Innovative Hurricane-Resistant UHPC Roof System

Abstract

An innovative composite flat roof was developed to resist hurricane wind forces for industrial, commercial, and low- to midrise residential building applications. Combining two advanced materials, ultra-high-performance concrete (UHPC) and high-strength steel (HSS), the proposed engineered system is superlight, with only 83 kg/m2 (17 lb/ft2) self-weight; low profile, with an overall depth of only 102 mm (4 in.); and ultra-thin-walled, with webs and flanges only 19 mm (3/4 in.) thick; additionally, it requires no transverse and shear reinforcement. Experimental work was conducted on two groups of specimens—single-cell and multicell specimens—under positive and negative bending configurations. Analysis based on the test results confirmed that the proposed system can withstand hurricane wind speeds of 336 km/hr (209 mph) for a span of 6.1 m (20 ft) (i.e., a span-to-depth ratio of 60:1). Test specimens showed flexural failure with considerable ductility and a strong panel action with a distribution factor of 0.33 among adjacent box-cells. Despite lack of any shear reinforcement, no shear crack was observed. Multicell specimens showed an improved performance in cracking and ductility over single-cell specimens, in part as a result of their transverse ribs. The proposed section showed optimal performance, as evident from similar capacity/demand ratios in positive and negative bending.