Multidimentional Vibration Control Of Long-span Spatialpipe Truss Structure

Long-span spatial pipe truss structure,with the spatial static behavior that can reduce the cross-section size of structural members and increase the use space of the building,has a rich form of expression and reflects the level of construction and comprehensive national strength of a country.Since the space structures is usually applied to a public building with large flow of people,such as railway station or terminal building.it is required to have superior performance than a conventional building.The Vibration of the spatial structure has multi-dimensionality.Although the conventional isolation technology shows good isolation effect in earthquakes,the damping effect on the vertical vibration of the structure is limited.Therefore,some scholars have proposed the damping method of using dampers to replace some members of the spatial structures.and put forward the method of using dampers to reduce vibration in space structures.The optimization objective and optimization algorithm for the damper arrangement in the space grid structure,double-layer cylindrical latticed shell,spherical shell and cantilever truss are proposed.In order to realize multidimensional vibration control of long-span pipe truss structure,the truss structure with different spans is established in this paper.Based on the vibration reduction of the isolation bearing,the viscoelastic dampers is used to replace the members in the structure to construct the multidimensional vibration controlsystem.By comparing the deformation energy of the members at different positions in the isolation structure,it is determined that the damper arrangement range is at the upper and lower chords of the middle 1/2 span where the dimensionless deformation energy E_mis greater than 70%.The time history analysis of the vibration isolation structure with the replacement of the members at different positionsunder the action of three-way earthquake has been implied.The results showthat in the truss of 100m span and80m span,the damper arrangement position with significant vertical vibration control effect is located in the middle 1/2 span of the upper and lower chords with large deformation energy,and in the 60m span truss,only the upper chord at the 1/3span has vertical vibration control effect.Based on the deflection of the truss structure,the range of equivalent stiffness of damper is determined.The equivalent stiffness of damper for different span vibration isolation structure should not be less than 30%.It can also be concluded that the smaller the equivalent stiffness is,the better the vertical vibration control effect of the vibration control structure is achieved.Under the condition that the location and stiffness of the damper are known,the optimal value of the damping coefficient of the damper exists and increases with the increase of the stiffness of the damper.The multidimensional dynamic response of structural joints and the dynamic response of members can be greatly reduced by reducing the equivalent stiffness of dampers and optimizing the damping coefficient of vibration isolation structures,which provides a reference for the design of multidimensional vibration control of long-span tubular truss structures.