Influence of strengthening and repair schemes on dowel type timber joints and moment resisting frames

Abstract

Timber has been a widely used construction material throughout the history of human development and it is still popular to this day. Timber frames are a common structural form used in historical and modern day structures. An effective means to connect timber members together is via bolts or dowels due to their high strength, ductile behaviour and flexibility in application. Such joints are, however, vulnerable and prone to damage especially during seismic attacks. In order to improve the performance and longevity of timber framed structures, it is necessary to develop simple but effective strengthening schemes for dowel-type timber joints. Additionally, strategies to repair and reinstate damaged joints are also required.

The main objectives of this program of doctoral research are to (1) develop strengthening and repair schemes for bolted timber joints using advanced composite materials (i.e. carbon fibre reinforced polymer, CFRP) as well as traditional materials (i.e. steel plates, epoxies and mortars), and (2) investigate the effectiveness of the schemes in improving the seismic performance of timber frames. The strengthening and repair schemes are applied to single-bolt joints and tested under monotonic load. Optimal strengthening and repair schemes are then applied to moment resisting joints and the joints are subjected to monotonic and cyclic loading. Finite element models are then assembled for the latter joint tests. The calibrated joint models are then used in finite element models of timber frames with varying number of storeys and support conditions. The seismic performances of the timber frames are investigated by conducting both nonlinear static and nonlinear time history analyses. The results of the experimental investigations and the finite element analyses show that the strengthening schemes can enhance the strength and stiffness of joints. Optimum strengthening schemes can also improve the seismic performance of timber frames. Based on the work arising from the program of research, future research needs are finally identified.