Prestressed Concrete Box Girder Research Articles

Experimental and numerical investigation on deck system of a 102 m simply supported prestressed UHPC box-girder highway bridge

To address two main challenges (excessive mid-span deflections and numerous cracks in the main girder) in long-span prestressed concrete (PC) box-girder bridges, this paper proposes a long-span simply-supported UHPC box-girder bridge. In comparison to conventional PC box-girder bridges with three-dimensional prestress, the proposed UHPC box-girder consists only one-dimensional (longitudinal) prestress, and the thickness of the bottom/top plate and web of the UHPC box-girder are relatively thin and are strengthened with dense diaphragms and stiffening ribs. The 4th Beijiang River Bridge adopts this type of bridge with a span of 102 m, which is the longest span simply supported prestressed UHPC box-girder highway bridge in the world. Considering the fact that the thickness of the top plate of the UHPC box-girder is relatively thin (only 20 cm) and the transverse prestress is removed from the top plate, thus, under the direct action of wheel loads, the risk of bridge deck cracking may correspondingly increase. To investigate the mechanical behavior of the deck system of UHPC box-girder bridges, a 1:2 scaled experimental specimen associated with the field bridge is tested. The mechanical behavior of the new deck system is investigated and discussed. It is found that because the support strength of the stiffening rib is significantly weaker than that of the web, the UHPC deck slab should still be regarded as a two-way slab rather than a one-way slab in the elastic stage. In addition, although the test load location is unfavorable to the UHPC deck slab and the first crack appears on the UHPC deck slab, this deck system finally suffers from bending failure of the transverse rib. Furthermore, finite element analysis is carried out to study the mechanical behavior of this new deck system. Parametric analysis considers some factors including the reinforcement ratio in the transverse rib, the height of the transverse rib, and the space between transverse ribs. The results provide a good reference for design and optimization in the new deck system of UHPC box-girder bridges.

Flexural and shear load rate evaluation on Pre-stressed concrete Box Girder Superstructure under the effect of IRC Loading

Flexural and shear load rate evaluation on Pre-stressed concrete Box Girder Superstructure under the effect of IRC Loading

Improved softened truss model of prestressed concrete box girders subjected to combined bending and torsion

Prestressed concrete (PC) box girder is an innovative structure that is widely used in large-span bridges. Under eccentric loads such as vehicles, PC girders are inevitably under combined bending and torsion. To study its bending-torsional behavior, a refined full-range analysis model based on the combined action softening truss model (CA-STM) was proposed, where a simple and effective solution procedure and failure criteria were provided. The equilibrium equation, initial estimation equation for torque, and material constitutive model were modified by considering the prestressing effect to improve the CA-STM. An optimized algorithm was also employed to simplify the solution procedure instead of the traditional trial-and-error method, thus increasing the solution rate and stability. The theoretical curves predicted from the improved CA-STM exhibited great agreement with the available experimental results, and the predicted cracking and ultimate loads were also close to the experimental values. Hence, the improved CA-STM can reasonably predict the full-range mechanical response and failure modes of PC box girders subjected to combined bending and torsion, which provides great support to the design evaluation of such bridges.

Investigation on mechanical performance of prestressed concrete box‐girder bridge strengthened using composite trusses with different shapes

AbstractIn this study, a finite element (FE) model of an existing prestressed concrete box‐girder (PCB) bridge is developed using Abaqus/Explicit (2022), and a series of FE simulations are conducted to examine the results of composite trusses (CTs) in strengthening PCB bridges with different shapes. A concrete damage plastic model of concrete is used to predict the nonlinear behavior of concrete. Field tests and theoretical calculations are performed to verify the rationality of the model. Three CTs of different shapes, that is, a K‐shaped composite truss (KCT), an X‐shaped composite truss (XCT), and a triangle‐shaped composite truss (TCT), are used to strengthen the PCB bridge models. The deflection, load distribution, distortion, and surface connection forces under two types of lane loads (European code [EU] and Chinese code [CC]) are discussed. The results show that the CT can reduce the deflection and distortion of the PCB bridge and improve the load distribution. However, the different CT shapes offer other strengthening effects. Among them, the XCT reduces deflection the most significantly, that is, by 8.9% and 17.1% under the two load modes, separately. In addition, the XCT improves the load distribution of the PCB bridge the most significantly. The KCT reduces the distortion of the PCB bridge the most significantly and decreases the stress ratio by 75.36%. Moreover, the deflection of the PCB bridge under the EC is more significant, indicating that the lane load defined by the EC is larger than that by the CC. The maximum surface connection forces are different under the same load mode for the different CTs. However, in all the models, the bending moment at surface‐2 is insignificant. Based on the analysis results, five assumptions are introduced. Using the KCT as an example, the plane model of the reinforced section is simplified, and a canonical equation is established to calculate the load distribution factor. The 324 coefficients and 18 free terms in this canonical equation are deduced, which provides a theoretical basis for strengthening PCB bridges using CTs.

