Open Access

ARTICLE

Long-Term Loading Test of Reinforced Glulam Beam

Nan Guo¹, Jing Ren¹, Ling Li^1,*, Yan Zhao², Mingtao Wu¹

1 College of Civil Engineering, Northeast Forestry University, Harbin, 150040, China
2 School of Civil Engineering and Architecture, Wuyi University, Wuyishan, 354300, China

* Corresponding Author: Ling Li. Email:

(This article belongs to the Special Issue: Renewable building materials and properties)

Journal of Renewable Materials 2022, 10(1), 183-201. https://doi.org/10.32604/jrm.2021.015756

Received 11 January 2021; Accepted 31 March 2021; Issue published 27 July 2021

Abstract

Due to creep characteristics of wood, long-term loading can cause a significant stress loss of steel bars in reinforced glulam beams and high long-term deflection of the beam midspan. In this study, 15 glulam beams were subjected to a 90-day long-term loading test, and the effects of long-term loading value, reinforcement ratio and prestress level on the stress of steel bars, midspan long-term deflection, and other parameters were compared and analyzed. The main conclusions drawn from this study were that the long-term deflection of the reinforced glulam beams accounted for 22.5%, 20.6%, and 18.2% of the total deflection respectively when the loading value was 20%, 30%, and 40% of the estimated ultimate load under the long-term loading. The higher the loading level was, the smaller the proportion of the long-term deflection in the total deflection was. Compared with ordinary glulam beams, the long-term deflection of the reinforced glulam beam was even smaller. Under the condition of the constant loading level, the total stress value of the steel bars decreased by 17.5%, 13.6%, and 9.1%, and the proportion of the long-term deflection of the beam midspan in the total deflection was 26.9%, 24.2%, and 20.6% respectively when the reinforcement ratio was 2.05%, 2.68 %, and 3.39%. With the increase of the reinforcement ratio, the stress loss of the steel bars decreased, and the proportion of the long-term deflection decreased as well. When other conditions remained constant and the prestress level of the steel bars was 0 MPa, 30 MPa, and 60 MPa, the total stress value of the steel bars decreased by 9.1%, 9.4%, and 10.2%, respectively, and the proportion of the long-term deflection in the total deflection was 20.6%, 26.1%, and 64.9%, respectively. With the increase of the prestress value, the stress loss of the steel bars increased, and the proportion of the long-term deflection increased as well.

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