CREEP IN COMPOSITE CONTINUOUS BEAMS .1. THEORETICAL TREATMENT

In this first part of the paper, the viscoelastic analysis of composit e steel-concrete continuous beams with flexible shear connectors is pe rformed. The method proposed evaluates the stress redistribution betwe en the concrete slab and the steel beam, and the evolution of the redu ndant restraint reactions, which occur with time as a result of creep and shrinkage of the concrete part. The effects produced both by geome tric and static actions are considered. The mathematical formulation o f the problem involves the equations of equilibrium. internal and exte rnal compatibility conditions, and constitutive relationships, i.e. an elastic law for the steel part and an integral-type creep law for the concrete part. Thus, the problem for a continuous beam with r redunda nt reactions is governed by a coupled system of r + 5 equations, of wh ich two are integral-differential-type equations. Successively, this s ystem is resolved by numerical step-by-step techniques. Therefore, per forming two standard discretizations, in time and along the beam axis, a numeric algorithm is proposed.