Applied Mechanics and Materials Vols. 105-107

Abstract: Wuhan Junshan Yangtze River Bridge is an important traffic hinge on Jing-Zhu freeway, it is very necessary to conduct the comprehensive and systemic investigation on the bridge aseismic. In this paper, the FEM model of it was established; the dynamic characteristic and nonlinear seismic responses under uniform and non-uniform excitations of it were systematic studied. The results show that: 1) the basic cycle of Wuhan Junshan Yangtze River Bridge is about 8.881s. Its first mode of vibration is longitudinal floating mode, which is favorable to the earthquake- response of structures. 2) Its former 40 rank frequency are located between 0.1~2Hz which is avail to the condition of traffic condition.3) the geometric nonlinearity has much influence on the response of this kind of bridge.4) the seismic responses are sensitive to the frequency spectra of the input earthquake wave. 5) The traveling wave excitations are unfavorable to the design of tower and the main girder when considering the three orthogonal seismic wave input. In order to get correct results, artificial seismic wave of the bridge address is necessary to the time-history analysis.

Abstract: The text, drawing Liede Bridge as project background, gives a detailed analysis about the transfer mechanism of the cable tower, with the aid of analytic theory methods, FEM calculations and model tests. While these model tests and calculations show that, on one aspect, the cable tower meets design requirements and falls into a safe state under construction load and bridge load. On another, its theoretical values are in accordance with the test values generally. To illustrate that the cable tower's transmission is in line with the plane-stress problem in Elasticity Theory verifies the overall static performance in cable tower along with the theory of design calculation.

Abstract: In the paper, two key technologies of cap beams of highway bridges are studied, and the reductions of the bending moment on a pillar top and the lateral loading of live one are calculated and done experimental research. For the reduction problem of the bending moment on a pillar top, we build a three-dimensional entity model by ANSYS, and extract the bending moment of cap beams by the method of using track variable operation in post-treatment. Comparing the results of three-dimensional entity model with that of measurement of cap beams of a bridge in Zhuhai, it reveals that the reduction theory of the bending moment on an intermediate supporting of continuous beams can be applicable. For the lateral loading problem of the live load on cap beams, a new delivery method for the live load on cap beams is proposed. The transferring method is more conform to actual structure.

Abstract: As the pretressed reinforcement of prestressed concrete structure leads to rust, it would bring serious disadvantage effect to load capacity of the concrete members and reduce the reliability of all concrete structure greatly more than that of ordinary steel caused. If the prestressed reinforcement can be detected in time, the prestressed concrete structure would be got effective maintenance. In the paper, magnetic leakage testing method used in ordinary steel detection is applied to test the simulation corrosion bug of the prestressed reinforcement in bridge with nondestructive mode. The result of experiment indicates that in the distance of 100 mm from the concrete surface the magnetic leakage testing method can detect effectively the loss ratio of cross-section more than 20 percent of a hank of prestressed strands caused by a part of prestressed strands corroded to break. At last, the paper also puts forward the experiment problems in existence and the improvement methods.

Abstract: Taking Yangjiawuchang Bridge 2 Slope Project on the national key high line of Hangzhou to Lanzhou in China as example, the deformation characteristics of typical profile 4-4’ of the deposits highway slope project was studied by means of numerical simulation (FLAC3D). Based on the deformation fields, the slope deformation features were analyzed. According to the slope coefficient that was solved by strength reduction method, the slope stability was evaluated. In consideration of numerical simulation results and field geological conditions, the combination engineering treatments of surface drainage, paring-earthwork and unloading and slope temporary protection were selected. Moreover, the paring-earthwork areas were calculated and optimized. The simulation results can be based on to guide the engineering treatment, meanwhile, the results can provide reference for the similar engineering.

Abstract: Six concrete piles reinforced with 500MPa fine-grain steel bars were tested under low cycle reversed loading to study the seismic behavior such as failure patterns, characteristics of hysteretic and skeleton curve. Three parameters, longitudinal reinforcement strength, reinforcement ratio and axial compression ratio were taken into consideration. The main failure patterns as well as hysteretic curve of those piles were obtained, and influence of each of the three parameters on the ductile behavior, ability of energy dissipation and law of strength degeneration were analyzed. The experimental results indicate that the mechanical behavior of reinforced concrete low cyclic reversed loading columns with fine grain high strength reinforcement is similar to normal reinforced columns. The concrete piles reinforced with 500MPa fine-grain steel bars show good seismic performance and 500MPa fine-grain steel bars can be used in seismic design.

Abstract: According to the degradation in strength and deformation of structure with intermediate state and failure-dependence, an assessment of seismic reliability of bridge engineering structures is brought forward, which assumed there is a three-stage work mode of safety, intermediate and failure. Freely supported beam bridge is reduced to serial parallel systems. Using base shear of piers and displacement of girders as calculation indexes, models of three-levels of reliability vector are put forward to calculate the reliability vector of piers, girders and bridges respectively. A practical method for dealing with failure-dependence of anti-seismic engineering systems is put forward by considering dependence parameter. The reliability of RC freely supported beam bridge can be effectively predict by the proposed approach. It provide theoretical basis for the assessment of seismic performance and offer accurate datum that are needed for the reinforcement of bridge, so the potential disaster of lifeline engineering can be prevented or decreased.

Abstract: This paper presents efficient modeling technique using multi-dimensional method for prediction of free edge stresses in laminate plates. For the efficient modeling, the p-convergent transition element based on two-dimensional layer elements is proposed in order to connect discrete layer elements. The elements considered are on the basis of subparametric element concept. The results obtained by this proposed model are compared with those available in literatures. Especially, three-dimensional out-of-plane stresses in the interior and near the free edges are evaluated. The present models using the p-convergent transition element are demonstrated to be more practical and economical than previously p-version FEM using only single element type.

Abstract: Hongdu Bridge is an extraordinarily huge bride across northern branch Ganjiang River, in the city of Nanchang. Main tower adopted single column slanted pylon space twist face back cable structure. Its construction is based on double-wall cofferdam method. The paper discuss thecalculation of key step and key position for the key technology in terms of double-wall cofferdam and platform underwater construction, Which include the design of the base construction and double-wall cofferdam,steel cofferdam construction, the calculation and checking of the cofferdam and so on. The whole length of 9.5 km, except the starting period of about 2.4 km for roadbed type, the other sections of approximately 7 km. The project always invests about 18 Billion yuan.

Abstract: Arch springing is an important critical joint in a steel truss arch bridge, and it has a great influence on the mechanical behavior of the global structure. The adoption of a reasonable structure of the springing joint is of important significance in the design of an arch bridge. In this paper, with regard to the structure of Xinshiji Bridge, two types of arch springing were put forward. In Scheme-1, the lower chords of steel truss arch ribs are connected to the concrete piers with shear studs on the ribs and cap plates welded on the ribs at the top of concrete piers., while Scheme-2 is a integrated spring joint with a base plate on the bottom of the steel arch ribs and with reinforcing bars through the holes on the joints steel arch ribs. 3D finite element models of the two types of springing joint were established and the relative slips between the concrete and steel were taken into account in the analyses. The mechanical behavior of the concrete and the steel structure of the joints under applied loads was investigated and the analysis result showed that Scheme-2 is a relative better structure of springing joint, with less principle tensile stress in concrete and less Mises stress in steel plates.