Parametric analysis of steel-concrete composite beams prestressed with external tendons

Abstract

The use of external prestressed tendons in steel-concrete composite beams can improve the performance of beams by strengthening their structure, increasing the ultimate moment resistance, and reducing deflections. The present research aims to investigate the behavior of simply supported steel-concrete composite beams, prestressed with external tendons and under positive bending moment through the development of a parametric study. Firstly, for the beam strength determination, an analytical model is discussed. To predict the ultimate increment in tendon stress Chen and Gu method is used. Additionally, a numerical model that can adequately simulate the behavior of prestressed composite beams is developed using the Abaqus software. The accuracy of this model is validated through comparisons between the obtained results and existing experimental tests. Then, a parametric study is carried out to identify the influence of the following variables: positioning and shape of the tendons, initial prestressing force, and tendon and span lengths. The effect of prestressing at the steel-concrete interface is also investigated. The results of the ultimate moment from the finite element models, are compared by applying the analytical procedure. It can be concluded that all the different tendon configurations considered in the parametric study improved the ultimate moment resistance in the composite beams, but some designs are more efficient than others, increasing the resistance even more, and significantly reducing the deflections and cracking in the concrete under service loads. Regarding the analytical procedure, it was found that the method can adequately estimate the strength capacity of the beams.