For calculation the reinforced concrete columns with mixed reinforcement
Effective use of high-strength reinforcement in concrete structures - an important task today. Studies of Russian and foreign scientists have shown that the most expedient are combination of prestressed and untensioned reinforcement in section. When designing the compressed concrete elements with prestressed reinforcement should strive to reduce the amount of pre-tension reinforcement in columns, on the contrary, to increase the pre-compressed in short elements. In elements with pre-compressed steel, untensioned reinforcement is needed, because it provides improving crack resistance during transmission technology process tensile stresses on the concrete and untensioned reinforcement. The percentage of this reinforcement should be the minimum necessary to achieve the required cracking resistance. Minimal amount of pre-tension reinforcement adopted at the level of prestressing (usually the highest) should be taken of the conditions provide the desired crack resistance and rigidness. Later in the article describes main principles the calculation minimum number of prestressed reinforcement in reinforced concrete elements to the presentation requirements of the first, second and third categories crack resistance.