Elastic Modulus of Prestressed and Reinforced Concrete Beams in Taiwan Under Dynamic Flexural Loading [台灣預力鋼筋混凝土梁受動態撓曲載重作用之彈性模數]
Journal
Journal of the Chinese Institute of Civil and Hydraulic Engineering
Journal Volume
33
Journal Issue
2
Pages
83-92
Date Issued
2021
Author(s)
Abstract
The elastic modulus plays a significant role in the dynamics of Reinforced (RC) and Prestressed Concrete (PC) structures. According to Model B4-TW, the effective elastic modulus of concrete in Taiwan is approximately 80% of that calculated by international standards due to smaller coarse aggregate amount and higher paste volume which reflect its mechanics. This work allowed to verify the influence of such a reduced modulus on the dynamic flexural response of RC and PC beams in Taiwan. Laboratory tests were conducted in distinct days, for a total period of ?2.5 months, on a RC beam made in Taiwan prestressed by a parabolic tendon. The RC beam was short term subjected to free flexural vibrations under prestress losses and different conditions of early-age curing. Simultaneously, its time-dependent daily elastic modulus was determined by Model B4- TW, and experimentally by ASTM C 469/C 469M-14 and the solution proposed by Bonopera et al. tuned on compression test results on cylinders. Subsequently, all test data were compared with prediction formulas based on the beam dynamics of Euler-Bernoulli. The predictions indicated that the fundamental frequency of RC and PC beams in Taiwan is well simulated by the variation of their reduced modulus due to the consolidation/hardening of concrete, according to Model B4-TW. Moreover, the accurate measurement of fundamental frequency was confirmed to be a reliable solution for flexural stiffness evaluation of RC and PC members. ? 2021, Chinese Institute of Civil and Hydraulic Engineering. All right reserved.
Subjects
Concrete beam
Elastic modulus
Flexural vibration
Frequency
Aggregates
Compression testing
Concrete aggregates
Concrete beams and girders
Elastic moduli
Natural frequencies
Prestressed concrete
Accurate measurement
Effective elastic modulus
Flexural response
Flexural stiffness
Flexural vibrations
Fundamental frequencies
International standards
Reinforced concrete beams
Reinforced concrete
Type
journal article