SUMMARY:Beam-column joints of reinforced concrete building frames play an important role under seismic excitations. These are one of the most congested areas in reinforced concrete framed structures; placement of concrete and proper compaction in such areas are hence substantially challenging. This offers a unique area of application for self-compacting concrete which can flow through every corner of extensively reinforced area without any vibration. Therefore if implementing self-compacting concrete in beam-column joints does not compromise seismic performance of the frame, it can be used instead of conventional concrete. This paper focuses on implementation of high-strength self-compacting concrete in beam-column joints and assessment of its seismic behaviour under reversed cyclic loading. Three interior beam-column subassemblies chosen to vary in concrete type and compressive strength are designed as per the New Zealand Standard NZ3101:2006. The specimens are instrumented to measure the load, displacement/drift, ductility, joint shear deformations, and elongation of the plastic hinge zone. The cracking pattern at different load levels and the mode of failure are also recorded and compared among different specimens.
In this experimental study, three identical reinforced concrete (RC) walls were tested under three different lateral loading patterns. These loading patterns were cyclic in‐plane, skewed with 45° angle and clover leaf. The main objective was to investigate the effects of these bi‐directional loading patterns on the seismic behavior of slender rectangular RC walls. The results showed significant increase in tensile and compressive strains in concrete and longitudinal bars that led to earlier cover concrete spalling and bar buckling in the specimens subjected to bi‐directional loading. The neutral axis depth and compression zone were found to be substantially larger when subjected to bi‐directional loading and this led to the occurrence of concrete crushing and bar buckling in the web. Moreover, lateral instability failure triggered earlier in the specimens under bi‐directional loading, as a result of reduction of out‐of‐plane stiffness of the wall. However, bi‐directional loading did not significantly increase out‐of‐plane buckling of the wall in terms of out‐of‐plane displacement. In‐plane and out‐of‐plane shear cracks formed in one of the specimens subjected to bi‐directional loading, whereas the same wall under in‐plane loading developed only flexural cracks. It was also found that in‐plane shear deformation was larger when the wall was subjected to bi‐directional loading. The results of this experimental study emphasize the need for further investigation of the effects of bi‐directional loading on RC structural walls.
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