| China has the world's largest population,relatively limited land resources and space,but it has more than 18000 kilometers of coastline,thousands of natural islands and 3million square kilometers of sovereign sea areas.These sea areas are composed of inland sea,territorial sea,contiguous zone and exclusive economic zone,and there are abundant resources to be utilized.The ocean occupies more than 60% of the global total area.It not only has rich mineral resources,power resources and biological resources,but also has vast space resources.China has carried out reclamation and island building in the South China Sea to further safeguard the rights and interests of the territorial sea.China has the ability to build a very large floating structure(VFLS)in the disputed South China Sea.Compared with the artificial island,VLFS has more flexibility,lower cost and shorter construction period.At present,the research of very large floating structure has become more and more mature,but the related research of floating structure superstructure is still in a blank stage.The influence of the motion of the very large floating body due to the wave action on the superstructure and the influence of elastic deformation of very large floating structure due to wave action on superstructure are the key problems in the design and construction of the building on the very large floating structure.The main work of this paper is as follows:(1)The motion response of a very large floating structure due to wave action under three typical sea conditions is studied.The solution flow of ANSYS / AQWA is introduced briefly.The AQWA is used to construct the whole wet surface model of the very large floating steel frame structure.The environmental parameters are set according to the sea conditions of the South China Sea,and the additional damping coefficient is considered to carry out the frequency-domain analysis of the hydrodynamic force.On this basis,the time history analysis is carried out to solve the acceleration time history curve in three directions under three sea conditions,which lays the foundation for the later structural analysis of the upper steel frame.(2)The dynamic response of the upper steel frame.Taking acceleration time history response of three groups of floating body motion response as input,structural analysis of steel frame model is carried out based on SAP2000.At the same time,a group of three-way natural seismic waves and a group of amplitude modulated seismic waves are introduced to compare and analyze the dynamic response of steel frame under the action of floating body and earthquake.Time history analysis is carried out for the same model.Through the modalanalysis,the natural vibration period and mode shape of the steel frame structure are solved,and then through the time history analysis of five groups of acceleration waves,the interlayer displacement and base shear of the steel frame are compared.The analysis shows that the very large floating structure movement has little influence on the upper steel frame under the wave action.(3)The overall strength of very large floating steel frame structure is studied.Taking the whole very large floating steel frame structure as the research object,the overall strength analysis is carried out based on SESAM software.In this paper,the solution flow of the software is briefly introduced,and the wet surface model and quality model are established respectively by SESAM.Using the wet surface model and mass model,the hydrodynamic analysis is carried out,and the overall motion response Rao and wave load transfer function in frequency domain are obtained.According to the function value,the long-term forecast is carried out,and the dangerous condition of 100 years return period is selected.The internal structure of each part of the very large floating steel frame structure is introduced.According to the dangerous condition,the overall strength of the structure is analyzed,and the deformation of the floating body and the high stress area of the upper steel frame are obtained.(4)The improvement scheme of local high stress area of super large floating steel frame structure is proposed,and the overall strength after local improvement is studied.In view of the deformation of the very large floating structure in dangerous condition and the high stress of steel frame,the local improvement scheme is proposed for the bottom of side column and the interior of floating body of steel frame.The overall strength analysis of the super large floating steel frame structure is carried out again to verify the rationality of the improvement. |
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