Abstract:

Pultruded fiber reinforced plastics (FRP) are a promising new structural system that can be used successfully in many areas of civil engineering.

The objective of this study is to examine the creep behavior of the composite materials that might be used in bridge construction and to review some existing theoretical and empirical creep models. Both viscoelastic mechanical models and models based on experimental results such as Findley's power law model are evaluated. Using both creep models, this study examines the fiber volume fraction effects and temperature effects on nonlinear creep behavior. The Marquardt algorithm is applied as a method for nonlinear curve fitting analysis. Estimates of the creep behavior for whole fiber volume fraction from limited fiber volume fraction information are carried out. This study verifies that the fiber volume fraction and temperature play important role in the mechanical behavior and in the creep behavior of composite materials.

Finite element analysis is used to conduct an evaluation of the mechanical performance of some currently proposed composite structural bridge components. In the finite element analysis, this study uses the commercial finite element software, ABAQUS, and a FORTRAN program which was developed for this study. A comparison is made of the analytic finite element results with a closed-form solution. From the material study it was concluded that the creep and creep-recovery behavior of FRP structural components could be satisfactorily based on Findley's power law. Four examples of typical pultruded bridge deck sections were selected for study. Two specific types of behavior that could be affected by creep were studied. The first is the effect of creep on the long-term deflection behavior of a FRP Bridge deck under self-weight. The second was a study to determine whether the change in loadings resulting from creep could affect the forces on individual sections of the bridge deck to cause local buckling effects.

After carrying out a rigorous finite element solution, a simplified method was evaluated using equations for total structural element behavior with specially modified coefficients to account for creep effects. This study also investigated the creep deflection analysis for live loads using Average Daily Truck Traffic (ADTT) and evaluated the creep deflection behavior with static truck loads and cyclic loads for the selected bridge deck systems. AASHTO truck loading conditions were used to determine if they introduce an important contribution to the long-time performance of the deck systems. (Abstract shortened by UMI.)