监视80年历史的加拿大皇家空军沃伦·桁架机库的结构健康
Case study
Author:TFD
监视80年历史的加拿大皇家空军沃伦·桁架机库的结构健康
Meant to be temporary, many of the hastily constructed aircraft hangars built during WWII are still in use across Canada. For example, the Canadian Armed Forces still maintain approximately 70 Warren truss hangars across the country. The Canadian Forces Base (CFB) in St-Jean in Québec has several Warren truss hangars that it takes care of to meet current operational requirements. Although still functional, the hangars do pose some structural integrity and serviceability concerns. Safety limits placed on the buildings have an impact on CFB St-Jean’s day-to-day operations, so the Canadian Department of National Defence (DND) asked a research team (The RMC Green Team) from the Royal Military College of Canada (RMC) to investigate. The team devised a remote, continuous, real-time structural health monitoring (SHM) programme that includes the use of Leica Geosystems instruments. The SHM is both an alert system and a tool for in-depth structural analysis.
Developing a research-based, data-driven approach to building safety
The heritage timber hangers, constructed using 34m long double-span Warren trusses, were part of the Royal Canadian Air Force’s contribution to the British Commonwealth Air Training Plan in 1942. Material shortages during wartime, material degradation, environmental stresses, and significant repairs have weakened or altered the stress distribution within the buildings. To define whether they are still safe to use, DND approached Dr Nicholas Vlachopoulos, Full Professor, Civil Engineering Department, from RMC to design and install a monitoring program. Lt Henry Helmer-Smith, a PhD student, is the lead researcher on the project, supervised by both, Dr Nicholas Vlachopoulos and Dr Marc-André Dagenais from the Civil Engineering Department at RMC.
机库1 -没有w serving as a supply depot at CFB St Jean – was the structure selected to be monitored. This hangar must be evacuated when snow on the roof exceeds 10 cm (4 inches), something that’s certainly not out of the ordinary in Québec during the winter months. Among other questions, the team wanted to find out if this snow accumulation limit warranted evacuations.
长期，连续和远程监控，并通过实时警报
RMC Green团队建立了一个监视系统，包括解决方案，例如Leica Nova TM50automatic total station with reflectorless EDM (R1000) andLeica GeoMoS software suite. Dr. Vlachopoulos says: “When first approached to come up with a structural health monitoring solution for the performance of Warren truss structures within the Department of National Defence, naturally, automatic total stations and in particular, Leica Geosystems products, were on the initial list of possible solutions.”
关键要求是总站可以连续可操作，远程访问，可就业，最重要的是能够传输警亚博5分钟快三报消息。该程序中包括挠度监测，这些仪器能够根据机库内的桁架和其他结构成员的绝对，短期和长期位移来向用户或机库乘员发送警报以撤离。综合且灵活的Geomos监视系统包括其他几个警报选项，包括传感器连接损失，功率故障，目标损失（视线问题）等。警报系统被编程为通过电子邮件（内置在Geomos Monitor中）或SMS文本通过ASPSMS.com直接与用户通信SMS监视解决方案which is compatible with the GeoMoS Suite.徕卡TM50被选中,是因为它满足了requirements and because compatible Leica software can transmit alerts via email and text in real-time for emergencies. This feature is often used for monitoring discrete points of buildings.
“非常有效的紧急监控工具”
The Leica TM50 automatic total station was installed in Hangar 1 in the spring of 2018 and is still operating today. It is programmed using GeoMoS Monitor to measure more than 20 targets throughout the building at two-hour intervals. GeoMoS Analyzer is then used to read and display all processed data both remotely and in real-time. Based on assigned limits, the frequency of readings can be increased and become continuous when needed. If limits are met, then alerts are issued. Helmer-Smith says: “The remotely operable capabilities of the TM50 combined with the transmitting and displaying of data in real-time make it an extremely effective instrument for emergency monitoring.” The base has been able to reduce the number of evacuations from Hangar 1, because of the accurate and real-time feedback provided by the total station.
“Significantly more user-friendly than other equipment”
在安装监测设备之前，研究团队建立了单跨桁架的四分之一尺寸尺度模型，以在RMC的结构实验室进行测试。实验室阶段旨在测试监测系统并解决任何局限性。Vlachopoulos博士说：“总站本身非常友好，只花了几个小时才能学习。软件和消息传递配置花了几天时间来优化和完全理解。值得注意的是，该仪器比我们测试的其他设备更具用户友好。”
Expanding the cost-effective monitoring program nationwide
Besides the successful emergency monitoring, the Leica Geosystems total station is also used for an in-depth structural analysis of Warren Truss hangars. This in-depth analysis has provided important information regarding the true behaviour of the truss structure. The solution has been cost-effective because it cuts down on necessary site visits. The team accesses the total station remotely via GeoMoS Monitor and carries out discrete surveying from their office in Kingston, more than 300 km away. Following the trial, the monitoring program will be optimised with a view to expand the project nationwide. If safe, the hangars will continue their long and exemplary service.
有兴趣监视吗？请随时阅读进一步的案例研究，显示我们的客户如何使用我们的解决方案来改善其监视工作流程：
