Long-Term Bridge Performance Committee Letter Report: August 3, 2012

The effective management of bridges requires a good understanding of their life expectancies. Improved prediction of bridge service life is required to be developed in order to better understand bridge deterioration and to find more effective maintenance and repair strategies. These models are integral components of the Long-Term Bridge Performance Program (LTBP), a 20-year research effort initiated by the U.S. Federal Highway Administration (FHWA) to improve the understanding of bridge performance. In this paper, the development of a life expectancy model framework, as part of the research effort in this program, is presented. The framework is established based on a semi-probabilistic approach to adherently maintain the advantages of both deterministic and probabilistic techniques. The modeling follows a step-by-step process which incorporates data collected from historical records, training the data, creating a model based on the most suitable approach, and reducing the associated uncertainties. The basic model is first trained by the network of bridge inventory and the uncertainties are reflected by determining lower and upper margins. Then the model is improved by introducing the new knowledge gained from the external attributes influencing the structure. Finally, the condition states of the bridge components are employed directly to refine the model for realistic assessment. The developed model is later automated into the Bridge Portal, the main core of the bridge-performance data warehouse. A detailed example using the Mid-Atlantic cluster bridge inventory data is presented in this paper to illustrate the application of the method described above.

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Cable effective length model error-based bridge performance warning method under thermal action

Advances in Structural Engineering ◽

10.1177/13694332211048007 ◽

2021 ◽

pp. 136943322110480

Author(s):

Yan Wang ◽

Dong-Hui Yang ◽

Yu-Zheng Zhou ◽

Ting-Hua Yi

Keyword(s):

Thermal Action ◽

Dynamic Responses ◽

Effective Length ◽

Time Variability ◽

Long Span ◽

The North ◽

Static Responses ◽

Bridge Performance ◽

The Relationship

The cables of long-span cable-stayed bridges are subjected to substantial tension during long-term service and are more susceptible to corrosion and fatigue failure than concrete structures. Most existing structural health monitoring (SHM) systems do not have monitoring equipment to directly measure cable length, and long-term monitoring of the change in cables is less involved. The displacement response of a bridge is induced by the combination of dynamic effects (wind and highways) and quasi-static effects (temperature). In this paper, the dynamic responses were eliminated by averaging the displacement data for 10 min, and the relationship between temperature and displacement was studied. Based on the monitoring data, the distribution of the thermal field for the bridge was studied and the time variability of the tower displacement was investigated. The correlation was analyzed to study the relationship between the temperature and the tower displacements, the north tower–south tower distance and the tower–girder distances. A strong linear relationship between the temperature and quasi-static responses of the displacements was observed. The thermal expansion coefficient of the effective length of cables was proposed as a quantitative index for long-term cable monitoring. The error in the cable effective length is proposed as the warning index for performance warning research. The results show that the proposed performance warning method can monitor cables and perform warnings when the cable is damaged.

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