A FEASIBILITY STUDY ON THE USE OF MEASURED VIBRATION DATA FOR THE DETECTION OF CLIP DAMAGE OF METAL ROOFING SYSTEM
Heung-Fai Lam 1 and Jun Hu 1*
1 Department of Architecture and Civil Engineering, City University of Hong Kong, Hong Kong SAR, China
A standing seam metal roofing system can be characterized as an assembly of metal panels supported on purlins using clips. Compared with the conventional roof deck system, this kind of metal roofs is cost-effective in construction and excellent in waterproof performance. It is widely used in long-span structures, such as exhibition halls, airport terminals and railway stations. However, due to the relatively weak connection (i.e., the clip) between the metal panels and the supported purlins, the metal roof is susceptible to sustained and repeated uplift wind pressure and temperature effects. It is found that clip detachment is the most common failure mode of metal roofs. The main objective of this paper is to carry out a feasibility study on the use of measured vibration data for detecting possible clip damage of the standing seam metal roofing system. The study consists of both numerical and experimental case studies. Finite element model with particular consideration of the seam-clip-purlin connection was first developed. An indoor test panel of a standing seam metal roof was constructed in the heavy structures testing laboratory of City University of Hong Kong. A series of ambient tests were carried out to measure vibration data for the intact system. The modal parameters were extracted from the measurement data using frequency domain decomposition. This set of measured data was employed to update the finite element model, which was then employed to simulated vibration data of the system under a clip damage scenario. The vibration test results as well as the model-predicted results were discussed in detail. The research finds will be helpful in the development of a vibration-based structural health monitoring method for standing seam metal roofing system in the future.
Standing seam metal roof; Finite element model; Operational modal analysis; Model updating