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1,1

Measures of design and execution management and quality control are aimed at eliminating failures due to gross errors, and at ensuring that the design resistance is achieved. Design supervision and execution inspection levels are given at Tables 2.7 and 2.8, with reference to each reliability class.

Table 2.T. Design supervision levels (DSL) [Table (B4)-EN1990]

Design supervision levels

Characteristics

Minimum recommended requirements for checking of calculations, drawings and specifications

DSL3 relating to RC3

Extended supervision

Checking performed by an organisation different from that which has prepared the design

DSL2 relating to RC2

Normal supervision

Checking by different persons than those originally responsible and in accordance with the procedure of the organisation.

DSL1 relating to RC1

Normal supervision

Self-checking: checking performed by the person who has prepared the design

Table 2.B. Inspection levels (IL) [Table (B5)-EN1990]

Inspection levels

Characteristics

Requirements

IL3 relating toRC3

Extended inspection

Third party inspection

IL2 relating to RC2

Normal inspection

Inspection in accordance with the procedures of the organisation

IL1 relating to RC1

Normal inspection

Self inspection

Design with partial factors given in EC2 and with the partial factors given in the EN1990 annexes results in a structure associated with the RC2 reliability class.

2.2 Principles of limit state C2.2 Principles of limit state design desi9" Eurocodes adopt the partial factors method, or limit states semi-probabilistic method, as the method for the verification of structural safety.

EC2 point 2.2 refers to EN1990 Section 3 for limit state design rules. These are here repeated, partially repeating the description of the three safety verification methods in Par. 2.1.2.

Design for limit states shall be based on the use of structural and load models for relevant limit states. It shall be verified that no limit state is exceeded when relevant design values for actions, material and product properties and geometrical data are used in these models.

The verifications shall be carried out for all relevant design situations and load cases.

Two categories are defined by the consequences associated with the attainment of a limit state:

ultimate limit state and serviceability limit state. Verification shall be carried out against both categories; verification of one of the two categories may be omitted only if it can be proven that it is satisfied by the verification of the other one.

The ultimate limit states are associated with loss of equilibrium of the whole structure, or failure or excessive deformation of a structural member and they generally concern safety of people. For the verification of ultimate limit state design actions shall not exceed the design resistance of the structure. Table 2.9 shows the ULS classification according to EN1990 [(EN1990 point (6.4.1)].

Table 2.9. ULS classification

Notation

Definition

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