Analytical Study of Eccentric Beam Column Joint

The beam-column joints are critical regions in reinforced concrete frames subjected to severe seismic attack. Beam moment reversal can produce high shear force and bond breakdown in the joint resulting in cracking of the joint. Bond strength is influenced by several factors such as bar diameter, clear cover of concrete over the bar, grade of the concrete, transverse reinforcement. Usually most of the beam column joints in reinforced concrete building are concentric but, for architectural reasons the beam column connections in reinforced concrete building is eccentric. In eccentric beam-column connections the axis of the spandrel beams is offset from the axis of the column. Bending in the spandrel beams produces internal compression and tension forces that act on the joint at an eccentric with the column centroid, thus producing torsion in the joint. The torsion in the joint will produce additional shear stresses, and it is unclear to what extent this will affect the shear capacity of the joint. To achieve the ductile detailing at beam column in reinforced concrete structures are given in IS 13920-1993 and also in ACI-318-14. The transverse reinforcement in the joint helps to confine the concrete and also increase the strength of the beam- column joint. When the shear forces at the joints become large, diagonally cracking occurs in the joint and then the crushing of concrete will take place in the beam- column joints. In the present study reinforced concrete building of G+10 stories having 4 bays in both the axis is analyzed using ETABS. The finite element model of external beam-column joint is developed and analyzed using ANSYS 11.0. Comparison is made between Indian code (IS 13920-1993) and American code (ACI 318-14) for reinforcement provision for exterior beam column joint. Analysis is done in terms of deflection, maximum stress, minimum stress and von misses stress. According to Indian code (IS 13920-1993) the development length recommended is more than required. The code revised for several times hence, the provision for the development length remains unchanged. The minimum column width recommended according to IS code is 300 mm which is true as per the study. The confinement length according to Indian code is more than the required.