Influence of prestressing on the behavior of uncracked concrete beams with a parabolic bonded tendon
Journal
Structural Engineering and Mechanics
Journal Volume
77
Journal Issue
1
Pages
1-17
Date Issued
2021
Author(s)
Abstract
The influence of prestress force on the fundamental frequency and static deflection shape of uncracked Prestressed Concrete (PC) beams with a parabolic bonded tendon was examined in this paper. Due to the conflicts among existing theories, the analytical solutions for properly considering the dynamic and static behavior of these members is not straightforward. A series of experiments were conducted for a total period of approximately 2.5 months on a PC beam made with high strength concrete, subsequently and closely to the 28 days of age of concrete. Specifically, the simply supported PC member was short term subjected to free transverse vibration and three-point bending tests during its early-age. Subsequently, the experimental data were compared with a model that describes the dynamic behavior of PC girders as a combination of two substructures interconnected, i.e., a compressed Euler-Bernoulli beam and a tensioned parabolic cable. It was established that the fundamental frequency of uncracked PC beams with a parabolic bonded tendon is sensitive to the variation of the initial elastic modulus of concrete in the early-age curing. Furthermore, the small variation in experimental frequency with time makes doubtful its use in inverse problem identifications. Conversely, the relationship between prestress force and static deflection shape is well described by the magnification factor formula of the "compression-softening" theory by assuming the variation of the chord elastic modulus of concrete with time. ? 2021 Techno Press. All rights reserved.
Subjects
Bending dies; Bending tests; Concrete beams and girders; Elastic moduli; High performance concrete; Inverse problems; Natural frequencies; Prestressed beams and girders; Prestressed concrete; Euler Bernoulli beams; Experimental frequencies; Fundamental frequencies; High strength concretes; Initial elastic modulus; Problem identification; Static deflection shape; Three-point bending test; Tendons
Type
journal article