Experimental and Analytical Investigation of the Pullout Behavior of FRP Bars in Engineered Timber

Glued-in rods are commonly used to strengthen or connect timber elements. To date, there has been relatively little testing to quantify the pullout capacity of fiber-reinforced polymer (FRP) bars in timber. This is particularly true for engineered timbers such as laminated veneer lumber (LVL), which is unique in that the timber-ply thickness is significantly less than the bar diameter. Likewise, few models can be applied to predict the pullout capacity of FRP rods in any timber, and those proposed to date have limited calibration. In this paper, tests were conducted to quantify the pullout capacity of FRP bars in LVL. A two-tier approach was then used to predict model behavior. That is, it was first shown how existing partial-interaction mechanics can be applied, using the results of a very small number of tests, to simulate the pullout behavior of all bonded lengths. Empirical models were then presented by recalibrating eleven existing model forms to a new database of 520 test results. From this, it was observed that simple model forms can sufficiently capture the observed behavior, whereas more complex forms may be prone to overfitting.