Study On The Safety Grade Index Of The Existing Building Capacity

In recent years,with the gradually change of architectural environment and production environment,remoulding the existing buildings becomes the focus which means a large number of buildings need appraisal.However in actual engineering,many problems exist if identified according to the current appraisal criteria.There is no uniform criterion to identify buildings at different time;the current identification criterion are separated from each other and are not systematic;A large number of buildings that can be used after maintenance and reinforcement are identified as dangerous buildings,The large demolition wastes the resources,also brings to the ordinary people and social pressure,and do not meet the requirements of the development of green building.Considering code for structural design is different in different ages and the demand of expecting working life is different,this paper aims to set up a new building appraisal safety level index which can meet the criterion in different ages and can meet different expecting working life of buildings.This paper detailed stipulation about practical design expressions from 70 S in the last century to the turn of the century,and provided resistance model in different ages as well as statistical parameters and sub-item coefficients about load action,and summarize the differences.;Considering continued working life of buildings is different(The main analysis of the follow-up period is 50 years,40 years,30 years,20 years and 10 years),the correlation coefficients of the existing buildings and the resistance are adjusted according to expecting working life;Both the reliability index of the existing buildings in the end value of the expected working life and the end value of the design working life are equal,according to this theory.This paper corrects the reliability index of the member,and considers the different expected working life,giving the specific value of the expected reliability index;In this paper,MATLAB software is used to calculate reliability index of different ratio between resistance and load,and to divide the security level of structural components accordingto different expected reliability index;In order to facilitate the consideration of the influence of the expected working life of exsiting buildings in pratical engineering,the ratio of resistance to load times an adjustment factor,which shall be adjusted to the safety level of the components specified in the standard for reliability appraisal of civil buildings;Finally,this paper introduces the application of the adjustment coefficient in the engineering example,and then simulates the engineering case with ABAQUS software.