Abstract
An experimental study on 24 PVC–CFRP-confined concrete (PCCC) columns with reinforced concrete (RC) ring beam joint under eccentric load is conducted, and several experimental parameters (i.e., width and height of ring beam, reinforcement ratio, eccentricity and CFRP strips spacing) are considered. Two failure modes, the damage of PCCC columns and the crushing of joint concrete, are observed in the experiments. The initial stiffness increases with the decrease in the ring beam height, eccentricity or CFRP strips spacing. The stiffness degradation rate increases with the increase in the ring beam height, eccentricity or CFRP strips spacing, while it decreases with increasing ring beam width. According to the experimental study, a theoretical model for estimating the flexural stiffness of PCCC columns with RC ring beam joint is established based on the cross-sectional strain equilibrium condition. Additionally, considering the impact of axial compression ratio \(n\) and equivalent confining effect coefficient \(\xi _{{{\text{ef}}}}\), a simplified moment–curvature model of PCCC columns with RC ring beam joint is proposed. The proposed models agree well with the test results.
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Abbreviations
- \(A_{{\text{s}}}\) :
-
Total sectional area of ring reinforcement in the ring beam
- \(A_{{\text{c}}}\) :
-
Concrete area of PFCC column
- \(A_{{\text{f}}}\) :
-
CFRP strips section area
- b :
-
Ring beam width
- \(B_{{\text{s}}}\) :
-
Flexural stiffness of PCCC columns with RC ring beam joint
- \(e_{0}\) :
-
Eccentricity
- \(e'\) :
-
Distance from the action point of axial force to resultant point of tensile steel bars
- \(E_{{\text{c}}}\) :
-
Elastic modulus of core concrete
- \(f_{{\text{c}}}\) :
-
Compressive strength of core concrete
- \(f_{{\text{f}}}\) :
-
Tensile strength of CFRP strips
- h :
-
Ring beam height
- \(h_{0}\) :
-
Effective height of column section
- \(I_{{\text{c}}}\) :
-
Inertia moment of core concrete
- \(k_{{\text{g}}}\) :
-
Confinement effect coefficient of CFRP strips
- \(K_{{\text{e}}}\) :
-
Elastic stage stiffness of PCCC columns with RC ring beam joint
- \(K_{{\text{p}}}\) :
-
Strengthening stiffness of PCCC columns with RC ring beam joint
- M e :
-
Measured moment of mid-span section of PFCC columns in Group F
- M u :
-
Measured moment of mid-span section of PFCC columns in Group S
- \(N_{{\text{e}}}\) :
-
Measured bearing capacity of specimens in Group F
- \(N_{{\text{u}}}\) :
-
Measured bearing capacity of specimens in Group S
- \(n_{{\text{f}}}\) :
-
Layer of CFRP strips
- \(s_{{\text{f}}}\) :
-
Spacing of CFRP strips
- \(s^{\prime}_{{\text{f}}}\) :
-
Width of CFRP strips
- \(\sigma _{{\text{c}}}\) :
-
Axial compressive stress of concrete approach axial force
- \(\sigma _{{\text{s}}}\) :
-
Tensile stress of steel bars far from axial force
- \(\varepsilon _{{\text{s}}}\) :
-
Measured tensile strain of the longitudinal bars of columns
- \(\varepsilon _{{\text{c}}}\) :
-
Measured compressive strain of core concrete in PVC–CFRP tube
- \(\phi\) :
-
Curvature of the mid-span section of PFCC column
- \(\varphi _{{\text{c}}}\) :
-
Strain inhomogeneity coefficients of concrete
- \(\varphi _{{\text{s}}}\) :
-
Strain inhomogeneity coefficients of steel bars
- \(\eta\) :
-
Eccentricity enhancement factor of RC columns
- \(\eta _{{\text{k}}}\) :
-
Coefficient of internal force arm
- \(\zeta\) :
-
Confining effect coefficient of PVC tube on core concrete
- \(\xi _{{{\text{ef}}}}\) :
-
Equivalent confinement effect coefficient
- \(\xi ^{\prime}_{{{\text{ef}}}}\) :
-
Equivalent confinement effect coefficient considering the effect of eccentricity
- \(\rho _{{\text{s}}}\) :
-
Reinforcement ratio of tensile steel bars
- \(\rho\) :
-
Reinforcement ratio of ring beam
- \(\nu\) :
-
Reduction coefficient of elastic modulus of compressive concrete
- \(\psi\) :
-
Influence coefficient of the flexural stiffness of PCCC columns
- \(\gamma _{{\text{e}}}\) :
-
Influence coefficient of eccentricity on the bearing capacity of PCCC columns
References
ACI 318-19. (2019). Building code requirements for structural concrete. American Concrete Institute, Farmington Hills.
