Influence of precast prestressed flooring on the seismic performance of reinforced concrete perimeter frame buildings

Abstract

Lateral load tests of reinforced concrete perimeter frames with diaphragms have shown that the addition of a floor slab (diaphragm) can have a major influence on structural performance. Three moment resisting frames were tested. Two of these frames were tested without a floor slab being attached to the beams, while the remaining frame was tested with the addition of a typical floor slab containing prestressed units. The tests showed that the addition of the floor slab increased the strength of the beams appreciably and as a result the lateral strength of the frame was increased by close to 80%. Clearly a strength increase of this order of magnitude is of major concern in seismic design in cases where it is essential to avoid the premature formation of a column sway mechanism.

The test results presented together with an analytical study show the origins of this strength increase. Understanding these mechanisms is a first step in establishing a design method for assessing over‐strength values in perimeter frames, which contain floors with prestressed units.