Analysis And Control Technology Of The Roof Garden Damping Effect

The development of the science and the accumulation of the population to the urban area has altered the human living space from the ground to higher latitude,resulting in high rise buildings.However,problems associated with the high rise buildings including the seismic design still need proper solutions.Despite the land saving aspect,the high rise buildings cost more and host more people than the regular buildings.Great loss may happen during the earthquake.Due to these reasons,the seismic design is critical for the engineers.The existing two methods:one method is increasing the strength and stiffness of the structure which inevitably will increase the building cost.Another way is the controlling technology which reduce the loss by minimising the amplitude.Tuned Mass Damper(TMD)is a useful approach.This research focus on a new TMD type-roof garden TMD.This approach reduce the amplitude by the great mass unit-roof garden fixing on the top of the building.Despite the amplitude reducing effect,this structure can also beautify the living circumstances.This research paper includes the following research on the roof garden TMD:?)the seismic computational model and seismic reaction functions for structures with and without roof garden were proposed.An improved LDR method was used in the analysis.?)The connection between spring and laminated plate lead core rubber bearings are researched.The design methods,connection methods,controlling techniques and the determination of the parameters were discussed.These information alleviates the difficulties in the practical design of such structures.?)A numerical model of a reinforced concrete frame based on the practical data was built using SAP 2000 package.Structures with and without roof garden TMD were analyzed for various mass and rubber isolater stiffness.Three kinds of seismic waves including El-centro Wave,Tangshang Wave,Lanzhou Wave were used to calculate the seismic displacement of the structure.Results showed:(1)The roof garden TMD can reduce the displacement by 30%compared with the structure without this method.(2)Theoretically,mass ratio,effective stiffness will contribute to the anti-seismic ability.However,according to this research,with the increment of the mass ration and effective stiffness,the reduction in the horizontal direction is not significant.Simply increasing these two parameters has its own limitations.The optimum values for these two parameters are 0.025 for mass ratio and 1000-2000 KN/m for effective stiffness.The maximum displacement reduction was 36.07%.(3)Roof garden TMD had different contribution to the anti-seismic design of different buildings.In this research,the contribution was not significant for the structure lower than three flours(including the basement).However,the effect was obvious for the higher structure.This research showed that the roof garden TMD not only beatify the landscape of the city,but also effectively reduce the seismic reaction of the high rise buildings,thus minimise the loss during the earthquake.This research provides useful information to the roof garden TMD design and will contribute to the wide spread use of this new technology.