Composite Girder Bridges Research Articles

Analytical Investigation of Fatigue Behavior in a Modified Composite Steel Box Concrete Girder Bridge with Corrugated Steel Webs under Pavement and Expansion Joint Deterioration

Analytical Investigation of Fatigue Behavior in a Modified Composite Steel Box Concrete Girder Bridge with Corrugated Steel Webs under Pavement and Expansion Joint Deterioration

Flexural capacity and fatigue performance of full-scale FRP-concrete composite vehicular bridge girders

Since 2020, hybrid fiber reinforced polymer composite tub (CT) girders have been used in the construction of four in-service vehicular bridges in the United States and two additional bridges are under construction. However, despite their growing acceptance, there are very few FRP highway girder bridges throughout the world, only one full-scale destructive test of a CT girder has been conducted to-date, and girder fatigue life has not been explored. To provide additional strength data, a full-scale CT girder was manufactured and tested to failure in flexure. The results of this test confirmed the CT girder’s design efficiency, performance of its novel girder-deck shear connectors, and expected capacity determined through nonlinear moment-curvature analysis that accounts for the nonlinear compressive response and cracking of the concrete deck. A second identical CT girder specimen was subjected to 3,000,000 cycles of factored fatigue load and subsequently tested to failure in flexure to provide a direct assessment of cumulative fatigue damage. Full-scale fatigue tests of complex, vacuum-infused, hybrid glass-carbon members are unusual, making this test particularly valuable. The girder did exhibit damage accumulation during the first 1,500,000 cycles as evidenced by increasing deflection for the same applied load, but deflections remained relatively constant for the remaining cycles. The failure test of this specimen revealed a 33% loss in flexural strength due to flexural fatigue damage. However, the post-fatigue flexural strength still exceeded AASHTO capacity requirements by 43%, indicating a significant post-fatigue safety margin. The subsequent examination of girder fatigue life accounting for damage accumulation under realistic truck loading spectra indicates that in many applications, CT girder bridges have estimated fatigue lives in excess of 100 years, although caution must be exercised with when interpreting this result given that only one specimen was tested under specific laboratory conditions.

Design resistance strengths of composite steel box girder bridge using different codes

Bridges design based on prescriptive normative rules regarding loads and their combinations, safety factors, material properties, analysis methods, required verifications, and other issues that are included in design codes. In addition, Composite Steel Box Girder (CSBG) bridges present a prominent structural solution for straight and curved bridges with moderate spans, because of their large bending resistance and high torsional stiffness as well as rapid erection. This paper aims to perform a detailed theoretical comparative study between fundamental calculations of the design resistance strengths of shear, Vn or VRd, and flexure, Mn or MRd, in positive (sagging) and negative (hogging) moment regions, of CSBG highway bridges. The comparison is involved with design specification methodologies proposed by Egyptian Code of Practice (ECP-207-part 6), Bridge Design Specifications (BDS) presented by Association of State Highway and Transportation Officials (AASHTO), and European Standard (EC-4). On its turn, the study aims to standing on differences and similarities between considered standards in the design of such bridges.

The thermal responses of composite box girder bridges with corrugated steel webs under solar radiation

Owing to the direct exposure to complex atmospheric environments, the temperature field of composite box girder bridge with corrugated steel webs (CBGB-CSW) is likely non-uniformly distributed. Whereas, the current researches regarding the thermal responses of CBGB-CSW are insufficient, and the thermal responses of CBGB-CSW under solar radiation are still unknown. Therefore, this paper conducted a long-term temperature experiment on a scaled model to explore the temperature distribution characteristics in CBGB-CSW. Meanwhile, a three-dimensional thermal–mechanical coupling Finite Element (FE) model is established to simulate the temperature field in the experiment girder. The accuracy and effectiveness of the developed FE model has been verified by the measured temperature data. Therewith, the thermal responses (i.e., stress and displacement) of a full-scale continuous CBGB-CSW with a span of 150 m are numerically investigated. The results indicate that the maximum stresses always occur at the midspan section (with a depth of 5 m) of the continuous CBGB-CSW, and considerable concentrations of stress are observed in the steel-concrete junction. The maximum longitudinal tensile and compressive normal stresses within 0.4 m of the upper junction can reach 5.55 MPa and −8.46 MPa respectively, and those of the lower junction can reach 6.96 MPa and −7.05 MPa respectively. Besides, owing to the impacts of vertical and horizontal temperature gradients, significant displacements of the whole bridge can also be observed. The maximum vertical displacement (5.33 mm) of the CBGB-CSW is estimated at the top plate in the midspan, while the maximum horizontal displacement (0.74 mm) is estimated at the trough of the southern corrugated steel web in the midspan. Notably, the outcomes of this paper can provide some useful references for engineers and scholars to understand the thermal responses of the CBGB-CSW.

