ABSTRACT
The construction of a precast concrete bridge is a hard and complex process, which involves different buildings techniques that can lead to structural problems if they are not taken into account with caution.
An realistic analysis of a bridge construction has to consider not only the final stage but also the development of the several stages that are required to erect the bridge, which plays an important role on the their overall behavior. The paper discuss the modelling of construction stage of a two-span precast-girder bridge through nonlinear staged constructions modelling taking into account the effects of time on structural concrete, such as: creep, shrinkage and aging of concrete. The bridge has fixed bearings at the bent, which restrain vertical, longitudinal, and transverse translation. The three dimensional finite element model is show in Figure 1. The model has 676 nodal points and 2.048 area elements to model the deck. In addition, 340 frame elements are used to represent girders and piers. Entire finite element model have 3.788 equilibrium equation. Finite element model. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig103_1.tif"/>
A time dependent analysis of the construction procedure and 1,825 (5 years) after completion of construction of the selected bridge is executed. Figure 2 gives the bending moments along the bridge deck in the case the construction stage procedure is considered and is not considered, respectively. Bending moments along bridge deck. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig103_2.tif"/>
Results obtained shows that affect in an important way bending moments along the bridge deck. Bending moments, if the construction stage is considered, increase around 60% when compared with the results obtained when the construction stage is not considered in the analysis. The results obtained showed that is very important to consider construction stage in the analysis of bridge because stress resultants that are important in design process are very different from those obtained without the consideration if construction stage. This fact is special important for bridges, because construction period continue along time and loads may change during the construction period and after.
