Bond Behavior of Concrete-Filled Steel Tube Mega Columns with Different Connectors
2. Parametric Finite-Element Analysis
2.1. Finite-Element Modeling
2.2. Validation of Finite-Element Model
3. Discussion of Results
- The maximum bond stress achieved by the CFST mega column models with mechanical connectors satisfies the minimum requirements of DBJ/T, AIJ, BS5400-5, and EN 1994 while the minimum requirement of the four codes was not met by the mega columns that relied on cohesion only.
- Closely spaced stud connectors (S2-Sp100D19L150) exhibited the highest bond stress, followed by rib connectors with circular holes (R-HD125) and connection plates that run across the CFST (S4-R-Cp).
- Although S2-Sp100D19L150 exhibited high bond stress, nonlinearity started early compared with other models that exhibited high bond stress.
- The rib plate connectors with circular holes exhibited both a high maximum bond stress and a high bond stress before losing linearity.
- Increasing the stud length had a negligible effect on the bond performance for the same number of studs. However, increasing the stud diameter resulted in improved bond performance.
- The use of closely spaced studs, rib plates with circular holes, and connecting plates that run between the parallel walls of the CFST resulted in a considerable slip before the strength degradation commenced. Moreover, the bond stiffnesses of these three connector types were on the same order.
- Increasing the circular hole diameter from 75 to 125 mm in the CFST columns with rib connectors improved the bond strength, stiffness, and maximum bond stress before the proportionality limit.
- The CFST columns that relied solely on the cohesion between steel and concrete (CFST without connectors and R-HD0) showed the poorest performance.
- The stud connectors followed by the rib plate connectors with circular holes were the most efficient with respect to maximum bond stress per connector unit volume.
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
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|Model Name||Stud Spacing||Stud|
|S4-Sp300D19L100||300||19||100||Studs on four faces of the CFST|
|S2-Sp100D19L150||100||19||150||Studs on two parallel faces of the CFST|
|Rib Depth||Rib Hole Diameter|
|Model Name||Rib Thickness||Rib Depth||Stud Spacing||Stud|
|Stud Length||Connecting Plate Thickness|
|Model Name||Total Connector Volume (×106 mm3)||Max Bond Stress (MPa)||Slip at Max. Bond Stress (mm)||Initial Bond Stress–Slip Slope (MPa/mm)||Bond Stress at Proportionality Limit (MPa)||Failure Mode|
|S4-Sp300D19L100||1.36||1.56||2.35||0.68||1.56||Stud–plate weld failure|
|S2-Sp100D19L150||13.10||6.50||24.65||1.02||1.59||Outward buckling of steel tube and stud–plate weld failure|
|R-HD0||33.75||0.06||3.60||0.16||0.06||Steel–concrete bond failure (decohesion)|
|R-HD75||31.54||4.21||16.35||1.16||2.51||Damage of concrete and rib plate near hole|
|R-HD125||27.61||4.45||30.00||1.41||2.82||No strength degradation up to 30-mm slip|
|S4-R||36.47||1.39||19||0.42||0.98||Stud–plate weld failure|
|S4-R-Cp||42.77||4.29||30.00||1.27||1.94||No strength degradation up to 30-mm slip|
|Without connector||-||0.05||3.60||0.16||0.05||Steel–concrete bond failure (decohesion)|
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Alemayehu, R.W.; Bae, J.; Ju, Y.K.; Park, M.J. Bond Behavior of Concrete-Filled Steel Tube Mega Columns with Different Connectors. Materials 2022, 15, 2791. https://doi.org/10.3390/ma15082791
Alemayehu RW, Bae J, Ju YK, Park MJ. Bond Behavior of Concrete-Filled Steel Tube Mega Columns with Different Connectors. Materials. 2022; 15(8):2791. https://doi.org/10.3390/ma15082791Chicago/Turabian Style
Alemayehu, Robel Wondimu, Jaehoon Bae, Young K. Ju, and Min Jae Park. 2022. "Bond Behavior of Concrete-Filled Steel Tube Mega Columns with Different Connectors" Materials 15, no. 8: 2791. https://doi.org/10.3390/ma15082791