Stabilizing techniques for curved steel I-girders during construction

There are many issues and challenges to deal with when designing a curved I-girder bridge. These challenges primarily deal with the many performance stages that curved I-girder bridges have such as the erection, construction, and in-service stages. When design engineers assess the stability of a...

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Main Author: Petruzzi, Brian James
Format: Others
Language:English
Published: 2010
Subjects:
Online Access:http://hdl.handle.net/2152/ETD-UT-2010-05-1364
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spelling ndltd-UTEXAS-oai-repositories.lib.utexas.edu-2152-ETD-UT-2010-05-13642015-09-20T16:55:32ZStabilizing techniques for curved steel I-girders during constructionPetruzzi, Brian JamesBridgesErectionConcrete placementStabilityCurved steel I-girdersI-girdersConstructionBridge constructionI-girder bridgesLiftingPartially constructed bridgesDesign and constructionThere are many issues and challenges to deal with when designing a curved I-girder bridge. These challenges primarily deal with the many performance stages that curved I-girder bridges have such as the erection, construction, and in-service stages. When design engineers assess the stability of a bridge system, they typically evaluate the system in its final configuration with all cross frames attached and the hardened concrete deck placed. The evaluation of girder stability during erection and early stages of construction stages is difficult because of the limited presence of bracing in the system. Due to a lack of readily available analytical tools, many contractors do not conduct detailed analytical evaluations of the bridge behavior during early stages of the construction when stability is often critical. Instead, many contractors use rules of thumb and experience to ensure stability during erection. Erection and construction practices typically vary among contractors and consistent erection methods are a rarity. Although some rules of thumb may be quite conservative, others are much less so. Therefore, coming up with design guidelines based on parametric studies rather than rules of thumb are desirable to help allow the contractor and the designer to work together to prevent issues that may occur due to the lack of communication between the two professions. Lastly, many challenges arise due to the complex geometry of curved I-girders. To prevent excessive rotation in erected girders, three points of vertical support are often provided. Two of these points usually consist of permanent supports in the form of bridge piers or abutments. The third point of support may consist of a temporary support in the form of a shore tower or holding crane. Cases where a holding crane may be satisfactory over a shore tower are also not well understood. To improve the understanding of lifting practices and temporary support requirements, parametric studies were conducted using the finite element program ANSYS. Field data consisting of displacement, stress, and girder rotations gathered from two tests were used to validate both the linear and geometric non-linear three-dimensional FEA models. Upon validation, the finite element model was used to conduct linear and geometric non-linear analyses to determine critical factors in curved I-girder bridges during construction. Specifically, serviceability limit states were studied for the lifting of curved girders. For partially constructed states, parametric studies were conducted to determine optimal locations to place temporary supports as well as to investigate stability differences between using a shore tower and a holding crane. Recommendations are presented to provide guidance for the lifting of curved I-girders as well as to maximize stability of partially constructed bridges.text2010-11-02T20:36:18Z2010-11-02T20:36:31Z2010-11-02T20:36:18Z2010-11-02T20:36:31Z2010-052010-11-02May 20102010-11-02T20:36:31Zthesisapplication/pdfhttp://hdl.handle.net/2152/ETD-UT-2010-05-1364eng
collection NDLTD
language English
format Others
sources NDLTD
topic Bridges
Erection
Concrete placement
Stability
Curved steel I-girders
I-girders
Construction
Bridge construction
I-girder bridges
Lifting
Partially constructed bridges
Design and construction
spellingShingle Bridges
Erection
Concrete placement
Stability
Curved steel I-girders
I-girders
Construction
Bridge construction
I-girder bridges
Lifting
Partially constructed bridges
Design and construction
Petruzzi, Brian James
Stabilizing techniques for curved steel I-girders during construction
description There are many issues and challenges to deal with when designing a curved I-girder bridge. These challenges primarily deal with the many performance stages that curved I-girder bridges have such as the erection, construction, and in-service stages. When design engineers assess the stability of a bridge system, they typically evaluate the system in its final configuration with all cross frames attached and the hardened concrete deck placed. The evaluation of girder stability during erection and early stages of construction stages is difficult because of the limited presence of bracing in the system. Due to a lack of readily available analytical tools, many contractors do not conduct detailed analytical evaluations of the bridge behavior during early stages of the construction when stability is often critical. Instead, many contractors use rules of thumb and experience to ensure stability during erection. Erection and construction practices typically vary among contractors and consistent erection methods are a rarity. Although some rules of thumb may be quite conservative, others are much less so. Therefore, coming up with design guidelines based on parametric studies rather than rules of thumb are desirable to help allow the contractor and the designer to work together to prevent issues that may occur due to the lack of communication between the two professions. Lastly, many challenges arise due to the complex geometry of curved I-girders. To prevent excessive rotation in erected girders, three points of vertical support are often provided. Two of these points usually consist of permanent supports in the form of bridge piers or abutments. The third point of support may consist of a temporary support in the form of a shore tower or holding crane. Cases where a holding crane may be satisfactory over a shore tower are also not well understood. To improve the understanding of lifting practices and temporary support requirements, parametric studies were conducted using the finite element program ANSYS. Field data consisting of displacement, stress, and girder rotations gathered from two tests were used to validate both the linear and geometric non-linear three-dimensional FEA models. Upon validation, the finite element model was used to conduct linear and geometric non-linear analyses to determine critical factors in curved I-girder bridges during construction. Specifically, serviceability limit states were studied for the lifting of curved girders. For partially constructed states, parametric studies were conducted to determine optimal locations to place temporary supports as well as to investigate stability differences between using a shore tower and a holding crane. Recommendations are presented to provide guidance for the lifting of curved I-girders as well as to maximize stability of partially constructed bridges. === text
author Petruzzi, Brian James
author_facet Petruzzi, Brian James
author_sort Petruzzi, Brian James
title Stabilizing techniques for curved steel I-girders during construction
title_short Stabilizing techniques for curved steel I-girders during construction
title_full Stabilizing techniques for curved steel I-girders during construction
title_fullStr Stabilizing techniques for curved steel I-girders during construction
title_full_unstemmed Stabilizing techniques for curved steel I-girders during construction
title_sort stabilizing techniques for curved steel i-girders during construction
publishDate 2010
url http://hdl.handle.net/2152/ETD-UT-2010-05-1364
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