Model-driven Seismic Damage Evaluation Method For Structures Based On Macroscopic Response

Earthquake is one of the most serious natural disasters facing mankind.After an earthquake,buildings have varying degrees of damage.An efficient and objective assessment of structural damage and residual seismic capacity as soon as possible is of great significance for guiding the resettlement of disaster victims and maintaining a stable society order in the disaster area.The traditional post-earthquake building emergency assessment requires a large number of experts to conduct on-site research in earthquake-stricken areas,which is characterized by heavy workload,strong subjectivity,and high risk.In recent years,with the development of the measurement technology,sensing technology and structural health monitoring,new solutions have been provided to achieve objective and efficient earthquake damage assessment.However,there are still problems such as difficulty in obtaining displacement time histories,lack of computational models for subsequent seismic capacity evaluation,and unclear quantitative relationships between apparent earthquake damage and mechanical performance degradation indicators.In this study,a model driven damage assessment method for earthquake-damaged structures is proposed: using a small amount of readily available measured macroscopic responses of the structure,the equivalent calculation model of the structure and the displacement response of each story are inverted.The equivalent calculation model is modified based on mechanical performance degradation model,so as to obtain the earthquake-damaged structural model,thereby achieving objective assessment of residual seismic performance.The main research content and innovations are as follows:(1)Aiming at the problem of baseline drift of acceleration signals,an acceleration baseline correction method based on measured residual displacement and L1-norm convex optimization is proposed.Numerical simulation and shaking table tests show that this method has good correction effects for both ground and floor motion acceleration time histories.The Pearson correlation coefficient between the corrected displacement time history and the actual displacement time history is greater than 95%,and the maximum displacement error is less than 5%.(2)A model-driven structural displacement response inversion method based on model driven and limited measured data has been developed,by equating the actual structure to a story model,optimizing parameters using optimization algorithms,and estimating the seismic response of the structure based on optimal parameter combinations.Numerical simulation and shaking table tests show that the inversion error of the maximum inter story displacement and the maximum displacement of each layer of the structure is less than 20%.The pushover analysis verifies the rationality of the equivalent calculation model.(3)Two-stage cyclic loading tests of several typical RC frame beam and columns were carried out,and the restoring force curves of 1/300,1/200,and 1/100 displacement angle earthquake damaged members were obtained.A degradation model of mechanical properties of components based on historical maximum deformation is established.Based on the statistical analysis of a large number of testing data,empirical formulas for the stiffness,strength,and peak displacement degradation coefficients of earthquake damaged RC beams and columns are established regarding the historical maximum deformation.(4)A degradation model for mechanical properties of the story model is established.A damage assessment framework for earthquake damaged structures based on story model is proposed.Taking the shaking table test data of a 4-story RC frame structure as study cases,the feasibility of this method in seismic response estimation and subsequent seismic performance prediction is verified.