Shear lag in thin web structures

Abstract

In Chapter 5 the stringer loads and the web shear flows were determined at cross sections of thin web beams. This Chapter 6 is concerned with the calculation of shear flows and stringer or stiffener loads in box beams and simple thin web structures under conditions in which the cross section analysis may not be applicable. The procedures in this Chapter also apply to local end problems for thin web beams. When concentrated loads are applied to a thin web or when cut-outs of webs and stringers are made in a structure, then the plane strain cross section analysis used in the previous Chapters does not apply so that an analysis of the shear flows along the length or spanwise direction of the beam must be made. The term beam, which usually implies a long structure with a plane strain cross section, will be used here for any long structure with or without plane sections. The beam may be very short in the following analysis. Although this spanwise problem is redundant requiring deflection equations, in some cases sufficient assumptions can be made to keep the solution determinate so that only equilibrium equations are needed.