Graduation Semester and Year

2011

Language

English

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering

Department

Civil Engineering

First Advisor

Nur Yazdani

Abstract

The purpose of this research is to evaluate a method proposed by Franz Dischinger (Dischinger, 1939) to consider the effects of a variable modulus of elasticity (MOE) of concrete over a period of time. Current guidelines suggested by the American Association of State Highways and Transportation Officials (AASHTO) assume a constant value for the MOE and base its calculation on the unit weight of concrete and the twenty eight day compressive strength of concrete. A few methods such as the ACI 209 Model Code (ACI 209, 1982) and CEB-FIP 1990 (CEB-FIP 1990, 1990) provide guidelines for the calculation of a variable modulus of elasticity. Dischinger's method varies the MOE through the use of a concrete creep function. The values of the time dependent MOE for each of the methods have been compared. Specifically this research focused on the effect Dischinger's method has on prestress losses in a prestressed concrete beam. This research also compared the losses between all three methods. The results showed that Dischinger's theory provides for higher values of modulus of elasticity and predicts higher losses. Over a period of time the prestress losses become constant. This is extremely useful since it can be used in conservative beam design.

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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