Applied Mechanics and Materials Vols. 256-259

Abstract: Large mass method is used to calculate structural seismic responses of long-span bridges. Due to the inherent characteristics of large mass method, the larger scale of long span bridge, different geological conditions, seismic input time delay of different foot stall, the displacement curve of seismic responses will be drifted and distorted from the normal. In this paper, Empirical Mode Decomposition（EMD) based on the large mass method is proposed to remove pseudo component and drift displacement. Then displacement response curve is reconstructed using the remaining components, the drift and distortion of structural seismic responses is successfully removed by this method.

Abstract: The two-stage design method for multi-story structures equipped metal dampers is put forward based on the Code for Seismic Design of Buildings (GB50011-2010) and the Code of Japan Society of Seismic Isolation. For preliminary design stage, simplified method is adopted to estimate added stiffness and damping on each story, offering an approximate requirement of dampers. For detail design, the time history analysis is employed to verify the performance of structure with added dampers and determine number of energy dissipation device. This new method will be valuable for enhancing design quality and reducing design period. This paper describes the theoretical basis of the method.

Abstract: An analytical approach based on branch mode method is formulated in this paper to study the dynamic response of eccentric structure considering soil-structure interaction The superstructure branch and foundation soil branch are coupled through mode aggregation procedure. The computational scale of system equations decreases to an acceptable level. Sample analysis indicate that the seismic response of eccentric structure increases first and then decreases with the decreasing of stiffness of soil-foundation system, which is affected by the inertia effect of foundation branch. For the soft soil case, the influence of SSI effect is more intensive that the trends of transfer function curves are fundamentally changed comparing to the results of other foundation conditions.

Abstract: For further study on the influence of ground motion on the seismic performance of brick masonry structure, two masonry buildings were designed and constructed according to common structure style in towns and villages. Two full-scale buildings were subjected to different earthquake motion using pseudo-dynamic test. The earthquake motions are artificial earthquake motion and strong motion recording. This paper presents hysteretic behavior and deformation under horizontal seismic action. Crack propagation of masonry structure is analyzed. These tests verify that displacement response of masonry structures under different ground motion is pretty much the same. Tie-column and ring-beam can effectively confined brick wall. The cracks are mostly diagonal cracks caused by shear failure.

Abstract: In this paper, PEER Ground Motion Databases (PGMD) at the Pacific Earthquake Engineering Research Center (PEER) was updated by 314 sets of ground motion records of great earthquakes in recent years, which expanded the application of this database. This paper reviews alternative selection methods for strong ground motion records. The expanded database could make the different selection and scaling of strong motion records in great earthquakes, and the conditional mean spectrum (CMS) method could be applied for the strong motion records selection in structural spectrum analysis.

Abstract: Friction pendulum systems are sliding bearing that make use of a spherical concave surface to provide a restoring force and friction force to dissipate earthquakes energy. Seismic response reduction effect of some tall pier and long span simply-supported steel truss girders with FPS is researched by using nonlinear time history analysis method. The results show that seismic response reduction effect is evident for the moment at the bottom of pier and displacement at the top of pier for the tall pier and long span simply-supported steel truss girders.

Abstract: Ground motions of the great Wenchuan earthquake were simulated using stochastic simulation technique with an improved source spectral model. In the model, the corner frequency for each subfault is determined based on a basic value calculated from the total seismic moment of the entire fault and an increment depending on the seismic moment assigned to the subfault. The model also includes a slip-based scaling factor accounts for the difference of the radiated energy from each subfault. The simulated ground motions were compared to those from using the source spectral model with dynamic corner frequency in terms of the mean spectral ratio over the 52 stations amd to the observation in terms of 5% damped response spectra. Based on the comparison, the effects of the slip-based corner frequency and the scaling factor on the simulation were discussed.

Abstract: In order to analyze and understand the seismic performance of UHV HGIS, and further improve it, the analysis of dynamic characteristics and seismic response spectra for 1100kV HGIS was carried out in four kinds of seismic waves, and then acquired structural frequencies and mode features. The situation that the natural frequency of UHV equipment and the main frequency of seismic wave were so similar that quasi resonance occurred was considered in the process of analysis. The calculation is conducted by the string of modulated wave that includes three sinusoidal-resonant waves and five sinusoidal-resonant modulated waves to analyze mechanical strength and seismic performance of integral structure. The results show that 1100kV HGIS under those seismic waves has certain safety margin, provide effective data for analysis of seismic performance of UHV equipment.

Abstract: A shaking table test of large-scale pile-soil-complex structure interaction is accomplished on the transport hub of Tianjin station, and some reliable testing data of soil-structure dynamic interaction laws are acquired. ANSYS is used to simulate the process of the test, including establishment of 3D FEM model, selections of material parameters and constitutive, treatment of boundary conditions. Comparative analysis is performed between simulation data and testing data. The results show that: the simulative results agree well with the experimental ones under small earthquake, but the deviation increases when it suffers medium earthquake. The rationality of the numerical simulation and test are verified by each other, and the causes of the deviation under medium earthquake are analyzed.

Abstract: The infilled frame structure is a kind of structural system used widely in the industrial and civil building. Although the infill walls are no-load-bearing components, the walls are also subjected to some earthquake actions. During some domestic and foreign large earthquakes in recent years, the infill wall were destroyed seriously and the frame were destroyed lightly. The damage of the infill wall not only influences the application of the building, but also increases repair costs for restoring the building, seriously, even endangers the life safety. This paper analyzes the influence of the connection method between the infill wall and the frame on the seismic behaviors of the infilled frame structure. Finally, some new technologies to protect the infill wall and the frame from damage under earthquake are introduced.