Jiashao Bridge Research Articles

Fatigue life of RC bridge decks affected by speed and load weight of wheel-type moving loads

Over the service life of a bridge, vehicles vary in terms of speed and load weight, leading to varying degrees of fatigue damage. Particularly under wet condition, the fatigue life of reinforced concrete (RC) bridge decks experiences a significant decline. In this study, the results of fatigue life of RC bridge decks are systematically calculated for under wheel-type moving loads with various speed and load weight according to practical situation of bridges in both dry and wet condition by an acceptable approach involves a multi-scale and multi-chemo–physics analysis system (DuCOM-COM3) that incorporates the water-crack interaction. The results indicate that the effect of speed on fatigue life is not significant and follows a complex pattern, and the effect of load weight on fatigue life is dominant, with a heightened sensitivity to load weight variations under wet condition. Based on the simulation results of fatigue life, calculation formulations for fatigue life are presented accurately for dry and wet condition respectively, considering both load weight and speed as parameters, with the determination coefficients R2 are 0.977 and 0.952, respectively. In addition, a predictive method for the service life under constant environmental condition is proposed based on the Palmgren-Miner’s linear rule, and a case analysis is conducted by utilizing practical traffic flow data monitored by a piezoelectric-based dynamic weigh-in-motion system set on Jiashao Bridge, showing that the service life under dry condition is 55.41 years, while that under wet condition reduces to 1.03 years. Finally, a comprehensive service life predictive method considering actual and alternating environmental conditions is proposed.

Data set from wind, temperature, humidity and cable acceleration monitoring of the Jiashao bridge

Data set from wind, temperature, humidity and cable acceleration monitoring of the Jiashao bridge

Influences of structural system characteristics on the dynamic characteristics and wind-induced buffeting response of multi-tower cable-stayed bridge

This study explores the dynamic characteristics and the nonlinear wind-induced buffeting response of the bridge based on a six-tower cable-stayed bridge, the Jiashao Bridge. The effect of structural system characteristics (number of anchor piers and different conditions of longitudinal constraints) on the dynamic characteristics and the wind-induced buffeting performance of multi-tower cable-stayed bridges has been studied in detail. The analysis indicates that the different amounts of anchor piers have a limited effect on changing the overall stiffness of the bridge, but have an obvious effect on the buffeting displacement response of the side spans to which they belong. As for the condition of longitudinal constraints between the girder and towers, it mainly changes the vertical and transverse bending stiffness of the girder which means with the enhancement of the longitudinal constraints, the bending stiffness of the girder increases, and meanwhile significantly influence the transverse buffeting response of the girder.

Estimation of Maximum Local Scour Depths at Multiple Piles of Sea/Bay-crossing Bridges

Estimation methods of local scour depths under complex marine environment have not been well understood for bridge design and constructions. This study focuses on estimating the maximum local scour depth at multiple piles of sea/bay-crossing bridges by developing a new formula using compiled 58 laboratory data and 21 field data. Scale model experiments of three practical bridges in China (Jiashao Bridge, Hangzhou Bay Bridge, and Jintang Bridge) were first conducted, and the results were used to calibrate the proposed universal formula. This formula was developed by using dimensional analysis and considering pile dimension, pile format and type, incoming wave flow condition, wave flow characteristics (acceleration of gravity, density, and dynamic viscosity), and sediment grain size. After the parameters were calibrated, two sets of field measurement data and two independent sets of laboratory testing data of maximum local scour depth were utilized to verify the formula. The results show a relatively good match between the calculated values from the formula and the measured data from the experiment and the field. The new formula is promising to be used to predict the maximum local scour depth at piles for the design of practical sea/bay-crossing bridges in the marine environment.

