Applied Mechanics and Materials Vols. 353-356

Abstract: To study the dynamic buckling characteristics of storage tank subjected to three-dimensional seismic excitation, selecting 50000m³ large vertical floating roof storage tanks as research object, the base isolation system was introduced and allowing for the impact of floating roof. The finite element models of non-isolation and base isolation storage tank were established respectively by ADINA. The seismic responses of these two types of storage tank were calculated and the numerical solutions were compared. The results indicate that the dynamic buckling modes of these two types of storage tank system belong to plastic buckling; base isolation measure can effectively increase the critical load value of dynamic buckling and plasticity yielding, the improve rates up to 38% and 60% respectively. The effectiveness of the base isolation can be verified from the angle of buckling.

Abstract: In this paper, a two-step space prediction approach is developed to image site 2D velocity structures. Firstly the average Vs of each layer are fixed, the interfaces between each two soils layers are predicted by the interpolation method of bi-harmonic Green function as spline in tension, to keep soil interfaces varying smoothly in space. Furthermore, a method to determine tension coefficient is proposed based on microtremor H/V method, which makes most use of H/V information and avoids choosing the tension coefficient at will. Secondly, the variance essence of the Vs structure as a regional variable is deeply excavated by Kriging method and its structural characteristic is taken into account. The spatial successive distribution of the Vs structure between soil interfaces is simulated by high precision space extrapolation and prediction, and finally the detailed 2D model is constructed. The two-step space prediction approach describes the characteristic of Vs structure as a regional variable from the sparsely and non-uniformly distributed microtremors data. Obviously, it also can easily make good use of the other exploration data.

Abstract: Three inclined-column transfer floor structures of frame-supported short-leg shearwall are tested under vertical loading and horizontal cyclic loading to analyze the influence of leg-thickness ratio (LTR) on the seismic performance of inclined column-shaped transfer floors. The failure process and patters, bearing capacity, hysteretic characteristics, stiffness degradation, deformation and ductility are analyzed in detail. The test results show that the force characteristic of inclined column-shaped transfer floor structure is similar to a simple truss, and leg-thickness ratio of the top short-leg shearwall has important implications to the transfer beam performance; if the design is reasonable, the inclined column-shaped transfer floor structure has a good ductility, multi-channel seismic line of defense and better seismic performance.

Abstract: Pre-stressed anchors were widely used to strengthen slopes, in this passage the dynamic responses of fill slope with pre-stressed anchors under the effect of seismic load were simulated by ANSYS program. And it was mainly analyzed the effect of pre-stress anchors on seismic performances of slope under general earthquake. The results indicate that changing the value of pre-stress has little effect on slope deformation, but has larger effect on stress distribution in slope. And with the increases of pre-stress value, stress response on the top of slope is small, the stress concentration in slope is alleviated, while the stress on slope toe increases a little, the seismic stability of slope is improved to some extent. And these conclusions may provide some theory basis for slope seismic design and study.

Abstract: This work is based on a typical RC frame that was closed to the epicenter and collapsed during the Wenchuan Earthquake. The seismic collapse resistance of the frame was strengthened by attached substructures, including conventional brace, buckling restrained brace (BRB) and viscous damper. Collapse fragility analysis based on incremental dynamic analysis is implemented for each strengthening scheme to compare their effects and to analyze the influence of critical parameters. The results show that the viscous damper performs better than the BRB, and the BRB performs better than the conventional brace. With the same strengthening parameters, the A-shaped bracing scheme is better than the X-shaped scheme.

Abstract: In this paper, the seismic behavior of partially encased concrete columns and steel beam connection are studied, which contains 4 different structures of beam-column joints. By applying a low cycle loading, the failure modes and the strain distribution of each connected component plate domain were studied. The effect of the end plate thickness, stiffened plate, and back plate on the node bearing capacity, stiffness and ductility was analyzed. The bearing capacity of the specimen is improved with the end plate thickness increases, and a lot increased with setting the back plate.

Abstract: An experiment of three T-shape beam-column steel joints with intensive cover plate was conducted under low cyclic loading with different cycle numbers, to study seismic performance of the joints subjected to long-period ground motions. Effects of cycle number on mechanical performance and length of plastic hinge were analyzed. The results show that as the cycle number increases, capacity of the joint decreases, and plastic hinge of the joint develops longer which appears closer to the cover plate, and the platform of skeleton curve grows longer, and the stiffness attenuates slightly.

Abstract: Slope anchorage structure of soil nail is a kind of economic and effective flexible slope supporting structure. This structure at present is widely used in China. The supporting structure belong to permanent slope anchorage structure, so the design must consider earthquake action. Its methods of dynamical analysis and seismic design can not be found for the time being. The seismic design theory and method of traditional rigidity retaining wall have not competent for this new type of flexible supporting structure analysis and design. Because the acceleration along the slope height has amplification effect under horizontal earthquake action, errors should be induced in calculating earthquake earth pressure using the constant acceleration along the slope height. Considering the linear change of the acceleration along the slope height and unstable soil with the fortification intensity the influence of the peak acceleration, the earthquake earth pressure calculation formula is deduced. The soil nailing slope anchorage structure seismic dynamic calculation model is established and the analytical solutions are obtained. The seismic design and calculation method are given. Finally this method is applied to a case record for illustration of its capability. The results show that soil nailing slope anchorage structure has good aseismic performance, the calculation method of soil nailing slope anchorage structure seismic design is simple, practical, effective. The calculation model provides theory basis for the soil nailing slope anchorage structure of seismic design. Key words: soil nailing; slope; earthquake action; seismic design;

Abstract: Column is the key member of the seismic structures. Tthe failure of column will cause a large number of casualties. With the development of modern technology, more attention on seismic performance evaluation of reinforced concrete column is paid by academics. The theoretical basis and the concepts of seismic performance evaluation of reinforced concrete column are introduced firstly, and then the existing reinforced concrete column seismic performance evaluation method, the principle and the existing problems are reviewed. Meanwhile the key problems and tendency of research of seismic performance evaluation methods are putted forward.

Abstract: Developing an analysis program and simulating the radiation damping effect in the infinite foundation and inputs ground motion rationally. The static and dynamic analysis of an intake tunnel for a nuclear power plant is performed with ANSYS based on some 2-D finite element models considering of structure-foundation interaction by Time-History Analysis. Aiming at different programs of two linings in tunnel, the stress and internal force distribution of the tunnel , the wall rocks and the lining is researched and analyzed, and the diagram of stress and internal force is drawn. The regularity obtained can provide the basis for the seismic response analysis and design of tunnels.