Study On Dynamic Behavior Of Single Layer Spherical Wooden Reticulated Shell With Central Steel Hub Joints

Wooden reticulated shell is a typical form of large-span wooden structures.Existing engineering examples of wooden reticulated shells showed good structural safety and durability,energy conservation,carbon fixation,ecofriendliness,and etc.In recent years,wooden reticulated shells are attracting increasing research efforts both in China and around the world.However,the research on dynamic performance of them are inadequate.In this paper,Taking Bijie dome(in Guizhou,China)as an example,the mechanical properties of central steel hub joints and the overall dynamic performance of wooden reticulated shells are studied.In terms of the mechanical properties of the joint,firstly,according to the structural characteristics of the central steel hub joint,a general finite element analysis model is established,and the applicability and accuracy of the model are verified by comparing with the results of some joint tests under compression and bending.Secondly,based on this finite element model,the influences of the tensile stiffness of connectors and axial force level on the rotational performance of the joint are studied.Thirdly,based on theoretical analysis,a total of six load carrying states(which fall into two general categories,I and II)of central steel hub joints are identified.For the two key status(?b,??a),further analysis were carried out to arrive at corresponding formula of the ultimate bending capacity of the joint,as a function of the ultimate state of the stress element in the joint.Methods of plotting the bending moment curve of the joints are also proposed on basis of above status.At last,by employing several examples,the performance of the theoretical formula is compared with the results of the finite element method.Good agreement was found and the theoretical formula is believed to be suitable for the calculation of the joint bending capacity.About the dynamic performance of wooden reticulated shell structures,first of all,the natural vibration characteristics and the response analysis under the earthquake are carried out employing a spatial beam finite element model of the wooden reticulated shell.In order to reflect the characteristics of strong restraint effect of wood lattice shell roof panel,a method of widening beam width was put forward.This method is simple to operate and easy to calculate,which can avoid the overall torsion trend of wood lattice shell in the spherical plane,so that the model is closer to the engineering practice.In the dynamic analysis of the spatial model of wooden reticulated shell,the influence of different roof conditions on its natural frequency distribution and the macroscopic time history response under the action of frequent earthquakes is compared,and the parametric analysis is carried out in combination with other influencing factors.After that,the failure mechanism of the wooden reticulated shell under the harmonic load is preliminarily explored,and the peak acceleration increment dynamic analysis of the horizontal and vertical harmonic load is carried out respectively.It was found that the failure mode of the wooden reticulated shell under the dynamic load obviously tends to the dynamic strength failure,showing good ductility in the failure process.The work of this paper provides a reference for improving the calculation of central steel hub joints of wooden latticed shells.A preliminary exploration of the dynamic performance of single-layer spherical wooden latticed shell was also made,which provides theoretical and technical supports for the seismic design of wooden latticed shells.