Shock-Absorbing Soft Story Concept for Multistory Earthquake Structures


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Title: Shock-Absorbing Soft Story Concept for Multistory Earthquake Structures

Author(s): Mark Fintel and Fazlur R. Khan

Publication: Journal Proceedings

Volume: 66

Issue: 5

Appears on pages(s): 381-390

Keywords: columns (supports) ; dynamic loads; earthquake resistant construction; earthquakes; frames; lateral loads; multistory buildings; reinforced concrete; shock resistance; stability; structural analysis; structural design; wind loads.

Date: 5/1/1969

A new concept for earthquake-resistant structures is suggested based on controlling the lateral forces (acceleration) that will occur i n the structure during an earthquake This is achieved by designing a shock-absorbing soft story with a bi-linear force-displacement characteristic, which forces all the inelastic deformations (or undesirable effects) due to high intensity earthquake soft story only. Above the soft story the structure is designed for wind only and will remain within the elastic range during- an earthquake. The system contains stability walls within the soft story which resist part of the overturning moments caused by earthquake distortions. Elastomeric strips are used to accommodate the large distortions. The system minimizes the oscillations during an earthquake, thus reducing damage while providing sufficient strength and rigidity for wind loading. Acceleration response spectra show that the highest lateral force to which the structure can be subjected is the yield level of the soft story. Consequently, the yield level of the soft story is the most significant design variable.