As part of the Whiteleys Redevelopment project in Bayswater, London, Praeter Engineering were asked to provide a solution to monitor the loads being transferred through 3 raking props supporting the capping beam at ground level. As part of the project’s top-down construction methodology it was critical for the site team that the loads in the props could be monitored as the excavation continued. The props were installed to provide additional support to the capping beam and prevent excessive deflections of the beam and unwanted movement of the beam towards the dig out area.
The solution was to affix 4 strain gauges at approximately mid-span and around the circumference of the prop, the strain on each of the 4 gauges around the props are averaged out for the alert system. The strain gauges were connected to wireless battery powered transmitters in pairs, a wireless battery powered access point was also installed to collect all of data from the transmitters and upload to our online monitoring system. We used magnetic fixing points to attach the transmitters and access points to the props to keep them out of harms way. The use of our battery powered monitoring equipment was critical as routing mains power to the work front that is constantly changing and therefore prone to damage is something that we can totally omit with the system.
A Red, Amber, Green (RAG) alert system has been input into the monitoring system and if the loads within the props exceed these trigger points the designated site team members will be automatically alerted to the breach for further investigation. The red trigger compression load in the props was set at in the range of 1000kN’s with a tension load in the range of 100kN’s.
Our online monitoring platform allows 24/7 access to the data for the site engineers to review as part of their daily checks and to be used in combination with physical surveying of the beam to monitor for excessive movements. Data is uploaded in 30-minute intervals to preserve battery life and is over and above the client’s brief of 2 data points per day.
This project is one of the many fully wireless structural health monitoring solutions we can provide our clients, our monitoring solutions are fully customisable for any project requirements.