Seismic Evaluation Of Masonry Structures

Rational seismic evaluation and reinforcement of masonry buildings are the important measures for reducing the earthquake disaster. However, researching on the method of seismic evaluation of existing masonry building was reported lightly. In Wenchuan earthquake, a large number of buildings designed by base on the different years’standards suffered varying degree of damage, which provided a lot of first-hand information for seismic evaluation of the buildings. The seismic evaluation methods of masonry buildings were studied based on the information of damage buildings from earthquake investigation, which was supported by the subject named "the key technology study of anti-collapse for masonry school building under severe earthquake". This subject was supported by the program fund of the ministry of science and technology. The main achievements of this dissertation are as follows:(1) The three stages evolution methods for seismic performance of multistory reinforced concrete buildings in Japan, the two stages evolution methods for seismic performance of multistory masonry buildings in China, and the relevant parameters of the above methods were introduced. The differences between Chinese and Japanese methods were studied, which provided lots of useful reference.(2) The earthquake intensity and degree of damage buildings were defined. Moreover, the characteristics and regularity of damaged masonry buildings were summarized, the relative factors of the seismic capacity were analyzed.(3) By analyzing the different anti-seismic process of masonry building and reinforced concrete building, and according to the anti-seismic capacity of masonry structure primarily depends on its bearing capacity because of the low ductility, the indice for evaluating masonry building were proposed which taken the wall number index named’wall ratio’as the main parameters, it can be applied to assess the anti-seismic performance quickly due to its easily caculated characteristic. In addition, the quantitative relationship between damage degree and the indice was established based on the data from Wenchuan earthquake investigation,and the advantages and disadvantages of the indice were analyzed.(4) By analyzing the effect of structural column, beam and floor slab impact on anti-seismic capacity of masonry building, the parameter of the effect was obtained, the parameter can be used to describe the contribution of structural column, floor slab and beam impact on anti-seismic capacity of masonry building. In additon, the index for evaluating masonry building was proposed which considered the contribution of structural column, floor slab and beam impact on anti-seismic capacity of masonry building, and the quantitative relationship between damage degree and the index was established based on the data from Wenchuan earthquake investigation, and the advantages and disadvantages of the index were analyzed. Finally, the applicability of masonry building in high intensity area were researched by analyzing the quantitative relationship between evaluation indice and earthquake damage degree.(5) The seismic evaluation method of masonry building was provided. By analyzing the differences in the damage degree evaluated between by using the seismic evaluation method and the current seismic appraisal standards with some same examples, and the differences in the damage degree between ctual earthquake damage degree on scene and evaluated by using the seismic evaluation method a with the same examples, the efficiency and rationality of the seismic evaluation method for evaluating anti-seismic capacity of the masonry building were researched:the evaluation results by using the seismic evaluation method were consistent with the current seismic appraisal standards, and the damage degree obtained by using the seismic evaluation method was consistent with actual earthquake damage degree on scene.(6) The anti-seismic wall area ratio regulations of seismic design codes in different years in China were introduced. The shortage of previous codes was studied, and some reasonable suggestion for improvement was provided:the different values of the anti-seismic wall area ratio were provided by considering effect of the structural column number and the types of floors impact on anti-seismic capacity, which made up for the deficiency of previous codes.(7) The limited value of height, layers and the structural column regulation of seismic design codes in different years in China were introduced. The shortage of previous codes was studied, and some reasonable suggestion for improvement was provided:the different values of limited value of height, layers and t the structural column regulation were provided by considering effect of the wall number and the types of floors impact on anti-seismic capacity, which made up for the deficiency of previous codes.