Author/Authors :
Lan Cheng نويسنده Bolina Ingegneria S.r.l, Via del Gazzato 20, Venice 30174, Italy , Tu Xi نويسنده College of Civil Engineering, Chongqing University, No. 174 Shazhengjie, Shapingba, Chongqing 400030, China , Xue Junqing نويسنده College of Civil Engineering, Fuzhou University, No. 2 Xueyuan Road, University Town, Fuzhou, Fujian 350116, China , Briseghella Bruno نويسنده College of Civil Engineering, Fuzhou University, No. 2 Xueyuan Road, University Town, Fuzhou, Fujian 350116, China , Zordan Tobia نويسنده Bolina Ingegneria S.r.l, Via del Gazzato 20, Venice 30174, Italy
Abstract :
An effective form-finding method for form-fixed spatial network structures is presented in this paper. The adaptive formfinding method is introduced along with the example of designing an ellipsoidal network dome with bar length variations
being as small as possible. A typical spherical geodesic network is selected as an initial state, having bar lengths in a limit
group number. Next, this network is transformed into the ellipsoidal shape as desired by applying compressions on bars
according to the bar length variations caused by transformation. Afterwards, the dynamic relaxation method is employed to
explicitly integrate the node positions by applying residual forces. During the form-finding process, the boundary condition
of constraining nodes on the ellipsoid surface is innovatively considered as reactions on the normal direction of the surface at
node positions, which are balanced with the components of the nodal forces in a reverse direction induced by compressions
on bars. The node positions are also corrected according to the fixed-form condition in each explicit iteration step. In the
serial results of time history, the optimal solution is found from a time history of states by properly choosing convergence
criteria, and the presented form-finding procedure is proved to be applicable for form-fxed problems.