Strength and behavior of reinforced concrete slab-column connections subjected to static and dynamic loadings
Criswell, Marvin E.
Technical reportAbstract: The objectives of this investigation were to study the strength and behavior of slowly (statically) loaded reinforced concrete slab-column connections and to determine the effect of rapid (dynamic) loading on the strength and behavior by comparison with the static test results. Nineteen full-scale models of a connection and adjoining slab area, consisting of a simply supported slab 84 or inches square and 6-1/2 inches thick loaded concentrically on a 10- or 20-inch-square stub column at the center of the slab, were tested. The main variables were the amounts of reinforcement in the slab (p = 0.75 and 1.50 percent), the column size, and the loading speed. Eight specimens were loaded to failure statically, two were subjected to a very rapidly applied load of short duration, and nine were loaded to failure by a rapidly applied load with a rise time chosen to represent the conditions in a blast-loaded structure. The behavior of the static and dynamic specimens was very similar. Failure deflections increased 25 to 50 percent at the rapid loading rate. The strength of specimens failing in shear after flexural yielding was reached (p = 0.0075) increased 18 percent with rapid loading; that of the more heavily reinforced specimens (p = 0.0150), 26 percent. These increases could be adequately explained by the effects of strain rate on material strength. The static test results are compared with 12 shear strength prediction methods. All methods became less conservative with the larger column size. The strengths of the specimens with p = 0.0075 were best predicted by a yield-line formula for flexural strength. Failure of connections with square columns was shown to start at the column corners and progress toward the column centerlines. Differences between the mechanism of shear failure in slabs and beams are examined. The shear-compression failure mechanism is shown to be not strictly applicable for slabs failing in shear.
Weapons Effects Laboratory (U.S.)Engineer Research and Development Center (U.S.)
Columns; Concrete slabs; Connections; Dynamic loads; Reinforced concrete; Slab-column connections; Static loads
Technical report (U.S. Army Engineer Waterways Experiment Station) ; N-70-1.
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