Advanced Steel Construction

Vol. 7, No. 4, pp. 330-343 (2011)


MECHANICAL CALCULATION MODEL FOR WELDED HOLLOW SPHERICAL JOINT IN SPATIAL LATTICED STRUCTURES

 

Yang Ding 1, Lin Qi 2,*, Zhongxian Li 3

1 Professor, Department of Civil Engineering, Tianjin University, Tianjin, China

2 Ph. d candidate, Department of Civil Engineering, Tianjin University, Tianjin, China

3 Professor, Department of Civil Engineering, Tianjin University, Tianjin, China

*(Corresponding author: E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.)

 

Received: 25 January 2011; Revised: 16 March 2011; Accepted: 24 March 2011

DOI:10.18057/IJASC.2011.7.4.2

 

ABSTRACT:

The welded hollow spherical joint has been extensively applied in spatial latticed structures in China. Currently the welded hollow spherical joint is generally modeled by rigid connection. No matter what great loads the structure bears, deformations at the ends of members connected by the same welded hollow spherical joint remain the same. However, in some cases the welded hollow spherical joint could rupture which results in the damage of the structure. Therefore, mechanical calculation model for welded hollow spherical joint should be established for the refined simulation of spatial latticed structures. In this paper multi-step finite element analysis model for welded hollow spherical joint is established. Mechanical behaviors of the joint under cyclic loads can be simulated by this model, and numerical calculation results correspond well with the experiment data. Numerical analysis indicates that when compression load is applied to the welded hollow spherical joint, the strain energy can be transferred in the sphere, and the joint will not rupture. When tension load is applied, deformations of the welded hollow spherical joint concentrate in the area where the tube meets the sphere. The strain energy accumulates continuously there and the joint ruptures when the local stress reaches ultimate shear strength. Mechanical calculation model for welded hollow spherical joint, by which the repeated loading-unloading processes and failure process of the joint under seismic excitations can be simulated, is established by parameter analysis. Numerical calculation results indicate that welded hollow spherical joints of single layer lamella grid cylindrical latticed shell could rupture under strong earthquakes, and the structure damages subsequently due to the topological structure transformation. Bearing capacities of welded hollow spherical joints under strong earthquake can be overestimated if they are modeled by rigid connection. The compression load applied to the joint cannot be bigger than the critical buckling loads of the connected member, so the compression load that the joint carries will not reach its ultimate compression load generally.

 

Keywords:Welded hollow spherical joint, Mechanical calculation model, Finite element analysis model, Rupture, Failure mechanism, Structural damage

 

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