Concrete Composite Girder Bridges Research Articles

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.

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.

Fragility Assessment of a Long-Unit Prestressed Concrete Composite Continuous Girder Bridge with Corrugated Steel Webs Subjected to Near-Fault Pulse-like Ground Motions Considering Spatial Variability Effects

Prestressed concrete composite girder bridges with corrugated steel webs (PCCGBCSWs) are extensively employed in bridge construction because of their low dead weight, fast construction, and high prestressing efficiency. Moreover, PCCGBCSWs will experience deformation and failure of the corrugated steel webs, including steel fatigue and fracture, during earthquakes. These changes will introduce safety hazards, which can be addressed via bridge disaster prevention and mitigation. Because near-fault pulse-like ground motions (NFPLGMs) have high peak accelerations, these motions can easily cause damage to a bridge. Therefore, in this study, a seismic fragility assessment is performed for long-unit PCCGBCSWs subjected to NFPLGMs considering spatial variability effects, and a sensitivity evaluation of the seismic fragility is conducted considering girder type, bearing type, ground motion type, and apparent wave velocity to offer a point of reference for seismic design. The results show that PCCGBCSWs are less vulnerable than concrete bridges. The shock absorption effect of the friction pendulum bearing is better than that of the viscous damper. The impact of NFPLGMs on bridges is greater than that of near-fault non-pulse-like ground motions (NFNPLMs) and far-fault ground motions (FFGMs). The seismic fragility under nonuniform excitation conditions is greater than that under uniform excitation conditions, showing an increasing trend with decreasing apparent wave velocity.

Experimental study and analysis for the long-term behavior of the steel–concrete composite girder bridge

Due to the influence of the meteorological factors, the long-term behaviors of steel–concrete composite girders of the real bridge is different from that of indoor laboratory models. In order to address this issue, a long-term field test of 4 years was performed on the simply-supported steel–concrete composite girder bridge to study the temperature, shrinkage and creep effects. The temperature field models (TFM) and mechanical behavior models (MBM) were built in sequence and verified by the test results of the concrete deck and steel girders of 2018 and 2019 since the temperature and strain changed greatly during this period. The temperature calculated by the TFM agreed well with the test results. Although the stress of composite girders obtained by the test is different from that of the MBM, the difference in the whole service stage is small. The test results of the steel cross beam, the steel–concrete interface, the wet joint and the concrete continuous layer were also discussed, and the former three were all under compressive state, while the concrete continuous layer is under tensile state in some time period with the maximum tensile stress 3.12 MPa. Then, the verified models were used to separate the temperature strain from the long-term tested strain, and the remaining tested strain is the shrinkage and creep strain. In summer and winter, the shrinkage and creep stress calculated by the age-adjusted effective modulus method (AEMM) was different from the tested values due to the influence of air humidity, initial load age, stress level and inherent error of the prediction model. Much attention should be paid to the influence of the meteorological factors on the long-term behaviors of steel–concrete composite girder bridges.

Assessment of Modal Characteristics of Steel–Concrete Composite Girder Bridge with V-Shaped Piers

