Experimental–theoretical investigation of the short-term vibration response of uncracked prestressed concrete members under long-age conditions
Journal
Structures
Journal Volume
35
Pages
260-273
Date Issued
2022
Author(s)
Abstract
The short-term vibration response of uncracked prestressed concrete (PC) members under long-age conditions was investigated. No study has examined long-term phenomena of concrete, such as its tendon relaxation, creep, curing, and shrinkage, under the aforementioned conditions. Therefore, a research sub-program was initiated at the National Center for Research on Earthquake Engineering on the basis of an experimental campaign on uncracked PC bridge members initiated in 2015. In particular, a simply supported PC beam composed of a parabolic-bonded tendon and high-strength concrete made in Taiwan was allowed to short and, consequently, long-term prestressing losses measured for approximately 9.5 months. During short-term prestressing losses and after long-term prestressing losses, free short-term transverse vibrations were induced in the PC beam characterized by a second-order initial curvature and an axial end constraint. The time-dependent Young's modulus of the beam was determined by conducting compression tests on cylinders during the short-term prestressing losses. Moreover, compression tests were conducted on cores drilled along the PC beam's span after free vibration tests. The theoretical time-dependent Young's modulus of the beam was evaluated according to the compression test results. The experimental data were compared with a reference Euler–Bernoulli solution and finite-element (FE) model that describe the dynamics of PC girders by considering the effective prestressing force. The fundamental frequencies of the PC beam were mainly sensitive to the variation in its initial tangent Young's modulus due to the consolidation or hardening of concrete. These frequencies were unaffected by the second-order initial curvature. In conclusion, the reference solution and FE model can accurately predict the short-term dynamics of uncracked PC members exposed for long times. ? 2021 Institution of Structural Engineers
Subjects
Consolidation/hardening
Fundamental frequency
Initial tangent Young's modulus
Prestressing force
Uncracked concrete beam
Vibration response
SDGs
Type
journal article