Steel columns strengthened/reinforced by prestressed CFRP strips: Concepts and behaviors under axial compressive loads

Abstract A novel strengthening method using prestressed (PS) carbon fiber reinforced polymer (CFRP) strips was proposed. This method can be used for repairing existing steel columns or constructing new columns for high-rise buildings, power transmission towers and other buildings. Specifically, a prestressing system (PS system) can be used to prestress CFRP strips without using a hydraulic jack. A steel column, PS CFRP strips and the PS system comprise a self-balanced system that offers much greater stiffness against overall buckling than a pure steel column. To verify this strengthening method, axial compression tests are conducted. The results show that the buckling load of the PS-strengthened specimen is 2.5 times greater than that of an unstrengthened specimen, and the failure mode ranges between the first order symmetric and the second order asymmetric overall buckling mode. In addition, finite element analysis (FEA) was adopted to obtain the optimal prestress value, which can also be used as a guide in design. Finally, a simple calculation method of axial bearing capacity was proposed.

[1]  John S. Ellis,et al.  Buckling of a Single-Crossarm Stayed Column, , 1975 .

[2]  Leroy Gardner,et al.  Experimental study of critical and post-buckling behaviour of prestressed stayed columns , 2012 .

[3]  Yu Bai,et al.  Combination of Bamboo Filling and FRP Wrapping to Strengthen Steel Members in Compression , 2013 .

[4]  Pedro F. Silva,et al.  Rehabilitation of Compression Steel Members Using FRP Pipes Filled with Non-Expansive and Expansive Light-Weight Concrete , 2005 .

[5]  Luís Simões da Silva,et al.  A full scale experimental study of prestressed stayed columns , 2015 .

[6]  P. Feng,et al.  Buckling behavior of CFRP-aluminum alloy hybrid tubes in axial compression , 2017 .

[7]  Daisuke Saito,et al.  Post-buckling behaviour of prestressed steel stayed columns , 2008 .

[8]  M. Motavalli,et al.  Fatigue strengthening of damaged metallic beams using prestressed unbonded and bonded CFRP plates , 2012 .

[9]  Sherif El-Tawil,et al.  Inhibiting Steel Brace Buckling Using Carbon Fiber-Reinforced Polymers: Large-Scale Tests , 2009 .

[10]  Amr Shaat,et al.  Slender Steel Columns Strengthened Using High-Modulus CFRP Plates for Buckling Control , 2009 .

[11]  Chan Ghee Koh,et al.  Buckling strength of slender circular tubular steel braces strengthened by CFRP , 2013 .

[12]  C. Khosla,et al.  Buckling loads of stayed columns using the finite element method. , 1975 .

[13]  Daisuke Saito,et al.  Buckling behaviour of prestressed steel stayed columns with imperfections and stress limitation , 2009 .

[14]  Leroy Gardner,et al.  Buckling mode interaction in prestressed stayed columns , 2013 .

[15]  K. C. Wong.  Single-crossarm stayed column with initial imperfections. , 1980 .

[16]  M. Motavalli,et al.  Lateral-torsional buckling of steel I-beams retrofitted by bonded and un-bonded CFRP laminates with different pre-stress levels: Experimental and numerical study , 2015 .

[17]  S. El-Tawil,et al.  Restraining Steel Brace Buckling Using a Carbon Fiber-Reinforced Polymer Composite System: Experiments and Computational Simulation , 2008 .

[18]  Yu Bai,et al.  Strengthening of steel members in compression by mortar-filled FRP tubes , 2013 .

[19]  P. Feng,et al.  Buckling of piecewise member composed of steel and high-strength materials in axial compression , 2017 .

[20]  Elyas Ghafoori,et al.  Innovative CFRP-Prestressing System for Strengthening Metallic Structures , 2015 .

[21]  Xiao Ling Zhao,et al.  FRP-Strengthened Metallic Structures , 2013 .

[22]  João Martins,et al.  Structural behaviour of prestressed stayed columns with single and double cross-arms using normal and high strength steel , 2016 .

[23]  P. Feng,et al.  Behavior analysis of FRP tube/filling strengthened steel members under axial compression , 2019, Thin-Walled Structures.

[24]  Kuang-Han Chu,et al.  Analysis and Design of Struts with Tension Ties , 1963 .

[25]  Murray C. Temple,et al.  Pretensioning of single-crossarm stayed columns. , 1979 .