As the standards of bridge design and construction continue to improve, more and more combination bridges are being put into use. The public’s demand for aesthetically pleasing bridges is also increasing, making it necessary to use the special structure of steel–concrete combinations, continuous V-shaped piers, and continuously stiffened bridges. This structure has the structural and mechanical characteristics of both a continuous girder and a V-shaped pier bridge. The span can be reduced to a certain extent because the support of the V-shaped piers can be applied directly to the main girder. The spanning capacity of the bridge is generally greater than that of a combined steel–concrete girder bridge with vertical piers. The whole bridge is continuous, without expansion joints, making it more stable and safe for traffic. At present, research on this structural bridge type is not yet complete. In this paper, the structural system and dynamic characteristics of this bridge are investigated in the context of real-life engineering. Firstly, the self-vibration characteristics of the three structures were analyzed, and their effects on the self-vibration characteristics were studied by varying the height of the crossbeam at the V-shaped piers’ support, the main beam stiffness, and the V-shaped piers’ stiffness in the three structures. The results show that the increase in main beam stiffness can effectively improve the vertical stiffness of the three structures, with the most obvious effect on structure one and the least effect on structure two; the increase in V-shaped pier stiffness causes a huge improvement in the transverse stiffness of the three structures. Subsequently, a two-unit rod system model of the background bridge was established using the finite element method, and the original model was improved by calculating the equivalent shear stiffness of the shear nail group so that it could simulate the shear joints more accurately. The effects of the shear connectors on the self-vibration characteristics of the steel–concrete combined continuous beam–V-shaped piers and continuous rigid-frame bridge were investigated through theoretical analysis and finite element simulation. It was found that due to the existence of flexible shear connectors, the interface between the steel beam and concrete slab in the combined beam has a slippage effect which causes the deformation to become unsynchronized, and there is a certain difference between vibration patterns. The stiffness of the shear connectors has a certain effect on the self-vibration frequency of the bridge. The damage to the local shear connectors does not have a large effect on the self-vibration frequency of the overall structure, but the damage to the shear connectors at the beginning of the connection between the V-shaped piers and the main beam is greater than that of the other areas. Damage to shear joints should be given special consideration in comparison to other areas.

Hybrid control of steel-concrete composite girder bridges considering the slip and shear-lag effects with MR–TMD based on train-bridge interactions

With the speed of trains higher and bridge structures towards larger spans with lighter weight, the train-bridge resonance will become fairly pronounced. Therefore, to ensure the safety of bridge structures, research on vibration control is of far-reaching significance, especially for steel–concrete composite girder bridges with mechanical properties, such as slip, and shear lag. Therefore, based on a magnetorheological tuned mass damper (MR–TMD), this paper proposes a hybrid control strategy for the steel–concrete composite girder bridge considering whether the trains are either on or off the bridge, and applies it to a numerical example, reducing vertical dynamic responses of a railway steel–concrete composite girder bridge based on train-bridge interactions. The results illustrate that this control strategy is suitable for the time-varying steel–concrete composite girder bridge-train coupling system, and exhibits reliability, stability and robustness to some extent, which has a bright future in engineering applications.

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.

Incorporating the unevenness of lane truck loading into fatigue load modeling of multi-lane bridges

The current codes in practice define fatigue load models (FLMs) to characterize the bridge damage that is induced by traffic loads. However, most FLMs are specified to load on any single traffic lane, and the characteristics of the uneven traffic load distribution over multiple lanes under real-world conditions are not revealed. This study analyzed the uneven distribution characteristic of truck loading over multiple lanes based on multiple sets of weigh-in-motion (WIM) data and investigated its effect on the fatigue performance of bridges. A novel multi-lane FLM is proposed, comprising a standard fatigue truck model and multi-lane fatigue coefficients. The standard fatigue truck model is the same as FLM II of the Chinese design specification; however, the load value is adjusted using a calibrated coefficient correlated with the bridge length. The multi-lane fatigue coefficients help define the reduction coefficients for the load value and number of fatigue cycles when applying the standard fatigue truck model to a certain traffic lane. Finally, the proposed model and the code-based model are applied to evaluate the fatigue performance of typical steel–concrete composite girder bridges, and the results are compared with the estimations using realistic multi-lane WIM data. The proposed model yields similar estimations of the stress range and fatigue life as using WIM data, whereas the code-based model shows large deviations. The comparisons validate the feasibility and superiority of the proposed multi-lane FLM for the fatigue evaluation of bridges under uneven multi-lane truck loadings.

