by In the article “Summary of the Method for Checking the Bearing Capacity of Concrete Structural Members According to the Appraisal Regulations”, Lao Chen summarized the seismic verification standards for existing buildings of various subsequent service life categories. The results are shown in the table below:.
From the above table, we can see that for most existing concrete buildings classified by their subsequent working years, we can perform seismic bearing capacity verification of components according to the original design standards. Only Class AA existing buildings should be verified according to the requirements of Class A buildings in the appraisal standard..
We know that current mainstream design software, such as PKPM and YJK, have added appraisal reinforcement modules, which provide several methods for seismic bearing capacity verification, including A-class buildings according to seismic appraisal standards, 89 version of the Code of Resistance, 01 version of the Code of Resistance, and 10 version of the Code of Resistance. Due to the provision of two calculation methods for seismic identification of Class A buildings in Article 5.3.2 of the appraisal regulations, these two calculation methods are actually different from the calculation methods in the 09 version of the seismic identification standard. Moreover, in our article “The deformation calculation results of the two methods in Article 5.3.2 of the appraisal regulations are not equivalent”, we also derived that the calculation results of the two calculation methods may be different. In this issue, we first take a typical case as an example to analyze the seismic bearing capacity calculation results of AA class buildings in the PKPM program (existing buildings that are classified as A-class buildings in both the appraisal standard and the 2009 version seismic appraisal standard), and explore the values of some calculation parameters..
Construct a simple four story reinforced concrete frame structure house in the Shanghai area, 7 degrees (0.1g), Class IV site soil, Class C building. Two different calculation methods and two different seismic levels were used in the PKPM identification reinforcement module, and the calculation results were compared..
The reason why the calculation model adopts the Shanghai region is twofold: firstly, Lao Chen is in Shanghai, and most of the projects are in Shanghai. Secondly, because the seismic response spectra in the Shanghai region have changed from 1992 to 2023, except for long periods, the response spectra of multi story and high-rise buildings generally do not change, thus avoiding the calculation deviation problem caused by the difference between the seismic design response spectra and the identification response spectra..
According to the requirements of the appraisal regulations and the 09 version of the seismic appraisal standards, the internal force design values of the component combinations of AA class buildings are not adjusted during calculation, which means that the calculation results of AA class buildings should be independent of their seismic grade. In this verification, seismic resistance levels of level 3 and level 4 were taken for the frame structure, and the differences in the calculation results in the PKPM module were analyzed..
There are four working conditions in this calculation, which are listed in the table below..
The reinforcement calculation results of the main components on the first floor under four working conditions are shown below..
In order to better compare the similarities and differences in the calculation results under four working conditions, the overall calculation indicators of the structure and the reinforcement calculation results of typical components are listed in the following two tables..
Based on the above calculation results, we can summarize the following aspects of the PKPM program:.
