Experimental Study On Mechanics Performence Of GFRP Tube Anti-buckling Strengthening Angle Steel Members

As a result of the artificial factors and the natural factors, such as the lower levelof the design, the improper construction and its long life span, the poor environment,the earthquake, overloading and so on, the traditional steelwork is generally facedwith different degrees of damage. Accordingly, it is an urgent problem that how tocement and maintain the steelwork economically, high efficiently and reliably.Buckling instability, the main damage form of steelwork, usually occurs suddenly,which causes serious losses for the construction. Fiber Reinforced Polymer (abbr.FRP), as an ideal material for strengthening and maintaining steel components, hashigh machinery, strongly bearing the fatique and good anti-corrosion. At the sametime, to cement FRP not only enhances the stiffness and ultimate bearing capacity,butalso improves its resistance of fatigue and corrosion. The thesis focuses onmechanical properties of reinforcing angle steel to resist buckling of GFRP tube.The study is divided into two experiments on the basis of two different forms ofends connection (steel plate scarf and high-strength bolt connection). The steel platescarf contains nine specimens which includes the factors of three slenderness ratio,two kinds of reinforcing structure forms and unreinforced angle steel components;The other experiment is the high-strength bolt connection which adds up to sixspecimens. It includes the factors of three slenderness ratio, reinforced andunreinforced angle steel components through b mode. After reinforcing the angle steelcomponents, the ultimate bearing capacity in the first experiment has increase by6.16%~37.58%, and the second experiment has increases by7.86%~58.4%. The twoexperimental studies show that before reinforcement, the angle steel componentsmostly decline rapidly when it reaches its ultimate load while the angle steelcomponents which have been reinforced mostly decline slowly till instability damage.What’s more, the ductility of strengthened angle steel components has been improved in certain extent.The study demonstrates that the anti-buckling strengthening method has goodoperability, and GFRP tube buckling resistant reinforcing method improves the abilityof anti-flexion of compressed angle steel components. The slenderness smallercomponent is part of section failure, with similar test phenomenon. The method ofslenderness larger component reinforcement effect is obvious, and it roughly belongsto the overall instability destruction. GFRP tube as pultrusion only has longitudinalfibers. The trial discoverers that the ends and the middle are the weak link, and furtherindicates that it is necessary for GFRP tube to strengthen locally. The resultscalculated by revised formulas of GFRP tube stiffness contribution coefficient, whichare proposed in this thesis, are in good agreement with the test results.