EXPERIMENTAL STUDY OF PRACTICES IN DETAILING OF REINFORCED CONCRETE COLUMNS

Abstract

In multistoreyed building the columns are must vulnerable to damages during earthquake. From past experience it is very much evident that there are large-scale damages to lives and properties because of failure of columns. The main reason of failure of columns is lack of designing and detailing practices for seismic forces. The designing and detailing practices play a very important role in improving seismic performance of columns. The objective of this dissertation are to study the performances of existing detailing practices of R.C. columns. In this dissertation the seismic behaviour of three R.0 column-models (one-third-scale) size has been studied under cyclic loading in Quasi-Static testing facility. The reinforcement detailing of these three models are as follows (i) Model (Ml)- Detailed as per IS 13920:1993 with special confining reinforcement. (ii) Model (M2)- Detailed as per IS 456:1978 without any special confining reinforcement. (iii) Model (M3)- Detailed with welded lap splices at the base of the column. The models have been constructed and fixed on the strong floor. The one end of the hydraulic actuator is attached to the reaction wall and the other end is fixed to the top of the model by means of plates and bolts. The models are subjected to alternate cyclic loading in the form of sine waves. The models have been tested upto ultimate failure and their strength, deformability, energy dissipation capacity, hysteretic response, damping, crack patterns has been studied. In this dissertation an attempt is also made to study the performance of retrofitting technique. After substantial damage to model (Ml), it is retrofitted with R.0 jacketing. The retrofitted model (MR) has been tested upto ultimate failure. vii The results obtained from these tests have been discussed in detail in this dissertation. Out of these three models tested, the model designed and detailed by IS: 13920-1993 has greater ductility and greater shear strength. The model detailed as per IS: 456-1978 has less shear strength as compared to flexural strength hence shear is occurred in this case. The ultimate strength of the model with welded lap splices has very less compared to other models. The quasi-static test of retrofitted column by R.0 jacketting has shown that ultimate strength of the column has been restored and in fact greater strength is achieved. viii