Applied Mechanics and Materials Vols. 166-169

Abstract: Abundant long-periodic components endue near-fault earthquakes with large velocity pulses while the viaducts owe long periodic fundamental period. To explore the seismic response patterns of viaducts under near-fault earthquakes, the paper analyzed the time history response of a viaduct under near-fault seismograms including TCU 1063, TCU 065, El centro and Artificial wave via FEM software Civil. The analysis shows a significant boost in near-fault seismic response as the value of PGV/PGA increased accordingly, indicates that the near-fault pulse affects strongly on the structural dynamic response of the viaducts.

Abstract: In recent years, wall panels have been more and more used in the steel residential houses. A series of investigations on the seismic performance of the steel frame with composite panels have been carried out. According to the connection types between the steel frames and the panels, the structural system can be divided into two kinds: steel frames with hanging composite panels and steel frame infilled with composite panels. Results of all researchers revealed that the composite panels could effectively improve the lateral stiffness and bearing capacity of the steel frames, at the same time could enhance the energy dissipation capacity. Morever, in this paper, the relevant research results of connections between the steel frame and composite panels obtained are compared and discussed. This review provides helpful directions to those who are already engaged in composite panels used in the steel residential houses, and points out the simplified method needed to promote safe and economic use of composite panels.

Abstract: The dynamic time-history response analysis method was employed to analyze the dynamic response of soft ground replacement with sand-gravel cushion. The deformation distribution of soft ground replacement with different thickness sand-gravel cushion was investigated under seismic wave. The results reveal that the bearing and asti-deformation capacity can be improved effectively for replacement sand-gravel cushion under earthquake loads by increasing the thick of cushion. The vertical displacement of foundation soil decreases gradually with the increase of the thick of cushion. The practice shows that replacement sand-gravel cushion provides a positive contribution to the aseismic effect of foundation soils mass. The present research can provide some references to similar projects.

Abstract: A new method that based on an interface program and secondary development of the analysis software FLAC3D was used to present the elastic-plastic dynamic interaction of earth dam and intermountain basin in 3D. By this method, we developed a complex 3D numerical model for a typical earth dam which was damaged seriously in the Wenchuan earthquake, along with its surrounding sites, considering the pore water pressure and the hysteretic damping of the soils, inputting the revised ground motion obtained from the station near the dam. The simulation reappeared the dam disaster process, gave the spatial and temporal distribution of PGA (peak ground acceleration) and residual deformation and the ratio of vertical and horizontal PGA. Our data demonstrate the mechanisms of the landslides, collapses and cracks on the earth dams. The present work shows that the existence of the dam has a significant influence on the distribution of ground motion in the intermountain basin.

Abstract: An analytical method was proposed to obtain the seismic fragility curve of reinforced concrete frames within the service life. Considering the variation law of nonlinear mechanical characteristics of un-carbonated concrete within service life, the seismic fragility curve of frames was developed based on the inter-storey drift corner in the weak storey of frame structures. According to the defined frame damage states, each seismic fragility curve reflects the probability change tendency of the defined damage state in frames within service life. A numerical example was modeled to illustrate the variation characteristic of seismic fragility within the service life.

Abstract: Based on direct shear tests of gravel silty clay from the high slope of Daju Mountain in Niufei Village, Pingtong Town, Sichuan Province after the 5.12 Wenchuan Earthquake, change laws of shear strength under different water content, dry density and maximal grain-diameter were studied. Through analyzing variation curves on shear strength and two indexes, cohesion C and angle of internal friction , conclusions can be drawn that shear strength goes down along with the growth of water content, goes up along with the growth of dry density, and is sensitive to the change of maximal grain-diameter; the influence of water content on shear strength and the two indexes, is largest, dry density larger and maximal grain-diameter worst. And the change mechanism of shear strength was interpreted rationally. Simultaneously the powerful functions were used to fit the relationships between shear strength indexes and the three influencing factors respectively. The paper accumulates basic data for shear strength study of the post-earthquake soil and provides important references for safety evaluation of the post-earthquake high slopes under harmful conditions, for example heavy rain and so on.

Abstract: Two different models are set up to analyze how the connection styles influence on the seismic behavior of frame-bent structure. In the earthquake input of both directions, mode superposition response spectrum method is used to calculate the parameters of frame-bent structure such as the story shear, seismic action deformation and so on. Analyzing the difference of the parameters of both models, explaining the reasons and drawing some rules are all done in this essay.

Abstract: This paper using time time-procedure analysis method to analyze seismic response on a 80 m × 80 m bidirectional beam string structure model. Under vertical seismic action, we respectively compared to the seismic performance under the structure have or no supporting frame and have the same supporting frame but different support conditions. Under vertical seismic action, the axial force of brace is almost the same considering or unconsidering the supporting frame, while the upper beam vertical displacement is increased and the surrounding of the roof even increased several times considering supporting frame; the boundary conditions for the sliding hinge support bidirectional beam string structure which under vertical seismic ( middle seismic ) action the brace axial force and winding beam vertical displacement are nearly same with the fixed hinged support, while the horizontal displacement of the winding beam is larger than the fixed hinged support; the change of support conditions affect the order of the various modes of the structure but no affect the structural vibration modes.

Abstract: Simulation of earthquake ground motion was a hot topic for structure seismic response analysis. According to the problems in simulating ground motion history with harmony superposition method, such as more interference of human factors and simulated ground motion history didn’t have frequency non-stationary characteristic, a novel method of ground motion simulation based on stationary discrete wavelet transform was presented. Using stationary discrete wavelet transform, the parent ground motion history was decomposed into different frequency bands, and the coefficients were modified. Using inverse stationary discrete wavelet transform, an ensemble of ground motions were simulated whose statistics closely resemble those of the parent history. Through a numerical example, the statistic characteristics of simulated histories were compared with the original values, and the feasibility and correctness of presented method was illustrated.

Abstract: we carried out shaking table tests for 2 layers of a residential brick structure with 1/2 reduced-scale. At the same time, the model structure is studied by finite element analysis with ANSYS. The dynamic response of structure under different seismic excitation and cracking destruction rules were compared and analyzed, seismic vulnerability for the type of brick mixes structures were summarized.. At end, in the light of this type of structure we give the suggestions and measures of aseismatic reinforcement.