Development of seismic retrofit technique of RC Frame using fully fastened haunch elements: Static to dynamic testing
In this paper an innovative method for seismic retrofitting of poorly detailed reinforced concrete beam-column joints and structures using haunch type elements connected with post-installed anchors is discussed. During an earthquake, the global behaviour of the structure significantly depends on behaviour of the beam-column connections, but no special emphasis was given to that till the eighty’s. Therefore, it is recognized that the joints of old and non-seismically detailed structures are more vulnerable and behave poorly under the earthquakes compared to the joints of new and seismically detailed structures. Thus, often the joints of such old structures require retrofitting in order to deliver better response during earthquakes. A relatively new technique for retrofitting the beam-column connections using steel diagonal elements to prevent a brittle failure of the joint core was investigated by mean of experiments on beam-column joints under quasi-cyclic loads and numerical simulations. Highly encouraging results were obtained that proved the efficacy of the system in improving the seismic behaviour of poorly detailed joints. In order to prove their usefulness at the structural level under dynamic loads, shake table tests on 2-D frames are planned. This paper presents the main results of the quasi-static cyclic tests carried out for seismic retrofitting of RC beam-column joints using haunch elements and the further research planned at the structural level. The strengths, limitations and the open issues of the proposed method are discussed in brief.