Seismic Design Criteria for Slab Column Connections

Two-way slabs without beams are popular floor systems
because of their relatively simple formwork and the potential
for shorter story heights due to their shallow profile. This
structural system is common in regions of low to moderate
seismic risk, where it is allowed as a lateral-force-resisting
system (LFRS), as well as in regions of high seismic risk for
gravity systems where moment frames or shear walls are
provided as the main LFRS. Earthquakes, however, have
demonstrated that slab-column frames are not suitable as a main
LFRS in regions of high seismic risk because they are relatively
flexible and because of the potential for brittle punching shear
failures in the slab-column connection region.
In the last 40 years, a significant number of experiments
have been conducted to evaluate the performance of slab-
column connections under cyclic lateral loading. This infor-
mation has formed the basis of current code provisions and
guidelines for the design of slab-column connections under
combined gravity and lateral loading. As performance-based
seismic design (PBSD) becomes more common in structural
engineering practice, it is important to evaluate the
recommended limits for various structural systems with
respect to the latest experimental data and post-earthquake
observations. This paper focuses on the behavior and
design of interior slab-column connections under combined
gravity and lateral loading and serves to review current design
procedures, PBSD approaches, and relevant experimental data.
Equation (23), for drift capacity of these systems in terms of
the gravity shear ratio, is derived using the collected experi-
mental data. Finally, practical recommendations are provided
for the PBSD of slab-column connections.
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