Applied Mechanics and Materials Vols. 353-356

Abstract: In order to study the characteristics of ground motions at the two dam sites damaged during the great Wenchuan earthquake in 2008, the motions at two observation stations nearby are synthesized in this paper. 30 finite fault based hybrid source models of the great Wenchuan earthquake with magnitude 8.0 is built. The global and local parameters are both generated from the truncated Normal distribution with mean and standard deviation values estimated by a set of semi-experiential calibration laws and from the regional seismo-tectonics, structure of the crust, and seismicity. A representative source model is then chosen from the corresponding response spectrum mostly close to the average one. The result motions are presented, and the characteristics of the time histories, response spectra and the peak accelerations are quite close to the recordings.

Abstract: In ancient China timber building earthquake damage records, often about "column small feet slip", scholars in ancient timber buildings for the seismic performance study, also thought that "column small feet slip" is one of the reasons for the ancient building in the earthquake Could be survived. This article through to column small feet slip phenomenon, to lead to column small feet slip condition were analyzed, and "column small feet slip" seismic effect evaluation, is to the ancient timber aseismic performance research achievements added.

Abstract: The ground motions on two dam sites during the great Wenchuan earthquake with magnitude 8.0, motions are synthesized from 30 finite fault based hybrid source models and inversed regional parameters of source spectrum and motion attenuation. The results show that the peak ground acceleration values are less than those estimated directly from the Intensities Ⅹ and Ⅺ at the two sites, with mean values 259 and 716 gals. The motion at Shapai is much stronger than that at Zipingpu, and the spectrum is also wider than the latter, but the corresponding duration is shorter during the earthquake.

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: This paper presents a sandwiched buckling-restrained brace (BRB) and a dual-core self-centering brace (SCB) for seismic resistance. The sandwiched BRB has two components: (1) a steel core plate that carries axial forces and (2) two restraining members that sandwich the core plate with A490 bolts. The proposed BRB can be disassembled easily in the field, which not only means that the core plate can be replaced independently of the restraining members but also provides an opportunity for inspection of the core after a large earthquake. Cyclic tests of five sandwiched BRBs and five BRB frames were conducted to verify their good cyclic performances up to a drift of 2.5%. To minimize residual deformations of structural systems under earthquakes, a new steel dual-core self-centering brace (SCB) with flag-shaped hysteretic responses is developed. The axial deformation capacity of the SCB is doubled by serial deformations of two sets of tensioning elements arranged in parallel. The mechanics and cyclic behavior of the brace are first explained; three 5350-mm long dual-core SCBs are tested and modeled to evaluate their cyclic performances. SCBs exhibit excellent performance up to a drift of 2.5% with a maximum axial load of 1300 kN. Test results showed that the application of dual cores in SCBs reduces significant strain demands on tensioning elements and enables self-centering responses to large deformation. Nonlinear time history analyses were conducted on three BRB and SCB frames to obtain seismic demands under both design and maximum considerable levels of earthquake motions. SCB frames generally exhibit smaller peak interstory drifts and residual drifts than BRB frames.

Abstract: Research on the dynamic characteristics of gravity dam was carried out by adopting ARX model using the seismic response data of concrete gravity dam at Shui-Kou hydropower station. The applicability and effectiveness of single-output-multiple-input ARX model were deduced and verified. A corresponding computer program was developed, and performed to identify the modal parameters of the system. The identified natural frequencies and damping ratios were basically same with the results by traditional peak point pick-up method, and also close to the finite element method (FEM) results. It is indicated that the structure natural frequencies and damping ratios are determined by the characteristics of the structure, the dynamic characteristics identified by ARX model are correct, and ARX model can avoid frequency leakiness when smoothing processing and Fourier transform are conducted in solving process of the peak point pick-up method. The modal identification can be applied to other structures.

Abstract: Ancient wood structure usually has good anti-seismic performance because of structural characteristics. Mortise joint and tenon joint of wood structure component parts of the node can be very good energy dissipation and mitigate the effects of earthquake damage at the time of seismic action. Column foot and foundation can effectively reduce the seismic response with friction-sliding. It can give clear status evaluation from the perspective of applicability to protecting the ancient timber structures which is of great importance to protection.

Abstract: There are similarity relations in hysteretic loops and parameters of viscoelastic (VE) dampers with same material but various sizes. Similarity coefficients of damper force and deformation of hysteretic loops were derived, and then similarity coefficients of characteristic parameters of VE dampers with various sizes were obtained consequently. Based on the similarity criteria, if the hysteretic loops of one of a series of VE dampers with same material but various sizes are obtained through test, then hysteretic loops of other dampers can be derived easily. Two kinds of VE dampers with different sizes have been tested under various strains to verify the proposed similarity criteria. The similarity criteria can be used in design of related tests and structural seismic design.

Abstract: In the paper, the equation of stiff characteristic coefficient of shear wall structure with unidirectional wall frames was derived, the deformation characteristics of structure with different wall frames ratio and height were analyzed. Through pushover analysis, the seismic performance of structures were evaluated by interlayer displacement angle and plastic hinge development process. Under earthquake action, increase of wall frames ratio will make plastic deformation increase and maximum interlayer displacement floor move down.The bottom of structure is the weak region, the short wall limbs of wall frames are the weak structural vertical members. The research results show that the wall frames bring adverse effects on the structural seismic performance, so the different design meathods should be carried out according to the overturning moment proportion of wall frames.

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.