Advanced Materials Research Vols. 838-841

Abstract: In this paper, using elastic-plastic fiber unit model for a continuous beam bridge structure and foundation to analyses the nonlinear seismic response of pier and pile foundation considering pile-soil interaction and the different types of seismic wave on the pile foundation and the pier dynamic response, focusing on the development of plastic zone and dynamic response of structure under different pile-pier reinforcement ration conditions. The results show that, with the pile pier reinforcement ratio increases, the response plasticity of pile and pier show a different trend; so pile-pier reinforcement ration is an important factor of dynamic characteristics for the bridge pier supported by group piles system; the pier reinforcement ratio not only impact on development of the plastic zone of the pier, but also impact on the pile. In addition, different types of seismic waves on the structure are different, the long-period seismic waves maximum, followed by inland direct seismic waves, plate boundary seismic wave minimum.

Abstract: Longitudinal seismic responses of CWR on bridges with high-piers and long-spans under uniform excitation and traveling wave effect were studied. Results are shown as follows: Under seismic action, rail longitudinal forces near beam joints increase greatly than rail expansion forces (due to beam expansion); Designing CWR on bridges with high-piers and long-spans needs to consider influences of traveling wave effect and wave spreading derection; With the increase of the apparent velocity of seismic waves, rail longitudinal force tends to decrease; We suggest that designing of CWR on bridges crossing high-intensity earthquake zone should consider impact of seismic action, and establish a reasonable check method.

Abstract: In the operation process of bridge structures, some bridges appear early failure without reaching design reference period due to the influences of external environment, vehicle load and other factors. Therefore, the problem of structure durability is very obvious. In this paper, a new durability assessment method is proposed based on fuzzy neural networks, which can take account of the defects and deficiencies of existing durability assessment methods. The simulation for learning and testing samples indicates that the proposed method possesses good learning ability and predictive analysis ability. Actual project verifies the effectiveness of the method

Abstract: As a main bearing structure of suspension bridges, the stability of anchorage foundation is very important. For the north-anchor foundation of the Run Yang Bridge, the stabilities against sliding and overturning are analyzed from the computation results of three-dimension finite element simulation models. The effect of soil resistance before and behind the pit on the stabilities is analyzed. Suppose the values of overload cable tension increase proportionally and by studying changes of the deformation and stress of anchor foundation, the basement resistance and the foundation stabilities against sliding and overturning with different overload coefficients, overload safety is obtained for anchor foundation. Based on the numerical computational results of the stability and overload analysis, some beneficial results are obtained for the stability analysis of anchorage foundation of suspension bridge.

Abstract: This paper apply displacement back analysis theory for geometry form monitoring and calculating work of segmental construction of prestressed concrete continuous girder bridge, making use of displacement back analysis method to optimize bridge structure parameters, ensuring accuracy of geometry form control with calculated results of every girder segment in entire construction. This method is used in the construction monitoring and supervision for Yuanyichang circular curved rigid frame bridge on Pingan-Adai highway, to make the closure accuracy and the bridge geometry form reaches the effect of aspiration. Through the result of the finished bridge, what we can obtain is that the displacement back analysis theory could fulfill the requirement of factual project and be widely used for geometry monitoring of segmental construction of prestressed concrete continuous girder bridge.

Abstract: Study and design a set of economical and practical mid-and-long term monitoring system for long-span prestressed concrete continuous rigid frame bridge relying on the engineering of Xintan Qijiang Bridge in Chongqing. Master the static characteristics of such parameters as displacement, stress and external cable force during operation process of bridge through finite element model and make a comparative analysis of the relevant data after running for two years to test the feasibility and practicability of mid-and-long term monitoring system for continuous rigid frame bridge suggested in the paper.

Abstract: The crack control of the thin-walled high pier for SanBei Bridge is effected by various uncertain factors such as loads, concrete strength and the release of hydration heat etc. Because of the fuzziness for the crack control of thin-walled high pier, it is difficult to accurately calculate the crack width to meet with the requirement of the limiting crack design for the structure. Based on the maximal permit crack formula issued in Concrete Design Specifications, the fuzziness analysis is made to the crack control reliability, the index of fuzzy reliable degrees of the girder maximal permit crack width is calculated by Monte Carlo method, and the sensitivity analysis to uncertain parameters is given to provide reference of the design for SanBei Bridge.

Abstract: A 3-D finite element model for Yueyang Dongting Lake bridge was established with a large scale general finite element analysis software, and the subspace iteration method was adopted to analyze the natural vibration characteristics of the bridge, meanwhile, the influences of settings different types of central buckles at the mid-span of the main spans between the main cables and girder on the dynamic behaviors of the long-span suspension bridge with deck-truss composite stiffening girder were studied. The results show that compared with only setting short hanger cable at mid-span, the the whole rigidity of suspension bridge is raised and the natural frequencies increase by the setting central buckle, but various types of vibration modes are affected in different extents; among all of these vibration modes, the antisymmetric vibration and Longitudinal floating of stiffening girder are most obviously affected. The stiffness of central buckle has a great influence on the vibration of main cable, while compared with only setting short hanger cable, the vibration of main cable increases 7.32% while setting the rigid central buckle. The conclusions of this paper provide theoretical basis for the using of central buckle in long-span suspension bridge.

Abstract: It put forward the new technology of reinforcing tie-beam with steel plate yoke to reinforcing the bridge based on analysis the reasons of the defection of the reinforcement trussed arch bridge deeply. In the text it analysis the mechanism of the steel plate yoke on the theory of the constant improvement in the horizontal distribution and transverse pre-tensile stress designing and introduce the construction technics of the reinforcement technology particularly. It is proved that the combined reinforcing technologies are effective according to test factual bridge.

Abstract: Instability exposed foundation due to scour around bridge pier caused displacement should be noted that erosion and destruction often occurs subsidence of river-bed soil in bearing layer changed place under water pressure bound to tilt the piers of the bridge, which can then produce another phase of secondary displacement, that is, if in the longer term forces such as earthquakes or floods overall resulting short and long term in unstable state. This study applied finite element model Plaxis-2D to analyze exposed foundation on bridge pier scour in 200-year return flood peak flow, involving consolidated with static load, water pressure, structures suffered the wind, driftwood impact, and debris thrust is to assess abutment security in flood erosion according to the alert and action warning.