Analytical and numerical assessment of the strengthening effect of structural sealant joints for the prediction of the LTB critical moment in laterally restrained glass beams

Glass beams and fins are frequently used in practice as stiffeners for roof and façade panels, and the mechanical interaction between them is often given by continuous silicone sealant joints. As a result, differing from traditional steel–concrete or timber–concrete sections, the so assembled systems behave as coupled laterally restrained (LR) assemblies with intermediate flexible joints, whose LTB structural contributions depend on a combination of multiple aspects. Since for design purposes a proper estimation of the theoretical LTB resistance of LR glass beams is a priority for a first assessment of the expected buckling response, as well as for the development of standardized design methods (e.g. design buckling curves, etc.), in this paper the strengthening effect of structural silicone joints on the LTB response of monolithic glass beams under constant bending moment is first investigated, based on analytical models derived from literature and extended finite element-numerical calculations. The validity and accuracy of existing closed-form solutions is verified for a wide set of geometrical and mechanical configurations of practical interest for structural glass applications. The effects of combined joint shear stiffnesses, beam slenderness and aspect ratios, load distributions and point of applications are emphasized both in terms of critical buckling moments and corresponding fundamental modal shapes. Correction coefficients are then also properly calibrated and proposed for a suitable calculation of the Euler’s critical buckling resistance of fork end restrained LR glass beams with shear flexible sealant joints and subjected to distributed loads or mid-span concentrated loads applied at both the top or bottom edges.