Applied Research For Seismic Appraiser And Retrofit Methods Of RC Frame Structure

Earthquake is frequently occurring and earthquake zone is extensive in our country. A lot of damage is made in all previous large earthquakes. Seismic appraiser and retrofit for the large quantity of existing buildings is needed urgently. The reason is that 1) seismic fortification intensity has been increased or structures needing seismic appraiser haven't been designed by seismic code 2) RC structures builded in 50~60 years or before 50 years have exceeded their active time .Security of structures has reduced. Seimic performance of structure isn't assured .so these structures should be appraised 3) structures should be appraised after an earthquake action. Standard for seismic appraiser of building (GB50023-95) has been promulgated and put in practice for a decade. Irrationality of fortification object and appraiser method exists in the standard. So the standard should be revised urgently. Although that retroft of increasing bearing capacity of frame member will affect general performance of structure has been realized by projecters and researchers, only increasing bearing capacity of frame member universally exsits at the present time in retrofit projects. Aiming at the above problems, Seismic appraiser program is worked out according to the standard firstly. Then the importance and existing problems of seismic appraiser method in the standard is studied from the theoretical background of seismic appraiser for RC frame structure. The necessity of checking calculation for elastic-plasticity deformation of structure by a fortification earthquake action should be presented by computation example analysis. Moreover, theoretical computation equations of the frequently using reinforcement methods of frame member are established. Safe reliability, convenience of construction, economic applicability of different retrofit methods is generalized so as to provide rules for seismic retrofit. At the end, seismic performance of an existing frame structure under an action of a frequently occurred earthquake, a fortification intensity earthquake and a seldom occurred earthquake is analyzed and compared using pushover and dynamic time-history methods. The problems to be attentioned in retrofit of increasing bearing capacity of frame member are generalized. The importance of controlling the uniformity of story rigity and strength from general structure after retrofit of frame member that the bearing capacity of its section is not enough is pointed out. The recension of standard for seismis appraiser of building according to research work of the paper is expected. The valuable advices for seismic retrofit projects are provided in the paper.