Applied Mechanics and Materials Vols. 90-93

Abstract: Many gravelly soils liquefied cases history especially in the 2008 Wenchuan earthquake warn that loose to moderate density of gravels have much potential to liquefy under a given earthquake shaking. The large diameter triaxial apparatus is a relative feasible means to explore the liquefaction mechanism of gravelly soils to some extent. Becker penetration test (BPT) could be droved hrough gravelly soils layer, but BPT was not directly correlated with field behavior. Because of a wider range of grain sizes than those reported from previous earthquakes, gravels characteristics liquefied in the Wenchuan earthquake are representative and universal. The gravels liquefaction evaluation method developed from the Wenchuan earthquake should be feasible for worldwide use. The recent and ongoing developments in gravels liquefaction was highlighted

Abstract: According to the seismic anisotropy theory and the test observation, this paper puts forward the conception of the ground micro tremor anisotropy, and researches the method of the micro tremor test analysis about the anisotropy of the ground dynamic characteristics. Given the anisotropic characteristics of the ground motion, it analyzes the influence of the ground motion anisotropy on the seismic dynamic response of the structure, and the existent problems about the selection and adjustment of the existing seismic time history in the structure analysis process. Finally, this paper puts forward the new selection and adjustment solution of ground motion input based on the ground micro tremor test to determine the ground dynamic characteristics and the ground anisotropy.

Abstract: Taking dual carriageway standard cross section given by the current highway tunnel design standard and supporting structure parameters of surrounding rock in V class for example, using ADINA large deformation nonlinear finite element software, this paper divides the supporting structure into small units, and analysis the stress and displacement characteristics in different position of five typical sections in the tunnel construction process. Analysis results show that displacement and stress-time change feature is different apparently between inner and outer side of supporting structure, and also at different sections; displacement at inner and outer side of the same section is similar, while there is considerable difference in different sections; stress at inside and outside of one section is obviously different with that of other sections, which provides scientific basis for the safety of tunnel support structure and the optimized design.

Abstract: An optimum reticulated shell structure is selected and its dynamic properties are analyzed. In this paper analyses the dynamic feature and gains the elementary parameters from the analysis of free vibration. The frequencies and modes are compared by two finite element methods. The paper analyzes the dynamic responses of the reticulated shell structure subjected to two-dimensional and three-dimensional earthquake waves respectively. Simultaneously analyses the linear，geometric nonlinear and both geometric and material nonlinear dynamic responses in two situations. The nodal displacements and stresses of members are compared and analyzed. The characteristics of elastoplastic seismic responses of the structure are revealed and the basic rules are obtained.

Abstract: Well seismic performance of abutment were safety precondition of whole bridge. According to destroyed multi-span simple beam bridge of Wenchuan earthquake, failure modes of abutment were summarized. On the basis of correlation literature home and overseas, analysis methods of abutment seismic research were investigated. Nether factors should be take into account : soil-abutment interaction, abutment stiffness, bridge span number, pier’s force-displacement curve , bearing stiffness and etc.. Interspace model of seismic analysis were constituted and nonlinear time history adopted, so mechanism of abutment failure modes(strength failure, whole slide and admixture failure )was obtained. Control variables between beam and abutment were discussed. Those variables were keys of research influence on fall-off by abutment failure.

Abstract: This paper adopts the energy method to construct a MDOF’s (Multi-degree-of-freedom) seismic energy response equation of a deck-arch bridge, from which the impact of different pier height and reinforcement ratio on distribution patterns of energy under the E2 seismic effect are studied . The results show that total input energy, hysteretic energy and damping energy increase with increasing pier height, displaying a linear trend. However, the growth rate of damping energy is smaller than that of total input energy and hysteretic energy. The arch bridge’s total input energy and hysteretic energy decrease with increasing reinforcement ratio, displaying a linear trend, while damping energy first decreases and then increases, displaying a parabolic trend.

Abstract: In structure-equipment system, there are complex dynamic interactions between structures and equipments. A fast discriminant condition whether the interaction will increase or decrease dynamic response of the structure is achieved in this paper. When the load frequency lies between the basic frequencies of the combined system, it decreases the absolute response of the structure and vice versa. In engineering project, the seismic load can be expanded based on ground characteristic frequency by Fourier transform, so our conclusion can be extended to seismic design for combined systems. Finite element method simulation for a chemical workshop further verifies the discriminant condition.

Abstract: Storage tanks after earthquake disaster may create the serious consequence, so their anti-seismic problems have drawn greater attention, and their seismic response become the focus of research. Considering the liquid-solid coupling and the interaction between foundation and storage tanks，three different volumes of storage tanks that have different liquid height were simulated under the earthquake using the software ADINA. The liquid sloshing wave height, peak acceleration of tank wall and hydrodynamic pressure were analyzed. The results show that the peak sloshing wave height shows a rising trend basically with the increase of liquid height, and the roofs of large tanks are more easier to be destroyed by liquid sloshing. With the increase of liquid height and tank volume, the response of peak acceleration is greater. The hydrodynamic pressure increases with the decrease of liquid height. Near the bottom of tank wall the value of hydrodynamic pressure is relatively large, so elephant foot buckling is easier to happen in that area.

Abstract: To evaluate the damage level of steel structure under different earthquakes, a kind of vulnerability analysis method based on seismic damage assessment was developed using the improved two-parameter damage model which was proposed by considering the effect of hysteretic deformation amplitude to accumulative damage energy dissipation. This method is firstly to establish large samples of earthquake-structure, conduct a series of dynamic analysis to obtain the probability function of structural response and bearing capacity corresponding to different damage states, and then to draw the vulnerability curves and evaluate the damage state of the structure under different earthquake intensity. As a numerical example, a 9-story steel benchmark structure model under strong earthquakes was analyzed, and the theoretical vulnerability curves with lognormal distribution were obtained and the exceeding probability of structure at different damage level had been assessed.

Abstract: Based on HHT method, the influences of site conditions and epicenter distance on non-stationarity of multidimensional ground motion were studied. Additionally, preliminary statistics were carried out on frequency characteristics of multidimensional ground motion under different site conditions. The analysis results showed that HHT method was more accurate in a quantitative description of frequency-domain non-stationarity of ground motion than zero-crossing rate method, and also can reflected the non-stationarity of multidimensional ground motion better.