Semester

Summer

Date of Graduation

2004

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Civil and Environmental Engineering

Committee Chair

Hota GangaRao.

Abstract

The temperature difference between the top and bottom of a fiber reinforced polymer (FRP) composite deck (120°F) is nearly three times that of conventional concrete decks (40°F). The large temperature difference is attributed to low thermal conductivity of FRP material and low thermal mass due to hollow core. Thermal response studies have been conducted for FRP bridge decks under thermal fluctuations and temperature difference across the deck depth.;In this study, thermal tests were conducted on two FRP bridge deck modules (4&inches; and 8&inches; deep decks) in the laboratory by heating or cooling at the top surface of FRP deck (i.e., room temperature at bottom surface). The FRP deck boundaries were either four free boundaries (FFFF) or two opposites boundaries being free while the remaining two were simply supported (SSFF). Deflections and strains were recorded at different location under thermal loads. Closed form solutions with first term approximation were derived using the plate bending theory using Macro Approach and Navier-Levy method for SSFF boundary conditions. Theoretical results (using Macro Approach, Navier-Levy, and FEM) were compared with experimental results. In addition, thermal responses of two FRP deck bridges (i.e., Market Street Bridge and Wickwire Run Bridge) under thermal difference between the deck top and bottom were evaluated after establishing coefficients of thermal expansion (CTE) of both FRP decks. The laboratory test data indicated that the FRP deck exhibits a hogging effect (upward convexity) when it was subjected to positive temperature difference (i.e., Ttop > Tbottom, heating test) and a sagging effect when it was subjected to negative temperature difference (i.e., Ttop < Tbottom , cooling test). Deflections increased with increasing magnitude of temperature difference. The positive strain (expansion) and compressive stress were induced in the FRP deck when temperature of FRP decks was increased by direct exposure to Sun light. Partial deck restraint, provided by steel stringer, resulted in partially induced stresses. The transient thermal stresses could be as high as 45% of the allowable stress of FRP decks and the transient thermal strain could be as high as 86% of allowable strain of the FRP bridge deck modules.

Download

Share

COinS