Experimental and Numerical Investigations of the Seismic Behavior of High-Strength Concrete Beam-Column Joints with Column Axial Load

This paper presents the experimental findings of high-strength concrete (HSC) interior beam-column joints under column axial compressive loading. Eight full-scale interior beam-column joints with varying degrees of reinforcement detailing were subjected to a constant column axial compressive load and quasi-static horizontal cyclic load. The test revealed that HSC improved the bond condition of bars with a larger diameter due to the higher achievable bond stress, thereby allowing for the use of longitudinal beams of a larger diameter. Parametric studies via finite-element (FE) modeling were performed to study the influence of various parameters on the strength and bond of HSC beam-column joints. The study confirmed that reinforcement of larger diameter can be used in HSC beams with the improvement in the bond condition. The presence of axial compressive load improved the bond stress of HSC beam-column joint but a threshold limit should be applied. Last, two standards were reviewed and improvements to the design equations were proposed. (C) 2014 American Society of Civil Engineers.