Advanced Materials Research Vols. 243-249

Abstract: Due to computer performance, nowadays only parts of the structure can be executed the simulation analysis of 3D. For the prestressed structure, after took out the target segment from the original structure, the accuracy of the result is mainly depended on the boundary conditions and the accurate simulation of the tendons. This article took the 3D simulation analysis of the arch foot for an 80m tied arch bridge for example which introduced a method that could simulate the tendons precisely when performed local stress analysis and compared the results of the common method to this method. Via the contrast the rationality and advantages of the method are clear. A certain accuracy method was presented in this article when came across the similar analysis of local structure.

Abstract: The double spherical seismic isolation (DSSI for short) bearing has been adopted in seismic design of several important engineering projects since developed recently. It was used generally as fixed bearings in a continuous girder bridge in these projects, and only a few fixed piers, usually just one fixed pier would transmit the horizontal earthquake action to the foundation, which is uneconomical and results in the much larger seismic risk in the longitudinal direction of a continuous girder bridge than that in the transverse direction. In order to share the earthquake effect with all the piers and avoid relative vertical displacement among all the bearings under the normal traffic conditions, a new seismic design method of continuous girder bridges is introduced. The configuration and working mechanism of two kinds of DSSI bearings used to make the new seismic design possible are introduced. It’s shown that the method is preferable for the seismic design of continuous girder bridges by a numerical seismic analysis with a four-span continuous girder bridge.

Abstract: It is a common construction method to pour arch concrete in arch centering. The deformation law of arch centering was analyzed in process of pouring arch concrete, a new method to determine concrete cast-in-situ section lengths and corresponding formulas which based on deformation scale of arch centering were presented. According to influence line of arch centering deflection, a program used to calculate cast lengths and arch centering deformations was developed. This program could automatically calculate each segment of arch concrete based on the assigned deformation conditions. A numerical result shows that when the arch centering deformation scale was taken as the target, deformation proportion caused by each segment of concrete should be controlled on 0.5-0.6.

Abstract: The geometric structure of steel deck plates is complex. So it is difficult to get precise results in the mechanics calculation of deck pavement with traditional methods. This paper adopts the finite element method for the mechanics analysis of the composite guss asphalt surfacing layer of curved steel box girder bridges. By taking the orthotropic steel deck and the pavement as a whole, a reasonable finite element model is established and optimized for the mechanical study of steel deck pavement. This model can be used to study the stress and deformation features of the surfacing layer. According to the common diseases in steel deck pavements and the effect of the overload and the horizontal load in braking to the pavement, this paper puts forward the comprehensive control indicators for pavement failures.

Abstract: For a super-long-span cable-stayed bridge, it is often required that the main tower be essentially elastic under a strong earthquake. Therefore, a seismic isolation structural system is often used to reduce the seismic response. Since the seismic displacement at the end of the deck may severely exceed the allowance, the elastic link device and viscous damper are often employed to control the displacement. In this article, a new damper (Metal Alloy Brace) is used to achieve this goal. Under the frequently occurred earthquake excitation, MAB’s hysteretic curve is plump, so the structural deformation is reduced. Under rare earthquake excitation, MAB can supply so big stiffness that the structural deformation is limited, and the damper will also dissipate much energy. And the damper has no problem with leakage and metamorphism. So, the prospect of MAB is brightening.

Abstract: Taking a long-span composite girder cable-stayed bridge with three pylons under construction as the object of research, this paper establishes a three-dimensional finite element model of a bridge considering the geometric nonlinearity, material nonlinearity and interface slip effect in composite girder, and analyzes the failure loads and failure modes of the structure at bearing capacity limited state. The results show that the ultimate load-carrying capacity is high at bearing capacity limited state, load case whose live load acts on one main span is more unfavorable, and according to the structural failure modes, increasing the ability of the middle pylon to resist bending moment can improve the ultimate load-carrying capacity of the whole bridge quickly.

Abstract: When the transport vehicles of large equipment pass through bridges, the main check-calculation coefficients affecting the bridge bearing capacity are the load transverse distribution coefficients, impact coefficient and load safety coefficient. Base on these affecting factors, this paper put forward a discriminant for modified equivalent load method. The triangle influencing line method is applied in measuring the equivalent load of commonly used vehicle plates for transportation of large equipment. Finally this seeks to verify and modify the accuracy and convenience of equivalent load discriminative method through engineering examples and thus suggests a concise and practical method for engineers and technicians： to conduct feasible study for bridge transportation for large scale equipments.

Abstract: According to the characteristics of self-anchored suspension bridge, a new method to detect damage is introduced in this paper.It works in two stages.First, a BP neural network model is built to predict damaged position. Next, based on the characteristics of genetic algorithm and simulated annealing algorithm, a new approach, genetic-simulated annealing algorithm, is put forward to identify damage extent of detected positions. Compared with the traditional genetic algorithm, the global convergence effect of this algorithm is enhanced by using of the Metropolis acceptance rule of the simulated annealing algorithm in the searching process.

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 the3×64 m through stud welding railway steel truss 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 the single-track simply supported bridge and this bridge vertical load-carrying natural frequency only one train on it. This bridge vertical load-carrying frequency when two train 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 6.0452%. The vertical load-carrying frequency can be replaced by the average value.

Abstract: Based on investigation and analysis of the diseases of Sujia river truss arch bridge, putting forward corresponding the reinforcing measures in accordance with the cause of disease. The results indicate that it is feasible to resume the bridge carrying capacity with pasting CFRP, pasting steel plate replacing bridge deck. It can be a reference to the other similar bridges.