chapter  5
30 Pages

Time-dependent internal forces in uncracked structures: analysis by the displacement method

A step-by-step procedure suitable for computer use is presented in Sec¬ tion 5.8. It accounts for the effects of creep, shrinkage of concrete and relaxation of steel in statically determinate or indeterminate structures. The cross-section may be made up of one concrete type or composite and the structure may be composed of members of different ages and the presence of non-prestressed steel is accounted for in the analysis. The loading, prestressing forces or prescribed support displacements may be introduced gradually at an arbitrary rate or in stages and the boundary conditions may be changed in any stage. The method is suitable when precast segments are assembled and made continuous by prestressing or by cast in situ concrete or both. The 'segmentaT (or lcanti/evef) method of construction, mainly used for bridges, is an example of a case in which the step-by-step analysis is most fitting.