Pull-out resistance of glued in rod connection in timber: Reliability analyses using an experimental database

Abstract

Glue in rod (GIR) connections in timber structures are used, as they enable the prefabrication of timber sections and frames. However, uncertainties of achieving perfect GIR connection owing to possible non-uniformity in the glue application and rod alignment hamper widespread usage of GIR connection in timber structures. Although plenty of experimental studies have been conducted to explore the effectiveness of GIR in different timbers through pull-out tests and some rational design formulations are developed, the structural reliabilities of the predicted pull-out resistances are not well explored. Thus, in this study, the reliabilities of the existing design formulations to determine the pull-out resistances of GIR timber connections were assessed. A comprehensive experimental database of GIR pull-out resistances was established from the past studies to analyse the reliability of the existing predictive models. The database is divided into two categories (1) single and (2) multi GIR timber pull-out test results. The database comprised of 349 (single GIR) and 75 (multi GIR) pull-out test results from various experimental studies conducted in the past. Then, the appropriateness of the existing design formulations were assessed against the experimental database. The structural reliabilities of the design formulations considered were assessed through the First Order Second Moment method (FOSM) with an applicable target reliability index (i.e. 4.0). It was found that the design formulation given in DIN 1052:2008-12 has shown to be the most conservative compared to other formulations considered. The formulations outlined to compute the pull-out resistance of multi GIR timber connections have shown to be conservative, as their reliabilities were higher than the target reliability index (>4) defined. Finally, suitable resistance reduction factors are suggested to calculate the pull-out resistances of GIR timber connection with appropriate reliability for all the design formulations considered.