Cheatsheet: Load Calculations

1. Dead Loads

1.1 Definition and Components

1.2 Material Unit Weights

1.3 Calculation Methods

• Dead Load = Volume × Unit Weight
• For composite members: DL = Σ(V_i × γ_i)
• Distributed load: w = A × γ (force per unit length)
• Point load: P = V × γ (concentrated force)

2. Live Loads

2.1 Definition and Types

2.2 Minimum Uniformly Distributed Live Loads (ASCE 7)

2.3 Live Load Reduction

2.3.1 Live Load Element Factor (K_LL)

2.4 Roof Live Load Reduction

3. Snow Loads

3.1 Snow Load Definitions

3.2 Flat Roof Snow Load Calculation

3.3 Exposure Factor (C_e)

3.4 Thermal Factor (C_t)

3.5 Snow Importance Factor (I_s)

3.6 Sloped Roof Snow Load

3.7 Drift Loads

3.7.1 Leeward Drift Load

3.7.2 Snow Density

3.8 Unbalanced Snow Loads

• Required for gable and hip roofs with slope > 2.38° (½:12) and <>
• Windward side: 0.3p_s or minimum from code
• Leeward side: 1.5p_s/C_e or 1.2p_s, whichever is less
• Apply to each roof configuration independently

4. Wind Loads

4.1 Wind Load Definitions

4.2 Velocity Pressure Calculation

4.3 Exposure Categories

4.4 Velocity Pressure Exposure Coefficient (K_z)

4.5 Topographic Factor (K_zt)

4.6 Wind Directionality Factor (K_d)

4.7 Gust Effect Factor (G)

4.8 External Pressure Coefficients (C_p) - Low-Rise Buildings

4.9 Internal Pressure Coefficient (GC_pi)

4.10 Wind Importance Factor (I_w)

4.11 Simplified Design Wind Pressure (Low-Rise Buildings)

5. Seismic Loads

5.1 Seismic Load Definitions

5.2 Seismic Base Shear (Equivalent Lateral Force)

5.3 Design Spectral Response Acceleration

5.4 Site Coefficients

5.4.1 Site Class Definitions

5.4.2 Short Period Site Coefficient (F_a)

5.4.3 Long Period Site Coefficient (F_v)

5.5 Seismic Design Category (SDC)

5.5.1 Based on Short Period Parameter

5.5.2 Based on 1-Second Period Parameter

5.6 Response Modification Factor (R)

5.7 Seismic Importance Factor (I_e)

5.8 Approximate Period of Vibration

5.9 Vertical Distribution of Seismic Force

5.10 Horizontal Distribution and Torsion

6. Load Combinations

6.1 Load Combination Methods

6.2 LRFD Load Combinations (ASCE 7)

6.3 ASD Load Combinations (ASCE 7)

6.4 Load Notation

6.5 Seismic Load Effect (E)

6.6 Special Load Combination Considerations

• Overturning: Use 0.9D to minimize resisting moment
• Uplift/Anchorage: Use 0.9D or 0.6D (ASD) to minimize stabilizing force
• Soil Pressure: Use service-level loads without factors
• Impact: Include impact factor with live load where applicable
• Construction loads: Consider temporary conditions with appropriate factors
• Pattern loading: Apply live load to produce maximum effect

7. Other Loads

7.1 Rain Loads

7.2 Flood Loads

7.3 Soil and Hydrostatic Pressure

7.4 Impact Loads

7.5 Temperature and Thermal Loads

7.6 Crane Loads

7.7 Vehicular Loads

8. Risk Categories and Importance Factors

8.1 Risk Category Definitions

8.2 Importance Factors Summary

9. Serviceability Considerations

9.1 Deflection Limits

9.2 Drift Limits (Lateral Displacement)

9.3 Vibration Considerations