Advanced Materials Research Vols. 243-249

Abstract: 320 strong motion records of four sites are appropriately selected. The elasto-plastic dynamic analysis program is used to research the effects of characteristics of earthquake motion on elasto-plastic acceleration spectra, elasto-plastic displacement spectra, residual displacement spectra and reduced strength spectra. The study results are obtained as follow: 1) The value of elasto-plastic acceleration spectra, elasto-plastic displacement spectra, residual displacement spectra are increased with the amplification of seismic magnitude. 2) When site soil softens, the elasto-plastic acceleration, displacement, residual displacement of the same period are amplified in site Ⅲ and Ⅳ. On the contrary, site conditions of site Ⅲ and Ⅳ have nothing to do with elasto-plastic response spectra. 3) When ductility is greater than two, reduced strength spectra can be affected by seismic magnitude and site conditions. 4) Elasto-plastic response spectra of other protected earthquake intensity can be obtained by adjusting elasto-plastic response spectra of the standard protected earthquake intensity according to the ratio of PGA (protected earthquake intensity) to PGA (standard protected earthquake). So, some meaningful references are provided for performance-based seismic design for bridge.

Abstract: Experimental evaluation of large scale MR fluid dampers for seismic hazard mitigation in buildings is presented in this paper. A simplified design procedure is applied to design a two-story, four-bay steel moment resisting frame (MRF) prototype structure with MR fluid dampers in passive mode. Real-time hybrid simulations are conducted to experimentally evaluate the performance of the MRF. The simulation results show that the simplified design procedure enables an efficient design to be achieved for an MRF with MR fluid dampers in passive-on mode.

Abstract: It is a well-known fact that an injection of the borehole fluids into surrounding porous rocks often results in fault reactivation,such as during hydrocarbon production from a reservoir, fluid injection for enhanced oil recovery, hot dry rock geothermal energy extraction, and waste disposal or carbon dioxide sequestration. However, no rigorously derived method for the description of spatial and temporal distribution of seismic events and for the estimation of the critical value of pore pressure of a porous rock sufficient for the generation of an microseismic has ever been developed. There a model developed within the context of Biot’s theory of poroelasticity is used to obtain the distribution of pore pressure, then the pore pressure is substituted into a Mohr–Coulomb failure criterion to predict the fault stability and the spatio-temporal cluster of microseismic events in a reservoir. in this model, the Biot system of equations is formulated for the radial symmetry case and is supplemented by the relevant boundary conditions, Then the solution is constructed analytically. A key advantage and the novelty of the proposed approach is it allows one to monitor an influence of pressure applied at the borehole within and surrounding reservoir and to predict the lower and upper bounds for the critical state of a natural rock, and it can be used in different reservoirs.

Abstract: The special type isolated building defined as asymmetric multi-tower base isolated structure with large floor is discussed in this paper. The rigid layers in series models are obtained and the elastic time history method is used to analyze the performance and seismic response of the structure. With the objective of studying the influence of the mass eccentricity in the towers and the asymmetric towers, coefficients of shear force, the ratios of period and the ratios of drift are discussed. The following conclusions have been attained: Torsional drift can be significant depending on the isolated layer in the asymmetric multi-tower with large floor. Comparing with the fixed base structures, this special type isolated building still can be reduced torsional response. The effect of isolation is reduced with the mass eccentricity in the towers and the asymmetric towers increases. It is concluded from the study that the multi-tower base isolated building with large floor should be symmetric and central in order to increase performance of isolation.

Abstract: In recent years, Seismic While Drilling has rapidly developed at home and abroad, as a new down-hole seismic technique. It has widely used in petroleum exploration, drilling engineering and oilfield development. We intend to study on shear-velocity measurement by Seismic While Drilling. After introducing the principle of Seismic While Drilling, we have designed both observation system and data processing method of shear-velocity measurement by Seismic While Drilling, providing a reference for shear-velocity measurement in the future.

Abstract: From the perspective of fractal geometry, the irregularity and complexity of near-fault ground motions and seismic responses of single degree of freedom (SDOF) are analyzed. Based on the box-counting method, the fractal dimensions of 30 acceleration time series of near-fault ground motions from Taiwan Chi-Chi earthquake and California Northridge earthquake are calculated. It is indicated that the acceleration time series of ground motions present the statistical fractal property, and the influence of characteristics of near-fault ground motions on their box dimensions is remarkable. Moreover, the box dimensions of ground motions reflect their frequency property to a large extent, and can be regarded as alternative index to represent their frequency content. Finally, for the time histories of seismic dynamic responses of elastic and inelastic SDOF systems subjected to near-fault ground motions, their box dimensions are computed to examine the fractal property.

Abstract: This study focus on derivation of such fragility curves using classic mid-story isolation and reduction structures (MIRS) in China metropolis. A set of stochastic earthquake waves compatible with the response spectrum of China seismic code selected to represent the variability in ground motion. Dynamic inelastic time history analysis was used to analyze the random sample of structures. The result reveal that good effect for superstructure and reduction effect for substructure of MIRS is favorable and obvious under major earthquake, Weak position of MIRS was be pointed out and fragility curves of typical MIRS of China was obtained finally.

Abstract: The performance-based design is a new development trend of seismic design. It is a breakthrough of the seismic design procedures. Based on the existing performance design method and some documents provided performance objective, computing and seismic structural measures, the performance-based seismic design is applied to the special structure of conventional island of the nuclear power plant. The performance-based seismic design is proved to be feasible according to a practical engineering case, as well the performance-based seismic design is needed to be further improved.

Abstract: The background of ancient wood structure buildings in China is elaborated in this article, and the seismic mechanism for structural features, pedestals, lateral foot column tendon joint structure and bracket arch of ancient Chinese architecture are analyzed. It is not only a great significance for the conservation , but also a promotion of Chinese culture. And a reference in solving the problem of earthquake control and isolation is provided.

Abstract: An anti-seismic analysis about two structures (an irregular high-rise building and the previous structure using eccentrically braces) is performed to study their torsional vibration response in earthquake. The self-vibration character and relative displacement between different floors are compared. It is found that adding some eccentrically braces properly can reduce the response of torsional vibration and other seismic response of the structures efficiently. From the example mentioned in the paper, it is verified that this method is a simple and economical one.