Predicting the long-term creep behaviour of glued laminated elements

Abstract

The long-term creep behaviour of timber structures is an ever-increasing research focus given the rise of mass timber buildings across the world. Experimentally examining such properties is a time-consuming and costly process and reducing the time required for such tests may prove very beneficial for the industry. This study examines experimentally determined long-term creep deflection data from unreinforced and reinforced glued laminated elements collected over 5 years and evaluates the data in periods of ﾽ, 1, 2, 3, 4 and 5-year intervals. The creep data is presented for unreinforced beams and beams reinforced with two basalt fibre reinforced polymer rods. The rods are adhesively bonded and housed within grooved routed in the tensile face of the beams. Furthermore, two environmental conditions are examined. A proportion of beams are subjected to creep testing at a constant climate of 65 ﾱ 5% relative humidity and temperature of 20 ﾱ 2 ﾰC and another proportion of the beams were subjected to creep loading in a variable climate which was cycled between 65 ﾱ 5% and 90 ﾱ 5% relative humidity. The midspan creep deflection of each beam was monitored over a 5-year period and curve fitting of a polynomial function utilising a least squares approach is implemented for the different time intervals. The model was then used to predict the relative creep behaviour after 50 years.