Study On Wind-Induced Dynamic Response And Aerodynamic Damping For Roof Structures

Wind effects on buildings especially on long-span flexible roofs became more and more important. The investigation on dynamic response and wind load factor of long-span flexible roof is not sufficient. Especially, the researches on dynamic response of roofs in the case of sudden opening are still in preliminary stage. Aerodynamic damping of long-span structure plays an important role in wind response of structures. This paper focuses on wind response and aerodynamic damping of long-span roof structures, and the main work is as following.1. Modal analysis on dynamic response of long-span roof structures. This paper brings forward the multi-modal force method using the result of rigid model wind tunnel test to determine wind-induced dynamic response and wind load factor of long-span roof structures. Compare with the results from the time domain method and aeroelastic model wind runnel test, it is shown that the results predicted by the present method have high precision. And in the present method, the contributions of higher vibration modes can be taken into account.2. Theoretical analysis of internal pressure on buildings in the case of sudden opening. Study on the internal pressure dynamics is not widely carried out in our country. This paper gives a summary of alien research results so far. Dynamic wind velocity on opening is simulated using Davenport spectrum and then the transient internal pressure response is computed by adopting a governing differential equation considering the flexibility of roof structure. The relationship of internal pressure to the size of opening, the bulk of building, the structural flexibility and aeroelastic stiffness are also studied. Finally, some significant conclusions are obtained.3. Determination of aerodynamic damping of buildings on conditions of sudden opening. Various methods for determination of aerodynamic damping are available, nevertheless the empirical mode decomposition (EMD) method is thought to be the most suitable method to extract data array trends or mean value, which can treat nonlinear problems objectively. Combined the EMD method, the random decrement technique (RDT) and the Hilbert transform (HT), the aerodynamic damping ratios of long-span flexible roof in the case of round close situation and sudden opening situation are calculated respectively. It is shown that the affect of aerodynamic damping to roof can't be ignored in the sudden opening case.