Crack assessment of RC beam–column joints subjected to cyclic lateral loading using acoustic emission (AE): the influence of shear links aspect

Abstract

Existing reinforced concrete (RC) beam–column joints, which are designed mainly to resist gravity load, may encounter serious problems in low to moderate seismic regions. The moderate earthquake in Ranau, Malaysia, affected numerous old buildings, mainly manifesting as uncontrolled crack propagation in RC members at the beam–column joint. Effects of shear reinforcement between shear link spacing on crack formation on four RC beam–column joints were investigated under cyclic lateral loading with acoustic emission (AE) monitoring. The control specimen (BCJ-1), which was designed in BS-8110, showed more irregular cracks thus concrete cover spall was observed at an earlier drift ratio (DR) level than for other specimens with additional shear reinforcement between shear link spacing. Sudden drop of AE hits beyond 2.25% DR level with a significant increase in crack width showed that BCJ-1 was no longer able to resist higher loads due to de-bonding between reinforcement and concrete. From the rise time/amplitude against average frequency (RA-AF) graphs, the mode of failure was determined according to DR stages concerning crack characteristics.