Nonlinear Design of Reinforced Concrete Continuous Beams

The nonlinear design of reinforced concrete continuous beams, according to Eurocode 2 and CEB Model Code, can be accomplished evaluating the plastic rotations required to obtain the structural compatibility with the loads, and checking that these rotations are lower than the allowable ones. A simplified analysis can be developed by means of redistribution of the bending moments, as a function only of the depth of the neutral axis at failure. In this paper the problem has been analyzed by means of a refined procedure, and the influence of all parameters which characterize the required plastic rotations is examined. Thus, it is shown that not always the simplified procedure, without compatibility check, is on the safe side; moreover, it is also shown that the redistribution due to the cracking can be very dangerous in the case of steel characterized by low ductility.