Experimental Research of the Time-Dependent Effects of Steel–Concrete Composite Girder Bridges during Construction and Operation Periods

The present work aimed to study the effects of temperature changes and concrete creep on I-shaped steel–concrete composite continuous girder bridges during construction and operation processes. This study combined structural health monitoring data, an ANSYS finite element simulation, and the age-adjusted effective modulus method to obtain the variation laws of temperature and internal force in composite girders. Moreover, a temperature gradient model was proposed that is suitable for bridges in Hebei, China. In addition, a concrete creep experiment under unidirectional axial compression was performed using concrete specimens prepared from the concrete batch used to create the composite girder. The long-term evolution laws of the deflection and internal force of the composite girder were obtained by predicting the concrete creep effect. The measured data showed that the temperature variation trends of the steel beam and concrete slab were characterized by a sinusoidal curve without a temperature lag. The heating rate of the concrete slab was higher than the cooling rate. The prediction results showed that the internal force changes in the composite girder were characterized by three stages. The stress changes in the composite girder during the first 10 days were significant and the stress charge rate of the concrete slab, the steel girder and the shear stud can reach 5%–28%. The stress change rate decreased continuously during 10–90 days. The stress changed slowly and smoothly after 90 days. This research can provide feedback and reference for structural health monitoring and service safety control of similar I-shaped steel–concrete composite bridges.

Research on temperature action and cracking risk of steel–concrete composite girder during the hydration process

Temperature changes due to hydration heat often cause cracks in the early-age concrete deck of steel–concrete composite girder bridges, even before opening to traffic. However, no available methods are provided in current specifications for the thermal effect calculation. To fill this gap, large-scale temperature measurements and fine finite-element model (FEM) analysis were performed on an actual composite girder bridge. Based on the fully validated FEM, a comprehensive parametric study was carried out to establish the spatio-temporal pattern of hydration-caused temperature, including a vertical pattern and an evolutionary pattern. Finally, a simplified method was presented for the thermal stress calculation of composite girders, and a case study was also provided. Measurements showed that temperature differences of concrete deck varied below 5 °C, much smaller than the entire composite section. FEM analysis then suggested that the influence of solar radiation can be basically ignored compared with hydration heat. The spatio-temporal pattern in the form of the coefficient of temperature rise was proposed based on the above findings and parametric study, and the reliability was properly verified with experimental or FEM results. For the final simplified method, the case study demonstrated that it can effectively facilitate the thermal stress calculation of composite girders during hydration process by adopting the proposed spatio-temporal pattern. As such, preliminary curing schemes can be easily selected to control the concrete cracking risk before casting.

Design of FRP decked concrete composite girder bridges I - Design method, deck design and connections details

Design of FRP decked concrete composite girder bridges I - Design method, deck design and connections details

Application of ZLD Automaticly Continuous Launching System in the Construction of Prestressed Concrete Composite Box-girder Bridge with Corrugated Steel Webs

The incremental launching construction method firstly is applied to the prestressed concrete composite girder bridge with corrugated steel webs and the bridge belongs to Zhengzhou Longhai Road Fast Track Project at Chang-zhuang reservoir in domestic. Under this background, ZLD automaticly continuous launching system is applied to the prestressed concrete composite girder bridge with corrugated steel webs and the construction scheme design, related construction technology and key points is introduced. Engineering practice shows that the advantage is synchronous control, automation, flexible construction, the force of incremental launching can be adjusted according to level of reaction force and deformation at the pier top. The construction efficiency, safety and reliability is improved for launching engineering, and it has a wide application prospect.

A framework for statistical distribution factor threshold determination of steel–concrete composite bridges under farm traffic

This paper presents a novel statistical framework to determine distribution factors (DFs) for steel–concrete composite girder bridges subjected to agricultural vehicles. The framework consists of multiple parts including live load field testing, finite element simulations, and statistical analyses. For field testing, strain sensors are installed at critical locations to monitor strain data resulting from passes of test agricultural vehicles. Measured strains are utilized to determine experimental DFs and also used to calibrate finite element models. As part of the model simulation, a number of vehicles of interest are selected and applied to the models to compute analytical DFs. Statistical thresholds for each group of interior and exterior girders are calculated by performing a statistical analysis of the computed data. To demonstrate this procedure, a sample application of interest is discussed. Findings indicate that the proposed framework is capable of reasonably estimate lateral live-load DFs for interior and exterior girders of the particular rural bridge under the effect of varying agricultural loads. The proposed framework is anticipated to provide a more sophisticated live load distribution characteristics’ estimate on such bridges loaded.

