ABSTRACT
This chapter presents the elements that will be subjected to in-plane normal stresses in addition to in-plane shear stresses, and the concrete will also exhibit a small average tensile strength even after cracking. Such elements are called membrane elements and the in-plane stresses are known as the membrane stresses. The stresses in a membrane element are best analyzed by the principle of stress transformation. The chapter illustrates an element in the stationary l-t coordinate system, defined by the directions of the longitudinal and transverse steel. The three stress components on the element, σl, σt, and τlt (or τtl) are shown in their positive directions. For the shear stress τlt the first subscript l represents the face on which the stress acts, and each face is defined by its outward normal. The second subscript t represents the direction of the stress itself. For the two normal stresses σl and σt the single subscript represents both the direction of face and stress.
