Steel Buildings in Europe

Part 10: Technical Software Specification for Composite Beams 10 - 28 Contribution of the concrete slab At each design point located at abscissa x , the bending resistance depends on the shear resistance of the connection, F sc , determined according to § 6.2.2. The position of the plastic neutral axis in the slab is obtained from the following expression (see Figure 6.1): cd eff sc pl,V,Rd pl,c ( ) 0,85 ; ) Min( f b x N F y   But: y pl,c  h f – h p For a plain slab: h p = 0 N pl,V,Rd is the plastic resistance to the axial force of the steel section, reduced by the effect of the shear force: N pl,V,Rd = [A –  (( h – 2 t f ) t w + (4 –  ) r 2 )] f y /  M0 Therefore, the resulting compression force in the concrete slab is: N c = y pl,c b eff ( x )  0,85 f cd It applies at y pl,c /2 from the top of the slab. Position of the plastic neutral axis in the steel section The plastic neutral axis in the steel section has to be determined. It can be located in one of the three following parts of the cross-section: 1. In the web if: N c  N pl,1 with: N pl,1 = ( h – 2 t f – 2 c ) t w (1 –  ) f y /  M0             y M0 w c pl,a / 1- 2 1   f t N h y 2. In the fillets if: N pl,1 < N c  N pl,2 with: N pl,2 = ( A – 2 b t f ) (1 –  ) f y /  M0                                   w y M0 c f w 2 w f pl,a / 2 1 2 4 2 1 t f N t h t c t y h t c   3. In the upper flange if: N pl,2 < N c  N pl,V,Rd y M0 c pl,V,Rd pl,a 2 /  b f N N y h    where: 2 / 2     c r