A novel method for determining the spatial responses of a cable-stayed bridge with four cable-planes

In this paper, a novel method for determining the spatial responses of a cable-stayed bridge with four cable-planes at the design and construction stages is proposed. Herein, the entire construction stage includes many intermediate steps and one completion step. In this method, the spatial responses of the bridge at the design stage (SRBDS) are firstly determined by minimizing the bending and torsion strain energy of the cable-stayed bridge. Simultaneously, the optimal cable forces and the ratios of the inside to outside plane cables are also determined at this stage. Note that the SRBDS are considered as the target responses of the construction stage at the completion step. Then, the Forward process method is used to calculate the spatial responses of the bridge at the construction stage (SRBCS). The least square method is employed to minimize the difference values of the selected control parameters, e.g., cable forces and displacement, between the completion step at the construction stage and the design stage. Finally, the revised results, which satisfy the designated error requirements, are preserved as the SRBCS. To verify the proposed method, an example cable-stayed bridge with four cable-planes and double-girders, the Jiashao bridge, is analyzed. The structural responses, e.g., the stress and displacement of the girder and tower, of the bridge at the design and construction stages are analyzed and compared to demonstrate the superiority of the proposed method and investigate the spatial responses, e.g., the torsion in the main girder, of this cable-stayed bridge with four cable-planes.

Pavement Evaluation for ERS Steel Deck Pavement Using Accelerated Loading Test

In order to verify the practical application of ERS steel deck pavement system, based on the project of Jia Shao bridge, the pavement accelerated loading system is used to test the long-term performance of the steel bridge deck pavement. Tests find that the absolute value of the average rut growth depth of ERS and ERN is less than 5mm when the number of axle loads is 2.05 million times. After more than 1.3 million loading tests, the two deck pavement structures are almost impermeable to water and their anti-skid properties also tend to be stable. The results show that ERS and ERN are not cracked under natural conditions and have excellent anti-rutting performance.

Investigation of Influence Factors of Wind-Induced Buffeting Response of a Six-Tower Cable-Stayed Bridge

This paper presents an investigation of the wind-induced buffeting responses of the Jiashao Bridge, the longest multispan cable-stayed bridge in the world. A three-dimensional finite element model for the Jiashao Bridge is established using the commercial software package ANSYS and a 3D fluctuating wind field is simulated for both bridge deck and towers. A time-domain procedure for analyzing buffeting responses of the bridge is implemented in ANSYS with the aeroelastic effect included. The characteristics of buffeting responses of the six-tower cable-stayed bridge are studied in some detail, focusing on the effects including the difference in the longitudinal stiffness between the side towers and central towers, partially longitudinal constraints between the bridge deck and part of bridge towers, self-excited aerodynamic forces, and the rigid hinge installed in the middle of the bridge deck. The analytical results can provide valuable references for wind-resistant design of multispan cable-stayed bridges in the future.

Multiobjective Optimal Control of Longitudinal Seismic Response of a Multitower Cable-Stayed Bridge

The dynamic behavior of a multitower cable-stayed bridge with the application of partially longitudinal constraint system using viscous fluid dampers under real earthquake ground motions is presented. The study is based on the dynamic finite element model of the Jiashao Bridge, a six-tower cable-stayed bridge in China. The prime aim of the study is to investigate the effectiveness of viscous fluid dampers on the longitudinal seismic responses of the bridge and put forth a multiobjective optimization design method to determine the optimized parameters of the viscous fluid dampers. The results of the investigations show that the control objective of the multitower cable-stayed bridge with the partially longitudinal constraint system is to yield maximum reductions in the base forces of bridge towers longitudinally restricted with the bridge deck, with slight increases in the base forces of bridge towers longitudinally unrestricted with the bridge deck. To this end, a multiobjective optimization design method that uses a nondominating sort genetic algorithm II (NSGA-II) is used to optimize parameters of the viscous fluid dampers. The effectiveness of the proposed optimization design method is demonstrated for the multitower cable-stayed bridge with the partially longitudinal constraint system, which reveals that a design engineer can choose a set of proper parameters of the viscous fluid dampers from Pareto optimal fronts that can satisfy the desired performance requirements.

