Steel Buildings in Europe

Part 10: Technical Software Specification for Composite Beams 10 - 16 5 CONSTRUCTION STAGE 5.1 General When the beam is unpropped at the construction stage, ULS verifications have to be carried out. The following actions are considered at this stage:  Self-weight of the steel profile ( G )  Weight of the concrete ( Q cf )  A construction load considered as variable action (Q ca ) The internal forces and moments are calculated according to Section 4 of this guide, for the following ULS combination of actions:  G G +  Q ( Q cf + Q ca ) The ULS verifications include:  Bending resistance  Shear resistance  Shear buckling resistance  Bending moment and shear force interaction  Lateral torsional buckling Regarding Lateral Torsional Buckling (LTB), it is up to the user to select the design assumption, either the beam is fully laterally restrained to prevent LTB, or the beam is laterally restrained at the supports only. The LTB verification is performed accordingly. 5.2 ULS verifications 5.2.1 General Different criteria are calculated at each design point along the beam. A criterion is the ratio of a design force to the relevant design resistance. Therefore the verification is satisfactory when the criterion, denoted  , does not exceed the unity:   1,0 5.2.2 Classification of the cross-section The bending resistance of the cross-section depends on the class of the cross- section. If 0,5 ( b – t w – 2 r )/ t f  9  then the flange is Class 1, If 0,5 ( b – t w – 2 r )/ t f  10  then the flange is Class 2, If 0,5 ( b – t w – 2 r )/ t f  14  then the flange is Class 3, Otherwise the flange is Class 4.