Abstract:
Beam-column joints are identified as potential critical components of reinforced concrete
moment resisting frames subjected to seismic lateral loading. Severe damage within a
joint panel may trigger deterioration of the performance of reinforced concrete beamcolumn
connections.
A comprehensive study has been carried out to investigate the seismic behavior of beamcolumn
joints with and without adequate ties at joint region. Seven half-scale specimens
of reinforced concrete beam-column joints were constructed considering three types of
categories. These test categories were a) joint region with and without seismic ties, b)
application of conventional and seismic stirrups in the joint region and c) different
column to beam cross-section ratios which were considered to observe their effects on the
performance of beam to column joint.
The specimens were subjected to cyclic incremental moment with sustained gravity load.
Different crack patterns were observed for different categories of specimens. Specimens
without ties at joint region showed diagonal cracking at joint; on the other hand, control
specimens with ties experienced vertical cracking at the faces of the joint where the
beams framed into the joint. The experimental data obtained in four deflection controlled
cycles were used to study overall performance of the beam to column joint. Loaddisplacement
as well as moment-rotation characteristics of the joints were obtained. At
the same time, maximum loads, load at first crack formation, maximum as well as
residual deflections and stiffness were measured or observed. Finally, the test results of
beam-column joints with and without seismic ties at joint region were compared.
The specimen with non-seismic stirrup detailing and without ties at joint region
performed poorly. The reinforced concrete beam-column joints with seismic ties at joint
region showed improved performance with respect to absorbed energy, relative resisting
moment and secant stiffness.
