義人 伊藤

Study on environmental durability of rubber bearing for bridges

IABSE Symposium, Towards a Better Built Environment-Innovation, Sustainability, Information Technology, Melbourne, Australia, September 11-13, 2002（CD-ROM). 2002, p.268-269

An Acceleration-Cyclic Corrosion Test of Coating Systems for Steel Bridges

Publisher Summary The chapter explores an acceleration cyclic corrosion test of coating systems for steel bridges. Painting systems are widely used to prevent corrosion attacks, and to maintain the functional ability and good appearance of steel structures. Recently, metallic coating systems, such as zinc hop dip galvanizing and thermal sprayed coating systems become popular in Japan because reduction in recoating costs at the maintenance stage of the steel bridges is expected. The remaining life of the coating systems, which is important to maintain steel bridges efficiently, is often predicted based on the statistical analysis on visual observation of real structural members and test specimens under atmospheric environments. Although they allow field examinations, it takes long time to obtain any deterioration data of the coating systems. The combined environmental factors, such as temperature, humidity, and salinity coming flying make it difficult to understand corrosion characteristics of the coating systems. The chapter focuses on corrosion degradation of the coating systems with initial defects or partially deteriorated regions. Three types of painting systems, A- and I-painting systems for mild corrosion environments and C-painting systems for severe corrosion environments in Japan, and four types of metal coating systems are corrosion-tested during the exposure time of 400 and 300 days, respectively.

Effect of Rubber Bearing Ageing on Seismic Response of Base-Isolated Steel Bridges

Publisher Summary The chapter discusses the effects of rubber bearing ageing on seismic response of base-isolated steel bridges. It focuses on the aged rubber bearings influence on the seismic response of base-isolated steel piers. The long-term properties of the natural rubber material are investigated through a series of accelerated exposure tests. Based on the test results, the aged rubber bearing is modeled considering the ageing degree in the outer regions, and the performances are predicted precisely using the finite element method. It shows that the shear stiffness of the rubber bearing increases over time. Then, the study on the seismic response of steel piers equipped with aged rubber bearings is carried out in the chapter. The results prove that the ageing of the rubber bearing has large effects on the seismic response of the isolated bridges. Generally, the damage degree of the steel pier upgrades to a higher level if the shear stiffness of the bearing increases by 20%, which is crucial from the design point of view.