Creep of a Cracked Reinforced Beam

Conventional cracked reinforced concrete beam theory is extended to include general linear viscoelastic behavior of the matrix (concrete) material in compression. An analytical formulation is developed which leads to a single governing equation on the position of the neutral axis. Although it has not been possible to obtain a general closed solution, some important properties of the solution of this nonlinear, Volterra-type integral equation are established. The relationship of this theory to a popular approximate procedure, known as the effective modulus method, is discussed. The nonlinear integral equation is resolved numerically, and results are shown for several cases of interest.