Steel frame with aseismic floor: From the viscoelastic decoupler model to the elastic structural response

Abstract

AbstractBy installing laminated viscoelastic materials (LVEM) between floor slabs and steel beams, the lateral motions of the floor and the frame are decoupled and the structural seismic response is mitigated. This paper presents a study of the elastic seismic performance of the steel frame with this floor system (hereafter termed the aseismic floor). First, the dynamic model of an LVEM under the combined precompression (vertical) and shear (lateral) is checked by experiment. The dynamic shearing behavior of the precompressed LVEM could be well simulated by the pure‐shear model (without precompression) using the modified shear area‐to‐thickness ratio. The storage modulus and the loss factor of the precompressed LVEM could be deemed the same as those without precompression. Second, the time‐varying dynamic properties of LVEM during the seismic response history are processed. In the processing, the transient frequency of LVEM is assumed to be equal to the fundamental frequency of the accordant conventional frame, and the dynamic property of the structure equipped with the aseismic floor is assumed stable throughout the response history. The accuracy of the processing is validated via numerical analyses. Third, based on the processed structural dynamic properties, the effectiveness of a complex Complete‐Quadratic‐Combination (CQC) method for predicting the peak structural seismic response is checked. The CQC method is recalibrated to account for the deviation between the pseudo‐ and relative velocities of the modal oscillators. The recalibrated CQC method could well predict the interstory drift of the frame and the shear deformation of the LVEM.