Abstracts

Profile-wall high-density polyethylene (HDPE) pipesare used at increasing rates to convey surface drainage underroadways. This is because these products are cost effective, easyto handle and resistant to environmental elements. The HDPE pipesare derived from a thermoplastic material and much more flexiblecompared to the conventional pipes made of concrete and metals.Because of this inherent flexibility and other concerns that existwith thermoplastic materials, many highway agencies in the U.S.specify a limit on the HDPE pipes vertical deflection. Forexample, the Ohio Department of Transportation (ODOT) currentlyimposes a threshold vertical deflection of 7.5% on all HDPEdrainage pipes installed in the ground. Many other state DOTs havesimilar vertical deflection limits for HDPE pipes. The origin ofthis vertical deflection limit is not well understood in theengineering community.This study aims at locating the foundation ofthe threshold vertical deflection enforced by the highway agencies.In the study, different analytical methods and computer simulationmodels are applied to establish general guidelines concerning thecritical vertical deflection for the profile-wall HDPE pipes. Theanalytical methods employed embrace theories of curved beams,elasticity, and viscoelasticity. In the finite element-basedcomputer simulations, several different diameter sizes of the HDPEpipes are installed in varied installation modes and backfillmaterials to reflect the AASHTO Construction Specifications. Themain outcome of the study makes a clear and reasonable statementabout the critical vertical deflection for the commonly usedthermoplastic drainage pipes.Advisors/Committee Members: Masada, Teruhisa (Advisor).