ABSTRACT
The aim of this chapter is to formulate space-averaged stress-strain relation of an RC in-plane element (see Figure 1.1). This model can be applied to finite elements consisting of shear walls, shells and beam/columns (see Figures 1.2 and 1.4). Here, cracks and reinforcing bars are idealized as being distributed or smeared over the whole element. The nonlinearity of a cracked RC element is primarily due to cracking, reinforcement plasticity and bond interaction between concrete and reinforcement. Although the local stress and strain distribution within the cracked RC element is not uniform physically, such locality need not be explicitly considered in structural analysis through space averaging. Figures 2.1 and 2.2 show the structural modeling of an in-plane RC element of finite control volume. First, total stress carried by RC is the sum of the averaged stresses of cracked concrete and reinforcement at equilibrium. Here, the concrete stress mechanics is assumed to comprise the stresses parallel and normal to cracks, and shear stress transfer along cracks on an averaged basis. In the same manner, the averaged stress of reinforcement is derived from its averaged strain developed in an RC element.
