# Load Combinations of Concrete Design

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## Concepts and Formulas of Load Combinations of Concrete Design:

Load combination or strength design (ASCE 7-10, sec, 2.3.2)

1. 1.4D

2. 1.2D+1.6L+0.5(Lr or S or R)

3. 1.2D+1.6(Lr or S or R)+(L or 0.5W)

4. 1.2D+1.0W+L+0.5(Lr or S or R)

5. 1.2D+1.0E+L+0.2S

6. 0.9D+1.0W

7. 0.9D+1.0E

Load combination for allowable stress design (ASCE 7-10, Sec. 2.4)

1. D

2. D+L

3. D+(Lr or S or R)

4. D+0.75L+0.75(Lror S or R)

5. D+ (0.6W or 0.7E)

6a. D+0.75L+0.75(0.6W)+0.75(Lr or S or R)

6b. D+0.75L+0.75(0.6E)+0.75S

7. 0.6D+0.6W

5. 0.6D+0.7E

Load combination or strength design (ASCE 7-05, sec, 2.3.2)

1. 1.4(D+H)

2. 1.2(D+F+T)+1.6(L+H)+0.5(Lr or S or R)

3. 1.2D+1.6(Lr or S or R)+(0.5L or 0.8W)

4. 1.2D+1.6W+0.5L+0.5(Lr or S or R)

5. 1.2D+1.0E+0.5L+0.5(Lr or S or R)

6. 0.9D+1.6W+1.6H

7. 0.9D+1.0E+1.6H

Load combination for allowable stress design (ASCE 7-05, Sec. 2.4.1)

1. D

2. D+L+F+H+T+(Lr or S or R)

3. D+(W or 0.7E)+L+(Lr or S or R)

4. 0.6D+W+H

5. 0.6D+0.7E+H

Where W is serviced design wind load, E is strength desogm earthquake load, F is fluid pressure, R is rain load, S is snow load, T is temperature force.

Load combinations from ACI 318-05, ACI 318-08

Load combination or strength design (Sec 9-2)

1. 1.4(D+F)                                                                       (9-1)

2. 1.2(D+F+T)+1.6(L+H)+0.5(Lor S or R)                     (9-2)

3. 1.2D+1.6(Lr or S or R)+(1.0L* or 0.8W)                      (9-3)

4. 1.2D+1.6W**+1.0L*+0.5(Lr or S or R)                        (9-4)

5. 1.2D+1.0E***+1.0L*+0.2S                                           (9-5)

6. 0.9D+1.6W**+1.6H                                                      (9-6)

7. 0.9D+1.0E***+1.6H                                                      (9-7)

*1.0L can be reduced to 0.5L except for garages, public assembly, and area that has 100 lb/ft2 of live load.

**1.6W can be reduced to 1.3W when wind load W is not reduced by directional factor (See ASCE 7-02 wind calculation)

*** Where seismic load, E is calculated based on service load, 1.4E shall be used instead of 1.0E.

Strength reduction factor, f, ACI 318-05, ACI 318-08

1. Tension-controlled sections, 0.9 (Sec. 9.3.2.1)

2. Compression-controlled sections (Sec. 9.3.2.2)

• Column with spiral reinforcement, 0.7
•  Tie columns, 0.65.

3.  is permitted to vary from 0.65 to 0.9 when the net tensile strain in extreme tension steel at nominal strength varies from compressive control strain to 0.005.

4. Shear and torsion, 0.75 (Sec. 9.3.2.3)

5. Bearing on concrete, 0.65 (Sec. 9.3.2.4)

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