Calculation method of temporary cable force in incremental launching construction of large span steel box girder without auxiliary pier

The Fenshui River Bridge is a steel–concrete composite girder bridge with a main span of 90 m. Due to the topographical constraints, the steel box girder was constructed without the use of auxiliary piers, employing incremental launching techniques. This article focuses on the construction technology used for the steel box girder of the Fenshui River Bridge. Firstly, using the influence matrix method, the cable force is determined based on the maximum cantilever state of the structure, with the vertical deformation of the front end of the guide beam and the horizontal deformation of the top of the tower as the control objectives. The unstressed cable length is then calculated based on the mechanical relationship between cable deformation and cable force. A calculation method for adaptive cable force is proposed, which is based on the variation of the stress-free cable length within the adaptive structural system. Next, the finite element analysis method was employed to determine the optimal layout position for the tower. The results indicate that during the incremental launching construction of the steel box girder, the calculated cable forces using the method proposed in this paper are in close agreement with the measured cable forces. At the maximum cantilever state of the structure, the calculated and measured values of the cable force resulted in a percentage difference of 3.96%. The calculated values of deformation and stress in key sections showed a percentage difference of 6.4% for deformation and 6.6% for stress. To maximize the effectiveness of the tower and cable, the tower should be positioned above the bridge pier when the guide beam crosses the maximum span. The findings of this paper can serve as a reference for the construction of similar types of bridges.

Temperature Extreme Value Evaluation of Composite Beams Based on Copula Functions

The solar temperature field of steel-concrete composite girder bridges has a significant impact on structural stress. To evaluate the distribution of solar temperatures, this paper conducted analyses of the solar temperature field of the Xuefeng Lake Bridge through on-site measurements and numerical simulations. The study investigated the temperature field characteristics of the composite girders according to the temperature data. Based on the numerical simulation results, a finite element computational model for the vertical temperature gradient of the steel-concrete composite girder bridge was established, and the maximum gradient temperature values of the composite girders were calculated by using the 24-year historical data from 2000 to 2023. The extreme value parameters related to the GEV distribution model were determined. Taking into account the correlation between the annual maximum environmental temperature and wind speed, a joint distribution model was established using Copula functions. The results indicate that the average error of the numerical model is within 5%. The wind-temperature joint distribution model, considering the effects of wind speed, tends to provide more conservative results. The calculated extreme values of temperature gradient load show an expanding trend, with the exceedance probabilities for recurrence periods of 100 years, 50 years, 20 years, 10 years, and 5 years being 0.64%, 1.34%, 2.29%, 3.51%, and 7.32%, respectively.

