BEHAVIOUR OF HIGH PERFORMANCE FIBER REINFORCED CONCRETE BEAM JOINTS UNDER SEISMIC LOADING
B. Pandu Ranga Rao1*, Prof. K. Rama Mohana Rao2 and Srinivas Tanuku3
1General Manager, National Council for Cement and Building Materials, New Delhi, India
2Professor in Civil Engineering, Jawaharlal Nehru Technological University, Hyderabad, India
3Senior Manager-Tower Assessment, RAMBOLL India Private Limited, Hyderabad, India
1Email: pandu5270@yahoo.com*(Corresponding author)
2Email: rkunapareddy@gmail.com
3Email: srinit@ramboll.com
Abstract:
The strength and ductility of structures primarily depend on proper detailing of reinforcement in beam-column joints. Under seismic excitations, beam-column joint region is subjected to high horizontal and vertical forces whose magnitude is much higher than those within the adjacent beams and columns. Beam-column joints have been recognized as critical element in seismic design of reinforced concrete (RC) frames. Conventional concrete loses its strength after formation of multiple cracks. Fiber reinforced high performance concrete (FRHPC) can be utilized to sustain for cyclic loading. Present study is aimed at investigating structural behaviour of beam-column joints using normal strength concrete (NSC) and FRHPC based beam-column joints utilizing steel fibers in varied aspect ratios, types and fiber contents. Beam-column joint of a multi-storeyed building has been modelled and scale down model experimented considering the scaling effect. Fifteen specimens of beam-column exterior joint were cast and tested using FRHPC in different fiber contents to study load-deformation behaviour, failure pattern, stiffness degradation and ductility associated parameters. The typical results illustrate significant increase in compressive, tensile and flexural strength values in HPFRC based control specimens. Beam-column joints corresponding to different grades of HPFRC with varied fiber content and aspect ratio & shape has been observed to give maximum load carrying capacity, energy absorption capacity and resilience. An optimum fiber contents corresponding to this value may therefore be utilized to provide significant dimensional stability, integrity, strength and ductility to beam- column joints subjected to cycle loading and can be substituted for conventional transverse reinforcement thereby allowing for relaxation in ties and stirrups in beam column joints.
Keywords: Beam-column joint, High performance concrete, Cyclic loading, Stiffness degradation.
https://doi.org/10.47412/KLGW4146
