Hybrid testing with model updating on steel panel damper substructures using a multi‐axial testing system

Abstract

Summary This paper describes a series of hybrid tests performed on a steel panel damper (SPD) specimen by using a multi‐axial testing system. The building under investigation adopted a three‐dimensional six‐story moment resisting frame with four SPDs installed at each story as the main seismic resisting system. The structural model was subjected to bi‐directional ground excitations of three hazard levels. The finite element analysis program “Platform of Inelastic Structural Analysis for 3D Systems” (PISA3D) was used as the analysis kernel for hybrid tests. Relevant programming extensions in PISA3D were created to support geographically distributed hybrid testing in a general‐purpose manner. An external displacement control (EDC) method was developed such that the actual boundary deformation of the specimen fixtures could be continuously measured and immediately compensated during tests. An online model updating (OMU) technique was developed and employed such that the material properties of the specimen could be identified directly from the specimen response during the test. The identified material properties were then immediately used to update those of the other relevant numerical elements to enhance the overall simulation fidelity. Superior flexibility of the underlying software architecture was well demonstrated in this series of hybrid tests since no hardcoding was used to support all the complex test settings. Test results confirmed the effectiveness of the proposed EDC method, as well as the capacity of the proposed OMU technique to satisfactorily and efficiently capture the hysteretic properties of the specimen.

Multi‐degree‐of‐freedom force‐displacement mixed control strategy for structural testing

“…Despite their different objectives, both testing methods require spatial loading in multiple degrees of freedom (MDOF) to emulate realistic boundary conditions at the loading points. This, however, leads to challenges for actuator control owing to the strong coupling between the actuators assembled for MDOF loading and the specimen 3–9 …”

“…Despite their different objectives, both testing methods require spatial loading in multiple degrees of freedom (MDOF) to emulate realistic boundary conditions at the loading points. This, however, leads to challenges for actuator control owing to the strong coupling between the actuators assembled for MDOF loading and the specimen [3][4][5][6][7][8][9] In response to this demand, special devices have been developed in the past decades, such as the multiaxial subassemblage testing (MAST) device, first developed at the University of Minnesota and later at Swinburne University of Technology 10 and Eidgenössische Technische Hochschule Zürich. 11 MAST has a six-DOF control system to enable accurate application of complex multidirectional loading schemes.…”

“…Therefore, displacement or force control cannot separately provide an effective solution. To address this challenge, various forcedisplacement mixed control schemes have been developed, 4,6,7,13 where the DOF associated with high stiffness is controlled by force, whereas the other DOFs are tested in displacement control mode. If necessary, force control can be switched to displacement control when stiffness degrades to an acceptable level.…”

A Distributed Computing Platform for Conventional Hybrid Simulation

“…The time-stepping integration method adopted is average acceleration method, the Newmark method with  = 1/4, with the 0.01-second integration time step. More details about the SPD-MRF and the SPD specimen can be found at [9].…”

“…However, since their sizes more resemble that of the SPDs installed on the 3 rd floor, an online model updating (OMU) technique was developed and applied in this series of HS tests to dynamically modify their material parameters based on the experimentally obtained behavior of the SPD specimen. More details about the implementation of the OMU technique have been documented [9]. Figure 10 shows the testing facilities utilized for this series of HS tests.…”