Masters Theses

Keywords and Phrases

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Abstract

"This thesis focuses on the structural properties of sand-lightweight aggregate concrete in terms of shear transfer strength at cold-joint interfaces. This type of interface is common for precast concrete connections which are typically designed using the shear-friction concept. This testing program was meant to expand the shear-friction database and evaluate the appropriateness of current shear-friction design provisions with respect to sand-lightweight concrete. This study builds on the work done by Shaw (2013) who studied lightweight expanded shale aggregate concrete. The current study included thirty-two push-off specimens constructed from sand-lightweight concrete with a target compressive strength of 5,000 psi. Either expanded clay or expanded slate was used as the course aggregate component, with the fine aggregate consisting of natural river sand. All specimens were cast with a construction joint (cold-joint), and the interface was either troweled smooth or roughened to a 0.25 in. amplitude. The reinforcement ratio was also varied by modifying the number of No. 3 double-legged stirrups crossing the shear plane.

The results of this thesis work have shown that shear transfer strength is higher for roughened versus smooth interface specimens, but the residual shear strength vur for roughened and smooth specimens was similar. The average ultimate shear stress vu,avg was generally higher for the slate aggregate specimens versus the clay aggregate specimens. The shear transfer strength vu and residual shear strength vur increased with increasing reinforcement ratio. However, for the roughened specimens, the shear transfer strength vu leveled off at higher reinforcement ratios. All shear transfer strengths vu for both the roughened and smooth specimens in this study were higher than those predicted by the current ACI, PCI, and AASHTO codes/provisions. The µe approach from the 7th Edition of the PCI Design Handbook conservatively predicts the shear strengths of smooth specimens, even though this approach is not applicable for a smooth interface. The use of a cohesion factor c in the AASHTO shear-friction design equation was conservative for all smooth interface specimens, even though AASHTO contains a provision which sets c = 0.0 for vertical interface shear cracks. This project was funded by the Precast/Prestressed Concrete Institute (PCI) and the American Concrete Institute Concrete Research Council"--Abstract, page iii.

Advisor(s)

Sneed, Lesley

Committee Member(s)

Myers, John
ElGawady, Mohamed
Meinheit, D. (Donald F.)

Department(s)

Civil, Architectural and Environmental Engineering

Degree Name

M.S. in Civil Engineering

Sponsor(s)

Precast/Prestressed Concrete Institute
American Concrete Institute

Publisher

Missouri University of Science and Technology

Publication Date

Fall 2015

Pagination

xxii, 182 pages

Note about bibliography

Includes bibliographical references (pages 176-181).

Rights

© 2015 Samantha Lynn Wermager, All rights reserved.

Document Type

Thesis - Open Access

File Type

text

Language

English

Subject Headings

Lightweight concrete -- Testing
Precast concrete -- Testing
Aggregates (Building materials)
Shear (Mechanics) -- Mathematical models
Friction -- Mathematical models

Thesis Number

T 10805

Electronic OCLC #

936209573

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