Analysis of the effect of Secondary Corrugation in Self-Supporting Double Corrugated Arched Roofing System

Abstract

Double corrugated arched roofing, commonly known as K-Span roofing, is a self-supporting frame-less
roofing system, made up of cold formed steel sheet profile. Cold formed steel sheet is bent into different types of main profiles like rectangular and trapezoidal with a thickness of around 0.6 mm to 1.5 mm. The main profile, generally called primary corrugations, are the converted into arch shape by making transverse corrugations, these transverse corrugations are the secondary corrugations. These transverse corrugations make the use of available design standard for cold formed steel difficult. The lack of proper scientific bases and available design standards make the designer to use common design practice and general information during designing of such structure. This may lead to under design the structure, because secondary corrugations reduce the actual load carrying capacity of main profile due to discontinuity in load path, and this can lead to failure and even collapse of structure. The study aims to analyses the effect of shape modification of secondary corrugation on the load carrying capacity of the arch. In the initial part of the study actual kspan samples of different diameter were modelled on ANSYS to check to draw the comparative analysis of their load carrying capacity with straight section. Secondly, some modifications were done in shape of secondary corrugation by varying the top, bottom widths and depth according to diameter. In coherence to previous researches the secondary corrugation resulted in reduction of load carrying capacity. However, as the diameter of k-span increase the load carrying capacity of the profile increases. Where, the secondary corrugation with Trapezoidal shape having lower depth with an internal angle in a manner that makes it closer to rectangular shape, proved to be best shape for secondary corrugation.