Using Fragility Curves for the Evaluation of Seismic Improvement of Steel Moment Frames

Year 2016, Volume: 16 Issue: 2, 323 - 337, 30.04.2016

Hadi Faghihmaleki Hamid Roosta Ali Hooshmand Aini Elmira Khaksar Najafi

Abstract

There are numerous methods for buildings’ seismic improvement, one of which is to increase the

lateral force demand. To do so, adding different types of frames or a shear wall in structures is quite

common as a new structural element. The present study selects three steel moment frame structures

with four, seven, and twelve stories, all of which have similar floor plans and are designed based on the

old seismic design code (UBC 1997 code), which is vulnerable in accordance with FEMA 356 code. For

seismic improvement Concentrically Braced Frame (CBF), Buckling Restrained Brace (BRB), and shear

wall have been used. The seismic performance level of the primary structure and improved structures

were compared by means of seismic fragility curve. Earthquake intensity index is “PGA”. Finally, by

selecting an appropriate damage index, fragility curves of the original structure as well as the improved

structures were presented and compared with a normal log distribution, the results of which was

analyzed.

Keywords

seismic improvement, steel moment frame, CBF frame, shear wall, BRB frame, time history dynamic analysis

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