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.

Load tests of damaged railroad timber stringers repaired by shear spiking

“…That extensive work is to be published in a future paper. However, a prior paper published in this journal (Gutkowski et al (2010) described a separate study of the successful application of shear spiking to damaged members obtained from the field. In addition, a field demonstration of shear spiking on an actual inservice timber trestle bridge has been arranged with a major railroad company and, when completed and documented, will also be published.…”

To repair or not to repair cracked wood

“…To approach the original strength of the wood piece, it appears that the most promising strategies are (a) gluing of rods, nails, bolts, or spikes into holes that are drilled perpendicular to the grain of the wood (Akbiyik et al 2007), and (b) attachment of high-tensile-strength "patches" to the side of the wood piece that is expected to be in tension (Clarke et al 1993;Campilho et al 2009;Barreto et al 2010). These types of repairs have been used in many practical cases, including the floor of an ancient building (Metelli et al 2016) and in the repair of timber bridges (Burgers et al 2008;Gutkowski et al 2010).…”

Editorial

“…Gutkowski et al (2010) show that glass fibre reinforced polymer (GFRP) spikes inserted vertically into and adhesively-bonded to the damaged members can strongly improve horizontal shear transfer at pre-existing cracks. The resulting factor by which load capacity is increased depends on the extent of pre-existing damage.…”