A Proposed Approach for Obtaining the Shear Centre and Monosymmetry Constant for an I-section Beam with a Welded Channel Cap

Abstract

Monosymmetric sections made from I-section beams with a channel cap welded to the top flange find use in crane runway beams or girders for medium duty cranes of moderate spans. These beams are susceptible to lateral-torsional buckling when the compression flange is laterally unsupported. In order to determine the critical elastic buckling moment several geometrical parameters must first be determined. Two of these are the shear centre location and the monosymmetry constant. These properties may be cumbersome to evaluate for these sections. A general equation for locating the shear centre is developed in this study and may be particularly useful for combinations of I-section and channel that are not standard or not found as standard combinations in books of data. The result is then used, in conjunction with other relevant properties, to evaluate the monosymmetry constant of the section using an approach previously suggested by other researchers. This approach is demonstrated to produce acceptable results when compared to benchmark values from books of data as well as output from suitable software. A suitable adjustment to the monosymmetry constant evaluated from the suggested approach is proposed and shown to give generally conservative values while retaining acceptable accuracy.