Preliminary Study On The Relationship Between Instrumental Seismic Intensity And Damage Of Masonry Structure

Instrumental seismic intensity(ISI) is a calculated intensity to reflect the damage intensity of the area near observation station, which is based on the empirical relationship between macroseismic intensity and ground motion parameter. ISI can provide an important scientific basis for earthquake loss assessment, reasonable post-earthquake relief and the disaster area reconstruction. However, the standard of ISI must meet two conditions: the first one is ISI should have a good relationship with damage of structure; and the second one is ISI should have a good relationship with macroseismic intensity. At present, there are many kinds of instrumental seismic intensity algorithms at home and abroad, but most of them are based on the second condition. With the first condition in consideration and in order to explore one or more ISI standards which can be well used to reflect the seismic damage of structures, this paper has concisely evaluated the ability of ISI commonly used worldwidly to reflect the seismic damage of masonry structures, and recommended a reasonable ISI that can evaluate the seismic damage of different functional masonry structure. The main contents of this dissertation are as follows:(1)This paper summarizes six kinds of calculation methods of ISI commonly used at home and abroad, and analyzes the physical meaning of ground motion parameters which are used by ISI from the characteristics of ground motion and structural seismic design aspects, in order to provide a theoretical support and to study the relationship between the ISI and the damage of structure. This paper also uses six kinds of calculation methods of ISI to obtain different intensity values by the 139 sets of strong ground motion records, which are collected from 12 earthquakes occurred in the mainland of China.(2)This paper has established several representative nonlinear masonry structural models from the investigative survey that are obtained from Wenchuan earthquake in Deyang, Guangyuan, Jiange and Jiangyou cities, and has calculated the responses of nonlinear models by elastic-plastic dynamic response analysis under 139 sets of strong ground motion records, with the help of seismic damage index and destroys rating to obtain mean earthquake damage index around the area of the observation station.(3)This paper has analyzed the statistical relationship between ten ground motion parameters and mean earthquake damage indices of masonry structure. It is found that effective peak acceleration and peak ground acceleration which indicate the characteristics of force to structure have good relationship with damage of masonry structure, and the story number of masonry structure directly affects the strength of correlation between ground motion parameters and damage of masonry structure.(4)This paper has evaluated the ability of ISI commonly used worldwide to reflect the seismic damage of masonry structures and has obtained the following conclusions. Six kinds of ISI all have a good relationship with the damage of masonry structure, and the fuzzy ISI which considers structural damage parameter has the best relationship with the damage of masonry structure. Although the failure mechanism of masonry structure is closely related with the story number of structure, the fuzzy ISI still has a good relationship with the damage of different stories of masonry housing structure.