Z-spike rejuvenation of timber railroad bridge members

Abstract

This study examined the effectiveness of using fibreglass reinforced polymer (FRP) spikes in rejuvenating naturally damaged and deteriorated timber railroad bridge chord members. Shear spiking involves inserting the spikes vertically into the members. They are held in place by an adhesive and serve to improve horizontal shear transfer at cracks in the members. Past research had shown that this process can be highly effective in improving the effective stiffness of bridge chord members that were intentionally damaged. This study included four specimens that were salvaged from the field with varying damage conditions. The effect of shear spiking on the effective stiffness of the members was examined by means of load testing. It was observed that the increase in the effective stiffness of the specimens was highly dependent on the initial condition of the specimens. Members with modest damage and deterioration exhibited only a modest benefit from shear spiking. The two most damaged specimens used in the study showed the most promising results, displaying a 267 and 291% increase in effective stiffness, respectively, after completing the spiking. This result suggests the potential for shear spiking as a highly effective technique for in situ repair of damaged or deteriorated timber railroad bridge chord members.