BEHAVIOR OF SOLID WALL AND SANDWICH FIBER REINFORCED POLYMER LINERS USED FOR REHABILITATION OF BURIED PIPES

Abstract

This research was focused on studying the behavior of fiber reinforced polymer (FRP) liners that could be bonded inside deteriorated buried pipes, as an effective rehabilitation system to increase strength and stiffness. The results of thin solid wall and sandwich FRP liners subjected to transverse compressive loading are discussed in this thesis. Specimens were tested under parallel plate loading method according to ASTM D2412–11 standards, using a customized compression testing machine with string potentiometers to measure the diametrical deflections. Solid wall glass fiber reinforced polymer (GFRP) and carbon fiber reinforced polymer (CFRP) liners, sandwich liners with GFRP/CFRP facesheets and three-dimensional (3D) woven fabric core, and sandwich liners with GFRP/CFRP facesheets and bulkermat core, were tested to find the diametrical deflection, pipe stiffness (PS) and stiffness factor (SF) at 1%, 2.5%, 5% and 10% vertical diametrical deflection. The structural behavior and mechanical properties of the FRP liners were used to develop an analytical model to determine the diametrical ring deflection occurring in the vertical and horizontal directions that causes geometric non-linearity while deforming substantially and corresponding strains at springline and crown/invert positions. The model was in good agreement with the experimental data and was able to predict the failure mode of specimens with linear elastic material behavior that was fully composite until failure in transverse compression. A parametric study was also conducted to analyze the effect of liner diameter, core thickness, facesheet thickness and shape geometry on liner behavior to establish a data platform for design purposes. Overall, the strength and ring stiffness based on vertical diametrical deflections were determined to understand the behavior and mechanical performance of thin solid wall and sandwich liners under transverse compression.