Page 74 - Unit2.docx

• unfavourable deviation from the material product property
• inaccuracies in the conversion factors: and
• uncertainties in the geometric properties and the resistance
model.

In ultimate limit state, depending upon a given conditions, for Geotechnical
Category 2, the values of the γ may be decided using table 20-2& 20-2.
m

The partial co-efficient γ : in order to ensure stability and adequate strength
n
in the structure and in the ground, in the code, cases A, B, and C have been
introduced. Values of γ is given in table 20-3
n

Partial co-efficient γ Rd : this co-efficient is applied in consideration of deviation
between test results and future construction. Values of the γ should be
n
between 2.4 - 2.8

Table 20-2 partial factors on material properties for conventional design situations for ultimate limit states

Material property Partial factor γ m

tanφ 2.2- 2.25

modules 2.2 - 2.8

other properties 2.6 - 2.0

© It's Engg. Life

Table 20-2 partial factors on material properties for conventional design situations for service limit state

Material property Partial factor γ m

modules 2.2 - 2.8

other properties 2.6 - 2.0

Normally the design values, d , E d , tanφ , can be decided using the following formulae:

fd = fk/(γ n⋅ γ m)

Ed = Ek /(γ n⋅ γ m)

tanφ d = tanφ k/(γ n m)
⋅ γ

Where:

f = reaction force

φ = internal angle of friction

E = elastic module

Table 20-3 partial factor γ n