Retrofitting of Earthquake Damaged Reinforced Concrete Frame Structures

The purpose of this paper is primarily aimed at the owner, consultant and contractor who wishes to retrofit a reinforced concrete frame structure of up to 15 m height including low rise RC frame buildings . It will also serve as a useful reference document for local engineers and other interested parties when retrofitting reinforced concrete buildings. Most of the illustrations in this paper have been obtained from sources listed in the References section i, ii, iii, iv, v, vi, vii, viii & ix . Assessment of building damage by a qualified structural engineer before carrying out repairs or strengthening is of utmost importance. A structural survey is essential to determine the strength of concrete, steel and infill bricks which have been used in the damaged structure. Starting with a detailed foundation investigation and assessment particular attention to vulnerable elements of the structure is the first essential step. When dealing with a low rise reinforced concrete frame, both non-structural and structural repairs might be required, but the priority repairs should be to the structuralcomponents before embarking on any non-structural repairs such as cracked slabs, falling plaster from walls and ceilings, rebuilding of parapets, etc. Repair works carried out on a damaged structure such as the rebuilding of reinforced concrete columns and connections between beam – columns, column-base, column - head are intended to restore the structural strength lost in an earthquake to the original level. Whereas, jacketing of columns and beams is intended to increase the structural capacity of that element. A damage survey was carried out by the Building and Housing Research Centrex on a group of 94 buildings along the main streets in the centre of Bam after the earthquake of 26 December 2003. It was concluded that only 1% of the building stock was simple masonry with reinforced concrete frames. The reinforced concrete structural frame of Bam’s water tower, railway station, Aflatouni hospital and this 1% of the total housing stock will be focused on this paper.