The National Academies

NCHRP IDEA 20-30/IDEA 196 [Active (IDEA)]

Smart Installation and Monitoring System for Large Anchor Bolts of Support Structure for Highway Signs, Luminaires, and Traffic Signals

  Project Data
Funds: $140,000
Staff Responsibility: Inam Jawed
Research Agency: Iowa State University
Principal Investigator: An Chen
Completion Date: 12/31/2018

This project will develop a sensor-based inexpensive system for monitoring tension in anchor bolts in support structures for highway signs, luminaires, and traffic signals. Work in Stage 1 focuses on the development of the smart installation and monitoring system, particularly designing the sensor, passive Radio Frequency Readout Device (RFRD), and washer. For sensor design, the best metal for the sensing plates and the best material for the insulating elastic filling will be identified. Both the sensor and the sensing washer will be characterized to develop a model that relates the capacitance of the sensor to the compressive force applied to the washer. Also, a method to automate sensor calibration in the field will be developed. For RFRD design, the RFRD circuit will be designed to allow results transmission using small amount of power obtained from the input RF signal. Additionally, the device and its circuit logic will be optimized for quick reading (from a moving vehicle, for example) and to coordinate readings in the presence of other devices. The sensors will be protected with the two-washer design. The RFRD and the wire leads of the sensors will be packaged to make them robust to the elements and vandalism. Work in Stage 2 will focus on prototype system evaluation and implementation through demonstration projects. The testing and evaluation will be done at two levels -- component level on single anchor bolt and structural level on the support structure. At the structural level, the specimen will represent an actual STLS support structure. Three types of tests will be conducted -- tightening, static loading, and fatigue loading. In all tests, anchor bolts will be instrumented with strain gages at different locations. The readings from the strain gages and the proposed sensing system will be correlated, and the capability of the proposed system to record the tension load in the anchor bolts will be evaluated. The testing will be followed by demonstration projects in collaboration with state DOTs.

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