Passive Control System for Mitigation of Longitudinal Buffeting Responses of a Six-Tower Cable-Stayed Bridge

This paper presents an investigation of mitigation of longitudinal buffeting responses of the Jiashao Bridge, the longest multispan cable-stayed bridge in the world. A time-domain procedure for analyzing buffeting responses of the bridge is implemented in ANSYS with the aeroelastic effect included. The characteristics of longitudinal buffeting responses of the six-tower cable-stayed bridge are studied in some detail, focusing on the effects of insufficient longitudinal stiffness of central towers and partially longitudinal constraints between the bridge deck and part of bridge towers. The effectiveness of viscous fluid dampers on the mitigation of longitudinal buffeting responses of the bridge is further investigated and a multiobjective optimization design method that uses a nondominating sort genetic algorithm II (NSGA-II) is used to optimize parameters of the viscous fluid dampers. The results of the parametric investigations show that, by appropriate use of viscous fluid dampers, the top displacements of central towers and base forces of bridge towers longitudinally restricted with the bridge deck can be reduced significantly, with hampering the significant gain achieved in the base forces of bridge towers longitudinally unrestricted with the bridge deck. And the optimized parameters for the viscous fluid dampers can be determined from Pareto-optimal fronts using the NSGA-II that can satisfy the desired performance requirements.

Influence of structural system measures on the dynamic characteristics of a multi-span cable-stayed bridge

A three-dimensional finite element model for the Jiashao Bridge, the longest multi-span cable-stayed bridge in the world, is established using the commercial software package ANSYS. Dynamic characteristics of the bridge are analyzed and the effects of structural system measures including the rigid hinge, auxiliary piers and longitudinal constraints between the girders and side towers on the dynamic properties including modal frequency, mode shape and effective mass are studied by referring to the Jiashao Bridge. The analysis results reveal that: (i) the installation of the rigid hinge significantly reduces the modal frequency of the first symmetric lateral bending mode of bridge deck. Moreover, the rigid hinge significantly changes the mode shape and effective mass of the first symmetric torsional mode of bridge deck; (ii) the layout of the auxiliary piers in the side-spans has a limited effect on changing the modal frequencies, mode shapes and effective masses of global vibration modes; (iii) the employment of the longitudinal constraints significantly increases the modal frequencies of the vertical bending modes and lateral bending modes of bridge deck and have significant effects on changing the mode shapes of vertical bending modes and lateral bending modes of bridge deck. Moreover, the effective mass of the first anti-symmetric vertical bending of bridge deck in the longitudinal direction of the fully floating system is significantly larger than that of the partially constrained system and fully constrained system. The results obtained indicate that the structural system measures of the multi-span cable-stayed bridge have a great effect on the dynamic properties, which deserves special attention for seismic design and wind-resistant design of the multi-span cable-stayed bridge.

The Key Technology Research of the Pushing Closure Process about Jiashao Bridge Based on Geometric Control Method

Based on the characteristics of the geometric control method during the construction of cable-stayed bridge, the key goal to complete the bridge is to ensure that the non-stress dimensions and profile of every component is constant. Because one of the key points to complete the cable-stayed bridge is to ensure that the non-stress length of the closure segments is constant, it is necessary to adjust the relative position of the final closure by the geometric closure method of incremental launching construction to satisfy the requirement of the non-stress length of the closure segments. Aimed at the critical technical problems existing in incremental launching construction process, taking Jiashao bridge as the research subject, the analysis of the incremental launching plan and the local stress of pushing bracket and bearing block are carried out. The research will provide scientific basis for the feasibility of geometric control incremental launching construction method and it will guarantee the smoothly incremental launching construction.

Passive control system for seismic protection of a multi-tower cable-stayed bridge

The performance of passive control system for the seismic protection of a multi-tower cable-stayed bridge with the application of partially longitudinal constraint system is investigated. The seismic responses of the Jiashao Bridge, a six-tower cable-stayed bridge using the partially longitudinal constraint system are studied under real earthquake ground motions. The effects of the passive control devices including the viscous fluid dampers and elastic cables on the seismic responses of the bridge are examined by taking different values of parameters of the devices. Further, the optimization design principle of passive control system using viscous fluid dampers is presented to determine the optimized parameters of the viscous fluid dampers. The results of the investigations show that the control objective of the multi-tower cable-stayed bridge with the partially longitudinal constraint system is to reduce the base shears and moments of bridge towers longitudinally restricted with the bridge deck. The viscous fluid dampers are found to be more effective than elastic cables in controlling the seismic responses. The optimized parameters for the viscous fluid dampers are determined following the principle that the peak displacement at the end of bridge deck reaches to the maximum value, which can yield maximum reductions in the base shears and moments of bridge towers longitudinally restricted with the bridge deck, with slight increases in the base shears and moments of bridge towers longitudinally unrestricted with the bridge deck.

