Advanced Materials Research Vols. 1065-1069

Abstract: In order to know seismic damage characteristics of multi-story brick masonry structure and improve its seismic capability, five kinds of earthquake damage or collapse forms of multi-story masonry brick structure are summed up based on earthquake disaster survey, each of which is analyzed with mechanics. And the failure mechanism of each seismic damage form of multi-story brick masonry structure are proposed, which provides effective engineering experience for the seismic or anti-collapse design of multi-story masonry brick structure. The research has the important significance in improving the seismic capacity of multi-story brick masonry structure and reducing the earthquake casualties.

Abstract: Based on stochastic seismic response and time-history seismic response analysis，Dynamic response laws of the high slope constructions by three real seismic waves and a synthetic seismic wave were studied using finite - element method, discussing the differentiation and relation between the high slope constructions and ground constructions. The results show that the dynamic response on high slope constructions are less intensive than ground constructions due to delaying effect of high slope soil acts on the structure, but its internal force stronger than ground constructions as the pile in high slope constructions are anti-sliding and bearing. Results are conducive to the seismic design of high slope constructions.

Abstract: A full scale masonry model of two-floor and single bay was built in this paper and was strengthened by ring-beam and constructional column. And then pseudo-dynamic testing was conducted to study the time-history curves of displacement, velocity, acceleration response and restoring force in 7 degree rarely earthquake. Results show that the earthquake performance is steady and there are no visible cracks on the model after the testing. Windows and doors perform well because of the constraint of ring-beam and column, whereas failures often occurred when the structures were not strengthened. Seismic performance is largely improved by ring-beam and constructional column and the structure can resist 7 degree rarely earthquake.

Abstract: In East China Sea, especially in Zhejiang and Fujian Provinces, classic marine deposit soft soil with characteristics of high compressibility, high sensitivity and low strength is widely distributed. Seismic subsidence occurs under earthquake causing substantial losses. Though a number of effective studies are carried out on the causes, mechanisms and methods on seismic subsidence, there are more other aspects to be studied due to marine soil’s complexity. In this paper, the classic marine soft soil in southern sea area of Taizhou Bay is studied on its seismic parameter based on the tri-axial seismic experiment. The seismic parameters and residual strain formula are obtained, and compared with normal continental deposit soft soil.

Abstract: According to a intake tower of spillway tunnel established the intake tower structure—water—foundation 3-D finite element model for seismic analysis, by the response spectrum method in original design seismic parameters and new parameters of the project on horizontal and vertical dynamic response of the intake tower. The results shown that the structure of maximum dynamic stress concentration appeared near the junction of the tower with backfill concrete, where the weak parts of seismic, used the new seismic parameters calculated show greater damage on the tower, but couldn’t overturn, meet the seismic design requirements.

Abstract: The breeding and occurrence of earthquake closely related to the intensity and spatial distribution of ambient shear stress field. Earthquakes would happen when the regional shear stress enhanced to the damage limit of rocks. In this paper, we used some acceleration records in Gansu province, and calculated corresponding seismic shear stress value according to the theory put forward by Professor Chen Peishan. Combined with the tectonic environment, we discussed the relationship of ambient shear stress with the magnitude and hypocentral depth.

Abstract: The selection of input ground motion for seismic analysis of the structure is a complicated task, especially when nonlinear dynamic analysis is utilized. A decision has to be made regarding the intensity measure better to represent the potential damage of the ground motion. This paper presents a lot of analysis to deal with the problem. A set of nonlinear dynamic analyses were conducted on reinforced concrete buildings widely present in China. Input ground motions contain uncertainty and variability comes from both natural recordings and synthetic data. First, a set of natural recordings is considered. Second, two ground motion modification schemes are used in this study: magnitude scaling and spectrum matching. Third, a set of ground motion is synthesized. The peak value of displacement has been selected as the response parameter better able to represent the structural damage level. Nonlinear dynamic analyses of reinforced concrete buildings simulated by OpenSEES are carried out to evaluate the correlation coefficients of displacement response and the chosen ground motion parameters. Findings from the investigation indicate that the Housner intensity is the more effective intensity measure for selecting the seismic input. The synthesized ground motion fit with code spectrum shows good performance as a design input motion. Considering ground motion modification, spectrum matching is generally more stable in response prediction than scaling.

Abstract: The natural frequency of model was analyzed by finite element software in the first and the result was consistent with the experience formula. Then, time history of ground motion was inputted. The seismic capacity of the structure was analyzed by parameters as structural damage, seismic shear and acceleration. Structural damage in seismic “three levels” and the results of seismic appraisal were consistent. The injury site structure put forward strengthening measure of circle beam and structural column. Scientific basis and technical support for seismic strengthening were provided for Tianjin Western-style dwellings.

Abstract: In the thesis, simulated analyses of six large-scale abutments under the low reversed cyclic horizontal load were performed by using the nonlinear finite element software of ABAQUS. The hysteresis behavior, skeleton curve, displacement ductility energy-dissipating capacity of the thin-walled hollow pier under the combined action of the bending, pressing, and shearing were discussed in this thesis. And it also analyzed factors that affect the bearing capacity and ductility of the bridge pier, such as the longitudinal reinforcement ratio, volume-stirrup ratio, the axial load ratio. Results indicate that the volume-stirrup ratio is the principal factor which affects the seismic performance of thin-walled hollow pier. With the increment of volume-stirrup ratio, the ductility factor increases; as the axial load increased, bearing capacity increased correspondingly; when the piers are under higher axial pressure, the longitudinal reinforcement ratio has more significant effect on the bearing capacity of structure.

Abstract: Based on the multi-degree of freedom in series model, structural displacement amplitude formula is derived in the frequency domain under the translation-rotation input situation, this formula indicates that the soil - structure interaction (SSI) could be considered as adding a correction term M˜ to the mass matrix of the structure with the hypothesis of Rigid foundation. This corrected mass matrix is actually a complex matrix, which related to the input frequency and damping. Equivalent translation-rotation input is coupled with two translation input components U* and Θ*. Besides, we uses case analysis to explain the characteristics of soil - structure interaction (SSI) in frequency domain by the end of this paper.