Pham Ngoc Vinh
a Study on Axially Loaded Steel Plates Strengthened with CFRP
Takeshi MIYASHITA
This experimental study investigates the construction method using CFRP to retrofit and strengthen structures which is applicable in axial-load subjected components such as trusses, flanges of steel girders. As concern with separation of CFRP sheet under buckling load, a compressive test of un-corroded steel specimen adhered by CFRP was carried out. Rayleigh-Ritz method was employed to evaluate the elastic buckling load from experimental result and to also exam the efficiency of retrofitting. Furthermore, a tensile test of corroded steel specimen retrofitted by CFRP was also carried out.
The following conclusions are drawn:
(1.) The failure load calculated by Rayleigh-Ritz method is lower than experimental results in most cases, except the case of CFRP sheets were adhered downsizing 10mm which each outer layer end offsets from inner layer end.
(2.) The calculated failure load is 5% lower than experimental results when number CFRP layers is low.
(3.) In case of CFRP sheets were adhered downsizing 10mm, calulated strength is 40% higher than experimental strength. The reason is speciment was failure in shifting position of sheet ends where is not strongest cross section along specimen.
(4.) With same number of CFRP layers, the retrofitted effeciency in case of using 25mm downsizing is larger than effeciency in case of using 10mm downsizing.
(5.) Results of tensile test of corroded steel specimen with CFRP adhered by conventional method confirmed that its ultimate strenght recovered to ultimate strength of origianal steel specimen before corroded as expected.
(6.) In case of using conventinal method in combination with tapering the steel specimen at corroded-original shifting, tapering work before adhering CFRP not only decrease shear stress and tensile stress in adhering material but also upgrade the ultimate strenght of speciment.
(7.) An alternative method caculating the required amoun of CFRP based on corroded level was also confirmed to be application by experimental results.
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