Full-Scale Static Loading and Free-Vibration Tests of a Real Bridge with Friction Pendulum Bearing System (FPS) and Design Parameter Estimation

ABSTRACT

Although the friction pendulum bearing system (FPS) has been widely used in the construction of buildings, bridges, and other structures to enhance their seismic performance, the FPS was adopted in bridge construction in Japan for the first time in 2020 on the Tokai-Hokuriku expressway. To validate the design hypotheses of the real bridge with FPS, a series of static and dynamic tests were performed, and the parameters of the FPSs were estimated. The girder of the bridge supported by four FPSs was pushed to various specified displacements considered in a maximum considered earthquake event in a quasi-static manner by hydraulic jacks equipped with large-caliber valves to enable quick pressure release. The load of the jacks was then suddenly released so that the bridge entered free vibration. The bearings in the site static tests are found to undergo a noncontinuous sliding motion (stick – slip) because a small loading rate of jacks is applied. This stick – slip phenomenon is confirmed in both the site and laboratory tests in cases where the sliding velocity either approached 0 or departed from 0, i.e. at every velocity reversal. The friction coefficient is estimated from the force and displacement data at the sliding points, and good agreement is observed between the site static tests and the laboratory tests. The friction coefficient model for dynamic analysis, accounting for the stick – slip effect and several dependencies, is calibrated by these test results. The free-vibration test results, including measured displacements and accelerations, show agreement with the simulation results based on a simplified model of the bridge with the FPSs. Finally, the unscented Kalman filter and its adaptive variant are applied to estimate the design parameters of the FPSs.

KEYWORDS:

• Bridge structures
• friction pendulum bearing
• full-scale test
• static loading
• free vibration
• parameter estimation
• Kalman filter

Author Contributions

Conceived and designed the analysis: Xinhao He, Shigeki Unjoh.

Project administration: Naofumi Inaba, Takaomi Urago.

Collected the data: Shinsuke Yamazaki, Tadayuki Noro, Xinhao He.

Performed the analysis: Xinhao He, Shinsuke Yamazaki, Tadayuki Noro.

Wrote the paper: Xinhao He.

Critical revision and review: Xinhao He, Shigeki Unjoh

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

Disclosure Statement

No potential conflict of interest was reported by the author(s).