Papers by Keyword: Seismic Response

Abstract: To study the effects of seismic waves directions on bridges, the time history analytic method was used. Two bridge types, the railway continuous curved rigid frame bridge and the railway continuous straight rigid frame bridge, have been taken into account. Both the two same span bridges were used for comparative analysis about free vibration and seismic response feature, then some practical application conclusions were obtained. The longitudinal and transversal seismic waves produce the maximum reaction values. Besides, the pier bottom sections and the beam sections at the piers top are the critical sections in the bridges. In addition, this small radius curved bridge can be designed as the straight bridge in seismic design.

Abstract: A three dimensional numerical model for a typical earth dam and its valley site was established and the nonlinear seismic response of this model was performed. Experimental data of cyclic triaxial tests were adopted to determine the curves of modulus ratio and damping ratio that vary with dynamic strain amplitude. Free-field artificial boundary and viscous artificial boundary were employed and the input waves were the revised ground motions obtained from the station near the dam. Distributions of the PGA, displacement, residual deformation, shear strain increment and element failure state were presented. Results demonstrate that the 3D local valley site effect has a significant influence on the seismic response of earth dam.

Abstract: Studying the important effects of sediments on the seismic response of dams ,This paper established the calculation model based on regarding the water reservoir as compressible fluid ,the dam and the foundation as an elastic solid, the sediment as Liquid-Solid two-phase porous medium. The results showed that the sediment thickness and properties have important effects on the dam seismic. Increasing the thickness of sediment ,the seismic response of acceleration significantly decreased, the hydrodynamic pressure significantly reduced , which is benefited to the safety of the dam.

Abstract: In order to explore the safety performance of continuous structure bridge near fault zone, a typical three spans continuous girder bridge of highway was selected to study the structural seismic response. The finite element model of whole bridge considered the force characteristics of bearing and pile-soil interaction was constructed. Typical near-fault records were selected from the important earthquake events. Several artificial waves characterized with the soil type in bridge site were simulated and used for dynamic analysis. The seismic performance of continuous bridge was studied by nonlinear dynamic time-history method. Research results indicate that, especially large amplitude pulse effect of near-fault records for strong near-fault earthquake, will significantly enhance the seismic response of continuous girder bridge under the second seismic level (EL2) leads to structure to collapse. The fact that the near-fault effect is not considered in China existing highway bridge seismic design code will increase the destructive risk of structure.

Abstract: In order to study the effect of different models on caisson-soil interaction, a linear model and two nonlinear models are established by finite element software SAP2000. It is found that with the increase of amplitude of seismic wave, the effect of nonlinear properties of caisson-soil interaction is increasingly large. The linear model, however, is not suitable any more under such condition, while the nonlinear models can simulate caisson-soil interaction reasonably.

Abstract: A state-of-the-art review of the seismic response of utility tunnels is presented. The objectives of the review are to present a view of current state of utility tunnel and to examine trends in the future. The review includes: the theoretical analysis, numerical simulation and experimental research on the utility tunnel under earthquake wave excitation. Based on the review, the future scope of work on the subject is outlined.

Abstract: Heat-insulating perforated brick is a new type energy-saving masonry material. In order to investigate seismic response of masonry wall with this new-type brick, a set of quasi-static full-scale cyclic tests are performed. The test results show that this brick owns a good cooperative work system between bearing layer and insulation layer, and vertical axial force is an obvious factor which affects seismic response of heat-insulating perforated brick walls. With the increase of vertical axial force, ultimate bearing capacity increases, however, ultimate displacement can be decreased. In the case of the same axial force, ultimate bearing capacity of the specimen wall with door opening is less than the one with window opening, and the ultimate displacement also is less than the one with window opening.

Abstract: Taking the Sifang Bridge in Yunnan Province in China as an example, this paper analysis the influences of soil-structure interaction on seismic response of extradosed cable-stayed bridge with response spectrum method. The results show that extradosed cable-stayed bridge has a shorter nature period than cable-stayed bridge, and torsional vibration mode does not happen in the first few modes as the beam has a bigger stiffness. The displacement of the structure will be underestimated if the soil-structure interaction is ignored while the design of some parts is conservative.

Abstract: Interaction between buildings and tower has not been considered in former research..In this paper an integrated seismic analysis method is proposed considering the interaction between the building and the tower crane. A 3D-FEM model of the building and the crane is established with ANSYS software and seismic responses such as the displacement, the acceleration and the stress of the crane are analyzed. The sensitivity of the stiffness of the building on the dynamic responses is also analyzed. The results with consideration of the building-crane interaction, is higher than the results without interaction, and it becomes more significant with the increase of stiffness of the building.

Abstract: The pipelines distribute extensively in China, but pipelines cracks caused pipeline damaged frequently. Once the pipeline’s cracks are considered in the seismic condition, the performance of pipelines will face many problems. The finite element method was used to analyze the seismic responses of pipeline’s cracks. According to fracture mechanics [1], the time-history responses of displacement, acceleration and stress of pipeline with crack defects and seamless pipeline were obtained, and the results were also compared and analyzed. The results indicate that cracks will cause the stress concentration of the pipeline, the pipeline cracks should be considered in seismic responses of pipelines to make the pipelines in safety and economy, and more attention should be paid to the design and study of pipelines with crack defects.