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4. AS/NZS 1170:2002 Load Combinations

# AS/NZS 1170:2002 Load Combinations

## A guide to Load Combinations: AS/NZS 1170:2002

In Australia and New Zealand, the suitable standard for the combination of actions (load combinations) is AS/NZS 1170:2002. The focus of this standard is to provide structural designers with representations of the values for structural design actions. The code is split into 6 parts,

• Part 0: General Principals
• Part 1: Permanent, imposed, and other actions
• Part 2: Wind Actions
• Part 3: Snow and ice actions
• Part 4: Earthquake Loads
• Part 5: Earthquake actions – New Zealand

This article will focus on how SkyCiv’s auto-generated load combinations feature meets the load combination equations as specified in AS/NZS 1170:2002.

## 4.2.1 Stability

Design Code Equation Design Code Comment SkyCiv Equation SkyCiv Comment
Ed,stb = [0.9G] Net Destabilizing: Permanent action only (does not apply to prestressing forces) 1.35G SPC: Permanent Destabilizing
Ed,stb = [1.35G] Net Stabilizing: Permanent action only (does not apply to prestressing forces) 0.9G SPC: Permanent Stabilizing
Ed,stb = [1.2G,1.5Q] Permanent and imposed action 1.2G + 1.5QL ULS: Permanent & Imposed.
Ed,stb = [1.2G, Wu, ψc,Q] Permanent, wind and imposed action 1.2G + ψ2,1QL + QW ULS: Permanent, Wind & Imposed. The imposed action factor represented by the psi is determined by the type of QL that this equation acts against.
Ed,stb = [1.2G, Su,ψc,Q] Permanent action, actions given in Clause 4.2.3 and imposed action. 1.2G + ψ0,3QL + QS ULS: Permanent, Other, & Imposed. The imposed action factor represented by the psi is determined by the type of QL that this equation acts against.

## 4.2.2 Strength

Design Code Equation Design Code Comment SkyCiv Equation SkyCiv Comment
Ed = [1.35G] Permanent action only (does not apply to prestressing forces) 1.35G Identical to Ed,stb
Ed = [1.2G,1.5Q] Permanent and imposed action 1.2G + 1.5QL Identical to Ed,stb
Ed = [1.2G,1.5ψlQ] Permanent and long term imposed action 1.2G + 1.5ψ1QL ULS: Permanent & Long-term Imposed. The imposed action factor represented by the psi is determined by the type of QL that this equation acts against.
Ed = [0.9G, Wu] Permanent and wind action reversal 0.9G + Qw ULS: Permanent, Wind
Ed = [G, Eu, ψc,Q] Permanent, earthquake and imposed action G + ψ2,nQL + E SPC: Permanent, Earthquake & Imposed
Ed = [1.2G, Su,ψc,Q] Permanent action, actions are given in Clause 4.2.3, and imposed action. 1.2G + ψ0,3QL + QS Identical to Ed,stb

## 4.2.3 Combinations for snow, liquid pressure, rainwater ponding, groundwater, and earth pressure

The actions 4.2.3 relate to snow, liquid pressure, water and earth pressure effects.

## 4.3 Combination of Actions for Serviceability Limit States

Appropriate combinations may include one or a number of the values for permanent, short-term imposed action, long-term imposed action, wind, earthquake, or other serviceability values of other actions as necessary.

SkyCiv Equation SkyCiv Comment
G + ψ0,1QL SLS Permanent and Short-term Imposed
G + ψ1QL SLS Permanent and Long-term Imposed

## Example: All Load Types Assigned

Whilst not practical, 12 load groups have been created and assigned to all 12 load types as seen below. This is done to check the equations that are formed from the load combinations

The results from the datasheet are shown below.