LOCAL STRESS BASED FATIGUE PERFORMANCE EVALUATION OF STEEL DECK VERTICAL STIFFENER DETAILS IMPROVED BY ULTRASONIC IMPACT TREATMENT

Abstract

  Many fatigue cracks are found at vertical stiffeners and rib cross points of steel deck structures. Fatigue improvement of these details by the application of Ultrasonic Impact Treatment was planned. Residual stress measurement by X-ray and stress range measurement by a test truck were conducted at a bridge under traffic. Based on these measured data, local stress based fatigue tests by joint specimens were conducted. In this test, the absolute value of local stress gives dominant effect to fatigue performance. Through the fatigue test and field measurement, it is confirmed that applying UIT to objective details can improve fatigue performance.