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TWO DIMENSIONAL LINEAR FINITE ELEMENT ANALYSIS OF POST-TENSIONED BEAMS WITH EMBEDDED ELEMENTS USING MATLAB
Title
TWO DIMENSIONAL LINEAR FINITE ELEMENT ANALYSIS OF POST-TENSIONED BEAMS WITH EMBEDDED ELEMENTS USING MATLAB.
Creator
Hutchinson, Rodolfo, Onyemelukwe, Okey, University of Central Florida
Abstract / Description
The objective of this research project was to create a Finite Element Routine for the Linear Analysis of Post-Tensioned beams using the program CALFEM® [20] developed at the division of Structural Mechanics in Lund University, Sweden. The program CALFEM and our own made files were written in MATLAB, an easy to learn and user-friendly computer language. The approach used in this thesis for analyzing the composite beam consists in embedding the steel tendons at the exact location where they...
Show moreThe objective of this research project was to create a Finite Element Routine for the Linear Analysis of Post-Tensioned beams using the program CALFEM® [20] developed at the division of Structural Mechanics in Lund University, Sweden. The program CALFEM and our own made files were written in MATLAB, an easy to learn and user-friendly computer language. The approach used in this thesis for analyzing the composite beam consists in embedding the steel tendons at the exact location where they intersect the concrete parent elements, without moving the concrete parent element nodes. The steel tendons are represented as one dimensional bar elements inserted into the concrete parent elements, which at the same time are represented as 8 node Iso-parametric plane elements. The theory presented in Ref. [4] served as basis for the modeling of the post-tensioned beams; however it only explained the procedure for modeling simple reinforced concrete beams, due to this we needed to make the appropriate adjustments so we could model post-tensioned beams. Assembly of the tendon stiffness into the concrete elements will depend on the bond interface between the steel and concrete, this bonding effect will be modeled using link elements; the stiffness of this link element used in the concrete-tendon interface will be the change in cohesion (between the grout or duct and the steel tendon) at the interface due to the relative slip between the concrete and the steel elements nodes. Loads (Distributed, Concentrated or Post-Tensioning) are applied directly into the concrete parent elements, and then from their resultant displacement the displacements and forces of all the steel tendon elements are obtained, this is done consecutively for all the post-tensioned tendons at every load increment. Four examples from different references and software programs are solved and compared with our results: (1) A simply reinforced cantilever plate. (2) A reinforced concrete beam, under the effect of a vertical concentrated load at mid-span. For this problem the force distribution along the steel reinforcement is obtained for two conditions, perfectly bonded and perfectly un-bonded, our results are compared with the ones obtained with the program SEGNID. (3) Consists of a continuous un-bonded post-tensioned beam with two spans, without stress losses on the tendon. The reactions at the supports and the concrete stress distribution at the location of the mid-support are obtained after the post-tensioning force is applied at both ends. (4) Consist on a un-bonded post-tensioned beam with stress losses on the tendons due to friction, wobbling and anchorage loss, under gradual loading and consecutive post-tensioning of two tendons, the results are compared with the ones reported using the program BEFE [5] developed at the University of Technology Graz, Austria. The results obtained using our program are very similar to the ones obtained with the other programs, including the more powerful curved embedded approach used by BEFE [5].
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Date Issued
2004
Identifier
CFE0000256, ucf:46227
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000256
TRANSFER AND DEVELOPMENT LENGTH OF STRANDS IN POST-TENSIONED MEMBERS AFTER ANCHOR HEAD FAILURE
Title
TRANSFER AND DEVELOPMENT LENGTH OF STRANDS IN POST-TENSIONED MEMBERS AFTER ANCHOR HEAD FAILURE.
Creator
El Zghayar, Elie, Mackie, Kevin, University of Central Florida
Abstract / Description
Post-tensioning tendons in segmental bridge construction are often only anchored within the deviator and pier segments. The effectiveness of the post-tensioning (PT) system is therefore dependent on proper functioning of the anchorages. On August 28, 2000 a routine inspection of the Mid-Bay Bridge (Okaloosa County, Florida) revealed corrosion in numerous PT tendons. Moreover, one of the 19-strand tendons was completely slacked, with later inspection revealing a corrosion-induced failure at...
Show morePost-tensioning tendons in segmental bridge construction are often only anchored within the deviator and pier segments. The effectiveness of the post-tensioning (PT) system is therefore dependent on proper functioning of the anchorages. On August 28, 2000 a routine inspection of the Mid-Bay Bridge (Okaloosa County, Florida) revealed corrosion in numerous PT tendons. Moreover, one of the 19-strand tendons was completely slacked, with later inspection revealing a corrosion-induced failure at the pier anchor location. Anchorage failure caused all PT force to transfer to the steel duct located within the pier segment that in turn slipped and caused the tendon to go completely slack. After the application of PT force, the anchorage assembly and steel pipes that house the tendon are filled with grout. These short grouted regions could, in the event of anchorage failure, provide a secondary anchorage mechanism preventing the scenario mentioned above from occurring. This paper presents the results of a full-scale experimental investigation on anchorage tendon pull-out and a finite element model to support the experimental results and interpretation. The study focuses on the length required to develop the in-service PT force within the pier segment grouted steel tube assembly. Seven, twelve, and nineteen 0.6ÂÂ" diameter strand tendons with various development lengths were considered. Recommendations for pier section pipe detailing and design will be discussed.
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Date Issued
2010
Identifier
CFE0003363, ucf:48465
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003363
STRUCTURAL CONDITION ASSESSMENT OF PRESTRESSED CONCRETE TRANSIT GUIDEWAYS
Title
STRUCTURAL CONDITION ASSESSMENT OF PRESTRESSED CONCRETE TRANSIT GUIDEWAYS.
Creator
Shmerling, Robert, Catbas, F. Necati, University of Central Florida
Abstract / Description
Objective condition assessment is essential to make better decisions for safety and serviceability of existing civil infrastructure systems. This study explores the condition of an existing transit guideway system that has been in service for thirty-five years. The structural system is composed of six-span continuous prestressed concrete bridge segments. The overall transit system incorporates a number of continuous bridges which share common design details, geometries, and loading conditions...
Show moreObjective condition assessment is essential to make better decisions for safety and serviceability of existing civil infrastructure systems. This study explores the condition of an existing transit guideway system that has been in service for thirty-five years. The structural system is composed of six-span continuous prestressed concrete bridge segments. The overall transit system incorporates a number of continuous bridges which share common design details, geometries, and loading conditions. The original analysis is based on certain simplifying assumptions such as rigid behavior over supports and simplified tendon/concrete/steel plate interaction. The current objective is to conduct a representative study for a more accurate understanding of the structural system and its behavior. The scope of the study is to generate finite element models (FEMs) to be used in static and dynamic parameter sensitivity studies, as well load rating and reliability analysis of the structure. The FEMs are used for eigenvalue analysis and simulations. Parameter sensitivity studies consider the effect of changing critical parameters, including material properties, prestress loss, and boundary and continuity conditions, on the static and dynamic structural response. Load ratings are developed using an American Association for State Highway Transportation Officials Load and Resistance Factor Rating (AASHTO LRFR) approach. The reliability of the structural system is evaluated based on the data obtained from various finite element models. Recommendations for experimental validation of the FEM are presented. This study is expected to provide information to make better decisions for operations, maintenance and safety requirements; to be a benchmark for future studies, to establish a procedure and methodology for structural condition assessment, and to contribute to the general research body of knowledge in condition assessment and structural health monitoring.
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Date Issued
2005
Identifier
CFE0000658, ucf:46520
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000658