AISC (2016) Specifications for structural steel buildings. ANSI/AISC 360-16, Chicago
Abdallaha MH, Mohameda HM, Masmoudia R et al (2018) Experimental evaluation and theoretical analysis of the effective flexural stiffness of reinforced CFFT columns. Eng Struct 175:155–167
Ahmad A, Khan Q, Raza A (2020) Reliability analysis of strength models for CFRP-confined concrete cylinders. Compos Struct 25(5):112312
Bonet JL, Miguel PF, Fernandez MA et al (2004) Biaxial bending moment magnifier method. Eng Struct 26(13):2007–2019
Bonet JL, Romero ML, Miguel PF (2011) Effective flexural stiffness of slender reinforced concrete columns under axial forces and biaxial bending. Eng Struct 33(3):881–893
Chen QJ, Cai J, Bradford MA et al (2014) Seismic behaviour of a through-beam connection between concrete-filled steel tubular columns and reinforced concrete beams. Eng Struct 80:24–39
Ding DJ, Huang DF, Jin ZS et al (1985) Experimental researches and calculational proposals for stiffness and crack width of reinforced concrete members. Chin Civil Eng J 18(4):1–13
Fakharifar M, Chen G (2016) Compressive behavior of FRP-confined concrete-filled PVC tubular columns. Compos Struct 141:91–109
Fakharifar M, Chen G (2017) FRP-confined concrete filled PVC tubes: a new design concept for ductile column construction in seismic regions. Constr Build Mater 130:1–10
Fang XD, Li SY, Chen AJ (1999) Experimental research on a new type of steel tube confined concrete column joint. J Build Struct 20(5):2–13
Fang XD, Li SY, Qian JR et al (2002) Experimental research on seismic behavior of concrete filled steel tubular column ring beam joint under cyclic loading. J Build Struct 23(6):10–18
Fang XD, Huang SJ, Li SY et al (2008) Design method of RC beam-STCC column joint connected with ring beam. J Build Struct 29(5):20–33
Fang Y, Yu F, Guan YC et al (2020) A model for predicting the stress-strain relation of PVC-CFRP confined concrete stub columns under axial compression. Structures 26:259–270
GB50010-2010 (2015) Code for design of concrete structures. China Architecture & Building Press, Beijing
GB/T8804.1-2003 (2003) Thermoplastic pipes-determination of tensile properties. China Architecture & Building Press, Beijing
GB/T3354-2014 (2014) Test method for tensile properties of orientation fiber reinforced polymer matrix composite materials. China Architecture & Building Press, Beijing
GB/T228.1-2010 (2010) Metallic materials-tensile testing. China Architecture & Building Press, Beijing
Han LH, Qu H, Tao Z et al (2009) Experimental behaviour of thin-walled steel tube confined concrete column to RC beam joints under cyclic loading. Thin-Walled Struct 47:847–857
Jiang SF, Ma SL, Wu ZQ (2014a) Experimental study and theoretical analysis on slender concrete-filled CFRP-PVC tubular columns. Constr Build Mater 53:475–487
Jiang SF, Wu ZL, Wu ZQ et al (2014b) Experimental study on hysteretic behavior of FRP-PVC confined circular section reinforced concrete composite columns. J Build Struct 35:111–118
Liu J (2019) Study on mechanical behavior of PVC-FRP confined concrete column-reinforced concrete ring beam joint under eccentric compression. MsD thesis, Anhui University of Technology, Ma´anshan
Mavichak V, Furlong RW (1976) Strength and stiffness of reinforced concrete columns under biaxial bending. Research report 7-2F. Center for Highway Research, November
