Research for the development of innovative hybrid connections for precast concrete construction has been carried out by Organic Building Materials Group at CSIR-Central Building Research Institute, Roorkee, with the aim:
• To develop an effective and economical hybrid connection technique using fibre-reinforced composites and mechanical splices at the joints in pre-cast framed structures.
• To investigate the effectiveness of the hybrid connection in transmitting the forces at beam-beam, column to column and beam-column joints subjected to static as well as cyclic loading.
The developed rebar coupler for different rebar diametres was used for making RC beam specimens and tested under static loading. Similar sizes of beam specimens with threaded couplers were also used for examining their effectiveness and compared with the performance of the hybrid rebar coupler-enabled beams. Fig. 1 shows the comparative load-deflection graph.
The developed couplers have been used to connect different precast elements and tested under tension and cyclic loading. Fig. 2 shows the static tension and cyclic tension test.
The precast beam to column joint section has been prepared with different configurations and with the proposed connection techniques, in which the precast column specimen was cast separately and the beam was cast separately and kept curing for 28 days. After proper curing, the specimens were connected together using the proposed connection technique as shown in Fig. 3. The specimens were then tested under cyclic loading. Fig. 4 shows the beam-column joint test setup.
In order to compare the performance of the developed precast connection, a connection, being currently used in construction practice, has been tested and the performance has been compared. Fig. 5 shows the comparative hysteresis behaviour. It shows that the CSIR-CBRI developed connection works well in lateral load resistance and offers better in elastic behaviour than the joints in practice.
S.R. Karade & R.S. Chidambaram
Organic Building Materials
CSIR-Central Building Research Institute, Roorkee
