Report - PEER - University of California, Berkeley

acceleration response spectra and smoothing them. The coefficient of variation of thenormalized mean response spectrum changes with period. But for general site and therange of period of multistory dwelling brick buildings, it can be taken as β R = 0.26according to Jiang (1995). The duration of strong motion is taken as the 1/2 peakacceleration duration τ. By utilizing 24 strong earthquake records longer than 2.75sfrom Jiang (1995), we obtain that the mean value is 8.25s, and the coefficient ofvariation β τ = 0.678. The standard response spectrum in the code is the one with thedamping ratio of 0.05. When the structural damping ratio isn’t 0.05, the responsespectrum is revised by the damping revising coefficient formula specified in theChinese “Design code for antiseismic of special structures” (GB50191-93). Thecoefficient of variation of the damping ratio is already given above. In the reliabilityanalysis, the peak ground acceleration is a given independent variable, so it should beregarded as deterministic.5. SEISMIC RELIABILITY ANALYSIS OF MULTISTORY DWELLINGBRICK BUILDINGS5.1 The Earthquake Load-Structure SystemIn order to analyze the seismic reliability of multistory dwelling brick buildings atdifferent performance levels, the Latin Hypercube Sampling technique is utilized toestablish the structure model assembly and the earthquake load assembly, and thenmatch them to obtain the earthquake load-structure system. In the analysis, fourparameters describing the structural model and four parameters describing theearthquake model are considered. The uncertainties of each parameter are expressedin terms of three representative values, i.e., mean, mean minus and plus one standarddeviation. So, for the ensemble of structural models, from the combinations of threerepresentative values of the four parameters, a total of 81 structural models can beestablished. For the ensemble of earthquake time histories, from the combinations ofthree representative values of response spectrum and damping ratio, nine responsespectra are obtained. For each response spectrum, three stationary time histories aregenerated. Thus, 27 stationary time histories are produced. It is noted that 27 differentsets of random phase angles are used to generate these time histories. And then threeenvelope functions represented by strong motion duration are applied to eachstationary time history to generate three normalized nonstationary time histories.Three strong motion durations are taken as its mean, mean minus and plus 0.8 timesstandard deviation (Zhang 2002). Thus, a total of 81 normalized earthquakeacceleration time histories are generated. Finally, these earthquake time histories arematched to the structural models so that the earthquake load-structure system with 81samples is constructed.413