Exact solution of shear problem for inclined cracked bending reinforced concrete elements

• Interaction between internal forces in concrete and links is studied.
• A method for calculating the inclined cracks angle is proposed.
• Proposed solution allows effective design of shear reinforcement.
• Recommendations for considering the concrete shear bearing capacity are given.

In spite of a wide experimental and theoretical data on shear that forms a basis for modern design approaches, exact solution of shear problem for inclined cracked bending reinforced concrete elements is still not found. It yields high dispersion in the bearing capacity of concrete according to the main compression stresses. A similar problem appears with the internal forces carried by shear reinforcement. The above mentioned problem is related to two parameters: the angle of the main compression stresses and that of the inclined links. Corresponding internal forces together with the force in the tensile reinforcement form a commonly used design model (truss model), therefore each force depends on the other. This fact is practically not considered in modern design provisions hence there are no tools to express the shear capacity accurately. The two angles should be considered simultaneously in every case, when the links section is taken according to the calculated value (but not to the minimum one). The present study is one of the first attempts, focused on considering the interaction between the internal forces in concrete and inks according to the design model. It allows calculation of an exact angle, defining the inclined cracks and forces in links within the known experimentally investigated limits of this angle.