Seismic Retrofit of Vulnerable Steel Frames Using Articulated Quadrilateral bracing system

Seismic Retrofit of Vulnerable Steel Frames Using Articulated Quadrilateral bracing system

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This paper investigates the applicabilty of an innovative bracing, called Articulated Quadrilateral (AQ) bracing system, which uses shape memory alloys (SMAs), for retroffiting low-rise to high-rise vulnerable SMFRs against strong ground motions.The paper investigates brace fundamental engineering characteristics, design of the system BIOTIN 300MCG and also configuration of the brace (the proportion of SMA wire, C-shape dissipator and Post-tensioning tendons).OpenSees program is utilized for nonlinear dynamic finite element analysis and the validation of modeling using data from full-scale experimental tests performed by Speicher et al.

at Georgia Institute of technology.Using 3-, 9- and 20-story steel moment resisting frames from the SAC phase II project, nonlinear pushover, incremental dynamic analysis, and fragility analysis of frames with and without AQ bracing were conducted using Accessories:Car FEMA P695 far-field ground acceleration records.Results show that by retrofitting MRF system with AQ bracing, strength of the buildings increases up to 40%.

Also, bracing of the frames yields more uniform drift distribution which reduces the likelihood of soft story formation.