Applicability of Thin Steel Plate with a Crack to Estimating of Fatigue Damage on Bridges (Report II): Effect of delayed retardation and applicability under fluctuating amplitude loads

摘要

Thin steel plates, which have initial crack at the center, are used as "Sacrificial Test Pieces " in this study. The Sacrificial Test Piece is attached to a bridge member in order to evaluate the damage before appearance of a crack in the member. The purpose of this study is to clarify the effect of delayed retardation and to show the applicability of the thin steel plates as sacrificial test pieces under fluctuating amplitude loads. The fatigue damage parameters calculated by crack propagation length of thin steel plates under some fluctuating amplitude loads are compared with those calculated by the stress measurement.rnFrom the results, the crack propagation lengths in the thin steel plates are affected by the delayed retardation of the crack propagation under fluctuating amplitude loads. However, it is shown that the relation between the fatigue damage parameter and the crack propagation length is almost linear through the hastening of the crack propagation after delayed retardation. And it is verified that the absolute value of the fatigue damage parameter can be monitored by the crack propagation length of the thin steel plates even under fluctuating amplitude loads.