Civil Engineering

 

Date of this Version

Fall 11-2011

Comments

A DISSERTATION Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Doctor of Philosophy, Major: Interdepartmental Area of Engineering (Civil Engineering), Under the Supervision of Professors Elizabeth G. Jones and Atorod Azizinamini. Lincoln, Nebraska: November, 2011

Copyright (c) 2011 Nima Ala

Abstract

Expansion joints are one of the main causes for high maintenance costs in bridges. The search for ideal expansion joints has proven fruitless. That is why it has been said that “the best joint is no joint”. A seamless bridge system is envisioned that results in bridges with long service lives by eliminating the joints over the entire length of the bridge, approach slab and a segment of the roadway called transition. All bridge thermal movements are dissipated to zero in the transition. The system is similar to a system developed in Australia but modifications had to be made to extend it for the U.S. practice in which jointed or flexible pavements are commonly used. While the remainder of paving within a roadway is jointed or flexible, a segment of roadway containing the bridge and the transition is similar to continuously reinforced concrete paving. The proposed transition system consists of a transition slab connected via “small piles” to a “secondary slab”, embedded in the base soil. The advantages of the new system include low maintenance costs, long service life, and enhanced seismic performance. The system is beneficial in the case of skewed and/or curved bridges. Parametric studies using SAP2000 have then been utilized to comprehend the system behavior and to develop an experimental program in which a segment from the transition system is simulated. The experiment elucidated the effectiveness of the transition system, the behavior of geomaterial, and the behavior of pile-slab connection. A small pile-concrete slab connection detail with a simple construction technique is proposed. Detailed FE model of the as-built connection was developed using ABAQUS to study the connection behavior and calibrate the models. SAP2000 models of the experimental sample were also developed. A special reinforcement reduction detail for the transition slab and cracked section analysis are explained to achieve a controlled cracking. Recommended design methods for the new components of the seamless system are explained. Life cycle cost analysis has been carried out.

Advisors: Elizabeth G. Jones and Atorod Azizinamini

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