Title: Measurements of rotational stiffness for precast concrete girder transport vehicles, part 1
Date Published: March - April 2024
Volume: 69
Issue: 2
Page Numbers: 37 - 54
Authors: C. Shawn Sun, Adam D. Sevenker, and Mostafa Abo El-Khier

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Long precast, prestressed concrete girders are becom­ing popular in bridge construction. Several states have constructed bridges using slender I-girders that exceed­ed 200 ft (61 m) in length. When such a girder is seated on flexible supports such as a jeep and dolly, it can roll about an axis located beneath its center of mass. This movement induces lateral bending, which raises concerns about the lateral stability of particularly long girders. While the stability of these girders is largely influenced by the hauling equipment, very few state transportation agencies offer guidelines addressing the rotational stiffness of transport vehicles and other critical parameters. This paper presents comprehensive field measurements of rotational stiffness from various precast concrete plants. It covers two methods— namely, the placement of eccentric loads and the parking of vehicles on a substantial cross slope—to gauge rotational stiffness. The measurements included a variety of transport vehicles with air and leaf suspensions. The examined vehicles displayed a rotational stiffness ranging from 22,000 to 42,000 kip-in. (2486 to 4745 kN-m) per radian. The paper also suggests a guideline for tilt measurements to gather essential data and pinpoint the rotational stiffness.