The Resistance of Welded Joints of Galvanized RHS Trusses with Different Vent Hole Geometries
Abstract
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Abstract
1. Introduction
- The numerical model needed to be validated against experimental results. For this purpose, the main source of experimental values for the development of design equations for welded joints of RHS trusses (i.e., the Delft University test reports) was used. Six tests on K gap joints between RHS were selected, because their observed failure was related to the so-called “brace failure” of K welded joints between RHS, which involves both the effective width failure and the local buckling failure on the brace elements. This is because they are clearly the failure modes that are expected to be more influenced by the presence of holes in the brace.
- As is clearly stated in the bibliography, in most cases, weld geometry must be modeled in situations where the gaps between the braces are important. However, this was not really modeled in the previous work mentioned, which only considered an estimation of the thermal effects of the weld process. This lack of geometrical weld modeling is solved in this new paper, and the thermal effects mentioned were neglected, since neither the bibliography nor the previous work carried out by the authors [24] showed any appreciable influence of this factor.
- The general design of the experiment presented in the previous work was not specifically focused on failure modes that could be more greatly affected by the vent holes. Nevertheless, in the present paper, a parametric study has been designed by selecting joints that, according to the design equations, could represent “brace failure” or, in some cases, the “chord face failure”, which is very close to a “brace failure”.
- The brace lengths in the models of the previous work led to brace buckling in some cases, but not local buckling at the connection location. The brace lengths were reduced in the present work to ensure that the results really showed joint failures.
- Elliptical holes were not considered in this work, because they are impractical.
- Finally, in this new paper, not only K-joints, but also N-joints were considered.
2. Finite Element Modeling
3. Validation of Finite Element Modeling
4. Parametric Study of K- and N-joints Results and Discussion
5. Conclusions
- -
- The developed FE simulation accurately reproduced the actual behavior of the analyzed joints, showing good agreement with the experimental results when the welds were modeled. Therefore, this model, based on shell elements, is adequate for simulating the RHS K- and N-joints in lattice girders and for predicting the strength and stiffness when fracture in welds can be avoided.
- -
- There is a reasonable agreement with the Eurocode equations, confirming that FEA is a useful tool for obtaining appropriate results regarding joint behavior.
- -
- In the numerical simulation, different combined failure modes were observed, but these were never dependent on the presence of a vent hole or on the shape of the vent hole.
- -
- The local buckling present in a brace failure occurs away from the vent holes and the welds; therefore, in these cases, the presence of holes has no influence on joint resistance.
- -
- If the thickness ratio between the brace and the chord results in chord plastification, the effect of the presence of a hole is also negligible with respect to joint resistance.
- -
- The presence of a ventilation hole for the hot-dip galvanizing process such as those considered in this study does not significantly affect the joint resistance.
- -
- Based on the small differences observed for joint resistance, it is possible to affirm that it does not matter what type of vent holes are used for the galvanization process. All the analyzed hole shapes presented fair performance in terms of the mechanical strength of the joint. Although the shapes that cut the brace-chord weld exerted slightly more influence over the resistance than holes at some distance, all of them could be proposed to be valid solutions for machining vent holes.
