Bond stress-slip relationship in concrete-filled square stainless steel tubes

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Some studies found that higher concrete strength may improve bond strength of concrete-filled steel tubes, whereas Yan et al. reached the opposite conclusion.

“Xue and Cai [4,5], Chang et al. [14] and Qu et al. [15] found that the higher concrete strength may improve the bond strength, whereas Yan et al. [16] reached the opposite conclusion.”

• cites [4] 4. L.H. Xue, S.H. Cai, Bond strength at interface of concrete-filled steel tube columns (a), Build. Sci. 03 (1996) 22-28.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [5] 5. L.H. Xue, S.H. Cai, Bond strength at interface of concrete-filled steel tube columns (b), Build. Sci. 04 (1996) 19-23.Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [14] 14. X. Chang, C.K. Huang, D.C. Jiang, Y.C. Song, Push-out test of pre-stressing concrete filled circular steel tube columns by means of expansive cement, Constr. Build. Mater. 23 (1) (2009) 491-497. sourceNot checked — no full text of the source
• cites [15] 15. X. S. Qu, Z. H. Chen, D. A. Nethercot, L. Gardner, and M. Theofanous, Push-out tests and bond strength of rectangular CFST columns, Steel Compos. Struct. 19 (1) (2015) 21-41. sourceSupported

The quote only partly states this claim.

The slip displacement corresponding to τu in CFSSST specimens without rib stiffeners is only around 1 mm over a bond length of 900 mm.

“For CFSSST specimens, the micro-interlocking force is the major component of the bond resistance before τu, as can be evidenced by Fig. 7 that the slip displacement corresponding to τu is only around 1 mm (compared to a bond length of 900 mm), which was unlikely to lead to large slide friction and be associated with the macro-interlocking force.”

May combine two claims.

With increasing slip, the bond stress increased linearly with no obvious friction sound at this stage.

“With the increase of the slip, the bond stress increased linearly with no obvious friction sound at this stage.”

May combine two claims.

After the first peak, a sudden huge sound occurred with the load dropping drastically without slipping.

“This was followed by a sudden huge sound with the load dropped drastically without slipping.”

May combine two claims.

In the later stage of loading, the load increased for a third time, accompanied by a large slip and intermittent slip sound.

“In the later stage of loading, the load increased for the third time accompanied by a large slip and intermittent slip 190 sound.”

May combine two claims.

The calculated and experimental bond stress-slip curves are basically consistent in the initial stage of loading due to the small confinement pressure of outer steel tubes to core concrete.

“It can be 319 found that the two are basically consistent in the initial stage of loading due to the small confinement 320 pressure of outer steel tubes to core concrete.”

• AssumptionThe authors state this as an assumption: At the initial stage of loading, there is no significant confinement force from the steel tube to the concrete.

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Increasing the concrete strength from 44 MPa to 77 MPa has a negative effect on τu for all four groups of specimens displayed, with a reduction of 24.4% on average.

“Fig. 13(a) shows that increasing the concrete strength from 44 MPa to 77 MPa has a negative effect on τu for all the four groups of specimens displayed, with a reduction of 24.4% on average.”

Probably not a substantial claim: may not pass S3 (load-bearing). The quote only partly states this claim.

There was no obvious local buckling wave presented on the steel tube of all the specimens.

“It is worth noting that there was no obvious local buckling wave presented on the 235 steel tube of all the specimens.”

May combine two claims.

Based on the test results, an idealized bond stress-slip strain (τ-εS) curve was proposed, and good agreement between the test and the proposed model was achieved.

“Based on the test results, an idealized bond stress-slip strain (τ-εS) curve was proposed, where good agreement between the test and the proposed model has been achieved.”

May combine two claims.

Strain measurement in CFSSST-PBL and CFSSST-SS specimens showed that S32205 and 304 steel reached strains of 4900 and 5650 με, corresponding to stresses of 362 and 263 MPa, demonstrating that S32205 specimens provided higher confinement pressures to the concrete at the ultimate bond stress than the 304 specimens.

