|M.Sc Student||Abutbul David Amir|
|Subject||Development and Implementation of Analytical Models to|
Predict the Two-Dimensional Response of
Reinforced Concrete Panels
|Department||Department of Civil and Environmental Engineering||Supervisor||Professor Emeritus David Yankelevsky|
|Full Thesis text - in Hebrew|
The present research deals with the behavior of a rectangular reinforced concrete panel that is subjected to membrane forces acting on its boundaries. When this panel is subjected to tensile loading, cracks are developed in the concrete and the panel continuity and resistance are maintained only due to the reinforcing bars bridging the cracks. Further increase of the loading may yield further cracking which affect the internal stresses, strains and displacements redistributions.
Various experimental programs of reinforced concrete panels indicate that the cracking of concrete is a major characteristic of the panel behavior. However, common modeling attempts of membrane behavior known in literature, ignore the gradual formation of discrete cracks and relate to the cracked concrete only implicitly in a simplified way, through introduction of empirical non-linear constitutive laws for the cracked reinforced concrete composite. This approach does not enable to separately follow the behavior characteristics and it is oversimplified and by far differs from the real complex conditions.
The proposed model focuses on the local behavior characteristics, on the evaluation of the variation of local concrete and reinforcement stresses and on the identification of the evolving cracking process. The complex behavior is simulated using a basic reinforced concrete element, composed of a concrete cylinder and a reinforcing bar that is located along the cylinder's axis of symmetry. This element, denoted as URCE, enables to analytically evaluate the distributions of the bond stresses and slips, of the stress, strain and displacement fields in the concrete and in the rebar and to follow their changes throughout the loading process. It also enables to determine the load levels at which cracks develop, their locations and to follow their width growth with further increase of the load. The model follows linear constitutive laws for concrete and adopts a linear bond stress-slip relationship. Thus, the continuous uncracked sub-member is characterized by its linear behavior. It is the cracks that gradually develop with loading that turns the behavior into a rather complex nonlinear relationship between loads and displacements.
The model enables a simple repetitive closed form solution and all the information of its response along the entire loading process may be simply and easily provided through analytical expressions, without any need of a numerical solution procedure whatsoever. It also enables to account for the splitting effect in panels.
A comparison with test results and with other theoretical predictions and analytical methods showed good agreement.