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    Öğe
    Engineering plastic gripping mechanism for tension testing of FRP bars
    (SAGE PUBLICATIONS LTD, 2020) Başaran, Boğaçhan; Yaka, Harun; Kalkan, İlker
    A new grip adaptor, made of an engineering plastic Cast Polyamide 6 (PA6G), was developed for tension testing of FRP reinforcing bars. The new adaptor offers several advantages over conventional anchors, including the ease of application and reuse, being economical, no need for skilled labor, smaller difference between the hardness of the adaptors and sample. Bars with three different diameters (6, 8 and 12 mm), three types of fiber (Carbon, Glass and Basalt) and four types of surface texture (ribbed, wound, fine-sand coated and coarse-sand coated with widely-spaced wrapping) were tested to failure under uniaxial tension. Two identical bars were tested for each combination of parameters (fiber type, surface texture and bar diameter), one with PA6G and the other with grout-filled steel anchors. The tests indicated that the proposed method was able to ensure FRP bars to reach their tensile capacities and fail by rupture without crushing in the gripping regions and pull-out from the jaws of the testing machine. The modulus of elasticity, tensile strength and ultimate strain values of the bars with PA6G anchors were in rather close agreement with the respective values of specimens with conventional steel anchors. This close agreement, i.e. mostly a difference below 5%, implies the success of the proposed method. Among all tested bars, only the ribbed ones failed in the gripping regions in the presence of both anchors as a result of the limited contact surface (rib area), pointing out the need for the use of longer anchors for ribbed bars.
  • [ X ]
    Öğe
    PVC and POM gripping mechanisms for tension testing of FRP bars
    (Techno-Press, 2021) Basaran, Bogachan; Yaka, Harun; Kalkan, Ilker
    The present study pertains to the introduction of two new types of grip adaptor for universal testing machines, namely Polyvinyl Chloride (PVC) and Polyoxymethylene (POM) grip adaptors, and their application to tension testing of FRP bars with different fiber and surface finish types. The tabs are connected to the FRP bar sample with the help of mechanical anchors, i.e. bolts. These new adaptors offer vital superiorities over the existing end tab designs (anchors with filling material or mechanical anchorage), including the reduction in the time and labor for production, reusability and the mild nature, i.e. low hardness of the tab material, which retards and even prevents peeling and crushing in the gripping regions of an FRP sample. The methods were successfully applied to FRP bars with different types of fiber (CFRP, GFRP and BFRP) and different types of surface texture (ribbed, wrapped, sand-coated and wound). The test results indicated that the both types of end caps prevented slip of the bar, crushing and peeling in the gripping zone. The mechanical properties from the material tests with the new caps were in perfect agreement with the ones from the material tests with steel tubular caps.