1. MINIMUM DESIGN LOADS
FOR BUILDINGS AND
OTHER STRUCTURES
BY THE
AMERICAN SOCIETY OF CIVIL ENGINEERS (ASCE)
2. ABSTRACT
This revision of the ASCE Standard Minimum Design Loads for Buildings
and Other Structures is a replacement of ASCE 7 -98. This Standard provides
requirements for dead, live, soil, flood, wind, snow, rain, ice, and earthquake loads,
and their combinations that are suitable for inclusion in building codes and other
documents.
3. SCOPE
This standard provides minimum load requirements for the design of
buildings and other structures that are subject to building code requirements.
Loads and appropriate load combinations, which have been developed to be used
together, are set forth for strength design and allowable stress design. For design
strengths and allowable stress limits, design specifications for conventional
structural materials used in buildings and modifications contained in this standard
shall be followed.
4. SECTION 1.4
GENERAL STRUCTURAL INTEGRITY
Buildings and other structures shall be designed to sustain local damage
with the structural system as a whole remaining stable and not being damaged to
an extent disproportionate to the original local damage.
5.
6. SECTION 2.3
COMBINING FACTORED LOADS USING STRENGTH DESIGN
2.3.2 Basic Combinations. Structures, components, and foundations shall be designed so that
their design strength equals or exceeds the effects of the factored loads in the following
combinations:
1. 1.4(D + F)
2. 1.2 (D + F + T) + 1.6(L + H) + 0.5(Lr or S or R)
3. 1.2D + 1.6(L,. or S or R) + (L or 0.8W)
4. 1.2D + 1.0W + L + 0.5 (Lr or S or R)
5. 1.2D + 1.0E + L + 0.2S
6. 0.9D + 1.6W + 1.6H
7. 0.9D + 1.0E + 1.6H
7. 4. 1.2D + 1.0W + L + 0.5(Lr or S or R)
This represents the wind storm of the century. Has a massive wind load.
Snow load or rain load, it may also represent a modern roofing.
D = dead load
W = wind load
L = live load
Lr = roof live load
S = snow load
R = rain load
8. EXCEPTIONS:
1. The load factor on L in combinations (3), (4), and (5) is permitted to equal 0.5 for
all occupancies in which La in Table 4.1 is less than or equal to 100 psf, with the
exception of garages or areas occupied as places of public assembly.
9. SAMPLE PROBLEM: DESIGN LOAD
The compression gravity loads for a building column have been estimated with the
following loads: D=700 kN ; live load from roof, Lr=300 kN ; and live load from floors,
L=1400 kN; compression wind, W=320kN; tensile wind, W=280kN; seismic compression
load, E=230kN; and tensile seismic load, E=180kN. Determine the critical design load.
Dead load, D = 700kN Compression wind, W = 320kN
Live load roof, Lr = 300kN Tensile wind, W = 280kN
Live load floors, L = 1400kN Seismic compression load, E = 230kN
Seismic tensile load, E = 180kN
10. SOLUTION:
Equation 1:
U = 1.4D = 1.4 (700kN)
U = 980kN
Equation 2:
U = 1.2D + 1.6L + 0.5 (Lr or R) = 1.2(700)+1.6(1400)+0.5(300)
U = 3230 kN
Equation 3:
U = 1.2D +1.6 (Lr or R) + (1.0L or 0.5W) = 1.2(700)+1.6(300)+1(1400)
U = 2720 kN
11. SOLUTION:
Equation 4:
U = 1.2D+1.0W+1.0L+0.5(Lr or R) = 1.2(700)+1(320)+1400+0.5(300)
U = 2710 kN
Equation 5:
U = 1.2D + 1.0E + 1.0L = 1.2(700)+1(230)+1400
U = 2470 kN
12. SOLUTION:
Equation 6:
U = 0.90D + 1.0W = 0.90 (700) + 320
U = 950 kN
Equation 7:
U = 0.90D + 1.0 E = 0.90 (700) + 1(230)
U = 860 kN
.: Governing load for the design is 3230 kN