Radial force analysis of long span bridge with trapezoidally corrugated steel webs

The study numerically and theoretically investigates the radial force effect of long span prestressed concrete (PC) box girders with trapezoidally corrugated steel webs (TCSWs). It reveals that under the influence of radial forces, the curved prestressing tendons in the bottom slab in long span box girder bridges with TCSWs exhibited higher levels of stress and deflection compared to conventional concrete box girder bridges due to the accordion effect of the TCSWs. Furthermore, this study simplifies the radial forces as concentrated forces of PC box girder with TCSWs. Based on this simplification, a formula is derived to accurately calculate the magnitude of these radial forces. Through parameter analysis of the power exponent in the equation defining the curve profile of the bottom slab, it was observed that lower power exponents result in more significant radial force effects. Finally, to eliminate the radial force effect, the study innovatively proposed an optimized structural scheme by adopting horizontal bottom slab at midspan and arranging horizontal diaphragms uniformly across the entire longitudinal span of the bridge. A contrastive study suggested that the horizontal arrangement of internal prestressing tendons in the bottom slab at midspan could effectively eliminate the negative impact of the radial force effects and greatly improve the overall bearing capacity of the box girders with TCSWs.

Improved Deflection Prediction Model for PSC Box Girder with Stay Cable System during Tensioning Phase

To improve the accuracy of deflection prediction for prestressed concrete (PSC) box-girder bridges with a stay cable system (SCS) during tensioning, this study employs the Latin hypercube sampling (LHS) technique to sample random variables affecting long-term deflection of the main girder. A long-term deflection randomness analysis model is established, and the shear stiffness degradation factor is included to quantify the contribution of diagonal web cracking to the main girder deflection. Uncertainty and sensitivity analysis are conducted for the Dongming Huanghe River Highway Bridge. An objective function is applied to select the optimal combination of random variables, and a modified model is established and verified for accuracy. Results show that diagonal web-cracking accounts for 8.8% of total deflection and cannot be ignored, and the prestressed tension control stress, creep uncertainty coefficient, and concrete density significantly impact long-term deflection. The modified model predicts deflection with greater accuracy than the mean value model.

Study on the Mechanical Performance of the Xiuzhen River Bridge Strengthened Using K-brace Composite Trusses

In this study, a finite element (FE) model of the Xiuzhen River bridge was developed, and the validity of the model was verified using monitoring results, load tests and theoretical calculations. Subsequently, a series of FE simulations were conducted on a model of the Xiuzhen River Bridge strengthened using K-brace composite trusses (K-BCTs). Static, eigenvalue and response spectrum analyses were carried out for 16 prestressed concrete box-girder (PCB) bridge strengthening models with different K-BCT stiffness and spacing. The results revealed that K-BCTs could reduce the girder deflection, improve the load distribution, and reduce the distortion stress. A slightly better-strengthening effect in the K-BCTs with higher stiffness and smaller spacing. The dynamic analysis revealed that the K-BCT stiffness and spacing influenced the higher vibration modes but had little effect on the lower modes. Furthermore, the K-BCT had no significant effect on the maximum internal force of the model under different seismic waves, and the maximum deviation was within 5%. Finally, two K-BCTs made of concrete-filled steel tubes, with a spacing of 3 m and an elastic modulus of 50 GPa, were used to strengthen the existing bridge. The experiment results indicated that the strain and deflection in the Xiuzhen River Bridge were reduced by 53.6% and 20.6%, respectively.

