Thursday, July 19, 2012


At the IABMAS (International Association for Bridge Maintenance and Safety) 2012 conference, I presented a case study we conducted some time ago for a local bridge owner.

The abstract of the paper is as follows:
A 50-year-old bridge showed large cracking in the approach bridge parts due to restraint of deformation and support settlement. After repair, it was uncertain at which crack width the traffic loads on the bridge should be further restricted. The shear capacity was calculated by counting on the aggregate interlock capacity of a supposedly fully cracked cross-section. An aggregate interlock relation between shear capacity and crack width based on an unreinforced section was used to find the crack width at which the shear capacity of the section with a through crack becomes smaller than the shear capacity of the section without a through crack. Limits for crack widths at which load restrictions should be imposed were found. The large structural capacity of the cracked concrete section shows that the residual bearing resistance based on the aggregate interlock capacity of reinforced concrete slab bridges with existing cracks is higher than expected.

And here are the slides of my presentation:


  1. Missed your presentation at IABMAS, but enjoyed reading your website and the links to similar ones. I'll be updating my own links now!

    On assessing the bridge for the Eurocode Notional Load Model 1 though - it's quite conservative (as it should be for new bridges). For a site-specific bridge assessment such as your work a site-specific load model based on weigh-in-motion data will be more cost-effective for a client if it eliminates replacement/major repairs.

    Best of luck with the research!

  2. Thanks!

    I agree - it's a conservative approach still when using the load models from the code.
    My main project deals with slab bridges in shear. As there are about 2000 of these bridges, with roughly 600 under discussion, we advised the ministry in the development of a quick assessment tool, based on the loads from Load Model 1. But that method is just considered to be a (in Model Code terminology) a "first level" approach - providing still a list of options for sections which might not qualify at first.