Mirza SA (1990) Flexural stiffness of rectangular reinforced concrete columns. ACI Struct J 87(4):425–435
Qian JR, Zhou DL, Fang XD (2003) Steel tube confined concrete column-RC ring beam joint and the application. Build Struct 33:60–62+72
Saafi M (2001) Development and behavior of a new hybrid column in infrastructure systems. PhD thesis, The University of Alabama, Huntsville
Saeed Z, Khan QZ, Ahmed A et al (2015) Experimental and finite element investigation of strengthened LSC bridge piers under quasi-static cyclic load test. Compos Struct 131:556–564
Song YP (2004) Reinforced concrete structure. Mechanical Engineering Press, Beijing
Tang XL, Cai J, Chen QJ et al (2016) Seismic behaviour of through-beam connection between square CFST columns and RC beams. J Constr Steel Res 122:151–166
Toutanji H, Saafi M (2001) Durability studies on concrete columns encased in PVC–FRP composite tubes. Compos Struct 54(1):27–35
Tikka TK, Mirza SA (2005) Nonlinear EI equation for slender reinforced concrete columns. ACI Struct J 102(6):839–848
Tikka TK, Mirza SA (2008) Effective flexural stiffness of slender structural concrete columns. Can J Civil Eng 35:384–399
Westerberg B (2002) Slender column with uniaxial bending. In: International Federation for structural concrete (fib). Technical report, bulletin 16. Design examples for 1996 FIP recommendations practical design of structural concrete, January, pp 121–142
Yu F (2007) Experimental study and theoretical analysis on mechanical behavior of PVC-FRP confined concrete column. PhD thesis, Xi’an University of Architecture and Technology, Xi’an
Yu F, Xu GS, Niu DT et al (2018) Experimental study on PVC-CFRP confined concrete columns under low cyclic loading. Constr Build Mater 177(20):287–302
Yu F, Li DG, Niu DT et al (2019a) A model for ultimate bearing capacity of PVC-CFRP confined concrete column with reinforced concrete beam joint under axial compression. Constr Build Mater 214:668–676
Yu F, Zhang NN, Niu DT et al (2019b) Strain analysis of PVC-CFRP confined concrete column with ring beam joint under axial compression. Compos Struct 224:111012
Yu F, Zhang NN, Fang Y et al (2020) Stress-strain model of weak PVC-FRP confined concrete column and strong RC ring beam joint under eccentric compression. Steel Compos Struct 35(1):13–27
Zadeh HJ, Nanni A (2017) Flexural stiffness and second-order effects in fiber- reinforced polymer-reinforced concrete frames. ACI Struct J 114(2):533–544
Zhou Y, Yu HY, Qian J et al (2015) Experimental study on ring beams of joints of concrete filled steel tubular laminated columns. J Build Struct 36(2):69–78
Acknowledgements
This study was sponsored by the National Natural Science Foundation of China (Nos. 51578001, 51878002, 52078001), Outstanding Youth Fund of Anhui Province (No. 2008085J29) and University Natural Science Research Project of Anhui Province (Nos. KJ2020A0234, KJ2020A0261).
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Wu, P., Liu, J., Yu, F. et al. Flexural Stiffness Analysis of the PVC–CFRP-Confined Concrete Columns with RC Ring Beam Joint Under Eccentric Load. Iran J Sci Technol Trans Civ Eng 46, 1825–1840 (2022). https://doi.org/10.1007/s40996-021-00693-w
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DOI: https://doi.org/10.1007/s40996-021-00693-w