EXPERIMENTAL STUDIES ON STRESS CONCENTRATION FACTORS FOR PARTIALLY OVERLAPPED CIRCULAR HOLLOW SECTION K-JOINTS

The aim of this paper is to investigate the effects of non-dimensional geometric parameters on stress concentration factors (SCFs) of circular hollow section CHS brace-to-H-shaped section T-connections under axial compression. This type of welded joints is used increasingly in steel construction. However, its fatigue design is not covered by codes, and its fatigue strength has not been given the deserved attention by researchers. This research, however, bridges the gab on SCFs in this type of welded connections when being loaded in axial compression. here, parametric study based on the numerical analysis was performed to evaluate the effect of CHS brace diameter to H-shaped chord flange width ratio (β), H-shaped chord flange width to thickness ratio (2γ) and CHS brace thickness to H-shaped chord flange thickness ratio (τ) on SCFs in the brace and the chord of the connection. Based on practical considerations, the validity range of these parameters was 0.3 ≤ β ≤ 0.7, 16 ≤ 2γ ≤ 30 and 0.2 ≤ τ ≤ 0.1. Three-dimensional finite element (FE) study using commercial software ABAQUS was performed to study the hot spot stress distribution and hence SCFs in this type of welded joints. To begin with, the results of FEM were verified against available experimental data and good agreement was achieved. Afterwards, 48 joints were modeled in Abaqus to study the effect of geometrical parameter on SCFs in brace and chord. Based on the results of this extensive study, the effect of geometrical parameters was revealed. The paper, thus, shows that whilst β increases, SCFs in the brace and chord increases. Moreover, increasing the parameter 2γ results in an increase in SCFs in the two members. However, the change in τ has no significant effect on the SCFs in the brace or the chord. Values of SCFs are found to be between 2 and 7.

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Stress concentration factors for non-90° X-connections made of square hollow sections

Canadian Journal of Civil Engineering ◽

10.1139/l97-085 ◽

1998 ◽

Vol 25 (2) ◽

pp. 370-375 ◽

Cited By ~ 11

Author(s):

J A Packer ◽

J Wardenier

Keyword(s):

Stress Concentration ◽

Strong Influence ◽

Hot Spot ◽

Steel Structures ◽

Hot Spot Stress ◽

Hollow Section ◽

Measured Stress ◽

Concentration Factors ◽

Stress Concentration Factors ◽

Hollow Structural Sections

A number of fatigue experiments and stress concentration factor measurements on non-90°, square hollow section X-connections have been carried out. Comparison of the measured stress concentration factors with those derived from existing parametric formulae for 90° T- and X-connections showed a strong influence of the brace angle. A tentative extension of the range of validity of the parametric formulae for 90° T- and X-connections for other brace angles has been derived.Key words: steel structures, connections, fatigue, hollow structural sections, hot spot stress, stress concentration factors.

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Experimental and numerical analysis of the stress concentration factor for concrete-filled square hollow section Y-joints

Advances in Structural Engineering ◽

10.1177/1369433219884462 ◽

2019 ◽

Vol 23 (5) ◽

pp. 869-883

Author(s):

Lei Jiang ◽

Yongjian Liu ◽

Jiang Liu ◽

Bin Liu

Keyword(s):

Finite Element ◽

Stress Concentration ◽

Parametric Design ◽

Hot Spot ◽

Design Parameters ◽

Finite Element Models ◽

Stress Concentrations ◽

Hollow Section ◽

Concentration Factors ◽

Stress Concentration Factors

Previous studies have shown that the stress concentration factors for 90° square hollow section T- and X-joints can be significantly reduced by filling the chord with concrete and stiffening the chord with perfobond ribs. The current study examined stress concentration factors for non-90° (Y-type) joints. A total of 11 Y-joints were tested under axial tension, and the hot spot stresses were measured. The measured results were employed to evaluate the influence of design parameters on the stress concentrations. In addition, the measured results were used to evaluate finite element models. A parametric study was then undertaken using the finite element models to generate an extensive database of stress concentration factors and to develop parametric design equations to estimate the maximum stress concentration factors on the brace and the chord of concrete-filled square hollow section Y-joints with perfobond ribs. It was found that decreases of 13.7%–59.9% in the stress concentration factors occurred in concrete-filled square hollow section Y-joints stiffened by perfobond ribs relative to conventional square hollow section joints for different loading cases.

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Stress concentration factors in concrete-filled square hollow section joints with perfobond ribs

Engineering Structures ◽

10.1016/j.engstruct.2018.12.016 ◽

2019 ◽

Vol 181 ◽

pp. 165-180 ◽

Cited By ~ 10

Author(s):

Lei Jiang ◽

Yongjian Liu ◽

Amir Fam

Keyword(s):

Stress Concentration ◽

Hollow Section ◽

Concentration Factors ◽

Stress Concentration Factors

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Relative Notch Factor for Tubular Joint Stress Concentration Under High Load

Volume 3: Materials Technology; Jan Vugts Symposium on Design Methodology of Offshore Structures; Jo Pinkster Symposium on Second Order Wave Drift Forces on Floating Structures; Johan Wichers Symposium on Mooring of Floating Structures in Waves ◽

10.1115/omae2011-49914 ◽

2011 ◽

Author(s):

Wangwen Zhao

Keyword(s):

Stress Concentration ◽

Hot Spot ◽

Experimental Studies ◽

Worst Case ◽

Joint Stress ◽

Non Linear ◽

Tubular Joint ◽

Concentration Factors ◽

Stress Concentration Factors ◽

Neuber's Rule

When load causes stress above the yielding stress, stress concentration factor from linear conditions can no longer be applied. Neuber’s rule has been traditionally used to estimate the non-linear stress concentration factors to avoid elaborate numerical analysis. However, the multiaxial stress state around the tubular intersection has been found to be too complex for Neuber’s rule to be applied directly. To facilitate calculation of non-linear stress concentration for tubular intersection, this paper proposed an effective relative notch factor for tubular connection stress concentration based on available linear stress concentration factors and fatigue experimental studies. This approach is validated by detailed FE analysis for three representative tubular joint configurations, two T joints and one Y joint. It has been found that although the stress states are different from typical notch specimen, the modified Neuber’s method using notch stress concentration factors Kt = Ktn as a product of tubular hot spot SCF and relative notch factor of 1.53 matches true stress closely initially but progressively become less and less accurate. When the applied load is about 70% of the plastic collapse load, the method give 30% under prediction at the worst case. This may be due to unaccounted non-linear effect from local buckling and excessive plasticity.

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