Experimental and Numerical Studies on Dynamic Characteristics of Long-Span Cable-Supported Pipe Systems

Abstract

Cable-supported pipe structure (CSPS) is a system of structure which has improved capacity over conventional elevated pipe structure, in terms of the capacity of span but with limited application owing to insufficient vibration characteristics and performance evidence. The study focuses on experimental modal and updating of the 64.8 m CSPS model to improve the dynamic behavior of the CSPS structure. Three scenarios of 8 m span scaled down CSPS models, which include the single tube pipe system, the double tube pipe system, and the truss spacing modification were evaluated. Comparative assessment of the modal frequencies of modes of the experimental and numerical set shows coupled torsion-lateral responses. The double tube and truss members modifications resulted in an upward shift of all resonating modal frequencies, improving the structural damping. The upward shift of frequencies of mass modification results produces modal assurances of about 100% which are attributed to matching modes with the original mode sets as against the numerical sets. The results of the scaled down models indicate large spans are more vulnerable to resonance considering the reduction of the modal frequencies of the 64.8 m CSPS finite element models. The results were compared with design guidelines and research findings of other Cable-supported structures. It was evident that minimising the vibration of the CSPS structure would prevent excessive deformation of the structure. The pipe and truss members modification provide effective vibration attenuation of the vibration but the CSPS structure would require the use of damping device in severe vibration conditions. Herein lies the limitation of this work as the application of vibration control device are left for further research.