Experimental Evaluation of Birch Rod Reinforcement for Improving Compression Strength Perpendicular to the Grain : Within the Context of Stress Laminated Timber (SLT) Decks

Compression perpendicular to the grain (CPG) is a critical limitation in timber structures,particularly in stress-laminated timber (SLT) decks where high transverse stresses nearanchor zones can compromise long-term performance. This thesis investigates theuse of birch rods as a sustainable, timber-compatible reinforcement method to improveCPG resistance. A series of experimental tests were conducted using C24 softwoodspecimens reinforced with birch rods of varying diameters (10 mm and 20 mm), embeddedin one- and two-layer configurations, with both partial and full engagement.Results demonstrated that birch rod reinforcement can significantly enhance yield capacitycompared to unreinforced samples, with fully engaged rods offering the mostconsistent improvements. The influence of rod diameter, reinforcement depth, andengagement ratio on mechanical performance was systematically analyzed. Findingshighlight the potential of rod-based reinforcement to mitigate local crushing and improveprestress retention in SLT systems. This study contributes valuable data for optimizingreinforcement design and supports the integration of biodegradable materialsinto advanced timber construction.