“The strain measurement in the CFSSST-PBL and CFSSST -SS specimens also showed that the S32205 and 304 steel have reached strains of 4900 and 5650 με, corresponding to stresses of 362 and 263 MPa (Fig. 4), respectively, demonstrating that the S32205 specimens provided higher confinement pressures (macrointerlocking force) to the concrete at the ultimate bond stress than the 304 specimens.”

May combine two claims.

CFSSST-RS specimens experienced relatively large slip displacements at failure of 5-8 mm, allowing the steel and concrete to develop large deformations and hence a large macro-interlocking force.

“On the other hand, the CFSSST-RS specimens experienced relatively large slip displacements at failure (5 -8 mm, as shown in Fig. 10), allowing the steel and concrete to develop large deformations hence a large macro-interlocking force.”

May combine two claims.

The initial bond stress τi is taken as 0.025 MPa for 304 and 0.064 MPa for S32205 CFSSST columns according to the test results.

“τi are taken as 0.025 and 0.064 MPa for 304 and S32205 CFSSST columns according to the test results.”

Classified as probably not a substantial claim. May combine two claims.

Bond strength in concrete-filled steel tubes can be affected by the diameter-wall thickness ratio D/t (width-thickness ratio B/t), concrete strength and concrete age.

“To investigate the bond behavior in CFSTs, numerous previous studies [3][4][5][6][7][8][9][12][13][14][15][16][17] have carried out push-out tests, with the results showing that the bond strength can be affected by the diameter-wall thickness ratio D/t (the width-thickness ratio B/t) ratio of the steel tube, concrete strength and concrete age.”

• cites [3][4][5][6][7][8][9][12][13][14][15][16][17]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Chemical adhesion in concrete-filled steel tubes is relatively small, depends on the mechanical properties of the core concrete, and may fail under a small external load, allowing interface slip.

“The magnitude of the chemical adhesion is relatively small and depends on the mechanical properties of the core concrete, indicating that the chemical adhesion bond may fail under a just small external load, and thus an interface slip in CFST may occur.”

• cites [3][4][5][6][7][8][9]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Increasing the D/t (B/t) ratio can lead to reductions in the ultimate bond stress of concrete-filled steel tubes.

“Virdi and Dowling [3], Roeder et al. [12], Parsley et al. [13], Chang et al. [14], Tao et al. [6], Qu et al. [15], Guan et al. [7], Lyu and Han [9] and Yan et al. [16] studied the effect of D/t (B/t) ratio on the bond strength of CFSTs and concluded that increasing D/t (B/t) can lead to reductions in the ultimate bond stress.”

• cites [3] 3. K.S. Virdi, P.J. Dowling, Bond strength in concrete filled steel tubes, IABSE Proceedings, vol. 80, 1980, pp. 125-139, P-33. sourceNot checked — no full text of the source
• cites [12] 12. C.W. Roeder, B. Cameron, C.B. Brown, Composite action in concrete filled tubes, J. Struct. Eng. ASCE 125 (5) (1999) 477-484. sourceNot checked — no full text of the source
• cites [13] 13. M.A. Parsley, J.A. Yura, J.O. Jirsa, Push-out behavior of rectangular concrete-filled steel tubes, Publication of American Concrete Institute, 196-5, 2000, pp. 87-107. sourceNot checked — no full text of the source

May combine two claims.

Compared with ordinary rib stiffeners, saw-shaped and PBL rib stiffeners can reduce the amount of steel used and improve the bond strength and ductility of concrete-filled steel tube columns.

“Compared with the ordinary rib stiffeners, the saw-shaped and PBL rib stiffeners can not only reduce the amount of steel used but also improve the bond strength and ductility of CFST columns [38,43].”

