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Behavior of Post-tensioned Steel-Concrete Composite Beams Subjected to Hogging Moments

AYMAN EL-ZOHAIRY, HANI SALIM

Abstract


This study presents a detailed finite element (FE) analysis of the nonlinear flexural response of continuous steel-concrete composite beams strengthened with externally post-tensioned tendons. The initial post-tensioning (PT) force is introduced as an initial strain in the truss element that used to simulate the external tendons. The accuracy of the FE model is validated using existing experimental works. The effects of tendon eccentricity, longitudinal steel rebars ratio, and initial PT force on the beam behavior are explored. Furthermore, deterministic and stochastic shrinkage effects are carried out to obtain the long-term random responses of the strengthened beams as well as plain beams. However, the ultimate capacity of the strengthened beam increases only by 8%, the cracked moment redoubles and an affirmative behavior over the un-strengthened beams is obtained. Also, using prestressed concrete flange deters the propagation of cracks and improves the composite action between the steel beam and the concrete flange. As the longitudinal steel rebars ratio increases, the contribution of the externally posttensioned tendons to enhance the beam capacity is diminished.

Keywords


Finite element; Composite beams; Hogging moment; Posttensioning; Deterministic; Stochastic; Shrinkage.

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