Eccentric Reinforced Concrete Beam-Column Connections Subjected to Cyclic Loading in Principal Directions

Shear failure in beam-column connections, leading to the
collapse of reinforced concrete (RC) buildings, has been
observed in the post-earthquake reconnaissance.
1-3
The
cause of collapse has been attributed to the lack of joint
confinement, especially for the exterior and corner beam-
column connections without beams framing into all four sides.
Since the late 1960s, amounts of experimental investigations
on the seismic performance of RC beam-column connections
have been extensively studied. The majority of the exper-
imental programs have concentric beam-column connections
isolated from a lateral-force-resisting frame at the nearest
inflection points in the beams and columns framing into the
joint. Since 1976, Joint ACI-ASCE Committee 352 has
issued design recommendations for RC beam-column
joints.
4,5 Throughout the years, these guidelines evolved into
state-of-the-art reports
6,7
by integrating results of new
experimental programs. Finally, a number of these design
recommendations for beam-column connections have been
adopted in Chapter 21 of the ACI 318 Building Code8
for
seismic design. Current ACI design provisions are primarily
developed from test results of concentric beam-column
connections, whereas eccentric beam-column connections
are rather common in practice. Relatively few tests of eccentric
RC beam-column connections have been reported in the
literature to date.
9-19
To clarify the effect of eccentric beams
on the behavior of connections, Joint ACI-ASCE Committee
352 has called for additional research on this topic over the
past two decades,
5-7 and appointed a task group to review
and summarize previous research on eccentric RC beam-
column connections.
20
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