Structural Steel

Dead-Load Deflection

Although, in general, building codes restrict the magnitude of live-load deflections, they do not contain criteria or limitations relating to dead-load deflections.
The dead-load deflection of the floor framing system will not affect the levelness of the floor surface if the concrete is finished level despite the deflection or if the floor framing members are cambered for deflection due to the concrete dead load. In cases where the concrete is finished with a level surface, the slab will be thicker at midspan and, hence, the floor framing members should be designed for the additional concrete dead load. In cases where the floor framing members are cambered, care must be taken to avoid providing too much camber. (See ‘‘Shored versus Unshored Construction’’ in Art. 8.8.)
When shored construction is used, or when the concrete floor thickness is kept constant, that is, the top surface follows the deflected shape of the framing members to avoid the placement of additional concrete, the dead-load deflection of the floor-framing system should be evaluated to determine whether the resulting floor levelness will be acceptable.


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