Hybrid Test Method With Bond-slip Model Updating

Hybrid test is one of the seismic tests, which divides the dynamic structure into test part and numerical simulation part, and is able to simulate the seismic responses of largescale or even full-scale specimens. Application of the substructure hybrid test improves the ability to assess the seismic performance of large and complex structures. For certain complex structures, many critical components of these structures have reached the elastoplastic stage under earthquake, while the number or size of substructures which can be tested in the laboratory is limited, then we have to take certain critical components as numerical substructures. Obviously, the accuracy of hybrid test will be reduced when such members occupy a large portion. Therefore, increasing the modeling accuracy of numerical substructures has become an urgent problem, and hybrid test with model updating provides an alternative method for solving such problem.Hybrid test with model updating identifies the experimental substructure model parameters online and then updates the numerical substructure parameters, which improves the accuracy of the numerical substructure response, thereby improving the accuracy of the overall structural response. This paper considers the influence of the bond slip and updates the bond-slip material parameters, which improves the accuracy of hybrid test. The main contents and conclusions can be summarized as follows:(1) The principles of bond-slip were researched in depth, and then Bond_SP01 material was chosen as the model considering bond-slip effects. Then the influences of bond-slip on structural hysteretic response were analyzed, and two cases, including a cantilever column and a reinforced concrete(RC) frame, were conducted respectively to investigate the changes in structural response after adding a zero-length element considering bond-slip effects.(2) The sensitivity of the reinforcing material and bond-slip material was analyzed, and the significance of updating bond-slip material parameters was discussed. Unscented Kalman filter(UKF) identification algorithm was established, which could identify the bond-slip material parameters. The identification results prove the effectiveness of the identification program.(3) The identification method of reinforced concrete constitutive parameter consider-ing bond-slip was proposed. The method considered the physical significance of material parameters in the identification algorithm and applied interval constraint to the parameters. The influences of different element types on identification results were researched, and the corresponding algorithm and its advantages and disadvantages were given. The reinforced concrete constitutive parameters were identified using the existing column and frame test data, and the results show that the method can identify the parameters effectively.(4) The identification program was applied to hybrid test simulation with model updating. A plane RC frame was simulated considering bond-slip by adding a zerolength element at the end of the column, and corresponding dynamic analysis model for hybrid test was established. Material parameters were identified stepwise and then the numerical substructure was updated. The simulation results verify the validity of the method.