Fiber beam-column element for circular concrete filled steel tube under axial–flexure–torsion combined load

When subjected to the horizontal earthquake load, compression–bending–torsion combined actions often exist in the piers of curved bridges because the center of stiffness and the center of mass of curved bridges do not locate at the same position. A new fiber beam-column element considering the nonlinear torsion behavior for concrete filled steel tubes with circular section was developed based on the traditional fiber beam-column model, which had widely been used. The calculation and solution procedures of the proposed fiber beam-column model were also illustrated. The reasonable geometrical relations, material constitutive law and force equilibrium equations were all applied. Based on the principles of fiber beam-column element considering torsion effect, a nonlinear solution program was developed using FORTRAN language. The entire loading history of concrete filled steel tube columns subjected to combined compression–bending–torsion load could be predicted with good agreement with test results. Using the proposed fiber beam-column model for the time-history analysis of curved steel–concrete composite girder bridges, the high solution precision and efficiency could be obtained, compared with the traditional finite element model.

Mechanical Properties of Shear Stud during and after Fire

Many examples of a bridge damaged due to accidental or incendiary fire heating up the bridge from below have been reported. When steel and concrete composite girder bridges are exposed to fire, it is important to understand the progression of damage to the shear connections. However, determination of the level of damage to the shear connection in experimental tests is a challenge. Furthermore, the postfire performance of the shear connection is not clear yet. To better understand the mechanical properties of the shear stud during and after fire, the authors conducted three different push-out tests of heated studs, in which the fire temperature varied from 300 to 700°C over a period of 90 min. From the results of the static push-out tests conducted after heating, it was found that the maximum shear resistance of shear studs is marginally affected by the heating, but the slip constant was decreased remarkably in proportion to the heating temperature. Furthermore, the fatigue strength of shear studs showed remarkable decrease due to the undesirable slip behavior.

Field Test and Analysis for the Static and Dynamic Behaviour of Multi-Box Steel Concrete Composite Girder Bridge

Taking the four-span 40m simply supported multi-box steel-concrete composite girder bridge in the ProjectⅡ of Qiushi Expressway in Hangzhou as the background, this paper analyzed the static and dynamic behaviour of the bridge by FEM, then finished a field test study for the bridge. Finally, comparing the test values with the results obtained from FEM analysis, it was verified that the rigidity transverse beam method with infinte stiffness is also adaptive to caculating and predicting the load transverse distribution of the multi-box steel-concrete composite bridge. Steel diaphragm and stiffening rib of the multi-box steel- concrete composite bridge can improve the flexural capacity of bridge to some extent, so these contributions should be reasonably considered during the design stage in order to reduce the engineering cost. The measured modes agree well with the results from FEM.

An actual test and FE analysis of a steel and concrete composite girder bridge exposed to fire

AbstractIt has been reported that there are many examples of bridges damaged by fire due to traffic accidents, doubt fires and incendiary fires. When steel and concrete composite girder bridges are exposed to fire, it is necessary to verify the decrease in strength of the structural steel and the concrete. This paper describes the fire test setup for a steel and concrete composite girder bridge. The experimental results are discussed. Furthermore, a finite element analysis is carried out for the steel and concrete composite girder. Finally, the experimental and analytical results are compared.

Lightweight Concrete Reduces Weight and Increases Span Length of Pretensioned Concrete Bridge Girders

The maximum length for simple span pretensioned concrete composite girder bridges using high strength lightweight concrete (HSLWC) were investigated analytically using concrete strengths of 8, 10, and 12 ksi (55, 60, and 83 MPa) and prestressing strands of 0.5 in. (15.2 mm) diameter. The use of HSLWC produced spans up to 4 percent longer than the same section made with high strength normal weight concrete (HSNWC). Based on the AASHTO I-girder and AASHTO PCI bulb tee sections examined in this study, the reduced girder weight eliminated the need for special transportation superload permits. Modified AASHTO-PCI bulb tees with one extra row of strands in the bottom flange extended the girders' maximum span length by at least 10 ft (3.1 m). Overall. the advantages of lightweight concrete with compressive strengths up to 12 ksi (83 MPa) include lower girder weight, relief from special permitting requirements, and longer span lengths.