based ultra-high-performance concrete (AAUHPC) has equivalent mechanical properties to ultra-high performance concrete (UHPC). In this paper, the effects of the loading regime, the thickness of concrete cover, reinforcement ratio and the degree of shear connection on the bending performance were investigated, and the failure mode, load–deflection behavior, load–strain response and interface slip between the AAUHPC overlay and steel deck were analyzed. The results show that the bending resistance of a steel-AAUHPC lightweight composite deck is equivalent to that of a steel-UHPC lightweight composite deck (LWCD). Under both positive and negative moment, the evolution of the load–deflection and load–strain response of a LWCD has staged characteristics. An increase of the thickness of concrete cover can delay the arrival of the yield stage and reduces the peak value of the bending strain, while improving its bending performance. An increase of the reinforcement ratio can effectively reduce the ultimate tensile strain at each stage of the composite plate, delay crack development, reduce the crack width, and greatly improve the ductility of the steel-AAUHPC lightweight composite deck. An increase of the degree of shear connection significantly increases the compressive strain in the steel deck, and significantly reduces the relative slip between the AAUHPC overlay and steel deck, thereby improving the composite action. It can provide a basis for the design and application of steel-AAUHPC lightweight composite decks and promote the development of more environmentally sustainable steel–concrete composite structures.

Impact of elevated temperature on the behavior of full-scale concrete bridge deck slabs reinforced with GFRP bars

The fiber reinforced polymer (FRP)-concrete composite bridge deck is expected to be a competitive alternative to the reinforced concrete bridge deck owing to its great durability, low weight, and high loading efficacy. The advantages of glass fiber reinforced polymer (GFRP) reinforcement in relation to heated damaged full-scale concrete bridge deck slabs encourage the extension of knowledge regarding the possibilities of combining the GFRP and heated damaged concrete to use the synergy of benefits that can be achieved in the construction and/or rehabilitation of bridges. This study presents a three-dimensional nonlinear finite element analysis (NLFEA) simulating the response of full-scale concrete bridge deck slabs reinforced with GFRP bars. A control slab model was developed initially and properly calibrated and validated against published independent experimental results. A parametric study was then conducted through creating twenty-four NLFEA models with different parameters: type of reinforcement (GFRP and steel), bottom transverse reinforcement ratio (ρ of 0.38, 0.46, and 0.57), and elevated temperature (20 °C, 100 °C, 200 °C, and 300 °C). The GFRP bars reinforcement of bridge deck slabs had superior effects on the ultimate load, elastic stiffness, post cracking stiffness, elastic energy absorption and post cracking energy and a little impact on ultimate deflection compared with steel reinforcement and the efficiency of GFRP bars increased with the heated damage level. Punching shear failure with a very similar cracking pattern was observed almost in all slabs and the bottom transverse reinforcement ratio is the main parameter affecting the tensile strains.

Discrete swarm intelligence optimization algorithms applied to steel–concrete composite bridges

Composite bridge optimization might be challenging because of the significant number of variables involved in the problem. The optimization of a box-girder steel–concrete composite bridge was done in this study with cost and CO2 emissions as objective functions. Given this challenge, this study proposes a hybrid algorithm that integrates the unsupervised learning technique of k-means with continuous swarm intelligence metaheuristics to strengthen the latter’s performance. In particular, the metaheuristics sine-cosine and cuckoo search are discretized. The contribution of the k-means operator regarding the quality of the solutions obtained is studied. First, random operators are designed to use transfer functions later to evaluate and compare the performances. Additionally, to have another point of comparison, a version of simulated annealing was adapted, which has solved related optimization problems efficiently. The results show that our hybrid proposal outperforms the different algorithms designed.

Application of Partial Shear Connection in Steel–Concrete Semi-Continuous Composite Girder Bridges

In the hogging moment regions of steel–concrete composite continuous girder bridges, a detrimental condition appears such that concrete slab bears tensile stress and the steel girder bears compressive stress. Decreasing the shear connection in the hogging moment regions helps to improve the mechanical performance for steel–concrete continuous composite girder bridges. In this paper, analytical models for the calculation of composite girders considering partial shear connection (PSC) action are discussed. A project case of Qiwu Bridge in Jiangxi Province using partial shear connection action is introduced. A nonlinear finite element model of Qiwu Bridge is established through ABAQUS® to simulate and predict the mechanical properties and structural performance. Based on the finite element method results, the influence of PSC on various parameters is analysed by performing a parametric analysis. Numerical results show that arranging a partial shear connection region can effectively reduce the crack region and disperse areas having high stress concentration, but shear stiffness mutation can significantly increase the stress level at the edge of the partial shear connection region.

