THE FRACTURED-BASED MODELING OF PULL-OUT PROBLEM WITH LONG EMBEDDED NYLON 600
Retno Susilorini, Rr. M.I.
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Fracture phenomenon happened during the pull-out process. Previous study of short embedded nylon 600 in cementitious matrix model has proved several new theories with main concern of fracture. Nevertheless, it is necessary to assure that the same theories can be applied accurately and consistently in the pull-out problem with long embedded nylon 600. The research conducts experiment method and analytical method. The experiment method applies pull-out test with long embedded nylon 600 in cementitious matrix and the analytical method is based on previous fractured based pull-out model. The pull-out specimens have embedded length of lf = 110-180 mm. The results of experiment show that all specimens suffer fibers broken. The pull-out process explains several stages: (a) Pre-slip stage, (b) Slip stage, and (c) Strain-hardening stage. The pre-slip loads are found as 400-430 N and pre-slip displacements of no more than 0.1 mm. The slip loads have been observed in the same range of pre-slip loads with displacements of 3-30 mm. The maximum strain-hardening loads are found as 1600-1800N while the broken loads are observed as 1400-1700 N. The maximum displacements are ranged about 100-200 mm. The previous model for pull-out problem with short embedded nylon 600 is applied to the long embedded nylon 600. Clearly, the model has been proven fit to the experimental results. It is emphasized that the theories for the pull-out problem with short embedded nylon 600 are still accurate and consistent applied to long embedded nylon 600. This research meets conclusions: (a) The same theories of pull-out problem with short embedded nylon 600 in cementitious matrix can be applied accurately and consistently for long embedded nylon 600, (b) The unstable and stable fracture process phenomenon exist during the pull-out process, (c) Several stages exist during the pull-out process, (d) The equation of stable crack length of previous model can also be applied for long embedded nylon 600, (e) The equation of load of previous model can also be applied for long embedded nylon 600, (f) The possibility of crack arrester presence is bigger for the long embedded fiber length than the short ones, thus the strain-hardening part in load-displacement curve is longer for the long embedded fiber length.