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Load Calculation - Dead and Live loads

Dead load:

Dead loads are weight of materials.  Mimimum design dead load can be find in ASCE 7 Table C3-1.

IBC website for free online code information:

http://publicecodes.cyberregs.com/icod/index.htm

Live load:

Live loads are based on function of use.  Mimimum design live load can be find in ASCE 7 Table 4-1 or IBC Table 1607.1.

Examples:Office building:

  • Lobbies and first-floor corridors: 100 psf (uniform)  2000 lbs (concentrated)
  • Offices: 50 psf (uniform), 2000 lbs (concentrated)
  • Corridors above first floor: 80 psf (uniform), 2000 lbs (concentrated)

Partition load: 15 psf

Live load reduction:

Floor live load reduction: (ASCE 7-05/10, IBC 2006/2009/2012)

For live load not exceeding 100 psf, not in passenger garages, not in assembly uses, with KLL x AT more than 400 square ft2, Live load can be reduced by the following equation

Live load reduction equation

Lo is unreduced live load, AT is tributary area. 

  • KLL is live load reduction element factors.
  • KLL = 4 for interior column and exterior columns without cantilever slabs.
  • KLL = 3 for edge column with cantilever slabs.
  • KLL = 2 for corner column with cantilever slabs, edge beams without cantilver slabs, and interior bams.
  • KLL = 1 for all other conditions

Example 1: Floor live load reduction

Liver reduction example 1

Alternate floor live load reduction: (IBC)

For live load not exceeding 100 psf, not in passenger garages, not in group A occupancies of IBC, supporting more than 150 square ft2, Live load can be reduced by the following percent.

R = 0.08*(A-150)

A is tributary area

R is percent of reduction shall not be more than 40 percent for horzontal member, and 60 percent for vertical member, and not exeeding

R = 23.1 (1+D/Lo)

D is floor ded load:

Example 2: Alternate live load reduction

Alt live load reduction

Roof live load reduction:

Roof live load may be reduced by the following equation:

Lr = Lo R1 R2

Where Lr shall not be less than 12 psf and not more than 20 psf

  • R1 =1                      for At less or equal 200 psf,
  • R1 = 1.2 - 0.001 At      for between 200 psf and 600 psf
  • R1 =0.6                     for At greater or equal 600 psf,
  • R2 =1                       for F less or equal 4
  • R2 = 1.2 - 0.01 F      for between 200
  • R2 =0.6                    for F greater or equal 600 psf,

F is number of inches of rise per foot.

Example 3: Roof live load reducton:

Roof live reduction

Handrails, Guardrail systems, and grab bar:

Handrail: 200 lbs concentrated load in any direction, any point.

Guardrail: 50 lb/ft uniform load and 200 lbs concentrated load at top. 50 lbs in 1 ft square area for intermediated rails, panel filers, etc.

Grab bar: 250 lbs concentrated load in any direction, any point.

Vehicle Barrier System:

6000 lbs concerated load in an 1 square foot area at 1 ft 6 inches above floor or ramp surface.

Fixed ladder: 300 lbs concentrated load in any direction.

Crane wheel loads:

Maximum Crane wheel oad shall be the sum of weight of bridge, crane load capacity, and weight of trolley with trolley in a position that produces maximum load

Design oad increase for crane wheel load:

Vertical impact force:

  • Monorail cranes (powered) : 25%
  • Cab-operated or remotely operated bridge cranes (powered) : 25%
  • Pendant-operated bridge crane (powered): 10%
  • Hand-geared bridge, trolley and hoist: 0%

Lateral force: 20%

Longitudinal force: 10%