Structural Behavior Of Semi-rigid Joints In Reticulated Timber Shells

The difficulty and key points to build single-layer reticulated timber sphericalshells are design of joint connections. The stability of wood shells and the forms andperformance of the joints are not yet well known,which is usually assumed to be eitherrigid or hinged. However, this doesn’t correspond to the actual situations.It is thusimportant and useful to design the forms of joint and investigate its structural behavior.This paper chose a50m span improved K6spherical shell，and conductedeigenvalue analysis and nonlinear analysis using ABAQUS, firstly supposing its jointconnections as rigid. The internal forces of members of the shell were obtainted underthe design load, and the force were used to design the forms of the specific joint and thedimensions of it’s components, considering the principle that the force should betransferred explicitly and effectively, and based on the study of bolted connections athome and abroad.Different situations were selected according to the internal forces of shell, and theflexural load-bearing performance of joint models was tested under axial compressionload cases of0kN,100kN,200kN and300kN, respectively. Test specimens’load-displacement curves and moment-rotation curves were obtained combining with itsrotation and vertical displacement.This paper also investigated the influence of axialforce on the ultimate strength and initial rotational stiffness, and classified thespecimens into modes. Mathematical model was selected to fit the moment-rotationcurves and the results were in good agreement with the experiment.The constitutive relation of bolt hole area of wood components was simplified andthe perfectly elasto plastic model was adopted instead of the actual working curve in theFE model of test specimens,and this method obtained satisfactory results. Based on thework above, the parametric analysis of joint connection was conducted to investigatethe influence of its ultimate flexural resistance by changing the bolt diameter, boltstrength, speicies of wood member and steel plate thickness.The moment-rotation curve of the condition without axial forces was employed tothe FE model of the reticulated timber shell, the stability analysis of the spherical shellwith semi-rigid joint connections was conducted. The result showed that the forms ofjoint designed in this paper can meet the requirement of the design value of load.