Civil Engineering

 

Date of this Version

Spring 5-2012

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Civil Engineering, Under the Supervision of Professor Maher K. Tadros and Professsor George Morcous. Lincoln, Nebraska: May, 2012

Copyright (c) 2012 Jenna L. Hansen

Abstract

Parking structures are essential to any growing commercial district, yet little thought is given to their longevity and appearance. This is particularly the case with precast parking structures. Typical issues include poor joint performance and the impact of stemmed members on interior building aesthetics. Research provided in this report proposes an alternate design that improves long term joint performance and optimizes the perspective spacing between deck members. These benefits (along with the others) are incorporated to reflect the benefits of parking structures designed using cast-in-place concrete and structural steel with concrete decking. Other benefits include: flexible column spacing, reduced / no shear walls, monolithic behavior of joints, lower maintenance costs, imperceptible floor vibration, the perception of higher ceilings, improved light distribution, and fewer ledges to collect dirt and debris. The system being proposed is based on the use of pre-topped box beams for the main deck members. Research focuses on the optimization of the main deck member's cross-sectional properties, prestress, shear, and transverse reinforcement. Investigation of a post-tensioned transverse connection between members is also presented and considered essential to improving the long term performance of joints. The joist support system is based on interior columns and exterior wall panels with 40 percent openings. Longitudinal and transverse testing was conducted as a part of this research in order to verify design assumptions and determine behavior of the deck system. Results for longitudinal testing indicate a highly ductile section in which strand bond controls over vertical or horizontal interface shear. Analysis of the transverse post-tensioned connection confirms that compression forces are distributed evenly along the joint and that transverse behavior is continuous. Both factors contribute to providing the system with a higher resistance to salt and chemical infiltration - the main source of joint deterioration.

Advisers: Maher K. Tadros and George Morcous

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