# Load Factors For Reinforced Concrete Design

Figure 1
ACI section 9.2 providing us with 7 equations, these equations represent load combination for different conditions and loads, the combination of loads will produce ultimate load, the ultimate load will be used for reinforced concrete design.

U = 1.4D                                                                                     (ACI Equation 9-1)
U = 1.2D + 1.6L + 0.5(Lr or S or R)                                          (ACI Equation 9-2)
U = 1.2D + 1.6(Lr or S or R) + (L or 0.5W)                               (ACI Equation 9-3)
U = 1.2D + 1.0W + L + 0.5(Lr or S or R)                                   (ACI Equation 9-4)
U = 1.2D + 1.0E + L + 0.2S                                                        (ACI Equation 9-5)
U = 0.9D + 1.0W                                                                         (ACI Equation 9-6)
U = 0.9D + 1.0E                                                                          (ACI Equation 9-7)

where
U = the design or ultimate load the structure needs to be able to resist

E = seismic or earthquake load effects

ACI 9.2.2 stating that impact load should be treated as a live load in the situation where it applied quickly such as elevator, garages, and cranes, etc..