Chapter 7 – Stress and Strain

Publisher Summary There are only two types of stresses—one that acts perpendicularly to the cross section of a member and the other that acts tangentially. The former is known as a direct stress, and the latter as a shear stress. The distribution of these stresses over the cross section of a structural member depends upon the internal force system at the section and also upon the geometry of the cross section. In some cases, these distributions are complex, particularly those produced by the bending and shear of unsymmetrical sections. This chapter examines the nature of each of these stresses by considering simple loading systems acting on structural members whose cross sections have some degree of symmetry. A system of shear stresses is induced in a different way in the circular-section bar where the internal torque (T) tends to produce a relative rotational sliding of the two faces of the cross section. The shear stresses are tangential to concentric circular paths in the faces of the cross section.