Geometry Control of The Steel Box Girder of Jiashao Bridge at The Fabrication Stage

The fabrication precision of steel box girder segments is critical to ensure the erection of girder segments is smooth. Taken Jiashao bridge as the research subject, based on geometry control theory, control elements of a steel box girder and control method were introduced, and measured data in the fabrication control of Jiashao bridge girder was given. Control practice shows the erection of the girder is smooth due to the precise control of steel box girder segments at the fabrication stage, and the profile of main girder at completion stage can achieve smoothly the design profile.

Research of Random Seismic Response of Large-Span Multi-Tower Cable-Stayed Bridge

Taking Jiashao Bridge as the research subject, this paper established finite element model by ANSYS to study random seismic response of multi-tower cable-stayed bridge. The results show that the constraint relations between tower and girder influence internal force at bottom of towers deeply, and the force of each tower is different. The vertical displacements in the midspan of girder are varied in different constraint relation. In addition, the effect of traveling waves on this bridge under excitation was analyzed, the results show that traveling wave velocity has an important implication on the seismic response of multi-tower bridge, and there are some regular relations between the response of structure and high traveling wave velocities.

Temperature Cracks Controlling Technology for the Mass Concrete in Solid Sections of Lower Pylon Column

According to the case that mass concrete in solid sections of lower pylon column of Jiashao Bridge was easy to crack in construction because of the bigger section size, larger content of cementitious material and lower water binder ratio, the temperature and thermal stresses distribution of mass concrete was simulated and temperature control scheme was adjusted constantly based on the results of field temperature monitoring. Through taking some temperature control measures such as applying circulating cooling water and prolonging the time appropriately, thermal insulation and moisture retention curing, extending the form removal time and controlling the quality of concrete, harmful cracks did not appear in solid sections of lower pylon column of Jiashao Bridge and anticipated temperature control requirements were achieved.

Vertical Motive Performance Test of the Rigid Hinge Expansion Joint of Jiashao Bridge

To adapt the serious temperature deformation, the rigid hinge expansion joint is used in the Jiashao Bridge. The vertical rotation test and shear deformation test are conducted to check the vertical motive performance of the expansion joint, and the test results show the rigid hinge expansion joint can meet the design requirements.

The Design of a Vibration Reduction Test Platform of the Rigid Hinge Expansion Joint of Jiashao Bridge

The temperature deformation of Jiashao Bridge is a serious problem. In order to solve this problem effectively, a kind of rigid hinge structure is adopted in the middle of the bridge. Unit sparse plate bridge expansion joint for multi-direction-displacement is installed on the rigid hinge of this bridge. Vibration reduction tests are needed to verify the performance of the expansion joint and the service condition of the bridge structure. In this paper, a finite element analysis of the rigid hinge expansion joint is performed and a vibration reduction test platform is designed.

Research on Wind-Induced Vibration Reduction Solution of the Longest Cantilever State of Jiashao Bridge

A research based on Jiashao Bridge is carried out to reduce buffeting response under strong wind of the control section of main girder of the longest cantilever state and to ensure the security of the bridge during the construction period. A method that the ends of cantilevers are connected with several temporary damping cables is considered as wind-resistant measure. 4 modes with different damping cable arrangement are supposed, and the wind-resistant effect corresponding to the 4 modes are compared by FEM analysis. A mode with the best wind-resistant effect and economical meanwhile is selected out and local optimization is added to the selected mode. Some valuable conclusion obtained from the research could be adopted in Jiashao Bridge and the similar projects.