Parameter Optimization and Bending Performance Analysis of a Corrugated Steel Plate-UHPC Composite Bridge Deck with PZ Shear Connectors

Composite bridge decks consisting of steel plates and concrete are used to minimize fatigue cracking and damage of asphalt pavement of orthotropic steel bridge decks subjected to wheel loads. This paper presents a methodology to optimize the parameters and mechanical performance of a corrugated steel plate-ultrahigh-performance concrete (UHPC) composite bridge deck with panel zone (PZ) shear connectors using the improved non-dominated sorting genetic algorithm (NSGA-II). A 3-D finite element model is established in ANSYS Workbench software to conduct numerical parameter analysis, and ABAQUS software is used to analyze the optimized model’s mechanical performance. The results show a significant improvement in the mechanical performance of the optimized composite bridge deck, with a 27.66% decrease in the maximum stress in the UHPC layer. The vertical displacement of the optimized composite bridge deck increases sharply when the load reaches 90% of the ultimate load, and a significant change in the strain is caused by the sliding displacement between the UHPC layer and steel plate. The bottom part of the corrugation yields first in the middle span, followed by failures of the ribs. In addition, as the tensile stress increases, damage occurs first in the UHPC layer near the PZ shear connectors in the shear bending area and the bottom in the bending area, expanding significantly to the entire bending and loading areas. The results indicate that the parameter optimization of the corrugated steel plate-UHPC composite bridge deck using NSGA-II improves the structure’s bending performance.

Accurate structural displacement monitoring by data fusion of a consumer-grade camera and accelerometers

The displacement responses of bridge structures are critical both for structural health monitoring and structural safety evaluation. Using vision-based sensors to measure structural displacement responses is an effective method and has attracted considerable attention owing to its advantages of achieving non-contact, time-saving, and full-field measurements. However, there are several obstacles, including the limited frame rate, insufficient accuracy in large-scale measurements, and camera instability, which prevent the application of vision-based sensors. To overcome the shortcomings and improve the accuracies of the vision-based sensors, a displacement monitoring system combined with a consumer-grade camera and accelerometers was developed. Accelerometers attached to the target structures were used to reconstruct the dynamic displacement for data fusion with the vision-based displacement, while an accelerometer attached to the camera was used for camera vibration cancellation. Dynamic loading tests on a self–anchored suspension model bridge were conducted and results of the proposed system, the linear variable differential transformers, and a conventional vision-based system were compared. Field tests on a steel–concrete composite continuous beam bridge and a cable-stayed railway bridge were conducted, and the potential of the proposed system for use in real structures was validated.

Experimental and numerical study on vibration and structure-borne noise of high-speed railway composite bridge

In order to investigate the characteristics of train-induced vibration and structure-borne noise of high-speed railway steel–concrete composite bridge, a 5 × 50 m continuous steel–concrete composite bridge is adopted and tested in this paper. The vibration acceleration response and radiated noise of the bridge are measured during the test. The prediction model of vibration and structure-borne noise is further established to explore the radiation spectrum characteristics of the composite bridge. Firstly, the train-track-bridge dynamic interaction theory is applied to calculate the vibration response of the bridge under high-speed train loading. The boundary element method (BEM) and Statistical Energy Analysis (SEA) are subsequently combined to predict the full-frequency band noise of the structure. The accuracy of the model is verified through comparison with the measured data. Based on the field test and numerical study, it is found that the dominant frequency range of vibration and structure-borne noise is 20 ∼ 1000 Hz. The root mean square (RMS) accelerations of vertical and transverse vibration are lower than 0.5 m/s2, while local vibration of the steel web can reach 1.0 ∼ 2.5 m/s2. As a result, the acoustical contribution of the web at far-field site can reach 80% of the structure-borne noise. In addition, the setting of the bottom concrete reduces the acceleration level of the bottom plate by 10.75 dB and the radiated noise by 7.16 dB, showing a good effect of vibration and noise reduction.

Push-out tests on studs with UHPC cover embedded in UHPC-NSC composite slab

To cope with the volumetric cost of the ultra-high-performance concrete (UHPC) and enhance performance of studs in steel–concrete composite bridges, a novel bridge slab system has been developed. In this system, the slab was made of UHPC and normal strength concrete (NSC), and the studs were covered with UHPC. Since the static behavior of studs with UHPC cover embedded in UHPC-NSC composite slab is different from in the NSC or UHPC slab, an experimental study is needed to investigate the ultimate strength of studs, as well as the relative slip and failure patterns. The mainly parameters considered include stud diameter, stud height, and stud root with or without UHPC cover. The experimental results reveal that the mechanical behavior of studs in the proposed composite slab system was successfully improved. The ultimate strengths of the studs with a diameter of 19 mm and 22 mm covered with UHPC embedded in UHPC-NSC composite slab are only 3.8 % and 2 % less than that in UHPC slab, respectively. The relative slips of stud with UHPC cover in the UHPC-NSC composite slab are larger than 6 mm, which satisfy the ductility demand in EC4. The results also show that the current design codes underestimate the actual shear strength of the stud with UHPC cover in the UHPC-NSC composite slab. Finally, an equation is proposed to predict the shear stiffness of a stud with UHPC cover embedded in the UHPC-NSC composite slab based on the energy equivalent model, and verified by the experimental results. The calculation value agrees well with the experimental result for a stud diameter≥16 mm.