A t is tributary area.
Floor live load reduction example.
For uses other than storage where approved additional live load reductions shall be permitted where shown by the registered design professional that a rational approach has been used and that such.
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.
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.
However if the attic is intended for storage the attic live load or some portion should also be considered for the design of.
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.
The asce 7 05 uses concept of influence area as a major factor in computing the reduction that a member can use.
In fact it become less likely as the size of the area supported increases.
And k ll is the live load reduction element factor.
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.
Floor live load reduction.
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 requirement is presented in asce 7 05 4 9.
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.
The probability of full live load on large areas in certain cases is unlikely.
I 400 sq ft the live load may be reduced according to the live load reduction equation.
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.
Where l 0 is unreduced live load.
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.
Let us take a practical example and look at the logic.
