Estudio de efectos diferidos en los viaductos de Espiñeiro, Ferreiras del Acebo y del Sella

Long term effects in Espiñeiro, Ferreiras, Acebo and Sella Viaducts

The object of this paper is to present both the step-by-step erection of a family of four precast segmental bridges, built by the balanced cantilever form of construction, and some results of the service analysis, accounting for long term effects of creep, self-induced and superimposed deformations. This paper is an attempt to provide a practical treatment of the serviceability analyses of concrete structres having an evolutive process of erection: 1. An ?exact? approach, using the classical incremental step-by-step time procedure, is presented, wich takes into account the effects described, based on the multilayer model. 2. A simplified approach for the inclusion of the timedependent effects of creep and shrinkage is presented, using a step-by-step procedure. 3. Comparison of both approaches is made showing their advantages and disadvantages. Practical conclusions are presented in order to treat these kind of problems by means of the ?simplified approach?. In both approaches the cross section may be formed by concrete of different ages, prestressed and non-prestressed reinforcement and even by a section of steel. In the case of the step-by-step procedure it is necessary to define as exactly as possible what the stages of construction are. Any sequence of construction may be taken into account, both tansversely and longitudinally, however complicated it may be.