Title:
Immediate and Long-Term Deflections of Reinforced Concrete Slabs Affected by Early-Age Loading and Low Temperature
Author(s):
Hong-Gun Park, Hyeon-Jong Hwang, Geon-Ho Hong, Yong-Nam Kim, and Jae-Yo Kim
Publication:
Structural Journal
Volume:
109
Issue:
3
Appears on pages(s):
413-422
Keywords:
creep; early age; elastic modulus; long-term deflection; low temperature; slab; strength
DOI:
10.14359/51683755
Date:
5/1/2012
Abstract:
An experimental study was performed to investigate the immediate and long-term deflections of reinforced concrete slabs subjected to construction load at their early ages. This study focused on the material properties of concrete cured at low temperature and its effect on the immediate and long-term deflections. Seven one-way slabs and one two-way slab were tested. The deflections were measured for a maximum of 291 days after initial loading. The test variables were the magnitude of loading, loading pattern, reinforcement ratio, presence of compression reinforcing bars, and concrete age at initial loading. The concrete properties and slab deflections were compared with the predictions by ACI 318, ACI 209R, and CEB-FIP 1990. The results showed that the design codes overestimated the compressive strength and elastic modulus of the early-age concrete cured at low temperature. In the prediction of the slab long-term deflections, ACI 209R showed a better correlation with the test results than ACI 318 and CEB-FIP 1990.