Study on Vibration and Noise of Railway Steel–Concrete Composite Box Girder Bridge Considering Vehicle–Bridge Coupling Effect

A steel–concrete composite beam bridge fully exploits the mechanical advantages of the concrete structure and steel structure, and has the advantages of a fast construction speed and large stiffness. It is of certain research value to explore the application of this bridge type in the field of railway bridges. However, with the rapid development of domestic high-speed railway construction, the problem of vibration and noise radiation of high-speed railway bridges caused by train loads is becoming more and more serious. A steel–concrete composite beam bridge combines the tensile characteristics of steel and the compressive characteristics of concrete perfectly. At the same time, it also has the characteristics of a steel bridge and concrete bridge in terms of vibration and noise radiation. This feature makes the study of the vibration and noise of the bridge type more complicated. Therefore, in this paper, the characteristics of vibration and noise radiation of a high-speed railway steel–concrete composite box girder bridge are studied in detail from two aspects: the theoretical basis and a numerical simulation. The main results obtained are as follows: Relying on the idea of vehicle–rail–bridge coupling dynamics, a structural dynamics analysis model of a steel–concrete combined girder bridge for a high-speed railroad was established, and numerical program simulation of the vibration of the vehicle–rail–bridge coupling system was carried out based on the parametric design language of ANSYS 18.0 and the language of MATLAB R2021a, and the structural vibration results were analyzed in both the time domain and frequency domain. By using different time-step loading for the vehicle–rail–bridge coupling vibration analysis, the computational efficiency can be effectively improved under the condition of guaranteeing the accuracy of the result analysis within 100 Hz. Based on the power flow equilibrium equation, a statistical energy method of calculating the high-frequency noise radiation is theoretically derived. Based on the theoretical basis of the statistical energy method, the high-frequency noise in the structure is numerically simulated in the VAONE 2021 software, and the average contribution of the concrete roof plate to the three acoustic field points constructed in this paper is as high as 50%, which is of great significance in the study of noise reduction in steel–concrete composite girders.

Fatigue performance of a steel truss web-concrete external joint in railway composite continuous girder bridges

ABSTRACT This study conducted fatigue tests on two 1:3 steel truss web-concrete external joints to investigate their fatigue performance. The fatigue failure mode of the external joints and the stress distribution of each component were investigated. In addition, a finite element analysis (FEA) model was established, and parametric analysis was carried out to discuss the influence of gusset plate thickness, stiffening plate layout, and gusset plate structural form on fatigue performance. The results show that the fatigue life of the external joints under the design load amplitude is 3.75 million times (187.5 years). Fatigue cracks appear in the junction area between the gusset plate and the end of the stiffening plate, which is a weak fatigue detail of the external joint. The fatigue cracks cause local stress redistribution of the gusset plate. The stress at the junction (GN3) between the gusset plate and the stiffening plate N3 can be reduced by up to 37%, 61%, and 21% by altering the above three factors. Furthermore, the fatigue life of the optimized joint is increased by 1.4 times, indicating that the fatigue performance can be significantly enhanced by improving the stiffening plate layout and the gusset plate structural form.

Research Progress on Shear Characteristics and Rapid Post-Disaster Construction of Narrow-Width Steel Box–UHPC Composite Beams

The narrow-width steel box girder is an important type of steel–concrete composite bridge structure, which is usually composed of reinforced concrete wing plates, narrow steel boxes partially injected with concrete, and shear connectors that promote shear force transfer. The utilization of narrow-width steel box girders, augmented by partially filled concrete, embodies the synthesis of steel and concrete elements, fostering structural efficiency. Moreover, its attributes, including reduced structural weight, diminished vertical profile, enhanced load-bearing capacity, and augmented stiffness, have prompted its gradual integration into bridge engineering applications. In this study, the calculated values of shear strength under three current design codes were reviewed, and the shear failure phenomena and its determinants of narrow-width steel box–ultra-high-performance concrete (UHPC) composite beams under negative bending moment conditions were investigated, which were mainly determined by shear span ratio, concrete wing plate, UHPC steel fiber content, UHPC plate thickness, and transverse partition inside the box. Concurrently, this paper evaluates two innovative structural designs, including a double-narrow steel box girder and a three-narrow steel box girder. In addition, strategies to reduce crack formation under the negative bending moment of long-span continuous narrow and wide box girder abutments are discussed, and we show that this measure can effectively control the formation of cracks to support the negative bending moment zone. At the same time, the scope of the application of a narrow-width steel box girder composite bridge is reviewed, and the conclusion is that a narrow-width steel box girder is mainly used in small-radius flat-curved bridges or widened-ramp bridges with a span of 30 m or more in interworking areas and in the main line with a 60–100 m span in mountainous or urban areas. Finally, the research direction of the shear resistance of the UHPC–narrow steel box girder under negative bending moments is proposed.

