We were recently approached by a Harbour authority worried that the harbour berth unloading ramps were reaching the end of their projected 20 year life.
The replacement cost was going to run into millions and they were interested in finding out whether the structural limits of the ramps were really being reached, due to the years of use and truck weight limits rising from 40 to 60 tonnes, or whether, due to the original over engineering of the structures, there was in fact many years of useful life left in them.
What was required was operational load monitoring of these structures. So we advised checking what loads the ramps and bridges actually experience and comparing with original tested loads, and the strength factors of the structures.
We advised them on how to instrument the bridges so they could measure the parameters they wanted to look at, in this case bending and torsion in each bridge.
What was then required was to do long term data collection so that a fatigue analysis could be carried out, which would provide a life prediction based on the data. We carried out the strain gauge installation, built data acquisition systems and wrote the software to do the data analysis and report generation.
The result was the finding that the structures were not being stressed nearly as much as originally predicted. Thus the planned lifespan was able to be extended, saving millions in replacement costs, disruption to travellers and the business as the replacements were being installed.