Crack development in concrete structures due to imposed strains - Part I: Modelling

In the present paper, a technique for the modelling of crack development in reinforced concrete structures exposed to imposed deformations is describe d. In a second paper, parametric studies are performed for a wall fully res trained at the base. The objective of this research is to improve the contr ol of cracking in engineering design. A two-dimensional Finite Element model with four-node elements is used to s imulate concrete. Closing forces in cracks are modelled with spring element s. The spring stiffness is estimated from bond stress - slip relations for reinforcement and tension softening of concrete. Yield of reinforcement is also included in the model. Temperature change is used as load and the calc ulations are performed stepwise with opening of nodes and implementation of spring elements. It is shown that tensile softening of concrete can be neglected but multipl e cracking must be considered in the calculations. The progression of crack ing in the structure is simulated in the analysis. Results are given in ter ms of development of crack width with increasing temperature load. The crac k widths approach an upper limit for large temperature loading. The propose d model can also be adapted to other structures and restraints.