The "combined approach" for the design of shear diaphragms made of trapezoidal profile sheeting

Dedicated to Prof. Dr.-Ing. Helmut Saal on the occasion of his 75th birthday
Diaphragms made of trapezoidal profile sheeting are often used to stabilize members or work as bracing to transfer horizontal loads (wind or seismic loads) to the ground. In Europe there are currently two approaches for the design of these shear diaphragms, both often denoted by the names of their corresponding developers: Schardt and Strehl and Bryan and Davies. Although the mechanical background to calculating the diaphragm stiffness is more or less identical in both approaches, there are differences in the level of detailing, i.e. in the number of parameters regarded as significant for practical design. Generally, the Schardt/Strehl approach was reworked much more and is therefore easier to use in practical design. On the other hand, the Bryan/Davies approach is much more realistic regarding the failure modes (shear buckling, failure of fasteners) and loadbearing capacity. This paper discusses the differences and similarities in detail, makes an assessment and highlights the particular advantages.
Recently, a new approach was elaborated based on work previously carried out by Baehre and Wolfram and taking into account new developments and findings. This “combined approach” presented here combines the advantages of the Schardt/Strehl and Bryan/Davies approaches as given above. The paper includes a comparison with test results with regard to both diaphragm stiffness and loadbearing capacity.
Detailed information is given on how to elaborate the sheeting-related parameters in tables, allowing for easy use in practical design. This is of special importance for implementation in practical design and in relation to the further development of the Eurocodes.