A Hybrid Testing Method And Platform Based On Control Points And Constitutive Model Updating

Model updating is an effective way to improve the accuracy of hybrid simulations.As long as there are some common properties between the experimental substructure and the numerical substructure,the experimental information can be utilized to identify these properties as well as update the model of numerical substructure.Usually these common properties are the constitutive parameters of material,section or element.By updating these parameters continuously in a hybrid simulation,the model error of the numerical substructure can be minimized.However,in most previous applications of hybrid simulation with model updating(HSMU),the numerical models were always over-simplified.On one hand,the models of numerical substructures were not precise enough to describe the nonlinearity of real structures.On the other hand,the numerical representative models of experimental substructures were too simplified to update the numerical substructures.To address this issue and extend HSMU method to more realistic structural models,the updating of constitutive parameters,including all kinds of materials,sections and elements in Open Sees,is realized.Accordingly,the method of hybrid simulation with finite model updating is proposed in this work.To further broaden the utilization of hybrid simulation in engineering applications,a control method based on control points is proposed and a general-purpose testing platform named HyTest is developed.The main research findings of this work are summarized as follows:(1)A control method based on control points is proposed.In a physical test,control points are all the nodes of which the motion and responses can represent the entire specimen.In this case,the control point is selected as the minimum loading cell in this method.By assigning the loading targets,actuators and sensors to each control point accordingly,a uniform testing procedure can be achieved for all the control points.The couplings of control points are considered during the calculation of loading targets for each step.After this calculation,the loading control loop of each control point is running independently.The proposed procedure can be adopted in any kind of testing configuration,including mixed force-displacement loading,and any kind of arrangements of actuators and sensors.(2)The finite element analysis software Open Sees is customized to be adopted and the updating of constitutive parameters,including all kinds of materials,sections and elements,is realized.A hybrid simulation method based on finite element model updating is proposed accordingly.Firstly,the numerical representative model of the experimental substructure can be modeled by Open Sees,representing the measurement equation implicitly;Secondly,the numerical substructure is modeled in Open Sees with changeable parameters,being updated incrementally during a test.This method can highly improve the accuracy and efficiency of model updating hybrid simulations.(3)A general-purpose testing platform named HyTest is developed.Both the control method based on control points,and the hybrid simulation method based on finite elment model updating,are realized in the platform.With the extendable architecture of the platform,HyTest is available to conduct multiple kinds of testing methods,including pseudo-static testing,traditional pseudo-dynamic testing,hybrid simulation,and hybrid simulation with model updating.(4)The proposed methods and platform are validated by a pseudo-static test on a shear wall structure,an identification case on a reinforced concrete column,a hybrid test on a single-floor steel frame and an HSMU test on a multi-floor steel frame.The efficiency of the testing method based on control points,as well as finite element model updating and its improvement on the accuracy of hybrid simulations,is well-demonstrated in those tests.Besides,the test results also verify the effectiveness and practicability of the HyTest platform.