Concept and flexural performance of non-prestressed steel plate-UHPC-NC composite girder bridge

A novel non-prestressed composite girder bridge, incorporating steel plates, ultra-high performance concrete (UHPC), and normal concrete (NC), is proposed for small and medium-span bridges. For the proposed steel plate-UHPC-NC composite bridge, UHPC girders are reinforced with steel plates on the bottom in lieu of part of closely-spaced rebars in the beam. Cast-in-situ NC deck slab is adopted to ensure its transverse integrity and to reduce costs in comparison with UHPC bridge deck. To verify the performance of the proposed novel composite bridge, three types of UHPC-NC composite beams with same reinforcement ratio (reinforced with only rebars, only steel plates, both rebars and steel plates) were first conducted with bending test. The impact of various reinforcement types on the flexural behaviors of UHPC-NC composite specimens was identified, including failure mode, crack distribution pattern, and crack width development. The findings demonstrated that the UHPC girder reinforced with both steel plates and rebars would significantly enhance the crack resistance of UHPC girders during bending in comparison with the other two. In addition, the composite girder reinforced with steel plates and rebars can achieve a nominal stress of 31.41 MPa at the serviceability limit state (with a UHPC crack width of 0.05 mm). The commercial software DIANA is then utilized to numerically simulate the mechanical properties of the proposed composite beam. The deviation between the finite element (FE) results and the experimental load-bearing capacity is within 1.9 %. Parameter analysis demonstrates that the bridge deck's strength has negligible influence on the load-carrying capacity of the proposed composite beam. Finally, a design scenario for a 30 m-span simple-supported bridge is conducted, and the initial cost analysis indicates that the proposed steel plate-UHPC-NC composite girder is 2 % lower than the conventional prestressed concrete T-girder. The proposed non-prestressed steel plate-UHPC-NC bridge presents notable benefits, including cost-effectiveness, strong crack resistance, and the prospect of complete prefabrication, offering a feasible alternative for small and medium-span bridges.

Residual Stress and Fatigue Strength Analysis of Stiffener Welds of Steel-Plate Composite Girder Bridge Considering Welding Sequence

Residual Stress and Fatigue Strength Analysis of Stiffener Welds of Steel-Plate Composite Girder Bridge Considering Welding Sequence

Comparative Study on the Seismic Vulnerability of Continuous Bridges with Steel–Concrete Composite Girder and Reinforced Concrete Girder

For medium- and small-span bridges, the weight of the superstructure in steel–concrete composite girder bridges is lighter than that of a reinforced concrete girder bridge. However, it is still uncertain whether steel–concrete composite girder bridges exhibit superior seismic performance compared to reinforced concrete girder bridges. This study quantitatively compared the seismic performance of the two types of bridges. Using the theory of probabilistic seismic demand analysis, the seismic vulnerability curves of bridges were derived. To conduct seismic demand analysis for probabilistic analysis on the OpenSEES platform, bridge samples were generated using the Latin hypercube stratified sampling method, which considers the uncertainties associated with the two types of bridges. The vulnerability curves of the piers, bearings, abutments, and the system of the two bridges were established using probabilistic analysis of the time history analyses. The results showed that the seismic vulnerabilities of components and the overall system of the steel–concrete composite girder bridge were both lower than those of the reinforced concrete girder bridge. When the peak ground acceleration (PGA) of the ground motion was 0.3 g, the moderate and serious damage probabilities of the piers in the steel–concrete composite bridge were only 54.61% and 60.89%, respectively, of those of the reinforced concrete bridge. Consequently, replacing the upper reinforced concrete girders with steel–concrete composite girders can significantly improve the seismic performance of a large number of existing bridges.

