American Society of Civil Engineers


Analytical Evaluation of Seismic Performance of RC Frames Rehabilitated Using FRP for Increased Ductility of Members


by Khaled Galal, (Assoc. Prof., Dept. of Bldg., Civ. and Envir. Engrg., Concordia Univ., Montréal, PQ, Canada H3 G 1M8. E-mail: galal@bcee.concordia.ca) and Hossam El-Sokkary, (Grad. Student, Dept. of Bldg., Civ. and Envir. Engrg., Concordia Univ., Montréal, PQ, Canada H3G 1M8)

Journal of Performance of Constructed Facilities, Vol. 22, No. 5, September/October 2008, pp. 276-288, (doi:  http://dx.doi.org/10.1061/(ASCE)0887-3828(2008)22:5(276))

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Document type: Journal Paper
Abstract: Many reinforced concrete (RC) frame structures designed according to pre1970 strength-based codes are susceptible to abrupt strength deterioration once the shear capacity of the columns is reached. Fiber composites are used to increase the shear strength of existing RC columns and beams by wrapping or partially wrapping the members. Increasing the shear strength can alter the failure mode to be more ductile with higher energy dissipation and interstorey drift ratio capacities. The objective of this study was to analytically evaluate the effect of varying distributions of fiber-reinforced polymer (FRP) rehabilitation on the seismic performance of three existing RC frames with different heights when subjected to three types of scaled ground motion records. The FRP wrapping is designed to increase the displacement ductility of frame members to reach certain values representing moderate ductility and high ductility levels. These values were assumed based on previous experimental work conducted on members wrapped using FRP. The study also investigates the effect of the selected element’s force — displacement backbone curve on the capacities of the structures with respect to maximum interstory drift ratio, maximum peak ground acceleration, or peak ground velocity resisted by the frames, maximum storey shear-to-weight ratio and maximum energy dissipation. It was found that for low-rise buildings, the FRP rehabilitation of columns only was effective in enhancing the seismic performance; while for high-rise ones, rehabilitation of columns only was not as effective as rehabilitation of both columns and beams. Ignoring representing the postpeak strength degradation in the hysteretic nonlinear model of FRP-rehabilitated RC members was found to lead to erroneous overestimation of the seismic performance of the structure.


ASCE Subject Headings:
Degradation
Ductility
Dynamic analysis
Fiber reinforced polymer
Frames
Rehabilitation
Reinforced concrete
Seismic effects