Development of the System for Foreseeing and Assessing Fatigue Damages in Steel Bridges

1989 Fiscal Year Final Research Report Summary

• Project/Area Number: 63302041
• Research Category: Grant-in-Aid for Co-operative Research (A)
• Allocation Type: Single-year Grants
• Research Field: 土木構造
• Research Institution: Saitama University
• Principal Investigator: TAJIMA Jiro Saitama University professor, 工学部, 教授 (30134331)
• Co-Investigator(Kenkyū-buntansha): SAKAMOTO Kenji Railway Technical Research Institute Chief Research Engineer, 線路構造研究室, 主任研究員 ; MIKI Chitoshi Tokyo Institute of Technology Associate Professor, 工学部, 助教授 (20016645) ; FUJIWARA Minoru Ministry of Construction Public Works Research Institute Head of Bridge Engineer, 橋梁研究室, 室長 ; IINO Tadao Metropolitan Expressway Public Corporation the chief of Brochure of Bayshore Con ; INABA Noriaki Japan Railway Construction Corporation Chief of Nagoya Branch
• Project Period (FY): 1988 – 1989
• Keywords: Steel Bridge / Fatigue Damage / Non-destructive Inspection / Inspection System / Variable Amplitude Stresses / Inspection Manual

Research Abstract

It is essential to pay attention to fatigue problems of steel highway and railroad bridges, because a number of bridges have experienced fatigue crackings. There are many factors to affect the fatigue of bridge, so it is difficult to accurately estimate the location and the time of the cracking. Following considerations, therefore, are effective in using the existing bridges safely : (1) to comprehend the cause and feature of past cracking experiences, (2) to inspect the pertinent locations at a adequate period of time by using an appropriate inspection system, (3) and to cope with the cracking with the use of a suitable retrofitting method.
This report describes the basic concepts of the system for inspecting the steel bridge components and for predicting the location and the tim of fatigue cracking. This system will be of great assistance in the safe use of existing steel bridges. The summaries of the report are as follows.
A large number of data for fatigue crackings in steel bridges in Japan are collected, arranged and analyzed. Furthermore, the papers in relation to the crackings are examined, and then we indicate the cause and repair method of the crackings.
We investigate the applicability of non-destructive testings ( visual examination, magnetic particle examination, eddy current examination, liquid penetrant examination and ultrasonic examination ) to detect and measure fatigue cracks in steel bridges through experiments on fillet welded joint specimens with surface fatigue cracks. We also examine the practicability of electrical potential method and AE (acoustic emission) method, which are suitable to continuous on-line inspection, for quantitative measurement of crack in steel plates and fillet welded joint specimens.
A method is presented for predicting the life of steel bridge components under variable amplitude stresses in highway and railroad bridges.
Case studies on some actual bridges are performed, with emphasis on inspecting system, assessment of fatigue damage and retrofit for the damage.
The features of inspection manuals of various administration facilities for bridges are indicated.