Bending Performance of a Prestressed Concrete Composite Girder Bridge with Steel Truss Webs

An experiment was conducted on a prestressed concrete (PC) composite girder bridge with steel truss webs to investigate its flexural performance. The mechanical characteristics and failure modes of a PC composite girder bridge with steel truss webs was clarified. Finite element (FE) analysis was carried out, and the influence of the girder height-to-span ratio and eccentric loading effect on the flexural performance of a composite beam bridge with a steel truss web was discussed. The method for calculating the cracking bending moment, the bending moment at the rebar yield stage, and the ultimate bending moment of a PC composite girder with steel truss webs was proposed. Key findings include that, in both the elastic and cracking elastic stages, the strain of the bottom and top conforms to the plane-section assumption. Throughout the loading process, there was no occurrence of joint failure or local buckling failure in the steel truss webs; the composite girder ultimately fails due to excessive deformation, indicating that the overall mechanical performance of the composite beam is good. The deflection and stress in the mid-span section decrease with an increasing height-to-span ratio, and there are significant impacts of eccentric loading on deflection and stress. Compared with the results of the FE analysis and test, the calculation methods of the cracking moment, reinforcement yield moment, and ultimate moment of PC composite girders with steel truss webs presented in this paper have a high accuracy.

Push-Out Analysis on the Shear Performance of a New Type of Bellow-Sleeved Stud

For continuous steel–concrete composite girder bridges based on the post-combined method, the conventional rectangular group studs contribute to the isolation of the steel girder and the concrete slab before prestressing, leading to the majority of prestress forces being introduced to the concrete slab. However, rectangular-group stud holes cause the prestress forces to be unevenly distributed. In this study, a new type of bellow-sleeved stud (BSS) was developed to mitigate the weakening effects of rectangular group stud holes on the slab. A steel corrugated sleeve with a diameter of 60 mm was employed to cover the stud, which served as an internal formwork to prevent the concrete from bonding with the root of the stud. After prestressing was complete, the steel sleeve was filled with ultra-high-performance concrete (UHPC) to create a reliable combination between the concrete slab and the steel girder. To investigate the shear performance of this new type of connection, eight push-out test specimens were designed, and finite-element models were built. This study drew a comparison between the BSS and the ordinary headed stud (OHS). The research findings suggested that the BSS is subjected to less bending–shear coupling and offers a 4.5% increase in shear strength and a 31.9% increase in shear stiffness compared with the OHS. The study also analyzed the structural parameters influencing the shear performance of the BSS. It is found that the steel sleeve of the BSS has a negative effect on shear performance, but this can be mitigated by infusing high-strength material into the sleeve. Furthermore, the study examined the effect of construction quality on shear performance and suggested that sleeve deviation and grout leakage considerably reduced the shear performance of the BSS. Accordingly, strict control over the construction quality of the BSS is necessary.

Study on Fatigue Life of PC Composite Box Girder Bridge with Corrugated Steel Webs under the Combined Action of Temperature and Static Wind Loads

The large-span bridge is highly sensitive to temperature and wind loads. Therefore, it is essential to study the bridge’s fatigue life under the combined effects of temperature and static wind loads. This study focuses on the main bridge of Qiao Jia-fan 2# on the Yinkun Expressway (G85), with a span of 250 m and a configuration of a PC composite box girder bridge with corrugated steel webs. Firstly, on-site temperature and wind direction measurements with wind speed were conducted at the bridge site. Origin 2022 software is used to make mathematical statistics on the data, the representative values of atmospheric temperature difference between day and night and the basic wind speeds are calculated. Secondly, based on the basic wind speed in the most unfavorable wind direction, the static three-component force coefficients of bridge at different angles of attack are calculated by FLUENT 2022 R1 software. By comparison, the most unfavorable wind angle of attack, wind direction and wind load value of Qiao Jia-fan 2# Bridge are obtained. Finally, the finite element software MIDAS/FEA NX 2022 is used to analyze the fatigue life of the main bridge of the Qiao Jia-fan 2# Bridge. The analysis results show that the representative value of the temperature difference between day and night in the area where PC composite box girder bridge with corrugated steel webs is located is 22 °C, the most unfavorable wind direction is NNE wind direction, and the most unfavorable wind attack angle is 3° wind attack angle. It is found that the maximum stress of concrete and corrugated steel webs appears near the 0# block, and the life of corrugated steel webs is far greater than that of concrete.

