Applied Mechanics and Materials Vols. 178-181

Abstract: Abstract:Based on the deflection theory and the virtual displacement principle, the stress state of different components of the self-anchored suspension bridge was analyzed; the formulas denoted by trigonometric series for computing the internal force and deformation of the stiffened girder, were derived respectively under a variety of loads, and the cable force was determined under the live load combined with Newton-Simpson iteration approach. On the basis, a practical method to calculate the internal force and deformation of the stiffening girder of self-anchored suspension bridge, was presented, and also the corresponding analysis program. Then, Sanchaji Bridge across Xiangjiang River in Changsha (self-anchored suspension bridge, main span of 328m), was taken for example, the calculation results compared with finite displacement theory, proved it to be simple, convenient, accurate and reliable; if the distribution of the hangers is uniform, the results were consistent between deflection theory and finite displacement theory. This shows that, this method proposed by this paper can be used to study the influences of design parameters, having on the internal force and deformation of self-anchored suspension bridge, especially in the preliminary design stage, can be easy for the selection of the main design parameters.

Abstract: Equivalent seismic wave can be formed by a main wave and two strong aftershock waves on the basis of energy equivalent principle. With a long-span arch bridge as a research object, the hysteretic energy distribution of the pier and arch were got by the action of the main wave and equivalent seismic wave based on energy method. And then the situation of bridge damage was assessed by Seismic Ditao Niu damage index, the regular pattern of structure damage affected by strong aftershock was revealed as well.

Abstract: In this paper, vibration theory is used to deduce vertical vibration’s analytical expressions of Euler- Bernoulli beam traveled by moving loads. In the analytical expression, the influences of the train’s travelling speed ,the mode of vibration ,the mass and rigidity of beam itself and the damping ratio of the system are considered comprehensively. Then the calculating program is made with MATLAB to analyze the dynamic response of a bridge as an illustrative example, so as to check the correctness of the analytical solution. Then a 32 meters simply supported beam traversed by moving loads of 8 ICE3 motor cars is analyzed. The calculation results show that the analysis method in this paper can really give accurate results to the beam subjected to arbitrarily spacing loads . The analytical expressions can be applied to preliminary design of railway bridges and assessment of the expected maximum vibration levels under high-speed trains.

Abstract: There is a big difference between force of the fulcrum positions when simply-supported continuous bridge(SSCB) is under load.This paper introduces a method of making SSCB’s fulcrum internal force under load more uniform through applying forced displacement produced by using enequal altitude bearings.Using the force method in structural mechanics infers the forced displacement formula, which provide a theoretical basis for improving SSCB’s structure stress.

Abstract: Pit excavation was easy to cause the deformation of the supporting structure and surrounding soil, and brought serious harm to the surrounding buildings and urban underground pipelines. How to carry on a comprehensive analysis of inter-linked pit monitoring points, and improve the overall prediction accuracy was the urgent problem needed to be solved in scientific predictions of pit deformation. In order to establish the multi-variable gray theory GM(1,N) first-order linear dynamic model, using pit mutual influential settlement deformation monitoring data, and the correlation degree analysis, it filtered out the parent sequence WY09 point as the object to be analyzed, and the remaining points were as the systematic analysis of influencing factors, and WY09 point settlement predictions was calculated. According to the comparison analysis of the prediction results and engineering measured results, GM(1,N) model overall prediction accuracy was higher than GM(2,1) model, and prediction results were almost consistent with the measured results, so good effects was produced.

Abstract: Traffic composition and the vehicle load were statistically analyzed and a fatigue vehicle load model was established according to the law of equivalent fatigue damage. Based on the MATLAB programming language and the Statistics Toolbox, vehicle fatigue load spectrum was simulated for accurately assessing actual fatigue stress of existing bridge under traffic loading. And the fatigue load could be used in the design for suspension bridge steel box girder.

Abstract: This paper describes the structural forms for hybrid FRP-concrete highway bridge deck. This bridge deck is applid in a project, which involved the implement of FRP-concrete deck over prestress concrete girders. In this project three forms of FRP reinforcing were combined to reinforce the concrete deck. This paper introduced another stiffened FRP deck panels connecte with the FRP composite girders in the steel-free FRP-composite modular bridge system. It is shown that the combination of FRP meterial and concrete for bridge deck is recommended in the design of highway bridge.

Abstract: From the 921 earthquake to the major typhoons, including the Morakot typhoon, they damaged original landscape of rivers in Taiwan. In recent years, it alleged that abutment bridge exposed to the most serious security problems. Because of bridge piers in addition to the face of long-term river erosion, the flood on the pier will produce localized erosion near the bridge. The pier will be due to inadequate bearing capacity, resulting in subsidence, displacement, bridge version accompanied by tilting and even caving. The river erosion of soil around the piers deposits and production of contraction will often reduce the bearing capacity. Therefore, how to accurately estimate the scour depth, calculate piers to withstand water impact and analyses its stability for preventing injuries in the first place is the current pressing issues. In this study, three-dimensional finite element method (FEM) analysis program Plaxis 3D foundation is used. Polaris second bridge is selected for analysis. Based on local scouring of the model and various numerical variable conditions, the parameter of bridge pier is studied.

Abstract: This paper established a spatial nonlinear finite element model based on the earthquake dynamic equation and the seismic response of a self-anchored suspension bridge is calculated. Taking the pylon bottom force as objective function, optimization theory is used to obtain the viscous damper parameters. Seismic responses of viscous dampers in different positions are also discussed. The results show that pylon bottom moment is 117492.0KN•m in earthquake and it is a key factor for bridge design. The best parameters of viscous dampers can be obtained using optimization theory and the calculating work reduced largely. Longitudinal displacement of the girder reduced 83% and the pylon bottom longitudinal moment reduced 62% if install viscous damper with appropriate parameters. The positions of dampers installed affect the seismic response largely, the variety of force and displacement in the structure must be fully considered.

Abstract: Prestressed concrete(PC) channel bridge, consisting of a PC deck slab, two PC girders and two end crossbeams, is a new type of bridge structures. The PC channel bridges have been widely used in the structures such as highway, railway as well as urban rail transport. This paper presents a finite element method (FEM) analysis of mechanical behaviours of channel bridges with three girders in the construction, service and ultimate limit stage. The primary results include:(1) the channel bridges act elastically in the construction stage. (2) under the service loads, the deflections in the mid-span and the stresses on the whole concrete cross section could meet the requirements of the current codes. (3) the FEA results of flexural capacity of the channel bridges agree well with the results calculated according to the current codes, and the average loads of flexural capacity are about 3.26 times the design loads.