ABSTRACT
In a practical design, a structure is usually subjected to a combination of different types of loading that generate different types of stresses within the structure. For example, the stress field in a beam-column joint is very complex, with combinations of bending, shearing and contact stresses (Figure 7.1(a)). If a cut (plane) is taken through a point, the stress on the plane is usually different to the stress on a different plane through the same point, not just in terms of magnitude but also direction. On an arbitrary plane through a point, a general ( ) stress can always be resolved into three independent components that are perpendicular to each other (Figure 7.1(b)). The three components include a normal stress (n), which is perpendicular to the plane, two shear stresses (1 and 2), which are parallel to the plane and perpendicular to each other. The stresses at a point inside the joint are best presented by the stresses acting on an infinitesimal cubic element taken around the point. The element has six faces (planes) that are
τ2
τ1
σn
σ
the faces there are three independent stresses, including two shear stresses and a normal stress.
