SEISMIC STRENGTHENING OF REINFORCED CEMENT CONCRETE (RCC) STRCTURES

Abstract

The Reinforced Concrete building stock of Pakistan is highly vulnerable to seismic hazard due to poor construction practices and lack of proper design. The aim of this research work is to analyze and assess the seismic vulnerability of reinforced concrete bare frames and compare with fiber reinforced polymer (FRP) wrapped frames. The experimental work done by Lam and Teng (2003) was used to model the stress strain behavior of FRP confined concrete. A program was developed to generate the model of reinforced concrete frames and their behavior under seismic excitation was analyzed using Drain 3DX software. It was tried to incorporate all the known structural responses such as slippage and bar pullout phenomenon which occur during a seismic event to precisely simulate the behavior of buildings. The frames were first analyzed as bare frames and then again by applying FRP to the joints. The purpose was to compare the extent to which the FRP improves the behavior of the frames under seismic loading. The procedure adopted was Non Linear Static Procedure (modified capacity spectrum approach) for the simulation of the structures response. It is specified by FEMA 440 and ATC-4. Work done by (Kyriakides, 2007), (Fajfar, 1996) is used to develop vulnerability curves for low, medium and high rise RC structures of Pakistan both with and without FRP wrapping. Comparison of the bare and wrapped vulnerability curves of different structures allows to draw conclusion over how effective the FRP wrapping technique is to reduce the extent of damage to the buildings. Comparison by varying storeys, bays and number of wraps has also been done. A method of economic comparison of damage to building has also been developed. The work allows for the comparison of any sort of retrofitting technique by just varying the stress strain models.