Applied Mechanics and Materials Vols. 580-583

Abstract: In recent years, the security of rural building has attracted more and more attention. The analysis of the existing problems of rural building summarized the distribution of dangerous points, and the use of finite element analysis method was carried out on the typical farmhouse seismic time history analysis to find out seismic weak places in the masonry structure buildings. Then the study also shows that the system with ring beam and structural concrete column has good reinforcement effect. This study plays an important role in improving the rural housing construction measures and the seismic performance of the building.

Abstract: The isolation effectiveness of the Geotechnical Seismic Isolation (GSI) system was further investigated via a series of prescribed shaking-table tests. The dynamic response of GSI system was also evaluated in detail of this work. A parametric study for assessment of the isolation performance of GSI was conducted by varying experimental key parameters, such as rubber percentage of rubber-sand mixtures (RSM), configuration of the foundation, storey number of the superstructure, and different kinds of seismic acceleration inputs. From the parametric survey, it can be concluded that the GSI system can to some extent attenuate the dynamic response of the superstructure under big earthquake shakings.

Abstract: In this paper, we intended to replace the fluid-structure interaction of deep water bridge piers with acceleration-dependent forces during an earthquake. The hydrodynamic pressure on bridge pier groups under seismic excitation is studied using the finite volume method. Different seismic waves with various spectrum components are selected in order to cover frequently encountered cases. The calculated forces of these cylinders are fitted into the Morison equation, and by calculation, the drag force term is negligible, thus the effect of fluid is converted into one added mass term. The paper further calculated the dynamic response of a continuous beam bridge with pier groups in water to check the validity of our proposed method.

Abstract: Lushan earthquake on 20th April, 2013 was another thrust fault earthquake occurred at Longmen Mountain Fault Zone after 2008 Wenchuan Ms8.0 earthquake. Based on ground motion attenuation model, this paper has chosen 45 strong motion records with rupture distance less than 200km, to analyze the hanging wall effect, topographic effect and rupture directivity effect of Lushan earthquake. The results show that hanging wall effect in Lushan earthquake was not obvious as 2008 Wenchuan earthquake; ground motion in mountain areas attenuated with increasing rupture distance more quickly than that in plain areas; rupture directivity effect is obvious for two components of horizontal ground motion, which are fault-perpendicular and fault-parallel components. PGA in the forward rupture area is larger than those in the backward rupture area. With the period increased, the gap between backward and forward rupture area become small, and finally PGD in backward rupture area is greater than those in the forward rupture area.

Abstract: Since entering the new century, bridge techniques are developing rapidly in our country. When bridge seismic techniques had not reached a certain degree, seismic design of bridge bearings was rarely involved. However, since the amount of the bridges that had collapsed in earthquakes due to the bearings damage were becoming larger, in the design of bridges, seismic design in current bridges has been taken seriously.This paper mainly introduces several widely used seismic bearings and analyzes the structures and hysteretic characteristics of them and forecasts the development direction of seismic bearings.

Abstract: With the rapid development of high-rise buildings in our country, the seismic design of structures is becoming more and more important. And the seismic performance of traditional seismic system is not perfect, there are still some room for improvement. This article points out the advantages of the human body vertebra seismic system by comparing the characteristics of the current building aseismic system with the deep analysis of the human body vertebra seismic system and the application of the seismic characteristics of the human body vertebra in seismic design of building structure application foreground is prospected.

Abstract: Solid concrete piers with low longitudinal reinforcement ratio are extensively used in high-speed railway in China. However, how to check such structures is not specified in current technical codes. Checking these structures by eccentricity and stress indexes is discussed hereby. The moment-curvature relationships for piers of various reinforcement ratios are presented by employing the software UCfyber and these moments are compared with moments calculated by allowable stress approach, moments corresponding to the code-specified permissible eccentricity, moments corresponding to the allowable reinforcement stress and stabilizing moments induced by tensile reinforcement and self-weight of the piers, respectively. The results show that the allowable stress approach could be used to check the strength and eccentricity of solid concrete piers with low longitudinal reinforcement ratio in high-speed railway; the restriction on permissible eccentricity may be to a proper extent relaxed for such piers, based on the fact that tensile reinforcement provides an additional stabilizing moment and the reinforcement contributes to the pier’s bearing capacity.

Abstract: For the shaking table system, the 90^o phase shift frequency of the servo valve system is close to the oil column resonance frequency, the bandwidth under the influence of servo valve features was so narrow that it cannot meet requirements. Multi-variable control is presented in this paper by introducing the jerk feedback on the basis of the three-variable control. The theoretical derivation and the system simulation show that: the jerk feedback can reduce the oil column resonance frequency, and decrease the influence of the system performance caused by the servo valve characteristics.

Abstract: At 8:02 a.m. Beijing time on April 20, 2013, an Ms 7.0 earthquake shook the city of Ya’an, China. Until 24:00:00 on 20 July 2013, a total of 339 strong-motion records from 113 free-field stations, 21 records from 1 strong-motion structure array and 1123 groups of aftershock records have been collected, processed and analyzed preliminarily by the China Strong Motion Network Center (CSMNC) in this paper. There are more than 26 stations located within Longmenshan fault zone and all peak ground acceleration (PGA) of records is larger than 50gal. The PGA of Baoxingdiban station reaches 1005.4 gal after zero-line initialization, which firstly breaks through 1g in the mainland of China. Based on the mainshock records, shakemaps of those PGAs are plotted and attenuation relationships of PGAs are presented in this article.

Abstract: Permanent displacement identification is one of key topics in near-fault ground-motion research. A new method based on Hermit interpolation and flatness technique is proposed to determine permanent displacements, since the Iwan law is not applicable in Mw9.0 Tohoku earthquake permanent displacement recognition. The method is then tested by coseismic displacements resulted from GPS station nearby. Results show that: the causes for strong motion record baseline drift are very complex so that Iwan method is not suitable for permanent displacements identification in the Mw9.0 Tohoku Earthquake, while the new baseline correction method combining Hermit interpolation and flatness technique is suitable for permanent displacement analysis of near-fault ground motion in 2011 Mw9.0 Tohoku Earthquake.