• cites [38] 38. F. Alatshan, S. A. Osman, R. Hamid, F. Mashiri, Stiffened concrete-filled steel tubes: A systematic review, Thin-Walled Struct. 148 (2020) 106590. sourceNot checked — no full text of the source
• cites [43] 43. Z. Tao, L.H. Han, D.Y. Wang, Strength and ductility of stiffened thin-walled hollow steel structural stub columns filled with concrete, Thin-Walled Struct. 46 (2008) 1113-1128. sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

The bond interface in concrete-filled stainless steel tubes can be broken in fire.

“Song et al. [34] studied the bond strength in CFSSTs at elevated temperatures and showed that the bond interface can be broken in fire.”

• cites [34] 34. T.Y. Song, Z. Tao, L.H. Han, B. Uy, Bond behavior of concrete-filled steel tubes at elevated temperatures, J. Struct. Eng. 143 (11) (2017) 04017147. sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Grzeszykow et al. carried out analytical analyses of bond behavior at the steel-concrete interface through push-out tests and presented two analytical models of stress distribution.

“Grzeszykow et al. [23] carried out analytical analyses of bond behavior at the interface between steel and concrete through push-out tests and presented two analytical models of stress distribution.”

• cites [23] 23. B. Grzeszykowski, M. Szadkowska, E. Szmigiera, Analysis of stress in steel and concrete in CFST push-out test samples, Civ. Environ. Eng. Rep. 26 (3) (2017) 145-159. sourceNot checked — no full text of the source

May combine two claims.

Square hot-rolled tubes welded at the corner forming a right angle led to normal stress concentration at these areas when the load increased, thereby resulting in increased calculated bond stress.

“The square hot-rolled tubes studied in the test program were welded at the corner, forming a right angle, which led to normal stress concentration at these areas when the load increased, thereby resulting in increased calculated bond stress.”

May combine two claims.

The macro-interlocking force is essentially friction related to the confinement pressure caused by the irregularity of diameter or width along the length of the tube, and it dominates the post-peak bond resistance.

“The macrointerlocking force is essentially friction related to the confinement pressure caused by the irregularity of diameter or width along the length of the tube, which dominates the post-peak bond resistance, as shown in Fig. 9(b).”

May combine two claims.

The bond strength of the steel-concrete interface in concrete-filled stainless steel tubes is less than that in concrete-filled steel tubes, caused by the smoother surface of the stainless steel tube.

“However, the bond strength of the steel-concrete interface in concrete-filled stainless steel tubes (CFSSTs) is less than that in CFSTs, as caused by the smoother surface of the stainless steel tube [31].”

• cites [31] 31. L.H. Han, C.Y. Xu, Z. Tao, Performance of concrete filled stainless steel tubular (CFSST) columns and joints: Summary of recent research, J. Constr. Steel Res. 152 (2019) 117-131. sourceNot checked — no full text of the source

May combine two claims.

Previous studies have only proved the lower bond strength of concrete-filled stainless steel tubes compared with concrete-filled steel tubes, whereas a design value has not been proposed.

“It should be noted that these previous studies have only proved the lower bond strength of CFSSTs compared with CFSTs, whereas a design value has not been proposed.”

May combine two claims.

Previous studies on the bond behavior of square CFSST specimens used seamless tubes with rounded corners, and no normal stress concentration was present.

“Previous studies [8,34,36] on the bond behavior of square CFSST specimens used seamless tubes with rounded corners and no normal stress concentration was present.”

• cites [8] 8. Z. Tao, T.Y. Song, B. Uy, L.H. Han, Bond behavior in concrete-filled steel tubes, J. Constr. Steel Res. 120 (2016) 81-93. sourceNot checked — no full text of the source
• cites [34] 34. T.Y. Song, Z. Tao, L.H. Han, B. Uy, Bond behavior of concrete-filled steel tubes at elevated temperatures, J. Struct. Eng. 143 (11) (2017) 04017147. sourceNot checked — no full text of the source
• cites [36] 36. R. Feng, Y. Chen, K. He, J.G. Wei, B.C. Chen, X.T. Zhang, Push-out tests of concrete-filled stainless steel SHS tubes, J. Constr. Steel Res. 145 (2018) 58-69. sourceNot checked — no full text of the source

Classified as probably not a substantial claim.

