Advanced Materials Research Vols. 255-260

Abstract: To prevent a long-span steel truss pedestrian bridge vibration problem, finite element model was established by analysis software ANSYS, studies on this pedestrian bridge’s vibration question were carried on by frequent spectrum analysis based on recorded data and modal analysis. It has determined the vibrating level. In addition, the reason for this pedestrian bridge’s vibration has been thoroughly analyzed from the pedestrian and traffic, and had dynamic response analysis of pedestrian bridges under the crowd of pedestrians walking load. Then the main reason which causes the actual vibration characteristic has been found. Thus these both gave the reasonable explanation to the vertical vibration and provided the reference for the similar structure’s dynamic performance research.

Abstract: With the structural method, the "bending - twisting" coupling of the curve bridge is possible. As the small-radius bridge’s radius become smaller and smaller, the "Bending-Twisting" coupling become more and more common in order to discuss and verify the mechanical behaviors performance of supports' influence on small-radius bridge. This is done by changing the small-radius bridge’s supporting approach, using girder lattice method to construct a finite element model, analysis on a small-radius bridge of supporting longitudinal bending moment, torque and the influence of reaction force. The data shows that the double supports can reduce the small-radius bridge’s torque, make the medial and lateral support bearings equal reaction, make the small-radius bridge’s mechanical behaviors performance more reasonable, but was less affected by longitudinal bending moment. This conclusion of the small-radius bridge is significant to the designing work in the future.

Abstract: The effect of concrete shrinkage and creep on the deformation of the bridge structure is posing a serious issue with increasing numbers of large-span bridges are being built. At the moment, only the creep coefficient is usually considered for calculating bridge creep, without taking other factors into consideration. This paper, based on aging theory, considers the influence of shrinkage on creep stress reduction, by simplifying the formula of creep strain under discrete load by using the integral mean-value theorem and deriving the formula of concrete creep strain. Taking a continuous rigid frame bridge for example, the paper calculated the creep considering creep stress reduction under shrinkage, which showed that the method can well predict the final shrinkage and creep values of large-span concrete bridge.

Abstract: The slanting cross special-shaped arch bridge is fit for urban landscape bridge, with unique design and updated style. Based on Tongtai Bridge in Zhangjiakou, the design method, static characteristic, and stability of the bridge are introduced. The stress envelopes of girder and arch under the most unfavorable load combination, the arch stability of various stages are obtained by spacial FEM. From the results, a conclusion can be drawn that the lateral load is governing load for slanting cross special-shaped arch bridge because of horizontal component of suspender and wind load.

Abstract: Jianshe bridge is the first self-anchored cable-stayed suspension bridge in the world, localed in Dalian, China. Cable-stayed suspension was presented in history, however cable-stayed bridge and self-anchored suspension combine to make a new type system, which is economy and fit for large span bridge. This paper presents the design of Jianshe bridge. The static and dynamic character of the system and the fatigue of suspender are presented. The computing model of this new system is also introduced in the paper. The structure internal force nonlinearity and stress of the bridge are analyzed. Then analyse the calculate results and draw the conclusions, which self-anchored cable-stayed suspension bridge is fit for large-span bridge, cross suspender can reduce stress amplitude and overcome fatigue problem, and Wind-resistant stability of self-anchored cable-stayed suspension bridge is better than earth anchored system.

Abstract: The railway double-track continuous bridge vertical load-carrying frequency is theoretical derived with the vehicle-bridge system mode1. The vertical load-carrying frequencies of the 40 m+4×72 m+40 m party pre-stressed concrete continuous box-girder bridge are calculated, when two trains with 20 same high-speed passenger vehicles are traveling on the bridge from both ends. The change regularity of this double-track continuous bridge vertical load-carrying natural frequency with two trains on it is similar with that of the single-track simply supported bridge and this bridge as one train on it. This bridge vertical load-carrying frequency when two trains on it is smaller than that only train on it. The maximum deviation percentage between the vertical load-carrying natural frequency and the vertical natural frequency is 1.17837%.This bridge vertical load-carrying frequency can be replaced by its natural frequency, and there isn’t obvious error. If the vertical load-carrying frequency should be calculated, it can be replaced by the average value.

Abstract: Taking one typical two-tower three-span self-anchored suspension bridge as an example, structural response has been characterized in detailed followed by its own construction steps. Meanwhile, the structure’s mechanics properties have been mathematically formulated through theoretical analysis method. Finally, the formulation has been further expressed by using a simplified beam subjected to external equivalent forces, and then the equivalent-beam theory of the self-anchored suspension bridge has been well established thereafter. As been demonstrated, the equivalent-beam theory can be easily and clearly applied to determine the vertical mechanical properties of the self-anchored suspension bridge, and could be utilized to guide the self-anchored suspension bridge deign in the future.

Abstract: Taking one irregular continuous bridge as an example, modal pushover analysis (MPA) has been conducted to judge whether it would be applicable for seismic analysis of irregular bridge structures. The bridge’s seismic demand in the transverse direction has been determined through two different methods, inelastic time history analysis (ITHA) and MPA respectively. The comparison between those two results indicates that MPA would be suitable only for bridges under elastic or slightly damaged state. Finally, some modifications are used to improve the MPA’s scope of application, and the results illustrate that the adapted MPA will be able to estimate bridges’ seismic demands to some extent.

Abstract: The features of a new type of continuous bridge suspended by triangle frame are introduced in this paper. In view of the segmental cantilever construction method engaged in main girder construction, we put forward to the method of pre-camber setting and the calculation of formwork elevation and field measurement of displacement.

Abstract: Simulation analysis is the basis for construction control of cable-stayed bridges, it monitors the process of the bridge construction. The relationship and importance of simulation and construction control are introduced in the paper. Based on the finite element theory and combined with construction theory of the cable -stayed bridges, according to use the software Midas/Civil, the construction characteristics of Masangxi Bridge is researched by making use of the forward calculation method and the backward calculation method. The results show that the system transformation of the bridge is occurred during the construction, thus, it is important to carry out careful and detailed forward simulation to ensure the safety of construction structure and meet with design requirements. The reasonable results can be drawn when the backward calculation method is combined with the forward calculation method.