Composite Action of Open-Web Steel Joist with metal Deck and Concrete Slab Floor System

摘要

In the last few decades, composite steel and concrete structures have been one of the most common structures widely used in construction. In particular, composite floor system consists of concrete deck slab poured on top of corrugated steel sheets supported over Open-Web steel Joist (OWST) is widely used in industrial and commercial building repeated floors, workshops and warehouses. However, to achieve the desirable composite action, extensive shear studs have to be welded on the top of the girder before concrete casting. Such method imposes extra cost, time and construction difficulties. The current design codes allow the use of alternative methods to connect the deck slab to the supporting girders (such as puddle welding or Hilti-screw pins), which greatly reduce the cost and speed the construction. Yet, no- composite action should be considered in this case. The objective of this research is to experimentally investigate the ability of puddle-weld and Hilti-screw pins to develop composite action between the deck slab and supporting girders. Two full-scale test prototypes each consisted of 2400 mm wide, 6700 mm long and 65 mm thick concrete deck cast on top of 3 mm thick corrugated steel sheets. The deck slab is supported over two OWSJ each of 250 mm depth and spaced transversally at 1200 mm with 600 mm overhang on each side. The composite floor system is simply supported in the longitudinal direction over 6700 mm span and was loaded monotonically till failure under two line loads at the third points. Test results are presented in terms of load-strain and load-deflection relationships at different locations over the concrete deck and across the depth. Test results show that full composite action is developed and can be considered in the analysis and design when puddle weld is used.