Roof Live Load Tributary Area

Don t get confused with what weight you might think or want to load the deck with.

Roof live load tributary area.

Additional collateral gravity cg and collateral uplift cu loads can be added to the building or shape as required on the live load tab as well to account for additional loading on the roof surfaces. The load w that that unit length supports equals the tributary area 1 tw times the uniform pressure load q. Such a grid of beams reduces the span of the slab and thus permits the designer to reduce the slab thickness. The reduction formula has two reduction terms.

R 1 is formulated in such a way that there is no reduction for tributary areas less than 200 sqft and is maximum when the tributary area reaches 600 sqft varying linearly in between. The area that it supports equals the tributary width times the unit length. 0 9d 1 0w a load factor of 1 6 when adding to load 7. Note to builder customer.

Minimum uniformly distributed live loads adapted from sei asce 7 10. So a 100 sqft deck would be designed to support 5000 lbs. It goes without saying that in a warmer climate the snow load probably would be less so you need to check your code book for live loads and dead loads in your region. The distribution of floor loads on floor beams is based on the geometric configuration of the beams forming the grid.

If the load is 100 psf the load to the beam would be 12 ft x 100 psf 1200 plf. The amount of reduction allowed depends on the tributary area that a member supports and is automatically determined. Now let s find the tributary areas of a deck to determine the maximum load capacity of your deck start by calculating its total area and multiply by 50 psf. 0 9d 1 0e effect or 0 9 when resisting the load when permanent.

Tributary areas many floor systems consist of a reinforced concrete slab sup ported on a rectangular grid of beams. Hence the load per that unit length is w 1 tw q q tw. One for the tributary area supported by the structural element r 1 and the other for the slope of the roof surface r 2. Example problem of determining distributed load on a beam and column reactions for a simple beam and plank system with unsymmetrical bay sizes reference.

Tributary loading or tributary widthis the accumulation of loads that are directed toward a particular structural member. Minimum design loads for buildings and other structures location uniform load psf. Tributary width is 7 ft 5 ft 12 ft. The idealized beam loading diagram is shown in figure ta 2 3.

Some building codes will permit the live load to be reduced only for some design members.