The Effect of Earthquake on Temporary Structures during Bridge Construction with Different Column Heights

This research aims to study the effect of earthquakes on temporary structures during bridge construction with different column heights for analysis and evaluation of the damage to temporary structures known as “Launching Gantry” and bridge structures. The primary focus is on temporary structures used in bridge construction with spans of 45 meters and heights of 7, 19, and 28 meters. The research examines four different stages of bridge construction: a single-span bridge, launching the gantry to install the next span, preparing to hang prestressed concrete box girders, and hanging the prestressed concrete box girders. The study uses 12 models created with the midas Civil computer program and nonlinear time history analysis to simulate seismic acceleration in the Bangkok area during the construction stage with a return period of 39 years to determine the internal force and the deformation. As a result, the forces were compared to the resistance according to Eurocode standards to evaluate the damage. The results show that the bridge structure is undamaged, with only minimal deformation, but significant damage was found in the legs of the supports, particularly the front support. The flexural moment and axial force were 1.53 times greater than the resistive strength, and the leg experienced deformation in the transverse direction of the bridge up to 71 millimeters, or 1/77 of the leg height.

Transfer Length and Prestress Losses of a Prestressed Concrete Box Girder with 18 mm Straight Strands

Despite the potential advantages of 18 mm strands, the limited research on the behavior of girders with larger-diameter strands hinders the application in bridges. Transfer length and prestress losses are two important indicators. In this research, a 32.6 m long prestressed concrete box girder with 18 mm straight strands and 15 mm harped strands was produced, and the transfer length and the prestress losses were studied. The transfer length was calculated based on the existing equations in codes and previous research. Three beam specimens were fabricated, and strain gauges were pasted on the concrete surface to measure the transfer length of 18 mm strands. It indicated that the average measured transfer length was 700 mm. This value was smaller than the transfer lengths predicted by AASHTO LRFD 2017 and ACI 318-19, while Mitchell’s equation offered the closest prediction to the average measured transfer length. Additionally, the prestress losses at different stages were evaluated. A one-end stressing test was conducted to analyze the effect of strand harping on the loss of tensile force. In comparison with the actual measured loss based on the concrete strain and the longitudinal shortening, the instantaneous prestress loss calculated using the AASTHO LRFD 2017 alternative equation was appropriate. The time-dependent prestress losses due to shrinkage, creep, and relaxation were predicted using two different methods addressed in AASHTO LRFD 2017. The time-dependent predicted losses of 69.2 MPa at 28 d using the refined method were 37% higher than the measured losses 47.4 MPa at 28 d, indicating an overestimation of AASHTO LRFD 2017. The accumulation of the total losses over time revealed that the prestress losses developed in the first two months occupied the majority of the total losses in the long term. The research may provide guidelines for the design of a pretensioned concrete box girder with 18 mm strands.

Structure-borne noise of steel and concrete box girders in an urban metro system: A hybrid evaluation and parametric study

Metro systems provide an efficient, convenient, and expeditious way to travel around crowded routes. Because these systems are established in cities, residential buildings close to metro viaducts are significantly affected by structure-borne noise (SBN). Although most previous studies developed SBN prediction with a focus on the accuracy and computational efficiency of a specific bridge type, only limited studies on parameters for the SBN on bridges were carried out. Thus, eliminating SBN is still a challenging task for both the design and operation phases of bridge design. Therefore, this study integrates simplified experiments with numerical analyses to evaluate the influential parameters on the structure-borne noise level (SBNL) for two types of bridge girders, that is, the double-box pre-stressed concrete girder and the double-box steel girder. The present study also proposes an optimization method for reducing the SBNL in the bridge design and operation phases and identifies the sources of SBN for these two types of bridges. In this paper, the solutions to mitigating SBN are first reviewed and briefly introduced. Theories associated with SBN are then derived and experimentally verified using a concrete or steel plate with a unit area. A hybrid evaluation method is developed to integrate transient finite-element simulation with experimental results, and the main sources (e.g., plate thickness, train speed, fastener stiffness, and track irregularity) that induce SBN are examined by this hybrid method. Consequently, the approach to resolving the SBN problem can be optimally determined. As demonstrated in the results from the hybrid evaluation method, the track condition dominates the SBNL for both types of bridges, and the relationship between train speed and plate eigenfrequency should be carefully investigated to avoid the effect of plate resonance. The pre-stressed concrete box girder is the recommended bridge type for use in urban areas from the viewpoint of minimizing the SBNL.

