Evaluation of Various Retrofitting Techniques for RC Framed Building

Abstract

In recent times due to the frequent earthquakes in the Indian subcontinent region, structures need to be designed seismic resistant as per the latest IS codal provisions. The IS codal guidelines for seismic resistant design of buildings have undergone significant change in the Sixth revision of IS1893 (Part1) “Criteria for Earthquake Resistant Design of Structures, Part 1: General Provisions and Buildings” in 2016. Thus, the old buildings which were constructed prior to year 2016 designed as per the fifth revision are more prone to seismic failures. In the present study an existing building has been analysed and checked as per the revised codal guidelines and has been retrofitted by various techniques. The building taken in this study is an existing residential S+6 building built in the district of Rohtak in Haryana. The existing building was constructed in the year 2013, hence the provisions followed in design were in accordance with IS1893:2002. In this study, this existing structure has been modelled in STAAD-Pro and a dynamic analysis is carried out following the latest revision of the code in 2016. It was observed after analysis that the model did not comply with some of the clauses of the latest code. There were also some structural members failures observed which required retrofitting of members for safe functioning of the building. Different retrofitting techniques such as Jacketing of distressed members, addition of Shear Walls and addition of Steel Bracings were studied. Jacketing was done by increasing the size of columns and beams experiencing failure. Shear walls were added in both x and z-directions in the building and analysed for various parameters. Similarly, a model with steel bracings in both the dimensions of building i.e. x and z direction of the building between columns with convenient and preferable location was analysed. All these models were analysed and studied for different parameters like Base Shear, Time Period, Lateral Displacement, Storey Drift, Bending Moment, Shear Force etc. It was seen that by applying these retrofitting techniques, the dynamic behaviour of the structure improved resulting in safe design as compared to existing building. A complete analysis as to which retrofitting procedure is preferable and at which location, also is performed in this research.