Floor Live Load Reduction Example

The probability of a 1 floor building is fully loaded is very high and hence no reduction for roof level slab supporting column or for 1 floor building.

Floor live load reduction example.

Example load distribution problem 7 the floor system of a library consists of a 6 in thick rein forced concrete slab resting on four floor steel beams which in turn are supported by two steel girders. A t is tributary area. Roof live load reduction. The requirement is presented in asce 7 05 4 9.

The asce 7 05 uses concept of influence area as a major factor in computing the reduction that a member can use. 2attic loads may be included in the floor live load but a 10 psf attic load is typically used only to size ceiling joists adequately for access purposes. Where l 0 is unreduced live load. There is another kind of live load reduction mentioned in is 1893 2016 in the mass source.

However if the attic is intended for storage the attic live load or some portion should also be considered for the design of. Asce 7 05 10 ibc 2006 2009 2012 for live load not exceeding 100 psf not in passenger garages not in assembly uses with k ll x a t more than 400 square ft 2 live load can be reduced by the following equation. In fact it become less likely as the size of the area supported increases. The nature of roof live load is different from that of floor live load so the approach to reducing roof live load is different from that used for floor live load.

The probability of full live load on large areas in certain cases is unlikely. Element k l l o 0 25 15 a i where l reduced live load l o code specified design live load a i influence area k ll a t k ll live load element factor see table table live load element factor k ll ll interior columns 4. And k ll is the live load reduction element factor. Let us take a practical example and look at the logic.

Cross sectional areas of the floor beams and girders are 14 7 in2 and 52 3 in2 respectively as shown on the next page figure. I 400 sq ft the live load may be reduced according to the live load reduction equation. The live loads for members supporting two or more floors are permitted to be reduced by a maximum of 20 percent but the live load shall not be less than l as calculated in section 1607 10 1.