Damage mechanism and damage evaluation of PC box girder bridge subjected to overheight vehicle impact

AbstractAccidental collisions from overheight vehicles often result in significant damage of bridges. To ensure the safety of the bridge structure, it is essential to develop a method to evaluate the damage caused by these impact loadings. This study aims to investigate the damage mechanism of a prestressed concrete (PC) box girder bridge subjected to overheight vehicle impact using the finite element analysis method. Parametric analyses were performed to study the effects of various factors on the impact force and deformation performance of the bridge. In addition, a damage assessment formula, based on the vertical residual bearing capacity, is proposed to evaluate the damage state of the impacted PC box girder. A mass–velocity (m–v) curve is developed to characterize the damage levels of the impacted PC girder under different vehicle velocity and mass conditions. Then, a theoretical equation for predicting the maximum impact force during the vehicle‐bridge collision is developed. The numerical analysis results show that vehicle‐related parameters have a significant influence on both impact force and local damage of the PC box girder bridge. The proposed mass–velocity (m–v) curve can be used to evaluate the damage state of the PC box girder by relating the performance levels of the girder to each damage index. Moreover, the predicted maximum impact force can be used as an important index to assess the extent of the local damage of the PC box girder.

Time-Dependent Reliability Assessment of Long-Span PSC Box-Girder Bridge Considering Vehicle-Induced Cyclic Creep

The neglect of the cyclic creep of concrete induced by vehicles may overestimate the deflection reliability of long-span prestressed concrete (PSC) box-girder bridges and increase structural safety risks. In this paper, a novel method considering the combined effects of the shrinkage, static creep, and cyclic creep of concrete and the stress relaxation of prestressed tendons is proposed to assess the time-dependent deflection reliability of PSC box-girder bridges. By employing the Kelvin chain model, the conventional integral-type method for calculating the static creep of concrete is converted to rate-type creep analysis, which has a higher computational efficiency and can consider various nonlinear effects. The cyclic creep of concrete is estimated by the fatigue mechanics-based model and integrated into the quasi-elastic incremental constitutive model. The proposed constitutive model is implemented in a general finite-element program DIANA, in which the mechanical behavior of the thin-walled box girder is described by the composite degenerated shell elements. An importance sampling method is applied when estimating the deflection reliability to balance the computational accuracy and efficiency. The proposed method is applied to a long-span PSC box-girder bridge with a main span of 150 m. The results indicate that the cyclic creep of concrete may accelerate the reduction of the deflection reliability indexes, which may fall below the target level before the expected service life of the bridge. In addition, heavy trucks passing in pairs have a significant impact on the deflection reliability. The research findings can be used for the reliable design and optimal maintenance of long-span PSC box-girder bridges.

Experimental and Numerical Study of the Ultimate Flexural Capacity of a Full-Size Damaged Prestressed Concrete Box Girder Strengthened with Bonded Steel Plates

Using steel plates attached with epoxy resin adhesive to strengthen prestressed reinforced concrete bridges has become a common method to increase bearing capacity in engineering because of the simple technology, low cost and good strengthening effects. The strengthening method of steel plates has been gradually applied to repair damaged bridges in practical engineering. After a cross-line box girder bridge was struck by a vehicle, the steel bars and concrete of a damaged girder were repaired and strengthened by steel plates, and then the ultimate bending bearing capacity was studied through a destructive test. The results of the destructive test were compared with those of an undamaged girder to verify the effect of the repair and strengthening of the damaged girder. The results showed that the actual flexural bearing capacity of the repaired girder strengthened by steel plates was 1.63 times the theoretical bearing capacity, 36.7% more than that of the damaged girder and 95.3% of that of an undamaged girder. The flexural cracking moment of the repaired girder strengthened by steel plates reached 66.3% of that of the undamaged girder. The maximum crack width decreased by 24.6%, and the maximum deflection increased by 2.7%, compared with the undamaged girder when the repaired girder strengthened by steel plates finally failed. Moreover, this method of attaching steel plates can increase the ductility of bridges and reduce the degree of cracking. Additionally, the actual safety factor of the repaired girder was greater than three, and it had a large safety reserve.