Current design rules of concrete-filled steel tubes are inapplicable to the bond strength of concrete-filled stainless steel tubes.

“Chen et al. [35] and Feng et al. [36] conducted push-out tests on CFSST specimens with circular and square sections, respectively, and concluded that the current design rules of CFSTs are inapplicable to the bond strength of CFSSTs.”

• cites [35] 35. Y. Chen, R. Feng, Y.B. Shao, X.T. Zhang, Bond-slip behaviour of concrete-filled stainless steel circular hollow section tubes, J. Constr. Steel Res. 130 (2017) 248-263. sourceNot checked — no full text of the source
• cites [36] 36. R. Feng, Y. Chen, K. He, J.G. Wei, B.C. Chen, X.T. Zhang, Push-out tests of concrete-filled stainless steel SHS tubes, J. Constr. Steel Res. 145 (2018) 58-69. sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

The age of concrete significantly reduces the bond resistance of concrete-filled steel tubes.

“Tao et al. [8] and Aly et al. [17] carried out push-out tests to investigate the effect of concrete age on the bond resistance, and found that the age of the concrete significantly reduces the bond resistance of CFSTs.”

• cites [8] 8. Z. Tao, T.Y. Song, B. Uy, L.H. Han, Bond behavior in concrete-filled steel tubes, J. Constr. Steel Res. 120 (2016) 81-93. sourceNot checked — no full text of the source
• cites [17] 17. T. Aly, M. Elchalakani, P. Thayalan, I. Patnaikuni, Incremental collapse threshold for pushout resistance of circular concrete filled steel tubular columns, J. Constr. Steel Res. 66 (2010) 11-18. sourceNot checked — no full text of the source

May combine two claims.

Concrete-filled square stainless steel tube members present different confinement conditions from circular concrete-filled stainless steel tube members and thus result in different bond stress-slip relationships.

“The present work focuses on concrete-filled square stainless steel tube (CFSSST) members, which present different confinement conditions to that in circular CFSST members and thus will result in different bond stress-slip relationships.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Chen et al. proposed a theoretical bond-slip model of concrete-filled checkered steel tube that accounted for the tensile strength of concrete and the height of the checkered part.

“Chen et al. [22] proposed a theoretical bond-slip model of concrete-filled checkered steel tube, which took account of the tensile strength of concrete and height of the checkered part.”

• cites [22] 22. L. Chen, J. Dai, Q. Jin, L. Chen, X. Liu, Refining bond-slip constitutive relationship between checkered steel tube and concrete, Constr. Build. Mater. 79 (2015) 153-164. sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Adding an internal ring is a more effective method in enhancing bond strength in concrete-filled steel tube specimens compared to adding shear studs.

“Song et al. [19] studied the bond behavior of CFSTs with shear studs or an internal ring and found that adding internal ring is a more effective method in enhancing the bond strength in CFST specimens compared to adding shear studs.”

• cites [19] 19. T.Y. Song, Z. Tao, B. Uy, L.H. Han, Bond strength in full-scale concrete-filled steel tubular columns, Proceedings of the 15th World Congress on Advances in Structural Engineering and Mechanics, Incheon, Korea, 2015.Not checked — no full text of the source

May combine two claims.

Thicker (stockier) tubes associated with larger confinement pressure may provide higher friction force (macro-interlocking force) in the later stage of loading than thinner (more slender) tubes, thus leading to higher strain hardening responses.

“Thicker (stockier) tubes associated 194 with larger confinement pressure may provide higher friction force (macro-interlocking force) in the 195 later stage of loading than thinner (more slender) tubes, thus leading to higher strain hardening responses.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Adding internal rings can be an effective method to enhance the bond strength of circular concrete-filled stainless steel tube members.

“This previous study [37] has also shown that adding internal rings can be an effective method to enhance the bond strength of circular CFSST members.”

