July 2, 2013

How to use Live Load Special

In RISAFloor, there are several different Load Categories that define Live Load. The IBC and the ASCE7 both have provisions that allow you to reduce the tributary area of the Live Loads. These codes have equations that adjust the Live load based on the tributary area and usage (KLL*AT). In RISAFloor, the Live Load Reducible (LL-Reduce) calculates the reduced live load based on the tributary area.


Live Load Special (LLS) should be used when the loads exceed 100 lb/ft2, there is no live load reduction except when there are multiple stories. This designation should be used for the following cases:

  • Heavy Live Loads: Live Load is considered a Heavy Live Loads when it exceeds 100 lb/ft2.
  • Passenger Vehicle Garages

There is live loading associated with Assembly loading (or previously named Special Occupancy Live Loads). Assembly loads should be considered as Live Loads not Live Loads Special. In the ASCE7-10, you cannot reduce assembly live loads so they would be LLS- Non. In IBC 2012, the assembly load is not specified, and the Load Combination (f1=1), so you would need to use LLS-Non.

In the previous years, you could not reduce any loads under 100psf and they could not get the multi-story reduction, so you would want to use LLS-Reduce for 100psf or higher, LLS-Non for loading under 100psf.

Tags: Loads RISAFloor

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