Parameter Identification And Progressive Collapse Analysis Based On Monitoring Data

With large cities developing quickly and a large number of population gathering,construction of supertall buildings becomes an important path to solve the problem of land scarcity.In the construction process of a supertall building,construction become complicated due to the complex and tall structure,difficulties of construction,constantly changing construction loads and unavailable emergency rescue.Serious safety accidents might happen which will lead to disastrous consequences while major structure of supertall building is under construction load and extreme conditions.Formwork system collapse accidents are one of the most frequent accidents among safety accidents of buildings,which reaches 27.3% of all safety accidents in building construction.In consequence,it is of great significance to conduct field experiments,identify structural parameters and analyze progressive collapse of temporary support structure and major structure.The research in this thesis is part of based on a national basic research program 2016YFC0802002.The research subjects are a supertall building and temporary support system.Structural health monitoring system over a supertall building and its temporary support system is set up.A new method of parameter identification based on nonlinear sensitivity analysis is derived.Parameters of high-formwork system and the major structure are identified,and the finite element models are updated based on the experiments data.Progressive collapse analyses of both are done based on updated models.The research contents are as follows:First,structural health monitoring system is set up for the supertall building major structure and high-formwork support system.Experiments over high-formwork system are conducted.Dimension,acceleration and strain of support system during concrete pouring are acquired.Problems of high-formwork system during its assembly are disclosed.Stress and deformation rules during concrete pouring are obtained.Furthermore,SHM system of major structure is set up.Monitoring data of major structure are acquired.Properties of its dynamic response are analyzed.Second,a nonlinear parameter identification method based on nonlinear sensitivity analysis is proposed.Solution of nonlinear response equations of fiber-section beam-column element are derived,sensitivity of nonlinear material parameters is obtained using Newmark integration method.Parameters of complex structures are identified,hence finite elements models are updated using least square optimization algorithm.The method is verified by a practical supertall building major structure and its high-formwork support system.The results of major structure show that the relative errors of the identified parameters are less than 0.5%.The finite element model of high-formwork system is updated by the experiment data of the high-formwork system.The results show that maximum error and minimum error both reduced,therefore updated finite element model is closer to practical engineering.Last,progressive collapse analysis is performed on the updated models of supertall building major structure and its high-formwork system using monitoring data and identified parameters.The process of structural collapse is simulated.Internal force,displacement and energy variation are demonstrated and analyzed.Collapse patterns of two models are obtained.Measures to prevent high-formwork collapse accidents are suggested according to results of field experiments and software simulation.The proposed method is of great significance to assess structural health status of supertall buildings and offer accident pre-warning.