Results of laboratory tests on four reinforced concrete flat slab-inte
rior column connections, carrying quasi-static, cyclic, horizontal loa
dings are presented. The specimens, at about two-thirds scale, had rei
nforcing steel arrangements representative of column strips. The major
aspects studied are the resistance and final failure mechanisms, the
relative influence of the cross-sectional width of the column. and the
contribution of vertical gravity loading on the propagation of failur
e. Test results show that combined primary bending, slab failures, and
final one-side punching-shear failures had occurred. The failure cont
ributors, their development areas, and final shape are described. The
results of the present series of tests are compared with solutions of
current calculation methods, which suggest using either the full slab
width between the field centerlines, beam analogies, or the linear she
ar stress distribution on a critical perimeter around the column.