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INVESTIGATION OF FRP STABILIZATION OF PLASTIC BUCKLING BEHAVIOR OF SLENDER STEEL SECTIONS

Peck, Andrew Jeffrey (2008) INVESTIGATION OF FRP STABILIZATION OF PLASTIC BUCKLING BEHAVIOR OF SLENDER STEEL SECTIONS. Master's Thesis, University of Pittsburgh. (Unpublished)

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Abstract

An innovative use of fiber reinforced polymer (FRP) composite materials, to control the manifestation of local buckling in a flanged steel section, is proposed. In this method, the high stiffness and linear behavior of FRP materials are utilized to provide "bracing" against web or flange local buckling in a manner that strategically leverages the unique mechanical properties of each material in an efficient application domain. The experimental research reported is aimed at demonstrating the feasibility of using small quantities of FRP to provide cross-sectional stability through the bonding of FRP strips to flange elements of the cross-section, thereby increasing the critical load of the member; constraining plastic flow in the cross-sectional flange elements; and facilitating the manifestation of a well-formed and stable hysteretic response of the member under cyclic loading. The member becomes, in effect, an FRP stabilized steel section.An experimental program investigating the inelastic buckling behavior of FRP stabilized members is reported. In all cases, WT 6x7 steel sections were used. Unretrofit control specimens and four retrofit scenarios were investigated using either high strength (HS) carbon FRP (CFRP) strips or ultra-high modulus (UHM) glass FRP (GFRP) strips. For each material two cases were considered: a single 2 in. (50.8 mm) wide strip applied to the WT stem; and two 1 in. (25.4 mm) wide strips placed on top of each other at the same location. The FRP strips were applied to each side of the WT stem. The two FRP configurations used result in the same area of FRP materials having the same centroid applied to the steel section. Fifteen 14 in. (356 mm) long WT sections were tested in concentric compression to failure. Three specimens of each detail were tested. The specimen length was selected to ensure local buckling of the WT stem with no lateral torsional buckling of the section. Each specimen was dominated by web (stem) local buckling (WLB) behavior. No evidence of flange local buckling or lateral torsional buckling was observed. The presence of the FRP increased the axial load carrying capacity of the WT section between 4% and 14%. The bifurcation loads were increased as much as 17%. In these tests, the CFRP specimens exhibited a more pronounced improvement in behavior. Similarly, the specimens having two 1 in. wide FRP strips performed better that those with one 2 in. strip. Debonding of the FRP strips was a post-peak phenomenon in all tests. Generally debonding occurred at an applied load of about 75% of the peak load on the descending branch of the load curve.


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Details

Item Type: University of Pittsburgh ETD
Status: Unpublished
Creators/Authors:
CreatorsEmailPitt UsernameORCID
Peck, Andrew Jeffreyajp43@pitt.eduAJP43
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Committee ChairHarries, Kent Akharries@engr.pitt.eduKHARRIES
Committee MemberKoubaa, Amirakoubaa@engr.pitt.edu
Committee MemberRizzo, Piervincenzoprizzo@engr.pitt.eduPIR3
Date: 30 January 2008
Date Type: Completion
Defense Date: 3 December 2007
Approval Date: 30 January 2008
Submission Date: 4 December 2007
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Civil and Environmental Engineering
Degree: MSCE - Master of Science in Civil Engineering
Thesis Type: Master's Thesis
Refereed: Yes
Uncontrolled Keywords: FRP Stabilization
Other ID: http://etd.library.pitt.edu/ETD/available/etd-12042007-151051/, etd-12042007-151051
Date Deposited: 10 Nov 2011 20:07
Last Modified: 15 Nov 2016 13:53
URI: http://d-scholarship.pitt.edu/id/eprint/10020

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