To Evaluate Seismic Performance of Special Moment Resisting Frames by Retrofitting beam Column joints using Haunch An Experimental and Numerical approach

Abstract

This retrofitting method comprises of installing haunches at the beam column joints of a reinforced concrete
frame, in order to modify structure’s response to seismic hazards. The experimental program consists of two small scale
models of one third of the actual structure sizes. The specimens were brought under construction at the civil engineering
department, UET Peshawar. Test frame comprised of a regular reinforced concrete frame and a frame with haunch at
various connections which were installed for the purpose of providing ample amount of joint rigidity to the structure.
Using a natural accelerogram compatible to the design spectrum dynamic test were carried out with increasing levels of
shaking. Dynamic characteristics were calculated for each phase of free vibration before and after every intensity check.
Haunch sizes were computed on trial and error basis considering 60 percent of the excitation provided by the shake
table. Displacement transducers and accelerometers were attached to the models for recording the structural response in
terms of displacement and acceleration time histories. After the analysis the data was processed further to compute
certain parameters including inter storey shears and base shear. Also the drift profile and the lateral deflected shape of
the structure were obtained giving insight of the structure’s behavior. Capacity curve was plotted co-relating the base
shear with the lateral displacement. The research showed experimentally and numerically that the proposed retrofitting
technique worked well in reducing the joint damageability of the RC frame structures enhancing the seismic capacity.
The technique ensures safety for the occupant’s lives during any devastating disaster promising less loss of economy and
human lives in future.