Analysis on the causes of cracking and excessive deflection of long span box girder bridges based on space frame lattice models

Long-span prestressed concrete box girder bridges (continuous girder and rigid frame bridges) tend to have some apparent diseases. On the one hand, cracks in various directions appear in different positions of different slabs of the box girder; on the other hand, the deflection of the structure develops for a long time, which significantly exceeds the design expectation eventually. This paper intends to use the space frame lattice model, combined with the complete stress index system, to analyze the causes of cracks in different forms in an actual bridge. Unlike the single beam model and the transverse frame model under the guidance of the existing code system, the space frame lattice model that discretizes an entire box girder section into individual slabs can more precisely simulate the load that exceeds the code but exists. In addition, the complete stress index system enriches the design of box girder bridges and can well explain the cracking causes of old bridges. This paper also discusses the effect of the difference in creep and shrinkage caused by the difference in thickness among slabs on the deflection.

Dynamic Response and Impact Force Calculation of PC Box Girder Bridge Subjected to Over-Height Vehicle Collision

The dynamic response of a prestressed concrete box girder bridge under the impact of an over-height vehicle is studied using the numerical simulation method. The finite element analysis software LS-DYNA is used to simulate the collision between the bridge superstructure and an over-height truck. Further, a parametric analysis is carried out to investigate the influence of six factors, i.e., girder configuration, vehicle speed, vehicle mass, impact angle, concrete strength and strand prestress, on both local damage and overall performance of the bridge. The numerical analysis results show that the girder configuration, vehicle speed, vehicle mass and impact angle have obvious effects on both local damage and the overall behavior of the PC box girder bridge. Whereas, the concrete strength and strand prestress only have a certain effect on the local damage at the impact area with very limited influence on the overall behavior of the bridge. In addition, based on the results obtained from the numerical simulation and parametric analysis, a formula for predicting the peak and average impact force of the prestressed concrete box girder bridge under the over-height vehicle impact is developed. The proposed impact force formula comprehensively accounts for the influence of the vehicle speed, vehicle mass and impact angle and can accurately predict the impact force generated under different working conditions, which confirms the promising prospect of the proposed formula in practical applications.

Effect of Shear Deformation at Segmental Joints on the Short-Term Deflection of Large-Span Cantilever Cast Prestressed Concrete Box Girders

The excessive deflection of large-span cantilever cast prestressed concrete (LCCPC) box girders has always been a complex problem to be solved in bridge engineering. To analyze the effect of shear deformation at segmental joints on the deflection of LCCPC box girders, comparison tests were carried out on three prestressed concrete (PC) I-girders with joints and a PC I-girder without joints, and a finite element simulation method of segmental joints was proposed based on the tests. Subsequently, finite element analysis was conducted on a test girder and the Assistant Shipping Channel Bridge of Humen Bridge (a PC continuous rigid frame bridge with a main span of 270 m) using this method. The experimental and theoretical analysis results showed that the effect of the shear deformation at joints compared to the deformation at midspan of the girder specimens was negligible. Deformation at midspan of the specimens would not significantly increase, even if shear rigidity at the joints was significantly reduced or there were more joints in the girder specimen. The effect of shear deformation at segmental joints on the deflection of LCCPC box girders was quite small and thus insignificant.

Research on Residual Bearing Capacity Calculation Method and Changing Law of Prestressed Concrete Box Girder with Damage

