Efficacy of Different Retrofitting Techniques used in Pakistan

Abstract

Building codes and construction practices plays a vital role in structure performance. Pakistan suffered a heavy loss of both life and property in the earthquake of 8 oct 2005. The main reasons were poor construction practices and building codes. Structures suffered from moderate to total destruction in different region. Though we had improved both our building codes and practices after studying the structures in damaged region, but we cannot turn a blind eye towards the existing structure. Buildings even built with good building codes and practices should be checked against the possible effect of any natural disaster or functional change on their structural performance. The purpose of our study was to investigate different retrofitting techniques used in Pakistan by studying various structures. The buildings were retrofitted against various structural problems. Detailed analysis on Etabs were done for two buildings that include Exam hall fauji foundation university rawalpindi campus and Commercial building in Bahria enclave Islamabad. The analysis of the different techniques shows that they were effective in increasing the structural efficiency of the system. Like in case of bahria enclave hospital Islamabad, almost all columns and shear walls were failing under seismic load condition. After the combination of column and shear wall jacketing, all column and shear wall passed the design criteria. For commercial building in bahria enclave Islamabad, the addition of pent house left some of previous casted members under designed. Retrofitting using CFRP were implemented and issue of under design was solved. For exam hall of Fauji foundation university Rawalpindi campus, no need of retrofitting was observed after addition of extra story to the originally proposed G+1 building. Yet the designer of building had provided the reinforced concrete jacketing on C-3 columns of ground floor to account for lapping of dowels of ground floor with the first floor. For Malam jabba five-star hotel, Swat improper soil investigation lead to the development of cracks in key elements. The reinforced concrete jacketing significantly increased the structural response of building. In case of kalar kahar hospital and oncology department Fauji foundation hospital the walls were badly cracked because of earthquake’s effects during their service life. Addition of steel girders proved helpful in taking all the loads which were previously coming on walls.