Study on Modeling for Damage Evaluation of Reinforced Concrete Beam-Column Joints Subjected to Multi-axial Combined Loading

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The objective of this project is to establish on unified mechanical model and damage evaluation method for reinforced concrete beam-column joints including interior, exterior and knee joints under seismic loading and verification of the model with test specimens. The results of this project is briefly described as follows,1.Results of analytical study on ultimate strength and failure mode of interior beam-column joint with proposed model called quadruple flexural resistance shows good correlation with previous test results and the effects of many parameters were declared.2.Third scale three reinforced concrete interior beam-column subassembladges with or without eccentricity were tested. The test results indicated that the eccentricity in the joints led to lower capacity in story shear and severe damage of concrete on the side to which the center line of beams shifted. In the case of eccentric joint, large deflection to out-of-plane direction occurred and it seemed to have accelerated the concrete damage on the side of the joint to which the beams shifted.3.Six specimens of one third scale reinforced concrete beam-column subassembladges with identical section and bar arrangement were loaded. In order to simulate the conditions of interior, exterior and knee joint, three types of boundary conditions and loading setup were provided. The test results indicated that the rotation of four parts of the joint divided with diagonal cracks was dominative in story drift deformation in case of joint failure after yielding of beams as the proposed model assumes. On the contrary, deflection of beams and rotation at beam ends were dominative in case of flexural failure of beam.4.A macro element of beam-column joint for non-linear frame analysis was proposed. The model is constructed with non-linear uni-axial springs that are modeling concrete, bars and bond actions.