Research on The Slip-Resistant Joints of Bridge with Corrosion Resistance Surfaces

1988 Fiscal Year Final Research Report Summary

• Project/Area Number: 61850087
• Research Category: Grant-in-Aid for Developmental Scientific Research
• Allocation Type: Single-year Grants
• Research Field: 土木構造
• Research Institution: Kobe University
• Principal Investigator: NISHIMURA Akira Kobe Univ., Faculty of Eng., Prof., 工学部, 教授 (00031039)
• Co-Investigator(Kenkyū-buntansha): 菊川 春三 川崎製鉄(株), エンジニアリング事業部・研究開発センター, 課長 ; 牛尾 正之 (株)ニチソウテック技術本部, エンジニアリング部, 部長 ; 江見 晋 阪神高速道路公団, 公務部, 次長 ; FUJII Manabu Kyoto Univ., Faculty of Eng., Prof., 工学部, 教授 (30031074) ; EMI Susumu Hanshin Highway Public Corp., Eng. Section, Vice Head of Section ; USHIO Masayuki Nichizo-Teck Corp., Eng. Section, Head of Section ; KIKUKAWA Shunzo Kawasaki Iron Works Corp., Research and Development Center Construction Method L
• Project Period (FY): 1986 – 1987
• Keywords: Friction Grip Connection with High Strength Bolts / Joint / Hot-dip Galvanizing / Zinc-Metallizing / Creep of Joints / ボルト軸力の経時変化

Research Abstract

This research studied the behavior of slip-resistant joints with corrosion resistance surfaces under a sustained load (1 year) and a short-duration static load. Mainly, hot-dip galvanized surfaces were tested together with zincmetallized ones, and as a comparison non-treatment ones were used too. The test variables were thickness of the galvanized coating, bolt grade, galvanizing of bolt and elapsed time after torquing.
The main conclusions derived from this study can be summarized as follows:
(1) The shear creep displacement under sustained load (about half the design joint stiffness) came to a constant value within 1-7 days after loading for the non-treatment and the zinc-metallized surfaces. For hot-dip galvanized surfaces, it was in proportion with the logarithmic value of elapsed time for the first 2 weeks (primary creep) and then increased at a constant speed (secondary creep) and finally reached a constant value after a year.
(2) The bolt tension decreased in proportion to elapsed time on a log scale. After a month,the loss in bolt tension was 9% for the non-treatment surfaces,11-16% for the hot-dip galvanized ones and 19% for the zinc-metallized ones as compared to the initial bolt tension.
(3) The coefficient of friction (the rate of the load at which slip occurred compared to the real bolt tension) kept a constant value for the non-treatment surfaces but had a tendency to increase in the case of hot-dip galvanized ones and zinc-metallized ones.