Advanced Steel Construction

Vol. 11, No. 4, pp. 452-468 (2015)


STATIC EQUILIBRIUM FORM-FINDING ANALYSIS OF CABLE-STRUT SYSTEM BASED ON NONLINEAR DYNAMIC FINITE ELEMENT METHOD

 

Bin Luo 1,2*, Zhengxing Guo 1,2, Xiangnan Chen 1 , Feng Gao 3 and Kai Wang 4

1 Key Laboratory of C& PC Structures of China Ministry of Education,

Southeast University, SiPaiLou 2, Nanjing, 210096, China

2 Nantional Prestress Engineering Research Center,

Southeast University, SiPaiLou 2, Nanjing, 210096, China

Shanghai Institute of Architectural Design & Research(Co., Ltd)

No.258 Shi Men Er Road, Shanghai, 200041 ,China

4 Architecture Design&Research Institue of Southeast University,

SiPaiLou 2, Nanjing, 210096, China

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

 

DOI:10.18057/IJASC.2015.11.4.4

 

ABSTRACT:
Full tensile structures (such as cable domes, cable networks and cable trusses) are structures that only consist of cables and struts. There are three steps in its onsite construction: (1) assembly and connection, (2) towing and lifting and (3) tensioning and shaping. During construction process, the structure may suffer from large mechanism displacement and cable slack, so its initial shape was far from equilibrium. The form-finding analysis is a major difficulty in the construction process analysis. In this paper, we propose a new method for static equilibrium form-finding analysis of a cable-strut system based on a nonlinear dynamic finite element method and introduce virtual inertia and viscous damping force, as well as a series analysis techniques and a multi-step continuous solver. When the total system kinetic energy reaches its peak, the finite element model is updated, and the dynamic equilibria gradually converge to a static equilibrium state through iterative updating. To improve the analysis efficiency, stability and accuracy, key technical measures are proposed for time-step lengths, total energy peak value, model updating, convergence criteria and static equilibrium verification. In the case of the rigid cable dome in Wuxi New District Science and Technology Exchange Centre in China, we used this method to perform the mechanical analysis during the integral tow-lifting and tensioning process, and the project corresponded with our analysis. Meanwhile, we have to mention that during the construction process of integral tow-lifting, an inflection point exists in the adjustment phase, at which point the configuration stability is the worst and struts can fall sideways. Especially, for cable domes with a high rise-span ratio, the stability at the inflection point needs to be addressed.

 

Keywords:cable-strut system; static equilibrium state; form-finding; nonlinear dynamic finite elements; non-bracket tow-lifting construction technology

 

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