Abstract
This paper introduces the influence factors of axial stiffness of tubular X-joints. The analysis model of tubular joints using plate and shell finite element method is also made. Systematic single-parameter analysis of tubular X-joints is performed using Ansys program. The influences of those factors, including ratio of brace diameter to chord diameter (β), ratio of chord diameter to twice chord thickness (γ), ratio of brace wall thickness to that of chord (τ), brace-to-chord intersection angle (θ), and chord stress ratio, ratio of another brace diameter to chord diameter, in-plane and out-of-plane moment of braces, etc., on stiffness of tubular X-joints are analyzed. Two non-dimensional parameters—joint axial stiffness factor η N and axial force capacity factor ω N are proposed, and the relationship curve of the two factors is determined. Computational formulas of tubular X-joint axial stiffness are obtained by multi-element regression technology. The formulas can be used in design and analysis of steel tubular structures.
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Abbreviations
- A :
-
The cross-sectional area of brace
- D :
-
Chord diameter
- d :
-
Brace diameter
- d 2 :
-
The other brace’s diameter
- E :
-
Elastic modulus
- f y :
-
Yield strength
- L :
-
Length of chord
- l :
-
Length of brace
- M I :
-
In-plane moment of braces
- M W :
-
Out-of-plane moment of braces
- N i :
-
Axial force of brace at the i load step
- N pj cX :
-
The designed value of the maximum pressure
- T :
-
Chord wall thickness
- t :
-
Brace wall thickness
- W :
-
Section modulus
- β :
-
β = d/D
- β 2 :
-
β 2 = d 2/D
- γ :
-
γ = D/(2T)
- δ i :
-
Deformation of the tubular joint at the ith load step
- η N :
-
Joint axial stiffness factor
- θ :
-
Brace-to-chord intersection angle
- σ/f y :
-
Chord stress ratio
- τ :
-
τ = t/T
- ω N :
-
Joint capacity factor
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Qiu, Gz., Zhao, Jc. Analysis and calculation of axial stiffness of tubular X-joints under compression on braces. J. Shanghai Jiaotong Univ. (Sci.) 14, 410–417 (2009). https://doi.org/10.1007/s12204-009-0410-y
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DOI: https://doi.org/10.1007/s12204-009-0410-y