Improvement Measures for Layer Limits and Tie Column Settings in Masonry Structures

In order to make up for some deficiencies in layer limits and tie column settings for brick masonry structures in seismic design code, where the provisions of layer limits and tie column settings are presented without considering the difference in wall area on a floor, an index of the ratio of wall areas in load-bearing direction to the floor areas (RWF) was proposed. Some differences in RWF due to different types and construction ages were studied by a statistical analysis of a lot of design data. In addition, according to the seismic evaluation theory and its judgment standard, the influences of RWF on layer limit and tie column setting were analyzed. Some suitable measures of layer limits in different performance target and structural columns settings were also suggested. The analysis results show that, in order to meet the requirement of a structure does not collapse in a major earthquake, the RWF of a seven-storey brick masonry structure with assembled slabs subjected to seismic fortification intensity of 7 degree shall not be less than 5.5%, and the RWF of the structure with cast-in-situ slabs shall not be less than 4.5%; the RWF of a six-storey structure with assembled slabs subjected to seismic fortification intensity of 8 degree shall not be less than 6.5%, and the RWF of the structure with cast-in-situ slabs shall not be less than 5.5%; the RWF of a four-storey structure with assembled slabs subjected to seismic fortification intensity of 9 degree shall not be less than 6.5%, and the RWF of the structure with cast-in-situ slabs shall not be less than 5.5%.