Study On Life Prediction Model And Evaluation Method Of Adjacent RC Frame Structures Considering Collision Damage Under Earthquake

Building structures may encounter a series of earthquake disasters within the designed service life.Among the existing building structures in cities and towns in China,the spacing between some adjacent RC building structures does not conform to the relevant provisions of the current code in China.And the spacing between a few building structures is even zero,that is,the adjacent structures are in contact with each other.Such adjacent building structures may be damaged due to collision under earthquake action,which poses a great threat to people’s lives and property losses.At present,adjacent RC frame structures that have been built for a long time and with insufficient spacing frequently appear in China.Most of the structures can still be used normally within the designed service life.Due to economic constraints,they cannot be removed.Therefore,it is necessary to study the life prediction model and reliability evaluation of existing adjacent RC frame structures considering collision damage within the design service life.In this thesis,by means of theoretical analysis and numerical simulation,the life prediction model and assessment method of adjacent RC frame structures considering collision damage under earthquake are studied.The main research contents are as follows:(1)In the process of life prediction of existing structures within the design service life,it is necessary to consider the characteristics of ground motion records of the building structure.Due to the lack of historical ground motion records,based on historical data and regional basic intensity probability calibration,reasonable ground motion records are selected from PEER ground motion record database according to the ground motion optimization method of fuzzy comprehensive decision-making to simulate the seismic action within the design service life of the structure.To verify the advantages and disadvantages of the ground motion records selected according to this theory in reducing the impact of the difference of ground motion records on the structural dynamic analysis,the SDOF system is taken as an example to conduct structural dynamic analysis.78 unselected and 13 screened ground motion records are input into the structure and the structural response is extracted respectively.The discreteness between the ground motion records index and the structural response is analyzed to verify the effectiveness of this method.(2)Due to the traditional structure life estimation model usually involves a tedious analytical process,complex mathematical theory,which makes it difficult to put into engineering use.Therefore,based on the theory of time domain reliability of structures,and by means of time interval analysis method of structural failure probability,a uniform Poisson process is proposed,which considers the main earthquake as having a constant average incidence rate,considering the structural performance degradation caused by earthquakes.Furthermore,assuming that the degradation of the studied structure performance is mainly controlled by the cumulative damage caused by a group of continuous seismic events in a certain period,the simplified structure life estimation model takes the structural cumulative damage as the evaluation index.On the premise of retaining the characteristics of the structural system,this model avoids complex mathematical operations and makes a good prediction of the structural life distribution.(3)Based on OpenSees finite element software,the simulation of Truss-Link model in the software is studied and compared with the shaking table test,which verifies the feasibility of the simulation method.The adjacent RC frame structures with different structural layout types and spacing are modeled.Six groups of ground motion records selected according to the fuzzy optimization theory for simulating the possible occurrence within the design service life are adjusted according to the small,medium and large earthquakes,and the adjusted ground motion records are input into the structural model.The cumulative maximum inter story drift and the maximum vertex drift response of the structure are calculated,and the dynamic and vulnerability analysis of adjacent structures are carried out as structural damage indicators.The structural failure probability under different structural performance levels is studied,and the influence of structural spacing on structural damage is discussed.The life distribution of the structure system within the design service life is predicted according to the nonparametric Kaplan-Meier estimation model,which provides a theoretical basis for structural reliability assessment.(4)In the process of life prediction and evaluation of structures,the use of different engineering demand parameters may have a great impact on the evaluation results.Therefore,this thesis uses the cumulative maximum inter story drift and the maximum vertex drift as the joint engineering demand parameters,calculates the structural failure probability and the corresponding reliability indicators of the results under different performance levels,and evaluates the reliability of adjacent structures of different types and distances.The probability analysis method is proposed to replace the theoretical analysis based on engineering experience and certainty in the current specifications,which provides a more reliable theoretical basis for the later decision-making of structural reinforcement,maintenance,or demolition.