The Dmaping Effect Analysis Of A Large Cantilevered Truss Structures

Under seismic action,certain components of the large-span truss structures absorb a large number of seismic energy into the elastic-plastic state, or even yield, destruction,and then they may resulte in the structure which can not be restored,even directly collapsed after the earthquake.Based on the seismic fortification goal that"a little earthquake was not bad,the medium earthquake could be repaired and the enormous earthquake would not fall",more and more energy dissipation technologies were applied to the large-span truss structures. Energy dissipation techniques were increasingly being applied in building structures,especially the large-span truss structures. Because of its good force features,Grid structure had become an increasing lovely by national architects and structural engineers.It had been used of a wide range of fields,such as sports architecture,culture architecture.With economic development and scientific and technological progress,spatial structure was moving towards to large-scale,complex,and it would bring in the calculation and design problems.Large cantilevered truss structure was a special form of the large-span space truss structure,and it was more applied to a large important gathering public buildings,so we must considered the safe application of such buildings under seismic action,especially the occasional value of earthquake.The using of damping on energy dissipation was no longer a fresh technology after seventies the twentieth century,and the viscous dampers was such components which was used damping to absorbe and dissipate the seismic energy.the dampers were reasonable arrangemented in the structure which could consume most of the seismic energy,reduce the structural displacement improve or enhance the seismic performance of the structures.There were many ways applied to structural analysis of energy dissipation,in this article,it was as a reference to five kinds of analytical methods.Among that,time-history analysis method was one that commonly used for structural energy dissipation.The Fast Nonlinear Analysis Method (FNA) method was a analysis method which based on nonlinear time history analysis,was especially applied to the system or structure which local was non-linear and the other parts was non-elastic.In this paper,the truss structural model is that two adjacent edges are large cantilevered. his structure is work together with the lower part of frame structure as a whole.Fist of all,it used the finite element analysis software Sap2000 to establish the truss structure model,through optimization of all bars, it reduces the bars types, reduces the grid weight and achieves the economy optimal of the truss structure; and then it applicates of the rapid non-linear analysis method,uses viscous dampers as energy dissipation components to carry on the analysis of structural damping. It introduces three kinds of seismic waves such as El centro wave,Taft wave and an artificial seismic wave,through six kinds of program design to optimize the choice. To the large cantilevered truss structure,the best location was less than half of the cantilevered length attached to the cantilever side;Finaly, through different damping coefficient,damping index,the number of optimal damper design,it got an optimization design model of the large cantilevered truss structure.It proved that viscous damper damping system was the effectiveness to grid structure.it provided the experiences and data for the future more in-depth effective theoretical and experimental study to long-span space structure.