Applied Mechanics and Materials Vols. 353-356

Abstract: Dynamic stability analysis of twelve single-story steel frame structures is analyzed based upon the finite element method. The influence of different earthquake excitations on dynamic stability of single-story frame is studied. Time history curves of displacement, hysteretic curves of restoring force, phase plane trajectory curves have been obtained. The results indicate that the ultimate displacements of frames when structures collapse are almost identical and ultimate displacements are independent of earthquake excitations.

Abstract: Based on a high-rise frame shear wall structure with high conversion layer, this essay makes compare among three structural models-wide flat beam, SRC and the common conversion beam by using Midas Building, analyzes seismic performance of three forms of conversion beam under gravity effect and seismic effect in consideration of the force of whole structure, force of conversion component and elastic earthquake, analyzes structure model when the wide flat beam is acted as conversion beam with static elastic-plastic analysis (Pushover) method to get the change of the displacement curve of base shear-vertex and the interbeded displacement angle, finds out the weak parts of the structure, comprehensively evaluates the seismic performance of the structure and put forward the key problems and the solutions through looking for performance point.

Abstract: This study investigates the influence of material nonlinear in slender reinforced concrete (RC) columns dynamic second-order effects under seismic load. The stiffness reduction coefficient is adopted in this paper. To identify the significance of various effects in terms of the dynamic second-order effects of the slender RC columns, nonlinear dynamic analyses are conducted for different periods and stability coefficients of simulated models with rare occurrence earthquake. On the basis of the obtained numerical results, the influence of material nonlinear for dynamic second-order effects are reviewed.

Abstract: Continuous bridges jolted the public attention into the awareness of the seismic vulnerability due to its wide application in bridge engineering. Viscous dampers can effectively improve the seismic performance of continuous bridge. In this paper, taking the Yellow River Bridge located in seismic region with intensity VIII as an example, the influence of the damping coefficient and velocity exponent of the damper on seismic responses of the bridge are carried out in detail. The applicable model parameters are also presented.

Abstract: The MASW method is robust in determine shear wave velocity of shallow site because the dispersive properties of Rayleigh wave was dominated by shear wave velocity of subsurface. Using this method, an assumption that the earth model is one dimensional and horizontal layered must be put to simplify the real earth model without considering the lateral variation. However, it is not always the truth. In order to obtain a two dimensional S-wave velocity profile of shallow site, a CMP cross-correlation (CMPCC) method was proposed by Hayashi and Suzuki (2004) to approximate two dimensional S-wave velocity profile with one dimensional inversion procedure. In order to verify its approximate resolution, a horizontal stepped layer model and a dipping layer model were chosen. The synthetic wave fields of the two models were calculated by staggered grid finite difference method. Result shows that this method can only be used to approximate horizontally stepped layer model and cannot be used to approximate dipping layer model.

Abstract: Dynamic analysis can be carried out quickly and accurately for the seismic performance of dam by using the finite element software. Added massed method is used for the dynamic water. Horizontal earthquake acceleration is 0.2G; vertical earthquake acceleration is two-third of horizontal earthquake acceleration; sub space iteration method is used for the modal analysis of the dam; Finding the maximum response-order mode shape, and then useing a combination of square and square root method to come to the conclusion of overall seismic response. The stress and strain of the dam had been analyzed and the weak link of key parts of the dam had been summarized in this article.It is concluded that seismic design requirement are satified for the dam.

Abstract: The determination of damping constitutes an essential part of the cyclic characterization of soils. While because of the damping of soils is nonlinear, ie., strain-dependent, the definition of shear strain amplitude under irregular loading process construct the key point of the damping based cyclic models. This paper introduces a new damping-based model (DBM) for nonlinear soil behavior simulation and discusses on the effect of shear strain amplitude definition on model behavior. Both qualitative and quantitative analysis re-sults show that the reversed hysteresis loading curve is significantly influenced by the pre-supposed loading amplitude and generally large pre-proposed shear strain amplitude will lead to low reversed loading trajectory. Analytical comparison among several definitions indicates that defining the maximum reversal point of history as the loading amplitude performs the best.

Abstract: This Earthquake liquefaction analysis of total stress method is often used, but the total stress method does not consider the variation of pore water pressure and the process of development of the liquefaction over time. Using two perspectives which the total stress method and effective stress dynamic analysis given liquefied range of offshore airport foundation under the earthquake , and giving recommendations for ground treatment methods.

Abstract: In this paper, we calculate and analyze a tall building project of seismic isolation design. It is a frame-shear wall structure, which has twelve stories on the ground. And then, we use the time history analysis method to calculate the isolation structure. It is found that isolation equipment can extend the period of the structure, reduce the story drift in frequency earthquake. And it also can control the response of the structure. In rare earthquake, the story drift can meet the demand of unclasped; the displacement and force of the equipment can satisfy the demand of the code for seismic design of building.

Abstract: The tuned mass damper (TMD) for vibration control of tower subjected to multi-dimensional seismic excitations is studied in this paper. Calculation model of the tuned mass damper is introduced, and the equations of motion of a tower with tuned mass damper are derived, and the calculation parameters of the tuned mass damper are given based on the control structure. According to a practical engineering, the three-dimensional finite element model of a tower is established using SAP2000. Three typical seismic records are selected according the code of seismic design. Vibration control for tower model with tuned mass damper under multi-dimensional seismic excitations is performed by using numerical simulation. The maximum responses of displacement and axial force of the tower structure without and with TMD are obtained. The results show that the TMD could decrease the responses of the tower in three directions, and the tower with TMD can be a reference for tower practice engineering application.