Survey Results for Concrete Construction Live Loads on Newly Poured Slabs

Live loads on newly poured slabs during construction of multistory concrete buildings are investigated. These loads include the weight of workers, equipment, and materials stored on slabs varying in age from less than one day to about three days. In each project that was surveyed data about various objects stored on the floor under construction were collected. These data included the weight, size, contact area with the floor, and location relative to a coordinate system. Examples of materials and equipment stored on newly poured slabs are bundles of reinforcement, packs of lumber and plywood, stacks of formwork frame, gang tool boxes, storage boxes, dumpsters, air compressors, generators, and finishers. The weights of various objects were determined either by the inventory method or by direct weighing. The required load data were collected by a survey of over 22 concrete building projects in 12 different cities. Since the standard deviation of live load is area‐dependent, the collected load data were used to calculate statistical moments for six different averaging areas ranging from 0.093 m² to 58 m². Several different probability models are investigated for the observed data. The observed formwork live loads are modeled with a mixed distribution with a discrete part at zero load intensity and a continuous part for nonzero loads. Both gamma and Weibull distributions provided good fit to the nonzero data.