Steel Buildings in Europe

Part 10: Technical Software Specification for Composite Beams 10 - 14 4 CALCULATION OF INTERNAL FORCES AND MOMENTS 4.1 General The section resistance of the composite beam has to be checked by taking into account the variation of the shear force and the bending moment, the variation of the bending resistance due to the effective width of the slab, the degree of connection and the influence of the shear force. Therefore the shear force and the bending moment should be calculated at several design points along the beam, for each elementary load case (i.e. G , Q 1 , Q 2 ). Then the design internal forces and moments will be obtained for each combination of actions. The design points are the supports and both sides of a point load. Additional design points are determined between the previous ones in order to get the critical section with sufficient accuracy. To this purpose, it is suggested that the distance between two consecutive design points is less than L /20. 4.2 Effects of a point load Vertical reaction at the left support: R VL = – F ( L – x F ) / L Vertical reaction at the right support: R VR = F – R VL Shear force at the abscissa x from the left support: If x  x F : V ( x ) = R VL Else: V ( x ) = R VL + F Bending moment at the abscissa x from the left support: If x  x F : M ( x ) = R VL x Else: M ( x ) = R VL x + F ( x – x F ) F x F x L Figure 4.1 Point load applied to the beam