- -
- Taking into account the above-mentioned conclusions, we can offer some recommendations for engineers when designing galvanized lattice girders with RHS. They may choose any of the considered vent hole configurations, observing only the suggested filling areas. Therefore, certain preferences throughout the manufacturing process could be reasons for making a final decision.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
Nomenclature
HDG | hot-dip galvanizing |
HSS | hollow structural section |
RHS | rectangular hollow section |
SHS | square hollow section |
b | width of the hollow section |
h | depth of the hollow section |
t | thickness of the hollow section |
g | gap of the joint |
β | ratio of widths (bi/b0) |
γ | ratio (b0/(2t0)) |
fu | ultimate strength |
fy | yield strength |
D | circular vent hole diameter |
H | height of V-notched vent hole |
B | half opening of V-notched vent hole |
R | radius of V-notched vent hole |
α | half angle of V-notched vent hole |
tw | weld throat |
εact, | actual strain |
εeng, | engineering strain |
σeng, | engineering stress |
σact, | actual stress |
Subscripts | |
i | denoting the brace |
o | denoting the chord |
act. | actual value |
eng. | engineering value |
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Test No | Gap (g/b0) | Joint Members | fy [N/mm2] | fu [N/mm2] | Tangent Modulus [N/mm2] |
---|---|---|---|---|---|
1 | 0.10 | Chord: 258 × 258 × 8.4 Comp. Brace: 99.4 × 99 × 6.0 Tension Brace: 103 × 99 × 5.2 | 289 337 317 | 409 402 405 | 1110 802 932 |
2 | 0.43 | Chord: 100 × 100 × 3.8 Braces: 40 × 40 × 4.0 | 261 279 | 363 383 | 963 996 |
3 | 0.15 | Chord: 100 × 100 × 4.1 Braces: 60 × 60 × 4.2 | 462 443 | 512 587 | 1291 1813 |
4 | 0.15 | Chord: 99.8 × 99.8 × 4.3 Braces: 59.7 × 59.7 × 4.4 | 333 376 | 373 411 | 907 958 |
5 | 0.10 | Chord: 102 × 102 × 3.9 Braces: 64 × 64 × 3.3 | 363 369 | 520 511 | 1440 1350 |
6 | 0.10 | Chord: 102 × 102 × 4.2 Braces: 64 × 64 × 4.0 | 321 349 | 501 401 | 1550 729 |
Joint | 2 | 3 | 4 | 5 | 6 |
---|---|---|---|---|---|
Test [kN] | 102 | 215 | 172 | 198 | 193 |
Model [kN] | 105.9 | 232.1 | 185.3 | 204.3 | 198.6 |
Deviation % | 3.8 | 7.9 | 7.7 | 3.2 | 2.9 |
Joint | Chord RHS (b0 × h0 × t0) | Braces SHS (b1 × t1) | β (b1/b0) | γ (b0/2t0) | Gap [mm] | (g/b0) | Angle [°] |
---|---|---|---|---|---|---|---|
KB1 | 60 × 80 × 5 | 30 × 3 | 0.5 | 6 | 37.6 | 0.62 | 45 |
KB2 | 60 × 80 × 5 | 40 × 3 | 0.66 | 6 | 23.4 | 0.39 | 45 |
KC3 | 60 × 80 × 4 | 40 × 3 | 0.66 | 7.5 | 23.4 | 0.39 | 45 |
KB4 | 60 × 80 × 5 | 30 × 3 | 0.5 | 6 | 19.4 | 0.32 | 55 |
KB5 | 80 × 100 × 5 | 40 × 3 | 0.5 | 8 | 43.4 | 0.54 | 45 |
KC6 | 80 × 100 × 5 | 40 × 4 | 0.5 | 8 | 43.4 | 0.54 | 45 |
KC7 | 80 × 100 × 5 | 40 × 5 | 0.5 | 8 | 43.4 | 0.54 | 45 |
KC8 | 60 × 110 × 5 | 30 × 3 | 0.5 | 6 | 28.8 | 0.48 | 60 |
NC9 | 60 × 110 × 4 | 30 × 3 | 0.5 | 7.5 | 18.8 | 0.31 | 45–90 |