Structural Design and Mechanical Behavior Investigation of Steel–Concrete Composite Decks of Narrow-Width Steel Box Composite Bridge

Steel–concrete composite decks are commonly employed in narrow-width steel box composite girder bridges to augment their lateral spanning capabilities, while the concurrent omission of longitudinal stiffeners leads to a substantial reduction in the number of components, thereby yielding a structurally optimized bridge configuration. This paper delineates the structural design parameters of a narrow-profile steel box composite girder bridge and assess the mechanical behavior of its incorporated steel–concrete composite deck under static and fatigue loading conditions. To this end, two full-scale segment specimens from the composite bridge decks were subjected to equal amplitude cyclic fatigue tests. The investigation specifically concentrated on the impacts of two types of shear connectors—namely, perforated steel plates combined with shear studs and perfobond rib shear connectors (PBL connectors)—on the static and fatigue performance, including fatigue stiffness, of the steel–concrete composite bridge decks. The results indicate that, under the static bending condition, the composite deck specimen equipped with stud connectors demonstrates superior overall flexural stiffness in comparison to the specimen featuring PBL connectors. Furthermore, the flexural stiffness of the steel–concrete composite specimens experiences a negligible alteration across two million fatigue loading cycles. Upon the completion of two million fatigue loading cycles, the composite deck specimens incorporating the shear connectors composed of perforated steel plates and shear studs exhibit relatively wider crack widths under the static peak load. Both configurations of the steel–concrete composite bridge deck specimens manifest evident interfacial detachment, signifying insufficient tensile pull-out stiffness of the shear connectors. It is recommended to increase the quantity of the shear connectors or select the pertinent types in order to enhance the interface shear resistance.

Experimental study on flexural behavior of steel-laminated concrete (NC and UHPC) composite beams with corrugated steel webs

The challenges of the substantial self-weight in prefabricated bridge deck slabs, the presence of numerous scattered steel beam components, and the low durability of bridge deck slabs have long been difficult issues to address in the context of traditional prefabricated steel-normal concrete (NC) composite girder bridges with flat steel webs. This paper proposes a solution through the optimization of structural forms and material properties by introducing a novel structural configuration as prefabricated steel-laminated concrete (LC) composite girder bridges with corrugated steel webs. The flat steel webs were substituted with corrugated steel webs, and the LC bridge deck slab was composed of a NC layer and an ultra-high performance concrete (UHPC) layer. This paper conducted three groups of experimental tests to comparatively analyze the effects of web forms and bridge deck materials on the flexural performance of composite beams. The results indicate that, under the conditions of consistent beam height and steel usage, composite beams with corrugated steel webs have fewer steel components, better stability, and smaller difference in bearing capacity compared to composite beams with flat steel webs. Compared with NC bridge deck slab, laminated bridge deck slab can increase the stiffness and bearing capacity of composite beam by about 13%, and the thickness of the bridge deck slab can be reduced by 20%. Furthermore, this paper presents a shear connection degree calculation method suitable for composite beams with corrugated steel webs, which effectively reduces the number of connectors.

Cracking performance in the hogging moment region of HSS-UHPC continuous composite girder bridges

