Study On Seismic Appraisal And Strengthening Performance Of Existing Masonry Structure

Since Wenchuan earthquake,the state council has implemented the safety engineering of primary and middle school buildings around the country to improve the ability of earthquake resistance and disaster reduction of these schoolhouses.Meanwhile,in order to meet the needs of seismic appraisal and reinforcement design of masonry buildings in Wenchuan earthquake area and the whole country,the relevant departments have revised and promulgated the relevant appraisal and reinforcement standards.However,due to the acceleration of the progress of the amendment and time is tight and limite,many issues have not been fully discussed and studied.At present,school building in some rigions are still not up to the requirements for seismic fortification,especially schoolhouses built at the end of last century and the early stage of compulsory education.Through the investigation and identification of the earthquake resistance and reinforcement to make it achieve the key fortification seismic fortification standards.In this paper,combining with the author's actual participation in the school safety engineering of Zhenjiang City,the main research work are as follows:According to the comparison of the different seismic appraisal requirements of class A and class B masonry buildings in the standard for seismic appraisal of buildings(GB 50023-2009),combined with some seismic code,such as the standard for seismic appraisal of buildings(GB 50023-2009),code for seismic design of buildings(GB 50011-2010),etc.the applicable scope,height and number of layers,height to width ratio,local size and seismic wall spacing are improved and adjusted.The calculation method of seismic bearing capacity checking of masonry structure and the calculation method of PKPM review are described.In addition,the formula for calculating the reference area rate of masonry buildings is deduced.The strengthening method of reinforced concrete splint is one of the commonly used method of masonry structures,the calculation methods of seismic shear capacity with concrete splint are put forward in technical specification for seismic strengthening of buildings(JGJ 116-2009)and code for design of strengthening of masonry structures(GB 50702-2011).In order to compare the difference between the two standards,the enhancement coefficient of the unified calculation results of the two standards is described,and the factors which influence the enhancement coefficient of seismic capacity are analyzed,such as brick wall's cement mortar strength,thickness of the concrete wall,vertical compressed stress of wall section,thickness of original brick wall,etc.In addition,the difference of calculation methods in the two standards are quantitatively analyzed,the code enhancement coefficient reference values of 240 mm brick wall are given in the following research.This paper introduces the analysis model,basic principle,horizontal lateral force distribution mode,target displacement,analysis of concrete steps and method limitations of pushover analysis of masonry structure,And the layered shell element model is more suitable for Pushover analysis of wall reinforcement of masonry building.The inter-story drift angles limits for the performance levels of masonry structures is established through the norms and related literature in the masonry structure seismic performance evaluation indicators summary.The essay would investigate the original data of masonry structure school dormitory with the field test and safety appraisal on it.On this basis,according to the current seismic appraisal standard,the appraisal of seismic measures,seismic bearing capacity checking and PKPM review calculation are taken.The concrete splint of building aseismic capacity of dormitory wall are insufficient reinforcement designed,according to the enhancement value and code reference value of enhancement coefficient are used for checking the bearing capacity of seismic wall after reinforcement.The SAP2000 software is used to analyze the three-dimensional finite element model of the dormitory,and the seismic performance of the building is evaluated by the value of the drift angle between layers.