Real-Time Multi-Directional Hybrid Simulation of Building Piping Systems

Observations during past earthquakes have demonstrated the seismic vulnerability of nonstructural components. Damage to these components can significantly reduce the functionality of essential facilities. Real-time hybrid simulation combines experimental testing and numerical simulation, and therefore provides an excellent technique for the dynamic testing of complete systems rather than testing components or subsystems. In this paper, a real-time multi-directional hybrid simulation of a system of nonstructural components is presented. In the simulation, a building piping system in a three-story moment resistant frame is subjected to bi-directional earthquake ground motions. The pressurized piping on the third story is selected as the experimental substructure, while the rest of the structure is modeled analytically. The Lehigh University Real-Time Multi-Directional Seismic Simulation Facility is used for the study. To ensure accuracy and stability during the simulation, the newly developed unconditionally stable explicit CR integration algorithm and inverse compensation method for actuator delay are used. The two horizontal components of the 1994 Northridge earthquake ground motion recorded at Canoga Park are scaled to the MCE seismic hazard level. Real-time hybrid simulation is performed to evaluate the seismic performance of the components of the piping system, including the bracing, joints, and piping members. The simulation results indicate that adequate piping joints and carefully designed bracing can enable the nonstructural piping system to perform well under strong earthquakes. The experimental study presented in this paper demonstrates the application of real-time hybrid simulation to the seismic testing of nonstructural components.