Proposed modified γ-method for predicting the effective bending stiffness of glubam-concrete composite beams with dowel type connectors in serviceability limit state

The γ-Method, devised to estimate the flexural stiffness of structural elements composed of two or more timber species, has been frequently applied in evaluating timber-concrete composite structures (TCC) and, more recently, of glued laminated bamboo (glubam) and concrete. However, as it was formulated for timber-timber composite elements, using the γ-Method may result in significant errors in estimating the flexural stiffness of glubam-concrete elements. This study proposes a modified γ-Method to predict the effective stiffness of glubam-concrete composite beams. To this, a parametric study was performed based on the finite element method (FEM), including 48 non-linear numerical models. A correction factor β was derived based on non-linear regression analyses with multiple variables to include the influence of physical and geometrical properties of the beams on the γ-Method. The proposed approach using the β-coefficient allowed us to predict the effective bending stiffness of glubam-concrete composite structures with a determination coefficient R2 of 98.71%. Therefore, this approach enables accurate prediction of member stiffness, aiding the evaluation of existing structures using this building system.