Reinforced concrete beams—the ultimate limit state

Abstract

It was pointed out in Section 3.3 that the actual stresses in a reinforced concrete column may bear little resemblance to the values calculated on the basis of the elastic theory. In reinforced concrete beams, in addition to the effects of shrinkage and creep and of loading history, there are the uncertain effects of the cracking of the concrete in the tension zone; as in columns, conventional calculations for the stresses in reinforced concrete beams do not give a clear indication of their potential strengths. Therefore, during the past several decades there has been a gradual move in design from elastic stress calculations to ultimate strength methods [1, 2]. For example, ultimate strength design for beams was introduced into both the American and British design codes in the 1950s, and the limit state design procedures in current British practice make specific requirements for ultimate strength calculations.