B. TECHNICAL

9. Dimensioning of beams

For the calculation model, it is assumed by way of simplification that the normal forces and bending moments are only taken up by the flanges (whereby the bending rigidity of the flange is ignored) and transverse forces are allocated only to the web. This corresponds to the similar procedure applied when calculating parallel plate lattice girders. The design and verification of corrugated web beams should be implemented analogously.

• Selecting the construction height by the slenderness of the beam
  h_s = L_St/15 to L_St/25
  (single-span girders .... continuous girders or horizontal beams of frames)

• Selecting the web thickness or verification of the web via the transverse force load carrying capacity V_Rd
  V_d = _gF.V < V_Rd = V_Rk/gM
  V_Rk in accordance with Section 8 or Table 1

• Selecting or verification of the flanges via the normal force loading capacity NRd

A ... Cross-sectional area of both flanges z .... Spacing of centres of gravity of flanges

N_g,d = _gF.N_g < N_g,Rd = N_g,Rk/gM N_Rk in accordance with Section 8 or Table 2 for tensile or compressive stresses, taking into account lateral stability.

As an alternative to verification of the flanges, it is possible to verify the bearing moment M_Rd = M_Rk / _gM of the total cross section directly. However, this presupposes that the stability of the compressed flange is guaranteed by constructional measures (eg. directly laid trapezoidal sheeting or purlins at a distance of e < c_lim).

• Verification of serviceability
  This is provided by verification of deflections. Shear deformation must be taken into account. The tables in Section 12 with the section properties give details of the "transverse force area" AQ, and/or the ratio A/AQ, required as an input for many computation programs to allow the shear flexibility to be taken into account when determining deformations and cross section forces.

• Verification of the load initiation points
  See Section 11 or Table 3.