NZS 1170.5: Earthquake actions

The notation for the ULS earthquake design action is:

• E

• E_d

• E_u

• E_s

The notation for the SLS earthquake design action is:

• E

• E_d

• E_u

• E_s

You are to design the structure for a building of importance level 3 which has a design life of 50 years. The annual probability of exceedance (A.P.E.) of the ULS and SLS design events respectively are: [ref. NZS 1170.0]

• 1/500 1/25

• 1/1000 ---

• 1/250 1/25

• 1/1000 1/25

In the equation C(T) = C_h(T) Z R N(T,D) , the value of C_h(T) is given by table 3.1 which is graphed as figure 3.1.

C_h(T) is called the spectral shape factor. It depends on two things:

• the size and period of the structure

• the site subsoil class and the importance level

• the importance level and the period of the structure

• the site subsoil class and the period of the structure

The spectral shape factor (C_h(T)) depends on the site subsoil class and the building period because

An earthquake combination factor (ref. Table 4.1 of NZS 1170.0) is applied to the imposed load (Q) in the combination E_d = [G, E_u, ψ_E Q] because

The hazard factor (Z) is related to

• the return period of the design earthquake

• the period of the structure

• the return period of the design earthquake and the proximity of a known fault

• the location of the site

The return period factor (R) is related to

• the annual probability of exceedance (A.P.E.) of the design earthquake

• the period of the structure

• the annual probability of exceedance (A.P.E.) of the design earthquake and the proximity of a known fault

• the location of the site

The near fault factor N(T,D) is related to

• the annual probability of exceedance (A.P.E.) of the design earthquake

• the period of the structure

• the period of the structure and the proximity of a known fault

• the location of the site

The horizontal design action coefficient C_d(T) for the structure is found by multiplying the site hazard coefficient C(T) by two factors related to the actual structure:

(choose both)

• a height factor

• a modified ductility factor

• a modified structural period factor

• a structural performance factor