Static structures (e.g. – buildings) – Cast in situ concrete barrier with laterally projecting... – Sheet-form backer supported on upper terminal of sustainer
Patent
1990-01-30
1992-04-28
Safavi, Michael
Static structures (e.g., buildings)
Cast in situ concrete barrier with laterally projecting...
Sheet-form backer supported on upper terminal of sustainer
52334, 52450, 52674, E04B 116, E04C 503
Patent
active
051076500
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the provision of mechanical anchorage in composite steel and concrete structural members such as slabs and beams, and more particularly to anchors adaptable as end anchors, to decking panels fitted with end anchors, and to composite structural members incorporating concrete slabs on such decking panels.
Composite steel and concrete structural members are normally formed in situ and typically comprise a concrete slab cast on underlying profiled steel sheet, commonly known as decking. The decking is usually an array of side-lapped panels, each with one to three longitudinally extending upstanding primary ribs and intermediate shallow stiffening ribs. The primary ribs may, for example, be of dovetail cross-section. It is known practice to anchor the slab and underlying sheet together against excessive relative longitudinal movement by providing transversely projecting keying elements, usually at regular intervals over the whole length of the sheet: these may be reinforcing rods welded to the rib tops (as, e.g., in Australian patent 223584 and French patent 1454164), tabs or perforations pressed from the ribs or pans of the sheet, or multiple shallow-ribbed embossments stamped to project out of the ribs or pans. It is also known to provide such anchorages only adjacent the ends of the sheet: one approach is to rely on the fastening of welded-stud or power-fastened shear connectors conventionally attached through the sheet onto the underlying supporting steel beams used in steel-frame composite building construction. An example of welded stud connection is provided by U.S. Pat. No. 3604167 to Hays. Such connectors cannot be welded to the sheet alone as the sheet is of insufficient gauge to provide a secure attachment. Another approach is to flatten the ends of the dovetail ribs using a hammer, and resistance from protrusion of the deformed rib into the concrete occurs to resist pull-out.
With the introduction of composite slabs and beams into construction of concrete-frame building structures, there is a requirement for these elements to be capable of carrying heavier loads and, as floor or roof components, spanning distances substantially further than those hitherto required in steel-frame construction. However, it is found that the beams or slabs may have inadequate load-baring capacity; loading of the span between supports puts the lower portion of the composite member into tension and induces concrete cracking and a shear force between the components of the composite member as the sheet is inclined to move inwardly from the supports and the concrete outwardly. Slippage between the steel and the concrete must be resisted if the slab or beam is to act compositely. Attempts to resolve this limitation by providing end anchorages of the known types have not been entirely successful: for example, the flattened rib ends lack sufficient mechanical strength and rigidity and tend to permit slip of the sheet ends. Welded-stud and power-fastened shear connectors, if sufficient in number, are prima facie satisfactory but their correct location relative to the edge of the plate is critically dependent on unskilled operators on site.
Another anchorage arrangement is disclosed in German patent application 2604399 by Muess. Multiple sets of three transverse curved anchoring rods extend through every second primary rib of the steel sheet but the maximum load capacity attainable with this arrangement is less than desirable and cannot be improved without enlarging the rod diameters to an impractical size. The desirable load capacity is greater than 100 kN per anchorage site. A similar approach, using transverse rods, is disclosed in German patent application 2521143 by Eggert.
U.S. Pat. No. 3,712,010 to Porter et al proposes upstanding brackets in the pans of a metal panel, for supporting longitudinal prestressing tendons. The brackets are simply welded to the panel and could not therefore have an adequate load capacity for the purpose now contemplated.
French patent 2359251 depicts U-shaped assembly
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John Lysaght (Australia) Limited
Safavi Michael
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