Modeling of Reinforced Concrete Two-Way Floor Slab Deflections due to Construction Loading

AbstractAn analytical algorithm was developed to compute the midpanel deflection history for reinforced concrete two-way floor slabs in multistory buildings. Midpanel deflection was determined using the crossing beam analogy, in which column strip and middle strip deflections are superimposed. The analysis procedure incorporated the effects of early-age construction loading and time-dependent (creep) deformations, the effects of which were shown to significantly increase slab deflections. The algorithm was implemented into a computer program, which may operate based on a prescribed loading history or can determine the loading history of the slab based on the details of construction schemes. A parametric study was conducted, and midpanel slab deflections computed by the model were found to be more sensitive to changes in slab thickness and aspect ratio (i.e., ratio of longer plan dimension to shorter plan dimension) than to changes in the construction scheme. Comparison of model results with published experimental results for seven slabs justifies the program as a valid means of computing two-way slab deflection histories.