Study On The Boundary Coordinating And Model Updating In Hybrid Test Of Engineering Structures

Hybrid testing is one of the important means to study the seismic performance of engineering structures.In hybrid test,part of the whole structure with complex behavior is commonly selected as the physical substructure,while the rest can be economically and efficiently reproduced by numerical simulation.In this way,the seismic response of the whole structure can be reproduced cost-effectively.The key to the successful implementation of the hybrid test is the boundary coordination and the accuracy of the numerical model.Boundary coordination between the physical and numerical substructures includes both numerical calculation and physical realization of boundary conditions.Simple,accurate and stable boundary coordination algorithm is usually welcomed by hybrid test.On the other hand,the boundary conditions between substructures become more and more complex.The accurate physical loading for physical substructure is crucial.For the convenience of hybrid test,the implementation of the integrated multi-degree-of-freedom(multi-DOF)loading device can meet the requirements of hybrid tests.In addition,the parallel processing of the physical substructure and the numerical substructure provides a convenient condition for making full use of the experimental data and updating the numerical substructure.Aiming at the above two problems,this thesis conducts research on substructure coordination algorithm,multi-degree-of-freedom loading device and algorithm,online model updating,etc.,and finally completes the general hybrid test software.The thesis mainly completed the following work:1.A staggered coordination algorithm is proposed to solve the boundary coordination approximately.Aiming at the difficulty of the predition of the complex static boundary between numerical and physical substructures,a strategy of alternately analyzing and loading numerical substructure and physical substructures is adopted,making physical substructure static boundary conditions easier to be implemented.An energy-based error index is proposed,and the effectiveness and accuracy of the staggered coordination algorithm is verified by hybrid simulation and hybrid test of the six-layer BRB-reinforced RC frame.2.A multi-DOF force-displacement mixed-control algorithm is put forward.a modified Newton-Raphson(NR)iteration integrated with a PI control(MNR-PI)is developed to handle material nonlinearity,and the incremental kinematic transformation method integrated with PI control(IKT-PI)is proposed to solve the nonlinear coordinate transformation problem.With the discrete control theory,the control gain is designed,and the convergence of the method is verified.The proposed method is applied to the development and design of Stewart mode multi-DOF loading devices,and the multi-DOF force-displacement mixed control under the high coupling state of the actuator is realized.3.The complex boundary substructure hybrid test system of the Open SeesOpen Fresco-Stewart platform is established to realize the accurate physical reproduction of the complex mechanical behavior of bending,compression,shear and torsion under the seismic action of complex structures.Taking a small-radius curved bridge as an example,the complex failure process of the pier under spatal loading is reproduced by using a small electric Stewart platform and a large hydraulic Stewart loading platform.4.An online model updating hybrid test method considering the boundary conditions with multiple inputs is proposed.Based on the monitoring of restoring force and boundary conditions of phsycial substructure,the parameters in the phsycial substructure are online identified with unscented Kalman Filtering method.And then the parameters are updated to the part of numerical substructure which share the same mechanical behavior with the physical substructure.Compared with the single-input model updating,after considering the boundary conditions,the parameter identification convergence rate is faster and more stable,and the accuracy of the numerical model is greatly improved.5.A general hybrid test control platform is established.A unified interfaces with numerical models are built.A general loading framework and data transmission format is established and can be compatible with various loading devices.Thereby the free configuration of various loading devices and data interaction with numerical models are realized which make the implementation of hybrid test simpler and more efficient.