Steel Buildings in Europe

Part 7: Model Construction Specification 7 - 12 National choice is allowed through clauses listed in the Foreword to EN 1991-1-6. Additional contract document requirements The rules concerning the safety of persons, on and around the construction site, shall be specified in the contract documents for the individual project, and are outside the scope of EN 1991-1-6. EN 1991-1-6 also provides rules for determining the actions that can be used for the calculation of auxiliary construction works needed for the execution phases. The contract documents shall classify construction loads in accordance with Tables 2.2 and 4.1 of EN 1991-1-6. Loads due to construction equipments, cranes and/or auxiliary structures can be classified as fixed or free loads, depending on their possible spatial variation; contract documents shall specify the loads and their classification. If construction loads are classified as fixed, then the contract documents shall define tolerances for the possible deviations to the theoretical position. If construction loads are classified as free, then the contract documents shall define the limits of the potential area of spatial variation. In the absence of any specific requirement in the National Annex, the contract documents shall specify:  Return periods for the assessment of the characteristic values of variable (climatic, seismic, etc.) actions during execution phases (see § 3.1(5) of EN 1991-1-6)  A minimum wind velocity during execution phases (see § 3.1(5) of EN 1991-1-6)  Rules of combination of snow loads and wind action with the construction loads (see § 3.1(7) of EN 1991-1-6)  Geometric imperfections of the structure and the structural elements, for the selected design situations during execution (see § 3.1(8) of EN 1991-1-6)  Criteria associated with serviceability limit states during execution (see § 3.3(2) of EN 1991-1-6)  When appropriate, frequent values of particular loads to be taken into account (see § 3.3(5) of EN 1991-1-6)  Requirements of suitability for service of auxiliary structures in order to avoid excessive deformation and/or deflection that affect the durability, fitness for use or aesthetic appearance in the final stage (see § 3.3(6) of EN 1991-1-6). Concerning the wind actions, the contract documents shall specify, whether or not a procedure is needed for calculating dynamic response of the structure, during the various stages of execution, taking into account the degree of