• cites [37] 37. P. Dai, L. Yang, J. Wang, J.W. Fan, M.F. Lin, Experimental study on the steel-concrete bond behaviour of circular concrete-filled stainless steel tubes, Thin-Walled Struct. 169 (2021) 108506. sourceNot checked — no full text of the source

May combine two claims.

The micro-interlocking force and macro-interlocking force can cause mechanical keying of the concrete core with the steel tube, and both can be viewed as friction.

“It should be noted that the micro-interlocking force, as well as the macro-interlocking force, can cause mechanical keying of the concrete core with the steel tube, and therefore both can be viewed as friction [6,9].”

• cites [6] 6. Z. Tao, L.H. Han, B. Uy, X. Chen, Post-fire bond between the steel tube and concrete in concrete- filled steel tubular columns, J. Constr. Steel Res. 67 (2011) 484-496. sourceNot checked — no full text of the source
• cites [9] 9. W. Q. Lyu, L. H. Han, Investigation on bond strength between recycled aggregate concrete (RAC) and steel tube in RAC-filled steel tubes, J. Constr. Steel Res. 155 (2019) 438-459. sourceNot checked — no full text of the source

May combine two claims.

As slip developed further, accumulated large local stress in the corner regions caused crushing of the concrete at these locations and led to loss of the locally increased stress, hence resulting in a sudden drop in the calculated bond stress.

“As the slip developed further, the accumulated large local stress in the corner regions caused the crushing of the concrete at these locations and led to the loss of the locally increased stress, hence resulting in a sudden drop in the calculated bond stress.”

Probably not a substantial claim: may not pass S3 (load-bearing).

The bond strength in concrete-filled stainless steel tubes decreases remarkably with increasing cross-sectional dimension and concrete age.

“Tao et al. [8] found that the bond strength in CFSSTs decreases remarkably with increasing cross-sectional dimension and concrete age in CFSST, and proposed methods to increase the bond strength.”

• cites [8] 8. Z. Tao, T.Y. Song, B. Uy, L.H. Han, Bond behavior in concrete-filled steel tubes, J. Constr. Steel Res. 120 (2016) 81-93. sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

In concrete-filled tubes, an exponential distribution of bond stress is expected prior to slip and a more uniform distribution occurs after slip.

“Roeder et al. [12] studied the composite action in concrete-filled tubes, concluding that an exponential distribution of bond stress is expected prior to slip and a more uniform distribution occurs after the slip.”

• cites [12] 12. C.W. Roeder, B. Cameron, C.B. Brown, Composite action in concrete filled tubes, J. Struct. Eng. ASCE 125 (5) (1999) 477-484. sourceNot checked — no full text of the source

May combine two claims.

The third increase in bond stress has not been observed in previous studies, which may be due to the different cross-sectional dimensions of the CFSSSTs considered.

“The third increase in the bond stress has not been observed in previous studies [8,34,36], which 191 may be due to the different cross-sectional dimensions of the CFSSSTs considered.”

• cites [8] 8. Z. Tao, T.Y. Song, B. Uy, L.H. Han, Bond behavior in concrete-filled steel tubes, J. Constr. Steel Res. 120 (2016) 81-93. sourceNot checked — no full text of the source
• cites [34] 34. T.Y. Song, Z. Tao, L.H. Han, B. Uy, Bond behavior of concrete-filled steel tubes at elevated temperatures, J. Struct. Eng. 143 (11) (2017) 04017147. sourceNot checked — no full text of the source
• cites [36] 36. R. Feng, Y. Chen, K. He, J.G. Wei, B.C. Chen, X.T. Zhang, Push-out tests of concrete-filled stainless steel SHS tubes, J. Constr. Steel Res. 145 (2018) 58-69. sourceNot checked — no full text of the source

May combine two claims.

Rib stiffeners can enhance bond strength and improve the confinement effect of the flat regions of square tubes to concrete.

“Rib stiffeners can not only enhance the bond strength but improve the confinement effect of the flat regions of square tubes to concrete [38].”

