ABSTRACT
The stay forces in service of the cable-stayed bridges are usually defined in early stages of design, when the construction process has not even been conceived in detail yet. For this reason, the effects of the evolutionary erection of the superstructure are rarely included into the definition of these forces. Nevertheless, these effects might play an important role in the structural behavior both during construction and in service. To fill this gap, this paper studies the effects of the evolutionary erection of the superstructure into the structural behavior of cable-stayed bridges. To this aim, a new method to include these effects into the definition of the OSS is proposed. This method is based on the minimization of the bending energy of the structure. Furthermore, to illustrate the effects of the evolutionary erection of the superstructure, this method is applied in steel cable-stayed bridges of growing complexity erected on temporary supports.
This paper is organized as follows. In Section 2, a new criterion to include the effects of the staggered erection of the superstructure into the calculation of the stay forces and the stress-state in service is presented. This criterion is based on the minimization of the bending energy of the structure. To illustrate the application of this criterion, a numerical example is presented. The main inconvenient of this criterion is that a numerical integration of the bending moment diagrams of the structure is required. The solution to this problem is presented in Section 3, where a simplified method to calculate suitable strains in the stays and the stress-state in service is developed. To illustrate the application of this method, a cable-stayed bridge is analyzed. This simplified, method is based on the analysis of the stay forces and it is easily implemented with the help of simple computer software. Finally, in Section 4, some conclusions are drawn. Example 1: (A) Objective Service Stage defined by {<italic>N<sup>OSS</sup> </italic>} and {<italic>M<sup>OSS</sup> </italic>}. (B) Passive state defined by {<italic>N<sub>P</sub> </italic>} and {<italic>M<sub>P</sub> </italic>}. (C) Active state defined by {<italic>N<sub>A</sub> </italic>} and {<italic>M<sub>A</sub> </italic>}. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig261_1.tif"/> Example 2: Bending moments by the simplified criterion. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315207681/cd556cd4-4dcf-4efe-8e29-56fc67b8bfbd/content/fig261_2.tif"/>
