Report - PEER - University of California, Berkeley

Figs. 2 and 3 show the seismic reliability indexes of four multistory brickbuildings designed for intensity VI, VII, VIII and IX in region of intensity VII(Tianjing) and VIII (Beijing) at three performance levels, respectively. The seismicreliability index at the second performance level is taken as the average of those forslight damage and moderate damage. Tables 4 and 5 list the seismic reliabilityindexes of four multistory brick buildings designed for the basic intensity in region ofintensity VII (Tianjing) and VIII (Beijing) at three performance levels, respectively.The averages in the table and figure are the ones of the seismic reliability indexes ofthree-story, four-story, five-story and six-story brick buildings for the multistory brickbuilding designed for intensity VI, VII and VIII, and the ones of the seismic reliabilityindexes of three-story and four-story brick buildings for the multistory brick buildingsdesigned for intensity IX. These averages represent the seismic reliability of thesekinds of multistory brick buildings.From Figs. 2 and 3, we can see the dispersion of the seismic reliability indexes ofvarious story brick buildings and the averages. For the buildings designed forintensity VI, the index is lower than the average for a five-story building at threeperformance levels, and higher than the average for a six-story building at the secondand third performance levels. This is mainly because constructional columns areinstalled rarely in five-story buildings and more frequently in six-story buildings. Forbuildings designed for intensity VII, the indexes of various story buildings are nearthe average at the first performance level. The index is near the average for a six-storybuilding, much higher than the average for a five-story building, and lower than theaverage for three-story and four-story buildings at the second and third performancelevels. The reason for the higher index of a five-story building is that the number ofconstructional columns in a five-story building is increased compared with thenumber used in buildings with fewer stories. For buildings designed for intensity VIII,the index is much higher than the average for a six-story building, and lower than theaverage for other buildings at the second and third performance levels. The reason forthe higher index of the six-story building is that a six-story building is installed withthe same number of constructional columns as a five-story building, but the grade ofmortar is higher than that in a five-story building. For buildings designed for intensityIX, because the number of constructional columns installed in three-story and fourstorybuildings is the same but the grade of mortar in a four-story building is muchhigher than that of a three-story building, there are many differences between theindexes of three-story and four-story buildings. The index is higher than the averagefor the four-story building, and lower than the average for the three-story building atthe three performance levels. For three performance levels, the indexes of the sixstorybuilding designed for intensity VI and VII are close. The index of a four-storybuilding designed for intensity VI is higher than a building designed for intensity VIIbecause the grade of mortar is much higher and the constructional columns installedare more for buildings designed for intensity VII than VI. The index of the five-storybuilding designed for intensity VII is much higher than the building designed for417