• cites [38] 38. F. Alatshan, S. A. Osman, R. Hamid, F. Mashiri, Stiffened concrete-filled steel tubes: A systematic review, Thin-Walled Struct. 148 (2020) 106590. sourceNot checked — no full text of the source

May combine two claims.

The macro-interlocking force increased in the later stage of loading, which led to an increase of the bond resistance.

“The macro-interlocking force here increased, which led to the increase of the bond resistance in the later stage of loading.”

Classified as probably not a substantial claim. May combine two claims.

The inconsistent effect of concrete strength on bond strength may be due to higher shrinkage from higher concrete strength reducing mechanical keying, while higher split tensile strength of the concrete core may increase resistance related to mechanical keying.

“This may be due to the fact that the higher shrinkage caused by the higher concrete strength may reduce the mechanical keying between concrete and steel tube, whereas the higher split tensile strength of the concrete core may increase the resistance related to the mechanical keying [9].”

• cites [9] 9. W. Q. Lyu, L. H. Han, Investigation on bond strength between recycled aggregate concrete (RAC) and steel tube in RAC-filled steel tubes, J. Constr. Steel Res. 155 (2019) 438-459. sourceNot checked — no full text of the source

May combine two claims.

Decreasing the B/t ratio can lead to improvement in τu for C40 specimens whereas this enhancement diminished in C80 specimens.

“decreasing the B/t ratio can lead to improvement in τu for the C40 specimens whereas this enhancement diminished in the C80 specimens”

May combine two claims.

The discrepancy after 1.2τb is because macro-interlocking force produced by the restraint of the steel tube on concrete dominates the bond stress and normal stress was not considered in the analysis.

“This 322 phenomenon is due to macro-interlocking force produced by the restraint of steel tube on concrete 323 dominates the bond stress, however, the normal stress was not considered in the analysis.”

May combine two claims.

S32205 steels with higher strengths than 304 steels at the same strain can provide a larger confinement pressure, thereby reaching a higher macro-interlocking force and thus higher bond stress in the later stage of loading.

“The S32205 steels with higher strengths than 304 steels at the same strain (Fig. 4) can provide a larger confinement pressure, thereby reaching a higher macro-interlocking force and thus higher bond stress in the later stage of loading.”

May combine two claims.

S32205 specimens with better corrosion resistance and a smoother surface provided a smaller micro-interlocking force than S304 specimens, hence resulting in smaller τu at failure for CFSSSTs without rib stiffeners.

“Therefore, the S32205 specimens with a better corrosion resistance [45,46] and a smoother surface provided a smaller micro-interlocking force than the S304 specimens, hence resulting in smaller τu at failure.”

• cites [45] 45. G.P. Shu, Y.Y. Gu, Y.Q. Zhang, X. Jin, B.F. Zheng, Q.L. Jiang, Experimental study of cold-drawn duplex stainless steel circular tubes under axial compression, Thin-Walled Struct. 138 (2019) 95- 104. sourceNot checked — no full text of the source
• cites [46] 46. S.K. Azad, D.X. Li, B. Uy, Axial slenderness limits for duplex and lean duplex stainless steel- concrete composite columns, J. Constr. Steel Res. 172 (2020) 106175. sourceNot checked — no full text of the source

May combine two claims.

Decreasing the B/t ratio of the steel tube can provide greater confinement pressure to the concrete, leading to a higher micro-interlocking force and hence a higher τu for C40 specimens.

“While decreasing the B/t ratio of the steel tube can provide a greater confinement pressure to the concrete, leading to a higher micro-interlocking force hence a higher τu as observed for the C40 specimens”

Probably not a substantial claim: may not pass S3 (load-bearing).

In branch OA, there is no slip due to chemical adhesion.

“In branch OA, there is no slip due to the chemical adhesion”

May combine two claims.

The sectional width-thickness ratio (B/t), concrete strength (fcu), and stainless steel type have obvious influence on the bond behavior of CFSSST columns.

“As above, sectional width-thickness ratio (B/t), concrete strength (fcu) and stainless steel types (grade 304 and S32205) have obvious influence on the bond behavior of CFSSST columns.”