ABSTRACT
Cross-sections of concrete frames or beams are often composed of three types of material: concrete, prestressed steel and non-prestressed reinforcement. In some cases, concrete of more than one type is employed in one cross-section, as for example in T-sections where the web is precast and the flanges are cast in situ. Concrete exhibits the properties of creep and shrinkage and prestressed steel loses part of its tension due to relaxation. Thus, the components forming one section tend to have different strains. However, because of the bond, the difference in strain is restrained. Thus, the stresses in 21concrete and the two types of reinforcement change with time as creep, shrinkage and relaxation develop.
