Screw reinforcement on dowel-type moment-resisting connections with cracks

This study uses partially threaded self-tapping screws to enhance the mechanical properties of damaged and undamaged dowel-type timber connections. The damaged connections have a 1.5 mm wide artificial crack across the middle row of the fasteners. Test results showed that screw reinforcement can restore the rotation capacity of damaged connections. The rotational capacity of reinforced connections without cracks is 45.6% higher than unreinforced connections while the improvement on moment-resisting capacity is slight. Digital image correlation (DIC) was used to detect the movement of the connections and validated that the fasteners rotate around the centre of rotation in reinforced connections. Screw reinforcement also demonstrated the ability to control crack propagation, with the reinforced groups showed a reduction of crack length by at least 37% when compared to the unreinforced groups. A calculation method is proposed to calculate the characteristic moment-resisting capacity of damaged and undamaged screw reinforced connections. The calculated values are proven to be conservative when compared with the characteristic value based on the experimental results.