Due to the simple design and convenient construction of prestressed concrete box girder bridges, it is widely used in bridge construction in China. At present, the load test of bridge is the most direct and effective method to evaluate the actual bearing capacity of the structure. However, this method has barriers including high cost, long time, and unfriendly to the damaged structure. Besides, the calculation method of the ultimate bearing capacity of damaged structures is relatively subjective and uncertain. Therefore, this study combines the full‐size model test results of a newly built 30 m prestressed concrete box girder, and the mechanical properties of the test beam under three different working states (elastic, elastic‐plastic, and plastic stage) are obtained. The stiffness degradation and bearing capacity change law of precast prestressed concrete box girder during failure are investigated. Two different stiffness damage reduction coefficients are defined. Combined with the structural characteristics of this kind of precast prestressed concrete box girder and the calculation formula of flexural rigidity of cracked members given by the code, the calculation formula of the actual residual bearing capacity of members is proposed based on the stiffness damage reduction coefficient. The results show that the reduction coefficients of flexural stiffness defined by the two methods have the same variation trend. The stiffness reduction effect of the box girder after damage is evident. The stiffness reduction of the box girder from the cracking damage to the ultimate bearing capacity state is about 40%, and the stiffness reduction of the two adjacent sections can be approximately linear distribution. The deviation between the residual bearing capacity calculated based on the stiffness damage reduction coefficient and the test value is less than 5%. Combined with the distribution law of the stiffness reduction coefficient along the longitudinal section of the box girder, the distribution law of the actual residual bearing capacity along the longitudinal section of the box girder after the damage occurred in the midspan section can be calculated. This calculation method changes the previous assessment method of structural technical condition from qualitative assessment to quantitative assessment, which can be the reference for evaluating the technical condition of damaged bridges and the calculation of residual bearing capacity in engineering.

Construction monitoring of a long-span prestressed concrete continuous box girder bridge with variable sections

The structural behaviors in each construction stage were monitored and analyzed against the background of a long-span prestressed concrete continuous box girder bridge with spans of 55+100+55 m. At first, the formwork erection elevation and pre-camber of the bridge in each stage, as well as stress values of key cross-sections were determined by simulating the whole construction process using the finite element software. Then, the design parameters were identified and the model was corrected by field data collection and considering various influencing factors, so as to ensure effectiveness of the model. Finally, the formwork erection elevation was adjusted according to the stress and altitude in each construction stage, followed by closure of the bridge. According to field monitoring and adjustment, the measured alignment and stress of the bridge conform to the design and the error meets the requirements of specification, indicating a favorable monitoring effect. The research can provide reference for construction of similar bridges.

Structural Design and Mechanical Properties of a Plate-Shell Structure Bridge

PDF HTML XML Export Cite reminder Structural Design and Mechanical Properties of a Plate-Shell Structure Bridge DOI: 10.59238/j.pt.2023.01.006 Author: Affiliation: (1.Department of Bridge Engineering, Tongji University, Shanghai 200092, China;2.Tongji Architectural Design (Group) Co., Ltd., Shanghai 200092, China) Clc Number: Fund Project: Article | Figures | Metrics | Reference | Related | Cited by | Materials | Comments Abstract:The main bridge of Quzhou Academy Bridge is a V-shaped rigid frame bridge with a hanging hole, the span arrangement is 75 m+150 m+75 m=300 m, the middle span hanging hole was provided with a 60 m steel box girder, and the V-leg structure and the main beam are all prestressed concrete box girders with variable height. Due to the need for bridge landscapes and pedestrian viewing platforms, the large extension arc V-leg structure extends 6 m to each side of the bridge deck, and the total width is 41 m. It was necessary to consider the stress effect of the shell in the longitudinal and transverse directions. The stress and deformation of the shell in two directions are analyzed by using the finite element method solid model, and the difference between the solid model and the frame model is compared in detail. Finally, the overall structure was analyzed and checked in the modified simplified frame finite element model. Reference Related Cited by

The Effect of Cold Waves on the Structural Performance of Concrete Box Girders

As the frequency of thermal extremes gradually increases owing to climate change, the role of thermal loads on bridge performance increasingly becomes a concern. The purpose of this study is to investigate the suitability of AASHTO Bridge Design Specifications in quantifying with confidence the design thermal gradients that account for cold wave events. An advanced finite element platform was used to model the thermal performance of a prestressed concrete box girder and to analyse the thermal gradients that occur during cold wave events. Meteorological data on four historical cold wave events in Ontario, Canada, were used as input in the thermal models to simulate the temperature distribution within the bridge deck. The temperature–time history distributions obtained were then used as boundary conditions in a structural finite element model to simulate the structural response. The thermal results indicate that the AASHTO recommended gradients failed to capture the true thermal load distribution within the superstructure, which led to an underestimation of the resulting structural implications.