Applied Mechanics and Materials Vols. 166-169

Abstract: This study consists in estimating the risk (potential) of liquefaction of a soil deposit saturated when it is submitted to a horizontal seismic excitement to its basis while using the approach in total constraints. This approach requires the determination of the shear constraint τa developed by the seismic solicitation, For the determination of τa, an equivalent linear dynamic analysis with concentrated mass has been used to adapt (iterable proceeding) the module of shear and the factor of damping according to the level of the resulting shear deformations because, the constraint-distortion diagram of the layer is nonlinear with dissipation of energy by hysteresis for each cycle. For this reason, in this survey, the behavior of soil has been represented by a hyperbolic relation of Hardin and Drenevich. For the determination of τl, the graph of Seed and al based on the results of the SPT. The report of the two constraints permits the definition of safety factor against the risk of liquefaction (CSL).

Abstract: This paper presents that the cross-correlation method is used for estimating the direction of wavefront propagation and the apparent velocity for seismic signals in the small-size dense seismic array. The near earthquake signals samples adopted from US Geological Survey Parkfield Dense Seismograph Array (UPSAR array) of the U.S are used for analyzing. The results analyzed indicate that the wavefront propagation and the apparent velocity of near earthquake signals can be succinctly and accurately estimated by the method proposed in this paper.

Abstract: In this paper,the definition and computation method of seismic behaviour factor is firstly explained,and then a V concentrically braced steel frame (CBSF) and an inverted-V CBSF were designed according to Chinese design codes,after that, the incremental dynamic analysis (IDA) was used to get the seismic behaviour factor.The results indicated that whether the connections between braces and columns or beams are rigid or hinged,which does not have much influence on the seismic behaviour factor of the structures.But the different seismic wave may bring different seismic behaviour factor for the same stuctures.Furthermore,the analysis method,limit state,failure criterion and finite element model of structures have some influrnce on the seismic behaviour factor of structures,and much work was needed in this research field.

Abstract: The limitations of traditional inelastic response spectra are discussed. Considering a one-storey asymmetric plan system subjected to perpendicular bi-directional earthquake motions, the inelastic multi-dimensional strength reduction factor spectra is presented. The yield rule of the asymmetric plan system is determined by two-dimensional yield-surface plasticity function. The spectral equation is simplified by the relationship of strength reduction factors between x-direction and y-direction.The multi-dimensional spectra are analyzed based on 30 pair strong earthquake motion records for hard soil site, intermediate soil site and soft soil site. Analytic results shows that the strength reduction factor mean spectra for each soil site has its own characteristics, and the strength reduction factor spectra is affected strongly by ductility, normalized stiffness eccentricity, period and rotation frequency ratio.

Abstract: The determination of structural stiffness for the currently seismic design method depends on subjective experience of designers which is not rational and economical. A method that uses displacements as the basis for the stiffness design procedure is then presented: (1)By means of preliminary design, the initial elastic structure are obtained and the 1th mode shape, period etc are then calculated by modal analyses; (2) The target period and lateral equivalent stiffness of structure are determined according to target displacement used in seismic code; (3)The two periods for initial designed structure and target structure are compared and the lateral stiffness is adjusted to make the displacement responses of the structural weak members meet the limited displacements by adjustment parameter. An example is implemented for demonstrating the process and verifying the accuracy of the procedure.

Abstract: Comparison of the vulnerabilities between former and current RC frame structures after the 2008 Wenchuan earthquake are performed in the paper. Two representative types of RC frame building in Wenchuan county town are studied by nonlinear finite element method (FEM). Probabilistic seismic demand models (PSDM) for RC frame structures is built to assess the safety levels of two representative RC frames in Wenchuan county town. The fragility curves for immediate occupancy (IO), significant damage (SD), and collapse prevention (CP) damage levels of the RC frame building are analyzed. The result indicates the safety levels of current RC frame building in Wenchuan district are well improved compared to the former RC frame building after the 2008 Wenchuan earthquake.

Abstract: Seismic design response spectrum and earthquake action in Chinese new seismic code (GB50011-2010), ASCE/SEI7-05 and Eurcode8 were gathered in this paper. Using base shear force method of each code, the authors computed the horizontal seismic forces of a three-story reinforced concrete frame building under the same conditions. The results show that the three static methods roughly approach, while the different parameters lead to discrepancies in calculated values.

Abstract: In this paper ,the parameter study of the instantaneous spectrum model is transformed to that of strength envelope model and instantaneous frequency model, based on the real ground motion array data, the statistical analysis result of the parameter of multipoint ground motion at local sites indicate that the most parameters are associated with projection distance and soil layer thickness, and the regression model and the value selection of various parameters provided in this paper can also be used for the reference of artificial synthesis of multipoint ground motion.

Abstract: Selection and modification of recorded earthquake ground motions is one of the most important issues for reliable seismic performance evaluation of the structure. In order to investigate the influence of ground motion spectral shape on nonlinear seismic response and to find the implication for ground motion selection and modification, a 3-storey RC planar frame is taken as case study in this paper. 15 ground motion records are chosen from PEER Ground Motion Database and Wenchuan Great Earthquake as dynamic analysis inputs.

Abstract: Anomalistic architecture especially overhanging structure has become a trend of architectural development, Based on the characteristics of a large vertical eccentric, more prominent facade and strong reverse effect,overhanging structure is often serious super-norm and extremely detrimental to the seismic design[1], Now it has become an important part of seismic review. By the analysis and comparison on the coupling of the translational and torsional seismic response from ANSYS program[2]. The behavior of seismic catastrophe of cantilever building structure is studied under bi-directional earthquake action and the change law of cantilever member with the length is obtained, the suggestions on engineering design are put forward for future seismic design of such structures.