Dissertation/Thesis Abstract

Evaluation of the Effect of a Modified Wedge Geometry on the Behavior of Mono-Strand Post-Tensioning Anchorages
by McAlpine, Patrick Charles, M.S.V., Villanova University, 2014, 170; 10185436
Abstract (Summary)

The objective of this study is to create and evaluate if finite element modeling is a feasible approach to modeling different wedge geometries of post tensioned systems by comparing the experimental data from two wedges to analytical data. The motivation to develop an accurate finite element model of a wedge, tendon, and anchor system is to better understand the internal stresses the system is subjugated to and the interactions between components. By not fully understanding what is occurring within the anchor, the most efficient anchor cannot be designed. This can lead to premature failures of the strand which can result in total collapse of the structure. In recent years the applications of post tensioned strands have grown rapidly. Some of these applications require the strand to withstand higher strains than can currently be reached. An example of one of these applications is a shear rocking wall in earthquake prone areas. To date there is some experimental data on strand testing, but very little research has been conducted examining a modified geometry wedge. There is even less in depth literature on finite element modeling of the interactions between the components. One reason for this lack of research is because of the great variability in anchor and wedge configurations. Therefore, the focus of this research is to develop the interaction laws for one type of anchorage from one manufacturer. Once these laws are established and considered scientifically sound, the most efficient anchor wedge mechanism can be designed.

This thesis presents one of the stepping stone models needed to help converge on the interaction laws. The experimental component of this report evaluated two different wedge geometries. In the experimental trials the modified wedges preformed more efficiently than the standard wedges. The modified wedges were able to reach much higher strains. These geometries were modeled in a finite element program and the experimental results were replicated by adjusting the interaction relationships. The starting point for the relationships were based off of the studies found in the literature review. The results from analytical model of the standard wedges matched the experimental results very accurately. The analytical model of the modified wedge requires refinement. The results of the analytical model did not match the experimental observations as well as they should. However, the results still support the theory that the computer software can differentiate between standard and modified wedge geometries.

Indexing (document details)
Advisor: Musselman, Eric, Dinehart, David
Commitee: Gross, Shawn
School: Villanova University
Department: Department of Civil & Environmental Engineering
School Location: United States -- Pennsylvania
Source: MAI 56/02M(E), Masters Abstracts International
Subjects: Civil engineering
Keywords: Abaqus, Finite modeling, Modified geometry, Mono strand, Post tension strand, Wedge
Publication Number: 10185436
ISBN: 9781369336283
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