SURVEY RESULTS FOR CONCRETE CONSTRUCTION LIVE LOADS ON NEWLY POURED SLABS

Live loads on newly poured slabs during construction of multistory con crete buildings are investigated. These loads include the weight of wo rkers, equipment, and materials stored on slabs varying in age from le ss than one day to about three days. In each project that was surveyed data about various objects stored on the floor under construction wer e collected. These data included the weight, size, contact area with t he floor, and location relative to a coordinate system. Examples of ma terials and equipment stored on newly poured slabs are bundles of rein forcement, packs of lumber and plywood, stacks of formwork frame, gang tool boxes, Storage boxes, dumpsters, air compressors, generations, a nd finishers. The weights of various objects were determined either by the inventory method or by direct weighing. The required load data we re collected by a survey of over 22 concrete building projects in 12 d ifferent cities. Since the standard deviation of live load is area-dep endent, the collected load data were used to calculate statistical mom ents for six different averaging areas ranging from 0.093 m2 to 58 m2. Several different probability models are investigated for the observe d data. The observed formwork live loads are modeled with a mixed dist ribution 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.