Seismic Performance and Sensitivity of Floor Isolation Systems in Steel Plate Shear Wall Structures

Open Access
Liu, Shi
Graduate Program:
Civil Engineering
Master of Science
Document Type:
Master Thesis
Date of Defense:
July 06, 2011
Committee Members:
  • Gordon Patrick Warn, Thesis Advisor
  • earthquake
  • steel plate shear wall
  • sensitivity
  • floor isolation system
  • performance
In the US, there is growing interest in utilizing the floor isolation systems to protect targeted valuable content or equipment, e.g., computer servers during earthquake. The concept of paring the steel plate shear wall frame (SPSW) with floor isolation system (FIS) is that SPSW might effectively limit drift, protect drift sensitive components, whereas the floor isolation system reduces acceleration demands on targeted acceleration sensitive components. This study investigates the performance and sensitivity of floor isolation systems in steel plate shear wall frames under design basis (DBE) and maximum considered earthquake (MCE). The floor isolation systems were first designed and modeled for the level 1, 2 and level 3, 5 and 8 for 3-story and 9-story steel plate shear walls in OpenSees, respectively; followed with a performance study using nonlinear response history analysis to investigate the performance of floor isolation systems in steel plate shear walls. Finally a sensitivity study was performed to investigate the effect that variations in the web plate strength and stiffness have on the performance of the FISs in SPSWs. The results show that: (i) the floor isolation system is effective in limiting acceleration demand on equipment in SPSW frame under DBE; and (ii) isolator displacement demands are large and need to be reduced; (iii) the floor isolation system performs better on the lower level in the steel plate shear wall frames. Moreover, from the sensitivity study, the results show that: (iv) the equipment absolute acceleration ratio is insensitive to the variations in the structure and do not need to be considered; (v) the maximum displacement response of the isolators is sensitive to the variations in strength and stiffness and need to be considered when designing the capacity of isolators; (vi) the floor absolute acceleration is sensitive to variations in web plate strength and stiffness which suggests that significant damage to rigidly attached equipment in SPSWs might be expected under DBE and MCE events.