Behaviour of Beams in Shear

Abstract

The discontinuous stress fields outlined in Chapter 4.2 provide a powerful and efficient design tool for structural concrete girders. According to the lower-bound theorem of limit analysis, Chapter 3.2.2, these models indicate the necessary amount, the correct position and the required dimensioning and detailing of the longitudinal as well as the transverse reinforcement and result in safe designs since the flow of forces is followed consistently throughout the structure. In order to ensure attainment of the theoretically determined ultimate loads a certain redistribution of the internal forces is required. However, the theory of plasticity does not answer the related questions of the demand for and the supply of deformation capacity, particularly regarding the degradation of the concrete compressive strength in the web due to transverse tensile strains. More detailed investigations are required to settle these questions.