Advanced Materials Research Vols. 255-260

Abstract: Guantifying the aseismatic factor of bridge and determining the factor domain,the weight and evaluation vector in different levels using the basic principle of fuzzy mathematics.Besides, the aseismatic performance of a large-scale bridge in Sichuan were studied and analysised by using the fuzzy comprehensive evaluation method.

Abstract: By use of large finite element analysis software, dynamic characteristics analysis is carried out for an aqueduct in South-to-North Water Transfer Project. Westergaard method and Housner method are used respectively to simulate the water. The natural frequencies and mode shapes (wet) of the aqueduct structure are calculated under two kinds of water depths (designed water depth, half water depth). The results show that the influence of the water on the dynamic characteristics of the aqueduct is obvious. Natural frequencies decrease with the increases of the water depth. The distinction between the two methods was analyzed: Housner method is closer to the practical engineering because both the pulsation effect and the convection effect of the water are considered. The results and conclusions can be referenced for seismic design of large aqueduct.

Abstract: Based on the numerical simulation and finite element method, the longitudinal seismic action of a long-span continuous bridge is systematically analyzed. Four load cases are considered, i.e. bridge without piers, bridge with piers, neglecting friction force and combining friction force and pier scouring respectively. Calculation results show that: when considering the piers, the contribution of piers to bridge longitudinal seismic forces is depending on the concrete problems; when the friction force of rubber supports is regarded, sliding support greatly enhances the longitudinal overall rigidity of the bridge, but the force is resolved to each rubber support and can improve the stress state of the fixed support; considering effect of scouring, the elongation of piers will lead to the decrease of longitudinal overall rigidity, thereby lowering the longitudinal seismic forces. From comparison of the two piers that, the relatively flexible structure has shock absorption to a certain extent, so it is more suitable for the bridge.

Abstract: Large finite element software is used to analyze Shuangji River rectangle aqueduct in the South-to-North Water Transfer Project. The stress and displacement of the whole structure are obtained under different stretching order of prestress during the aqueduct construction period. Calculation results show that, from the point of stress, the better prestress stretching order is stretching longitudinal first, then the transverse and finally vertical; from the point of displacement, drawing order variation has little influence on displacements in the stretching process; it is a relatively good simulation method to add a steel plate to the area where the prestressed strands are acted on. In this way, the real anchor state can be simulated, and the local stress concentration can be reduced.

Abstract: Based on the vehicle load model for fatigue design, the stress influence line of the reinforcement in the concrete slab of northern approach of Jiubao bridge, a multi-span continous composite bridge, under the global live load was obtained by spatial frame structure finite element model, while the stress history of the reinforcement under the local live load was obtained by the spatial refined finite element model. Then the stress spectrums under global and local live load were obtained by Rain-flow method according to the predicted traffic volume in the future 100 years and comparisons of amplitudes of equivalent stress under different loads were achieved. At last the fatigue lives of the slab under the different loads were calculated and compared either.

Abstract: In order to study the reasonable installation lengths of zero block concrete segment in prestressed concrete box-girder beams with corrugated steel webs, a numerical analysis on the length of different zero blocks in PC box girder beams with corrugated steel webs is made by the finite element software ANSYS. The influence of the installation lengths of zero block concrete segment on the structure control section's internal forces and deformation is discussed. The results indicate: the impact of length changes of zero block on box girder deflection is greater than its impact on internal forces; in terms of deflection, the displacement influence in quarter-section in middle span is the largest; and in terms of internal forces, the internal forces influence of the junction section formed by zero block concrete segment and beam segment with corrugated steel webs is the largest. According to the above results and the relevant information of constructed bridges, the reasonable setting length of zero block concrete segment has been provided, that the ratio L₀/L of installation lengths and span for zero block of box girder should be in the range of 0.05 to 0.10.

Abstract: The paper treated the beam-arch association bridge as a two-component structure of beam-arch closure and suspender, and assumed the suspender force as one of membrane tension. By the assumption, expressions of ratio between tensile-tension moment and free beam moment, and moment ratio between arch and beam, were supplied under uniform load for beam-arch association bridge. Moreover, its influencing factors and inter-relationship were discussed. With these researches, the paper comparatively fully opens out the transfer mechanism of free beam moment for beam-arch association bridge.

Abstract: Dynamic response analysis is carried out for an aqueduct structure of the South-to-North Water Transfer Project. The interaction of water and aqueduct wall is simplified using Housner method. Six different water depths (empty aqueduct, 1/4 water depth, 1/2 water depth, 3/4 water depth, designed water depth and full water depth) are considered and calculation is conducted using time-history analysis method. The variation rule of dynamic stress and dynamic displacement are gained under different water depths. Results show that water has great influence on aqueduct body and its dynamic response. Dynamic displacement and dynamic stress of the aqueduct structure increase with the aqueduct water level increases. When water depth is bigger, dynamic displacement response and dynamic stress response are later than corresponding earthquake excitation. The relative stiffness of the longitudinal beam and the transverse beam should be fully considered in order to reduce stress concentration of aqueduct body.

Abstract: Using large structure analysis software, the stress and displacement are calculated for Shuangji River rectangle aqueduct structure during construction and operation periods. The 19 different load combination cases are considered. The variation rule of mechanics behavior is obtained for concrete material during different load combination period. The simulation results show that the conventional method simulating prestress can lead to stress concentration in the point the force is acted on. It is a relatively good simulation method to add a steel plate to the area where the prestressed strands are acted on. In this way, the local stress concentration can be reduced. When use pseudo-static method for calculation of the seismic load, the load case considering the seismic load is a control load case. The Shuangji River aqueduct can meet the requirement of intensity and rigidity during construction and operation periods.

Abstract: Based on scheme of Dalian gulf cross-sea bridge, in this paper, a 3-dimensional FE model for Self-anchored cable-stayed suspension bridge is established with finite element program and pile-soil-structure interaction is simulated by use of the equivalent embed fixation model. Based on the FE model, model analysis is carried out and the effects of pile-soil-structure interaction on dynamic behavior of long-span self-anchored cable-stayed suspension bridge are specially studied. The seismic response analysis result considering that pile-soil-structure interaction was compared with that of without considering such interaction. The analysis result show that interaction extend the nature period of structure, has the greatest impact to the first vibration mode; meanwhile, enlarged longitudinal displacement and moment of stiffening beam in middle of main span, longitudinal displacement on top of tower and axial force at bottom, but reduced the moment of tower at bottom. The research results provide some theoretical foundation to composite structure system.