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Xue D.,Tongji University | Liu Y.,Tongji University | He J.,Tongji University | Ma B.,Shanghai Municipal Engineering Design General Institute
Journal of Constructional Steel Research | Year: 2011

This paper presents a model test and numerical finite element analysis (FEA) on the mechanical behavior of a composite joint in a truss cable-stayed bridge. The model test with the scale of 1:2.5 for the truss joint was conduct to fully understand the safety and serviceability. In the experiment, stress distribution, crack resistance ability and shear resistance of headed studs were carefully measured to investigate the mechanical performance, force transmission of the joint part. The maximum strain of the steel plate and concrete chord remained in the linear elastic region until 1.7 times the design load, which means there is a significant safety margin for such composites. On the basis of the experimental results of composite truss joints, three-dimensional finite element models are established. The results of the finite element analysis are in good agreement with those of the tests in terms of strength and stiffness. It is also expected that the results presented in this paper would be useful as references for the further research and the design of composite truss bridges and composite joints. © 2010 Elsevier Ltd. All rights reserved. Source

Shao C.,Shanghai Municipal Engineering Design General Institute
Structural Engineering International: Journal of the International Association for Bridge and Structural Engineering (IABSE) | Year: 2010

The Shanghai Yangtze River Bridge, which is 10 km long crossing the north Yangtze River Channel, is built to serve both highway and light-rail transit line. This paper describes the following three main problems: (1) The structure restriction system and the specialty of separate type steel box girder of the main navigation channel cable-stayed bridge. (2) The scheme conformation, structure characteristics and construction methods of the composite girder in deep water area, specially the optimization design of structure and construction step based on the condition that the whole span hoisting construction method should be used. (3) The security of light-rail train on a bridge serves both highway and light-rail transit line, mainly the feasibility and relevant research results on the problem that the light-railway is set on the cantilever of the girder. Source

Li Q.,Tongji University | Wu D.-J.,Tongji University | Shao C.-Y.,Shanghai Municipal Engineering Design General Institute
Zhendong Gongcheng Xuebao/Journal of Vibration Engineering | Year: 2011

The car-body of a railway vehicle is flexible in nature. Car-body flexibility is considered while the wheel-sets and the bogies of a railway vehicle are regarded as rigid bodies in the proposed vehicle-bridge dynamic interaction analysis method. The vehicle is considered as a spatial structure supported on the wheel-rail interface through Hertz nonlinear spring. The wheel-sets and bogies are established by rigid beam elements coded in general finite element software. The car-body is modeled by flexible beam elements, and linear stiffness of the primary and the secondary suspensions is modeled by spring elements in the same software. The damping forces of the suspensions and the wheel-rail interaction forces on wheel-sets are treated as pseudo forces acted on the vehicle subsystem. The wheel-rail interaction forces on the rails are similarly treated as pseudo forces acted on the bridge subsystem. Mode analyses are conducted based on finite element models of the vehicle and the bridge. And then mode superposition method associated with pseudo force treatment is applied to establish equations of motion of the coupling vehicle-bridge system. An iterative scheme is used to solve the equations of the system. The proposed method is firstly verified by a numerical example, and then the vibration of the car-body with different flexibility is numerically simulated when high speed train traverses multi-span simply supported bridges. The car-body acceleration is found to be underestimated if its flexibility is not considered, especially when flexible car-body resonance phenomena occur. Nevertheless, the bridge acceleration is hardly affected by flexible car-body vibration. Source

Cheng B.,Shanghai JiaoTong University | Qian Q.,Shanghai JiaoTong University | Sun H.,Shanghai Municipal Engineering Design General Institute
Journal of Constructional Steel Research | Year: 2013

The second part of the paper presents the minimum weight optimization based on the provisions of current design codes for both conventional and bowknot trusses. The optimization philosophies are illustrated first through the analytic derivation of minimum weight optimization of a single member. These results indicate that the member weight reduction increases as the primary stress to secondary stress ratio, or the end moment reduction, is increased. The minimum weight optimization of the truss then proceeds on the basis of linear finite element analysis of the same truss that was discussed in Part I, by the use of first-order optimization method. In the optimization formulation, the cost rise due to steel strength enhancement of shrunken segments is taken into account in the nominal weight of whole truss, and a series of requirements related to truss vertical stiffness, member strength, member stability, and truss stability are set as constraint functions. The optimization results show that the optimal weights of bowknot trusses are less than those of conventional trusses on the premise that the steel strength of shrunken segments has been moderately improved. © 2012 Elsevier Ltd. All rights reserved. Source

Cheng B.,Shanghai JiaoTong University | Qian Q.,Shanghai JiaoTong University | Sun H.,Shanghai Municipal Engineering Design General Institute
Journal of Constructional Steel Research | Year: 2013

The first part of the papers focuses on linear and non-linear analyses of a typical Warren steel truss bridge consisting of welded box-section members and bowknot integral joints. The truss studied is simply supported at two end nodes of bottom chords with two concentrated dead and live loads being applied at each unsupported bottom chord node. The finite element method (FEM) was employed to analyze the elastic and elasto-plastic behaviors of trusses with bowknot/conventional integral joints. The results show that the secondary moments at the member ends and the sectional maximum stresses of the un-shrunken segments of the truss are significantly reduced by the section-shrinking of the member ends, but the vertical stiffness and elastic stability of the bowknot truss are deteriorated compared to the conventional one. When the steel strength of the shrunken segments has been moderately enhanced, the ultimate bearing capacities of axially compressed shrunken members and of Warren trusses with bowknot integral joints are as high as those of uniform members and of conventional trusses, respectively. © 2012 Elsevier Ltd. All rights reserved. Source

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