SEISMIC ANALYSIS OF REINFORCED CONCRETE STRUCTURES IN PAKISTAN

Abstract

The objective of this research work is to compare seismic vulnerability of unrettrofitted frame structures and the retrofitted frame structures and to use those seismic vulnerabilities for the determination of risk in terms of monetary loss and casualties for the Mansehra which is used as a study region. For that purpose a hypothetical four story reinforced concrete frame structure is assumed to be the representative of the frames that are there in the study region, which is designed under gravity load since buildings which were constructed before the 2005 earthquake were not properly detailed, and according to new provisions the hazard levels were also changed. The proposed building is modeled in perform 3D to study the effect of lateral forces. Vulnerability Curve is generated by using Capacity Spectrum Method. The joints of the RC frame are retrofitted using CFRP. By using the confined properties of concrete as given by the experimental research work available, an analytical curve is developed again using analytical methods. These curves are compared and conclusions are made. Moreover earthquake risk assessment framework of the reinforced concrete frames is formulated to utilize the vulnerability curves formed for socio and economic analysis for the study region Mansehra. Hazard of the region for a single event of Kashmir earthquake 2005 is determined in ArcGIS environment. The worth of a structure is reasonably estimated and the vulnerability of a structure already generated is used. Using seismic Hazard, Value and seismic Vulnerability of confined and unconfined frame, seismic risk in terms of monetary loss and casualties is calculated for both unconfined and confined structures and compared. Risk per building of the study region is calculated for confined and unconfined structures. It is concluded that by applying CFRP’s (retrofitting technique), the performance of the structure may increase up to 50% i.e. 100% damage would be at approximately 0.65g instead of 0.43g. The seismic risk (monetary) can reduce up to 65%, the collapse of buildings after confinement may reduce up to 51% and the casualties may be reduce up to 48%.