To elucidate the cracking performance of concrete slabs at the negative bending moment region of high strength steel (HSS)-ultra high performance concrete (UHPC) continuous composite girder bridges, eight scale-reduced steel-concrete composite beams, constructed using HSS and UHPC that varying parameters of UHPC slab thickness and width and shear connection degree at the steel-concrete interface were prepared and tested. The composite beams' cracking pattern, bending stiffness, load-deflection curve, steel-concrete interfacial slippage, and strain history were presented and discussed. The test results show that the HSS-UHPC composite beams subjected to negative bending moments exhibited favorable cracking performance. With the UHPC slab width increasing from 450 mm to 550 mm, the composite beams' initial cracking moment, bending stiffness, and flexural ductility increased by 33.4%, 20.5%, and 39.8%, respectively. The utilization of a thick UHPC slab benefited the performance of the composite beams under negative bending moments. Replacing the 80 mm-thick slab with a 110 mm-thick slab improved the structure’s cracking moment and bending stiffness by 15.0% and 21.4%, respectively. Additionally, as the shear connection degree increases from 0.64 to 1.02, the initial cracking and ultimate failure moments of the composite beam were improved by 7.2% and 1.6%, respectively. In contrast, the bending stiffness of the beams with a shear connection degree of 1.02 was 12.4% smaller than those of 0.64. A comprehensive comparison between the formula-predicted cracking performance and current experimental results was performed to examine the capability of existing design approaches in calculating the HSS-UHPC composite beams. The flexural resistance algorithm proffered by Xu exhibits favorable alignment with test results, thereby providing a compelling methodology for designing HSS-UHPC continuous composite girder bridges.

Vehicle–Bridge Interaction Dynamic Analysis of Continuous Rigid Frame Composite Box Girder Bridge with Corrugated Steel Webs under Seismic Excitation

To study the vehicle–bridge interaction (VBI) of highway bridges under seismic excitation, a vehicle–bridge couple analysis method based on Ansys is proposed. The 1/2 vehicle model and space beam element model were established to analyze the VBI response of Lanzhou Xiaoshagou bridge. The self-excited excitation of the system is represented by road surface irregularity randomness, while the external excitation is represented by an earthquake. The impact of seismic types, seismic direction, seismic intensity, vehicle speed, and road surface irregularity on the bridge vibration under the vehicle–bridge coupling during an earthquake is thoroughly analyzed. The results reveal that the type of earthquake significantly influences the dynamic response of the bridge, showing a minimum difference of 31.4%. The intensity of the earthquake is positively correlated with the dynamic response of the bridge. Longitudinal and vertical earthquakes have a more noticeable effect on the bridge’s vertical vibration compared to lateral earthquakes. The ratio of the bridge response under vertical or longitudinal seismic excitation to the response of lateral earthquakes ranges from 1.50 to 26.61. Vehicle speed, road irregularity grade, and randomness have a negligible impact on the dynamic response of vehicle–bridge interaction under an earthquake, accounting for less than 3%. These findings indicate that the analysis of earthquake-bridge vibration can simplify the VBI analysis for continuous rigid frame composite box girder bridges with corrugated steel webs under seismic conditions.

The Influence of the Flexibility of a Polymeric Adhesive Layer on the Mechanical Response of a Composite Reinforced Concrete Slab and a Reinforced Concrete Beam Girder.

This study addresses the challenges of modeling flexible connections in composite structures employing a polymeric adhesive layer. These types of connections provide a more uniform stress distribution compared to conventional rigid connectors. However, they lack standardized design rules and still require much research to sufficiently comprehend their properties. The novelty of this research lies in proposing an analytical solution to address these issues. Its aim is to investigate the influence of the stiffness of the polymer adhesive on the girder's deflection and on the maximum stresses in both the adhesive and concrete. The analyzed composite structure consists of a reinforced concrete (RC) slab and an RC beam connected with a layer of flexible polyurethane (FPU) adhesive. Analytical and numerical approaches for the description of the mechanical response of a composite bridge girder are presented. Another objective is to validate the analytical design formulas using 3D nonlinear numerical analysis, both in the case of uncracked and cracked concrete. Seven types of FPUs are tested in the uniaxial tension test, each examined at five strain rates. The obtained data is used to predict the mechanical response of the considered girder using finite element analysis (FEA) as well as with a simplified one-dimensional composite beam theory. Fair agreement is found between the FEA results and theoretical predictions. A comparison of the results obtained for these two models is performed, and the similarities and discrepancies are highlighted and discussed.