Design of tie bars in Portland cement concrete pavement considering nonlinear temperature variations

Seongcheol Choi, Moon C. Won

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Tie bar design at longitudinal construction joints in portland cement concrete pavement is based on the so-called subgrade drag theory. According to this theory, the required maximum spacing between tie bars is inversely proportional to the widths of the lanes that are tied together. As the number of lanes increases to accommodate greater traffic demand, tie bar spacing decreases. In a recent IH-10 project in Houston, Texas, the width of pavement lanes tied together was great enough to require 30-cm (1-ft) tie bar spacing. In Texas Department of Transportation design standards for continuously reinforced concrete pavement, the same spacing is required for both tie bars and transverse steel. The use of 30-cm spacing for both tie bars and transverse steel results in a substantial increase in the cost of the project. The subgrade drag theory assumes uniform temperature distribution through the concrete slab depth and no curling effect is incorporated. This assumption needs reconsideration. Field testing was conducted to investigate slab behavior and to develop more rational designs for tie bars and transverse steel. Concrete displacement gauges were installed at the free edge of the concrete slab to measure transverse horizontal as well as vertical displacements. Steel strain gauges were installed at different locations in tie bars. The concrete slab showed curling behavior; the stresses in tie bars clearly demonstrated the effects of curling. Theoretical analysis was conducted, and the results verified the field data. A new design method was proposed for tie bars.

Original languageEnglish
Pages (from-to)24-33
Number of pages10
JournalTransportation Research Record
Issue number2095
DOIs
StatePublished - 2009

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