Applied Mechanics and Materials Vols. 587-589

Abstract: This paper presents the design of an experimental prestressed arch pedestrian bridge made of ultra-high performance concrete (UHPC). The structure is designed as a permanent single-span bridge with an intermediate deck. The span of the bridge structure is 58.5 m, the total width is 5.1 m, and the clearance width of the bridge is 4.5 m. The main structure of the bridge consists of two prestressed beams made of UHPC with dispersed steel fibers. The main beams are composed of prefabricated parts, subsequently prestressed.

Abstract: With the rapid development of technology of bridge, bridge as an important part of the traffic network, the safety of its operations was getting more and more attention by people. In order to ensure the bridge can be safe and reliable operating, the newly built bridge testing had become a necessary measures. In this paper, a three span continuous box girder bridge (28+36+28m) was taken as an example, To analyze and calculate its dynamic characteristics, the finite element software MISAS was used. And it was verified through experiments.

Abstract: Taking an engineering design case about a three-span uniform section continuous curved box-girders bridge of city viaduct,this paper sets up a finite element calculating model for the curved box-girders bridge by means of finite element analysis program ANSYS and researchs the influence of dynamic characteristic and seismic response on curved box-girders bridge with the different curvature radius under the same span. The analysis results show that in the same span of curved beam , the low-level frequency impact of changes in different curvature radius of the curved beam bridge is larger,the curvature radius is an importance parameter which influence on dynamic characteristic, and have significant influence on tangential stiffness、radial stiffness and seismic response of curved box-girders bridge.

Abstract: Due to the complexity involved and limited study on the topic, the equivalent static method, adopted in the current codes for structural design of bridges under ship collisions, does not take into account the dynamic amplification effect correctly. An accurate assessment of impact force based on refined numerical simulation is time consuming and is normally too complex for ordinary design procedure. Herein, with reference to the earthquake response spectrum method, an impact response spectrum method, which considers the dynamic amplification effect and is efficient for design, is proposed. Through refined numerical simulations of ship-rigid wall collisions, 81 impact force time histories associated with 9 typical ships under 9 velocities are obtained. The dynamic magnification factor (DMF) of single-degree-of-freedom (SDOF) systems with different periods and damping ratios experiencing the 81 impact force time histories are then studied. The relationship of DMF and period under different damping ratios, i.e. the DMF spectrum, is yielded by statistical analysis, based on which the impact response spectrum is obtained. Finally, the design combination method for multi-degree-of-freedom based on the impact response spectrum of SDOF is discussed for a continuous beam bridge.

Abstract: This paper presents an experimental and computer analysis of an integral bridge structure exposed to a load caused by the horizontal pressure of water during floods. The paper focuses on the residual load-bearing capacity of an integral bridge structure that was able to withstand the effects of flooding. ​​Three models of integral bridges built to a scale of 1:5 were made for the purpose of testing. The frames have a span of 2.6 m, the thickness of the supports is 0.2 m, and the thickness of the deck in the middle is 0.125 m. The frames are loaded by horizontal forces representing the water pressure during floods. Each frame is securely anchored at the base and is gradually loaded by two horizontal forces situated in the corners of the frame. Loading is interrupted when cracks of 0.3 mm appear. Subsequently, the frame is loaded by a pair of vertical forces acting on the top surface of the frame, up to the load-bearing capacity. This procedure was established in order to find the residual load-bearing capacity of an integral bridge that managed to withstand the effects of flooding. . The paper includes a set of computer simulations.

Abstract: The nonlinear basic theory and nonlinear influence factor of cable-stayed bridge has been introduced. Quantitative analysis to the sag effect, beam-column effect and large deformation effect has been done based on a cable-stayed bridge. Analysis show that the sag effect, beam-column effect and large deformation effect of cable force is not obvious, but the sag effect should not been ignored in the calculation of the main beam.

Abstract: According to the disease status of a dilapidated double curvature arched bridge in Baotou city, the reinforcement scheme of Shotcrete Increasing the Section is proposed. The finite element model was established by Midas software. The simulation analysis results show that for the bridge span structure after reinforcement, the bearing capacity and stiffness is increased significantly, the displacement and stress is reduced effectively, the overall mechanical performance is improved, the reinforcement scheme is practicable.

Abstract: This paper investigates the characteristics of riding comfort of double-deck bridges under multi-lane moving vehicles based on a framework for spatial dynamic analysis of double-deck bridges carrying both road vehicles and monorail trains taking into account road surface roughness and both vertical and lateral track irregularities. The bridge is modelled by finite elements with proper boundary conditions. And the road vehicle is modelled as a mass-spring-damper system with 7 degrees of freedom (DOFs) while that of the monorail train has 15 DOFs. Then holistic bridge-vehicle interaction system was assembled using a fully computerized approach and solved by direct integration method. The riding characteristics of an authentic long-span bridge carrying both road vehicles and monorail trains are investigated in details as per ISO 2631.

Abstract: In order to solve structural optimization problems in the past, it is necessary to integrate structure analysis software and optimization software. Since structural analysis has been the only function considered when developing most of structure analysis software, they suffer from closeness of system. Therefore, it is not easy to integrate them with optimization software. This study proposes an experimental design method to solve this problem including following steps: (1) generate experimental design, (2) implement experimental design, (3) construct a response variable model, (4) define optimization problem, (5) solve optimization problem. The purpose of step (1) through step (3) is to create a response variable model of alternative structure analysis software. This model is a set of regular and simple functions, it can easily define the optimization problem in step (4), in order to facilitate step (5) to solve the optimization problem. The reason to employ neural network instead of traditional regression analysis in step (3) is that the relationship between internal forces and displaced cross section dimension of the structure are often nonlinear. Neural network is a nonlinear system that gives itself the greatest advantage to accurately construct a nonlinear model. This case study is based on optimization design of cable force and tower height in an extradosed bridge, evaluating the feasibility of above method and comparing with published references to confirm the proposed method in this study is applicable to the optimization design of extradosed bridge.

Abstract: In view of the difference in design, construction and the usage of the old and the new bridges, there are always stress defects in seamline because of the concrete creep and shrinkage, temperature effect and prestress loss, which seriously affect the service and driving safety. The current ways in foreign and domestic, such as plant steel and semi-rigid connection method, are passive processing based on structure, can’t ensure the long-term performance. According to the three direction stress existing in the seamline, this paper decomposes the material contribution and structure influence, putting forward respectively using material and structure to overcome the adverse situation, using material to remove partial long-term effect, and through the sensitivity analysis of related parameters, to make the structure bearing the rest adverse effect, ensuring the long-term performance of seamline. The relevant conclusion can provide reference for the design and construction of the concrete bridge seamline.