Monte Carlo Study of Short Time Deflections of Reinforced Concrete Beams

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Title: Monte Carlo Study of Short Time Deflections of Reinforced Concrete Beams

Author(s): Robert J. Ramsay, Sher Ali Mirza, and James G. MacGregor

Publication: Journal Proceedings

Volume: 76

Issue: 8

Appears on pages(s): 897-918

Keywords: beams (supports); cracking (fracturing ); deflection;one-way slabs;reinforced concrete;statistical analysis; stiffness; structural analysis; T-beams.

Date: 8/1/1979

Abstract:
The deflection of a reinforced concrete beam is affected by the variations in the strength of concrete and reinforcement, the cross section dimensions and steel placement, and the applied loads. The effects of these variables on the variability of short time midspan deflections of reinforced concrete fixed-ended T-beams and fixed-ended, one-way slabs were studied using the Monte Carlo technique. The results of this study indicate that the major causes of variability in deflections are variations in the beam stiffness due to cracking of the concrete and the concrete tensile strength. It was also observed that "Building Code Requirements for Reinforced Concrete (ACI 318-77)" predicts the theoretical deflections more accurately than does the 1963 ACI Building Code. Even so, in 1 percent of the cases studied, the 1977 ACI Building Code deflections were less than 50 percent of the theoretical deflections for service loads and in another 1 percent of the cases studied they exceeded 250 percent of the theoretical deflections.