Fatigue Experiments on Composite Slab Floors

Composite slabs consisting of cold-formed light-gage steel sheets and normal or lightweight concrete have been used extensively under static loading conditions but are generally not used under heavy moving loads. Preliminary tests indicated a favorable response when these composite slabs were subjected to repreated loadings. Additional fatigue information is presented for composite slabs using steel sheets with different embossments, and 12-in., 18-in., and 24-in (305-mm, 460-mm and 610-mm) shear spans. A total of 19 slabs (seven static and 12 repeated loading) were tested. Despite the fact that first slip had occurred when the repeated loading was applied, only four of 12 specimens subjected to repeated loading failed in less than 2,000,000 cycles. Three of four failures were due to a fatigue failure of the steel sheet. The response of composite slabs when subjected to repeated loading was good. Special attention has to be paid to cases in which the tensile stresses in the steel sheets are relatively high as this may lead to a fatigue failure of the steel sheet.