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A B S T R A C TIn order to understand the seismic performance and mechanism of bottom frame seismic wall masonry structure (BFSWMS) and its vulnerability in empirical seismic damage, based on the statistical and numerical analysis of the field seismic damage observation data of 2178 Dujiangyan structures in the Wenchuan great earthquake urban of China on May 12, 2008, a non-linear function model between the seismic grade and the number of field damage samples is established, and the regression curve is given. The empirical seismic vulnerability matrices in multiple intensity regions are established, and the regression model functions of each intensity region and the vulnerability curves based on seismic damage grade and exceeding probability are obtained, respectively. A vulnerability matrix model with mean damage index (MDI) as its parameter is proposed, and the empirical vulnerability matrix is embedded in it. The vulnerability matrix based on this parameter and the regression curve of MDI in Dujiangyan city are derived. The above research results can provide the necessary practical reference for the vulnerability study of BFSWMS and the seismic code of China.

A B S T R A C TTo understand the seismic damage characteristics of bottom frame-wall buildings and to study their seismic performance, the seismic damage outcomes of bottom frame-wall structures in Du jiang weir by the Wen chuan earthquake on May 12,2008, China were field observed and studied. The assesment of the seismic damage to the bottom frame-wall masonry in Du jiang weir urban showed that the damage to the type of structure system was serious and including damage to the bottom frame, the bottom storey, the transition storey, the bottom node and the rear longitudinal wall, combining with the failure characteristics, the failure reasons and mechanism were analyzed and the corresponding treatment measurements are given. However, a substantial number of bottom frame seismic wall masonry structures (BFSWMSs) after 2000 are basically undamaged. The field inspections team sampled 2178 buildings of the urban ensemble observation. A considerable number of buildings seismic fortified have shown excellent seismic performance in Wenchuan earthquake, which sufficient illustrates the significant role of seismic fortification factors in structural design. Through, the investigation and analysis of its empirical seismic damage, the main measures to improve its seismic performance of construction structure. The above analysis results can provide a reference for seismic design and the revision of seismic intensity scales.

In practice, seismic intensity is evaluated in accordance with a macroseismic-intensity scale recognized in the field of seismic engineering globally. The application of different seismic-intensity scales to evaluate the seismic damage of a specific structure due to an earthquake yields diverse results. On this basis, this study compared a few extensively used macroseismic-intensity scales. The results can be used as a reference to develop an international intensity scale. According to empirical structural-damage survey data from the Wenchuan earthquake (Mw = 8.0) that occurred on 12 May 2008 in China, the European Macroseismic Scale (EMS)-98, Medvedev, Sponheuer, and Karnik (MSK)-81, and Chinese Seismic Intensity Scale (CSIS)-08 intensity scales were utilized to evaluate the resulting damage. This study carried out a vulnerability analysis of typical structures, established vulnerability seismic-damage matrices, and mapped out vulnerability curves under different intensities. Our objective is to demonstrate that the use of multiple intensity scales can lead to very different intensity levels. The differences in the damage of typical structures under different intensity levels were obtained from an evaluation using the three aforementioned intensity scales. As a result, a calculation model of the mean damage index is proposed herein. Ultimately, this article conducted an analysis on the failure characteristics of typical structures in an earthquake and provided effective measures to improve seismic performance for future reference.

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