NP10 | 60 × 110 × 5 | 30 × 3 | 0.5 | 6 | 18.8 | 0.31 | 45–90 |
NP11 | 60 × 110 × 6 | 30 × 3 | 0.5 | 5 | 18.8 | 0.31 | 45–90 |
Joint | Chord | Braces | Circular | Semi-Circular | V-Notch | |
---|---|---|---|---|---|---|
(b0 × h0 × t0) | (b1 × t1) | D [mm] | D [mm] | B [mm] | H [mm] | |
KB1 | 60 × 80 × 5 | 30 × 3 | 8.5 | 12.0 | 3.3 | 12.8 |
KB2 | 60 × 80 × 5 | 40 × 3 | 12.0 | 17.0 | 4.5 | 20.0 |
KC3 | 60 × 80 × 4 | 40 × 3 | 8.5 | 12.0 | 3.3 | 12.8 |
KB4 | 60 × 80 × 5 | 30 × 3 | 8.5 | 12.0 | 3.3 | 12.8 |
KB5 | 80 × 100 × 5 | 40 × 3 | 12.0 | 17.0 | 4.5 | 20.0 |
KC6 | 80 × 100 × 5 | 40 × 4 | 11.3 | 16.0 | 4.3 | 18.5 |
KC7 | 80 × 100 × 5 | 40 × 5 | 10.6 | 15.0 | 4.0 | 17.1 |
KC8 | 60 × 110 × 5 | 30 × 3 | 8.5 | 12.0 | 3.3 | 12.8 |
NC9 | 60 × 110 × 4 | 30 × 3 | 8.5 | 12.0 | 3.3 | 12.8 |
NP10 | 60 × 110 × 5 | 30 × 3 | 8.5 | 12.0 | 3.3 | 12.8 |
NP11 | 60 × 110 × 6 | 30 × 3 | 8.5 | 12.0 | 3.3 | 12.8 |
Joint | | | | | Type of Failure | |||||
---|---|---|---|---|---|---|---|---|---|---|
KB1 | 85.6 | 88.8 | 84.7 | 87.8 | 84.3 | 88.1 | 82.5 | 86.8 | BF | |
KB2 | 125.1 | 125.7 | 124.8 | 126.2 | 123.9 | 124.9 | 121.9 | 123.5 | BF | |
KC3 | 100.9 | 108.9 | 100.8 | 107.6 | 96.7 | 107.3 | 96.9 | 106.0 | CF | |
KB4 | 75.5 | 90.6 | 75.3 | 89.8 | 74.4 | 89.5 | 72.8 | 88.7 | BF | |
KB5 | 94.5 | 107.0 | 92.3 | 105.9 | 92.6 | 106.5 | 91.5 | 105.2 | BF | |
KC6 | 105.2 | 142.0 | 103.4 | 141.7 | 102.5 | 140.6 | 101.3 | 138.6 | CF | |
KC7 | 112.7 | 183.5 | 111.7 | 184.1 | 109.3 | 181.7 | 109.2 | 178.8 | CF | |
KC8 | 74.1 | 95.5 | 74.4 | 94.4 | 72.6 | 94.4 | 71.5 | 93.8 | CF | |
NC9 | 42.8 | 99.9 | 42.7 | 99.5 | 41.4 | 96.7 | 42.0 | 98.2 | CF | |
NP10 | 67.0 | 99.8 | 65.7 | 100.1 | 64.2 | 98.0 | 64.1 | 98.8 | PS | |
NP11 | 91.2 | 102.6 | 91.1 | 102.7 | 87.2 | 101.3 | 87.7 | 101.7 | PS |
Type of vent hole | ||||||
---|---|---|---|---|---|---|
Circular | Semi-circular | V-notched | ||||
3%b0 | Max. load | 3%b0 | Max. load | 3%b0 | Max. load | |
Mean of deviation [%] | −0.78 | −0.45 | −2.25 | −1.30 | −3.43 | −1.91 |
Maximum deviation [%] | −2.34 | −1.2 | −4.23 | −3.23 | −4.31 | −2.69 |
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Serrano, M.A.; López-Colina, C.; Gayarre, F.L.; Wilkinson, T.; Suárez, J. The Resistance of Welded Joints of Galvanized RHS Trusses with Different Vent Hole Geometries. Appl. Sci. 2019, 9, 1553. https://doi.org/10.3390/app9081553
Serrano MA, López-Colina C, Gayarre FL, Wilkinson T, Suárez J. The Resistance of Welded Joints of Galvanized RHS Trusses with Different Vent Hole Geometries. Applied Sciences. 2019; 9(8):1553. https://doi.org/10.3390/app9081553
Chicago/Turabian StyleSerrano, Miguel A., Carlos López-Colina, Fernando L. Gayarre, Tim Wilkinson, and Jesús Suárez. 2019. "The Resistance of Welded Joints of Galvanized RHS Trusses with Different Vent Hole Geometries" Applied Sciences 9, no. 8: 1553. https://doi.org/10.3390/app9081553