Upper limit to compression reinforcement ratio in flexural elements

The upper limit to the tension reinforcement ratio in flexural RC members i s based on the requirement that tension failure as well as sufficient rotat ion capacity are ensured at ultimate limit state. However, the provisions f or the total amount of longitudinal reinforcement ratio are not associated with any rational derivation. A quantitative measure to evaluate an upper l imit to the compression reinforcement ratio rho'(max) of flexural RC member s is proposed. It is shown that a quantitative criterion to rho'(max) can b e derived from steel congestion and proficient-design considerations and fr om considerations that are related to the diagonal compression bearing capa city. Parameters that affect this limit include the concrete and steel stre ngths, the beam's geometry (L/d ratio, cross section's dimensions, and conc rete cover), the steel bars' diameter, and the moment-to-shear loading rati o (or the loading type). When shear loading is dominant, the limit to rho' is set by the diagonal compression criterion, while in cases of dominant fl exural loading (relative to the shear loading) rho'(max) is determined by t he congestion criterion.