Live Loads

 

L, L₀, L_r - live loads related to use/occupancy of structure  (italics L stands for span length)

ASCE 7 table 4-1 (2 pages), IBC table 1607.1 (2 pages)

 

contractor must ensure construction loads don't exceed capacity

trussnet

 

reductions

If a member has a small area contributing live load, it is likely that a fairly high unit live load will be imposed over that relatively small area.  On the other hand, as the area contributing live load become large, it is less likely that this large area will be uniformly loaded by the same high unit load considered in the design of a member with small area.

high unit loads are likely to occur over small areas, but not large areas

situations with no reduction

• L > 100 psf
• public assembly
• parking garages

 

floor live loads

30-250 psf

use influence area

small influence area < 400 sqft

influence area > 400 sqft

 

alternate concentrated loads

IBC sec. 1607.4, IBC sec. 1607.9.2, NDS sec. 15.1 (for vehicle traffic)

use the type that produces the most critical condition in load combinations (sec. 2.17) is to be used

non-vehicle loads		2.5 ft x 2.5 ft
vehicle loads		4.5 in. x 4.5 in.

 

partition live load

ASCE 7 sec. 4.2.2, IBC sec. 1607.5

+15 psf minimum if L < 80 psf  (no reduction)

 

roof live loads L_r

roofing, reroofing, equipment installation and servicing, fire-fighting equipment

ASCE 7 sec. 4.2 and sec. 4.9, IBC sec. 1607.11

use tributary area

20 psf with reduction for A_T > 200 sqft and slopes F > 4 in./ft

ASCE 7 and IBC values are on horizontal plane

 

special live loads

IBC 1607.7 Loads on handrails, guards, grab bars and vehicle barriers
IBC 1607.8 Impact loads
IBC 1607.12 Crane loads
etc