04-22-2010, 10:31 AM
The steel deck normally runs or spans perpendicular (normal) to the direction of beam span so that it could act as a floor supported on the beams. There is no common span for this kind of floor/beam/girder arrangement. The span depends on your exigency and this will determine the class or grade of the deck to employ, though the extent to which you could go as to the spacing of the supporting beams (i.e., the span of the deck ) depends on the class or grade of deck that is available. Determine you design load, use it to load the deck and treat it as simply supported between the adjacent beams-in which case you calculate the design bending moment as wL^2/8 or treat is as semi fixed-ended thus the design bending moment as wL^2/10. Here w = load/unit width of slab (which is the distance between adjacent crests or troughs of the deck) and L = spacing of the supporting beams (which could be primary or secondary beams). Employ the equation, design stress (s) = My/I which implies that the moment of inertia (I) of the required deck section = My/s (M being the moment that you have just calculated as above). With the moment of inertia (I) calculated above, you can chose your deck section. Check the deck for deflection (as this could govern your design-thus, determine the deck section to be used). Remember also to design the studs (which in most cases will be satisfied by the provision of the nominal quantity as recommended by the relevant code. Your framing might require you to provide lateral ties as you should avoid employing the deck as lateral support to the framework (since this could impose unexpected structural demand on the deck as such could lead to its failure). The beams and columns (frame) design follow the normal procedure. I have a design sample that I could have sent to you but it is in Italian and I am so occupied now that I won’t have enough time to translate it, but if you still needed further tips after this, please do post again.
Regards
Teddy