An experimental study on R.C beam-column joints under cyclic loading

Abstract

Studies on the performance of structures under cyclic loads have attained great significance in the recent past, in the context of increased structural damages during disasters like earthquakes. A closer observation of such damages with particular reference to R.C framed buildings reveals that beam-column junctions are very crucial in determining the performance of the total building structure subjected to cyclic loading. An experimental study is taken up in the present work to stimulate cyclic load on structural models of R.C beam-column junctions and investigate the influence of certain key parameters on their performance. Three commonly found field practices viz., Normal detailing at the junction, ductile detailing at the junctions and defective workmanship at the junction, are chosen for the study. IS 13,920 guidelines are adopted for ductile detailing while use of M−20 mix in place of supposed M30 grade to be used, is adopted as indicator of defective workmanship. Responses of the specimens were noted in terms of load-deflection behavior, first cracking, complete crushing, number of cycles taken for failure etc. From the results obtained, the performance of the specimens were noted in terms of load-deflection hysteresis loops, cracking pattern and behavior, stiffness degradation, ductility factor and energy absorption. It is observed that the specimens with good workmanship and ductile detailing are performing better under cyclic loads.