Experimental and numerical investigation of an exterior reinforced concrete beam-column joint subjected to shock loading

Beam-column joints are critical elements in a special moment resisting frames as they govern the structural behavior and failure mechanisms under extreme events such as earthquake, blast, and impact. This work was undertaken to investigate the dynamic response of a reinforced concrete (RC) external beam-column sub-assembly subjected to shockwave. To this effect, a well-instrumented shock tube setup was developed to investigate the dynamic response of the joint. The shock-induced transient displacement and acceleration were measured at discrete locations along the length of the beam, and the entire shock event was recorded using a high-speed video camera. The maximum displacements acquired through the experimental study are compared with the numerical and the analytical results. These joint assemblies were incorporated with various deficiencies such as a beam weak in shear, beam weak in flexure and column weak in shear, to account for limitations in design guidelines. The influence of confining reinforcements on the shock-resistant behavior of a beam-column joint is studied. Findings from the current research indicate that steel confinement conforming with seismic design criteria strengthens the joint assemblies when subjected to shockwave loading conditions. It is also found that additional transverse reinforcement arrests the development of shear cracks in the disturbed (D - region) of the joint. The results obtained from the finite element and analytical models agree well with the experimental results.