Stress singularities in CLT with holes and notches: A unified FE–LEFM framework validated on extensive experimental evidence

Abstract

Cross-laminated timber (CLT) members with geometric discontinuities such as holes and notches exhibit pronounced stress concentrations, which lead to stress singularities in linear elastic finite element (FE) analyses and complicate structural verification. This paper presents a methodology based on linear elastic fracture mechanics (LEFM) for the assessment of such singularities. The proposed framework combines 2D FE stress analysis with fracture-mechanics-based criteria to evaluate crack initiation in CLT members under in-plane and out-of-plane loading. In particular, the approach is extended to out-of-plane configurations, for which no consistent FE–LEFM-based assessment procedure is currently available. The focus was on the practical applicability, with the ultimate goal of establishing a consistent assessment framework for timber engineering applications. In total, ten experimental studies comprising 44 test configurations from the literature were simulated, of which 34 configurations governed by the investigated corner-induced crack-initiation mechanism were included in the quantitative validation metrics. For these 34 configurations, the most conservative crack-initiation estimates were on average about 22 % lower than the experimental mean maximum loads and were conservative in more than 90 % of the considered cases. Larger deviations were observed in some configurations, particularly where additional failure mechanisms or stress redistribution effects influenced the structural response. Overall, the results indicate that linear FE analyses combined with LEFM provide a practical and physically motivated approach for the conservative assessment of stress singularities in CLT members, while maintaining computational efficiency and applicability within standard engineering workflows.