The Flexibility and Strength of Corrugated Diaphragms and Folded Plates

Lawson, RM

Abstract

Trapozoi, lally corrugated sheeting has been previously studied
with regald to applications in shear diaphragms, making use of its
inherent strength and stiffness prepeitios by suitable connections.
The in-plane deflection is an important design factor and the shear
distortion component, due to eccentric transfer of fastener force into
profile shear, is a major contributor to the total. A design formu]a
is developed for the distortional shear flexibility for .ets taste ed
in every trough and in intermediate purlins which takes account of the
localized distortion at the sheet ends by using an energy method analysis
of assumed displacement functions to represent plate bending.
For fastening in alternate or multiple of troughs, an additional
profile concertina distortiOn occurs, resulting in a large increase in
the shear flexibility. A similar energy method is performed as for the
previous case, developing the same basic formula for the distortional
deflection. A corresponding study is made for sinusoidally corrugated
sheeting.
A nuMber of practical design factors have been examined - including
the effect of longitudinally overlapping sheets, and purlin restraint on
profile distortion. For sheets spanning over rafters into different
shear fields, the expressions for shear flexibility have been modified.
The strength of diaphragms has been investigated, especially with
regard to fastening on two sides only, which includes the torsional and
bending stiffness of laterally weak purlins. Diaphragm openings cause an
increase in the sheet flexibility and constrain purlins to follow the
resulting displaced shape. Consequently locally high purlin bending
stresses and sheet-purlin forces may be generated, as revealed by
differential equation and finite element studies.
Corrugated sheeting has many applications in frameless structures
such as folded plates and hyperbolic paraboloids. The flexibility and •
strength expressions have been used to design a prototype three bay folded
plate roof Which utilizes specially pressed sheeting to reduce the shear
distortion component of roof deflection,
The shear buckling strength of corrugated diaphragms is an
impottant factor in such construction. For larger roof diaphragms
with only periodic intenrediate fixings to purlins, buckling may occur
over the complete diaphragm depth rather than separately in each bay,
and design tables are shown for this condition.

Citation

Lawson, R. The Flexibility and Strength of Corrugated Diaphragms and Folded Plates. (Thesis). University of Salford

• Thesis Type: Thesis
• Deposit Date: Jul 22, 2011
• Publicly Available Date: Jul 22, 2011
• Award Date: Jan 1, 1976