Section Classification of actions

(1) For ease of use of this Part of Eurocode 1, some of the Principles and Application rules defined in ENV 1991-1 are quoted in the following.

(2)P The actions to be taken into account during execution shall be classified as:

- permanent, variable or accidental;

- static, quasi-static or dynamic;

- direct or indirect;

- uni- or multi-component.

These classifications shall, where relevant, be made separately for any design situation.

Note : Some actions, may have to be differently classified for different execution phases, and therefore for different design situations.

(3) Some classifications are specified in the following Clauses and some others in the design Eurocodes. They should be, as relevant, supplemented for each particular project.

(4) Indirect actions include intentional imposed deformations (e.g. imposed displacements at supports of steel beams) or constrained deformations, e.g. due to shrinkage, uneven settlements or temperature changes. Direct actions should be taken into account in combinations. Depending on the structure and on the limit state under consideration, indirect actions should either be taken into account in combinations or in detailing provisions.

(5)P In case of soil settlement, the settlements (absolute and differential values) to be expected during execution shall be classified as permanent actions (see ENV 1997-1).

(6) Unless otherwise specified, the effects of prestressing during execution should be classified as permanent actions. However, the jack forces during the application of prestressing should be considered as variable actions with regard to the design of the anchorage zones.

(7)P The shrinkage of concrete during execution shall be classified as permanent actions.

(8)P Where the structural system changes during execution, the remaining effects of loads applied in one structural system and removed in subsequent structural system shall be considered as permanent for the construction works with their new structural system.

(9) Where structural members are temporarily propped for the concrete, the effects of propping and unpropping systems should be classified as permanent. Consideration should be given to the effects of the elasticity of the propping systems and their possible deflection due to soil settlement.

(10) Unless otherwise specified, all actions due to construction loads should be considered as variable actions.

Note : In the case of heavy equipment as defined in 4.8.1 (Qcc), this action may be considered as a variable action only during movement. When heavy equipment is in position for use, it is more reasonable to consider it as a permanent action (e.g. self-weight of a travelling form for the construction of a bridge deck). The situations during which construction loads have to be considered as permanent or variable, their reprsentative values and the associated y factors should be defined, e.g. in the project specification.

(11) Construction loads due to cranes, equipment, scaffolding, etc. should be considered as free or fixed variable actions, depending on their possible location. Where such actions may be considered as fixed, due allowance should be made for possible inaccuracies in their location. Where such actions may be considered as free, the boundaries of their possible location should be defined.

Note 1 : Control measures may be taken in some cases to ensure that the assumed position is maintained during execution.

Note 2 : Particular positions may have to be considered, in some cases, as accidental.

(12)P Where construction loads due to people need to be considered, these loads shall be considered as free variable actions.

(13) Actions due to the handling and positioning of precast structural elements, which are intended to be connected to other parts of a permanent structure, should be considered as static or dynamic variable actions.

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