Analytical approach to determine the increase in loadcarrying capacity due to shear reinforcement in structural elements from glued-laminated and cross-laminated timber This article presents an analytical approach to determine the load-carrying capacity of timber elements from glued-laminated or cross-laminated timber, featuring shear reinforcements like self-tapping screws. Using matrix format, the approach is based on common theoretical concepts and constitutive equations for material properties. It uses the structural anisotropy of the cross-sections with shear reinforcement, also enabling to incorporate the semi-rigid composite action between the reinforcement and the wood material. The description of the general approach is followed by a comparison with experimental data from tests on both timber products. It is shown that shear reinforcements have a distinct positive influence on cross-laminated timber elements. Shear reinforcement by self-tapping screws in glued-laminated timber elements does in contrast only result in a small increase in shear stiffness and shear strength.Bild 1 Selbstbohrende Vollgewindeschrauben nach abZ-9.1-519 [1]Self-tapping screws according to abZ-9.1-519 [1] AUFSATZ ARTICLEBild 2 Schubverstärkungen aus Vollgewindeschrauben in BSH-Träger (links) und in BSP-Element (rechts) Self-tapping screws as shear reinforcement in glulam beam (left) and in CLT-element (right) Bild 3 Querschnittsaufbau von Brettsperrholz Principle structure of cross-laminated timber Bild 4 Schubverformung und Rollschubversagen eines Brettsperrholzelementes Shear deformation and rolling-shear failure of a CLT-element

<p>Following the Bad Reichenhall ice-arena collapse, numerous expertises on the structural safety of wide-span timber structures were carried out at the Chair of Timber Structures and Building Construction. It became evident that inadequate structural design and detailing as well as inadequate manufacturing principles were the main reasons for observed failures. The design and manufacture of connections in wide-span timber structures are still amongst the most challenging tasks for both the structural engineer as well as the executing company. This paper will, on the basis of an exemplary expertise, discuss specific issues in the structural reliability of connections in wide- span timber trusses and give recommendations towards a state-of-the art design of such connections.</p>

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