Investigation On The Wind-induced Dynamic Response And Vibration Attenuation Of Metal Composite Roof Panels

Metal composite roof panel is a kind of light roofing system which is widely used in large span roof structures. The finite stiffness and high damping capability of the metal composite roof panel will affect the wind-induced dynamic response of the roof structures, which shouldn’t be ignored. Currently, however, this effect is neglected when performing wind-resistant design for roof structures. The article studies on the widely-used polyurethane sandwich roof panel and fiber sandwich roof panel and explores the influence regularity of these two kinds of composite roof panels for the wind-induced response of the main structure. The article’s work and main results are listed as follows:(1)The article systematically elaborate the algorithm theory and the mathematical description method of metal composite roof panel. The damping property of these two kinds of roof panels is analyzed by the modal strain energy method. The calculation indicates that both of these two kinds of roof panels show high damping capacity. For polyurethane sandwich roof panel, The modal loss factor of low-frequency mode is relatively low, but the modal loss factor of high-frequency mode(50-90Hz) become higher, with the highest modal loss factor reaching to 0.4. For fiber sandwich roof panel, the modal loss factor of both low-frequency and high frequency mode (4.56～69.3Hz) is quite high. The highest modal loss factor is more than 0.5.(2) Wind pressure is applied to roof panel with typical span to analyze the effect of the loss factor of sandwich material, the thickness of sandwich layer, the thickness of metal layer and the stiffness of main structure on pulsating property of wind pressure by investigating support reaction of roof panel. The analysis shows that the support reaction is enlarged and the energy of fluctuating wind is concentrated on the basic frequency area of roof panel because of the finite stiffness of roof panel, while the support reaction is decreased significantly by the damping of the roof panel. Compared to the thickness of sandwich layer and the thickness of metal layer, the loss factor of sandwich material is the decisive factor to the effect of support reaction of roof panel. The finite bearing stiffness of main structure will also enlarge support reaction of roof panel and change the frequency spectrum characteristic of fluctuating wind. For fiber sandwich roof panel, support reaction will decrease as the stiffness of main structure increases. For polyurethane sandwich roof panel, support reaction has no significant regularity with the stiffness of main structure.(3)Effect of the stiffness and damping of these two kinds of roof panels on the wind-induced response of the roof structure is investigated by means of a 30-metre span cross arch shell. The analysis shows that whether the calculation model includes roof panel or not will make a nonnegligible difference to the wind-induced response of the main structure, and the effect is concerned with the stiffness of the main structure. The effect will increase if the stiffness of the main structure decrease. The finite stiffness of roof panel will enlarge the wind-induced response of the main structure while the damping of roof panel plays a role in vibration attenuation. For polyurethane sandwich roof panel, the stiffness of roof panel is more important to the wind-induced response of the main structure, while the damping of roof panel has little effect on the response. For fiber sandwich roof panel, both of the stiffness and damping of roof panel are important to the wind-induced response of the main structure if the stiffness of the main structure is relatively smaller. The vibration-damping property of roof panel becomes the key factor in the wind-induced response of the main structure if the stiffness of the main structure is relatively greater. Overall, the wind-induced response of the main structure will be overvalued without considering the effect of these two kinds of roof panel if the basic frequency of the main structure is no more than 5Hz.