The impact of blast load is always taken into consideration in significant building and protective construction. In order to study the mechanical behavior of the concrete slab under blast load, the dynamic responses of a square concrete slab under surface explosion are simulated by the nonlinear finite element program ANSYS/LS-DYNA. The JOHNSON_HOLMQUIST_CONCRETE model is used for concrete material and the damage and strain rate effect are considered in this mode1. The simplified exponential load is used as blast load. The Z-displacement,Mises effective stress and damage state of concrete slab under different blast load of corresponding scaled distance are investigated and discussed. It can be found from the results that the influence of blast pressure can be neglected when scaled distance is around 2.0 and the damage of slab is beginning from the edge.
Regarding the design response spectrum in the code for seismic design of buildings as target spectra,the 28 acceleration histories are formed artificially.They are used as the inputs ground motion in earthquake response analysis.Four site classifications profiles were selected or constructed from practical site profiles.With the use of 1-D equivalent linearization wave motion method that is wildly used at present in site seismic response analysis, the platform values of surface response spectrum for different profiles under different ground motion inputs were calculated.Different platform values of the response spectrum and relational expression which is seven input earthquake motion intensity and site classifications have been given by statistical analysis.
In this paper, important buildings of different structure in Xichang are calculated by using the powerful design software PKPM. First, the drawings of the buildings are simplified and the structure forms are input the computer in PMCAD software interface to make model, and the comprehensive seismic capacity index of floors or the story drift angle are calculated. Then, according to the judging principle, the earthquake damage level is gotten.
Seismic design response spectrum is the basis of structure seismic design. Calibration of seismic design response spectrum is the main chain of structures’ seismic input determination. This paper proposes a new method of calibrating seismic design response spectrum. Based on summarizing the main form of calibrated seismic design response spectrum, which is related to the determination of the characteristic parameters of response spectrum, this paper advances least square fitting method based on coordinate transformation, and by comparing different calibrating methods, points out that least square fitting method is a simple and logical calibrating method.
Based on the energy analysis of a multi-degree-of-freedom (MDOF) system, a mode decomposition method for the input seismic energy is proposed, which substitutes a MDOF system with equivalent single-degree-of-freedom (SDOF) systems. The input seismic energy is obtained, using the actual earthquake data. The influence of ground motion parameters is analyzed. The results show that the seismic input energy increases proportionally with the square of ground motion acceleration peak. The bigger the predominant period is, the more the input seismic energy is.
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