Instrumentation and Monitoring of Integral Bridge Abutment-to-approach Slab Connection
Instrumentation and Monitoring of Integral Bridge Abutment-to-approach Slab Connection

Author:

Publisher:

Published: 2008

Total Pages: 170

ISBN-13:

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The Iowa Department of Transportation has long recognized that approach slab pavements of integral abutment bridges are prone to settlement and cracking, which manifests as the "bump at the end of the bridge". A commonly recommended solution is to integrally attach the approach slab to the bridge abutment. Two different approach slabs, one being precast concrete and the other being cast-in-place concrete, were integrally connected to side-by-side bridges and investigated. The primary objective of this investigation was to evaluate the approach slab performance and the impacts the approach slabs have on the bridge. To satisfy the research needs, the project scope involved a literature review, survey of Midwest Department of Transportation current practices, implementing a health monitoring system on the bridge and approach slab, interpreting the data obtained during the evaluation, and conducting periodic visual inspections. Based on the information obtained from the testing the following general conclusions were made: The integral connection between the approach slabs and the bridges appear to function well with no observed distress at this location and no relative longitudinal movement measured between the two components; Tying the approach slab to the bridge appears to impact the bridge; The two different approach slabs, the longer precast slab and the shorter cast-in-place slab, appear to impact the bridge differently; The measured strains in the approach slabs indicate a force exists at the expansion joint and should be taken into consideration when designing both the approach slab and the bridge; The observed responses generally followed an annual cyclic and/or short term cyclic pattern over time.

Behavior of Semi-integral Abutment Bridge with Turn-back Wingwalls Supported on Drilled Shafts
Behavior of Semi-integral Abutment Bridge with Turn-back Wingwalls Supported on Drilled Shafts

Author: Safiya Ahmed

Publisher:

Published: 2022

Total Pages: 0

ISBN-13:

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Semi-integral abutment bridges are integral abutment bridges with a flexible interface at the abutment to reduce the force transferred to the foundation. Wingwalls in abutment and semi-integral abutment bridges are designed as retaining walls to avoid the sliding of the backfill soil behind the bridge abutments and roadways. Using turn-back wingwalls that are parallel to the bridge diaphragm can provide support for the parapets and minimize the total longitudinal pressure on the abutments. These walls are subjected to axial forces and bending moments due to the thermal movements. These forces can affect the orientation and the connection details of the wingwalls, which could cause cracks in the wingwalls. Despite several studies on integral abutment bridges, there are no studies that combined the behavior of the drilled shafts, footings, abutment walls, and the turnback wingwalls of semi-integral abutment bridges. The long-term performance of a semi-integral abutment bridge with turn-back wingwalls supported on drilled shafts in Ohio was investigated in this doctorate study by instrumenting five drilled shafts, footing, the forward abutment wall, and one of the wingwalls during construction. Strain and temperature were collected in 2017, 2018, and 2019. It was found that the seasonal and daily temperature changes have a significant effect on the changes in the strain in the substructure. The behavior of the abutment wall significantly affects the behavior of the wingwall, footing, and drilled shafts. It was also noticed that the behavior of the abutment was irreversible, and the top of the abutment wall and the top of the drilled shaft induced higher strain than the bottom. Cracks were noticed at the front face of the abutment wall and wingwall, and these cracks tended to close as the air temperature decreased and open as the air temperature increased. The extremely cold weather conditions induced tensile strain higher than the allowable strain at the top corner of the front face of the abutment wall and the rear face of the wingwall. Finite element results were compared with the field data, and the behavior of the substructure was achieved by the model. Parametric studies were conducted on the bridge substructure with different wingwall types and soil backfill. The results showed lower stiffness of soil backfill induces higher stresses in the bridge substructure. Moreover, inline wingwalls induce the highest thermal stresses in the substructure, while flared wingwalls induce the lowest thermal stress compared to the other types of wingwalls.

Instrumentation and Monitoring of Precast Bridge Approach Tied to an Integral Abutment Bridge in Bremer County
Instrumentation and Monitoring of Precast Bridge Approach Tied to an Integral Abutment Bridge in Bremer County

Author: Anna Nadermann

Publisher:

Published: 2010

Total Pages: 48

ISBN-13:

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Approach slab pavement at integral abutment (I-A) bridges are prone to settlement and cracking, which has been long recognized by the Iowa Department of Transportation (DOT). A commonly recommended solution is to integrally attach the approach slab to the bridge abutment. This study sought to supplement a previous project by instrumenting, monitoring, and analyzing the behavior of an approach slab tied to a integral abutment bridge. The primary objective of this investigation was to evaluate the performance of the approach slab. To satisfy the research needs, the project scope involved reviewing a similar previous study, implementing a health monitoring system on the approach slab, interpreting the data obtained during the evaluation, and conducting periodic visual inspections of the bridge and approach slab. Based on the information obtained from the testing, the following general conclusions were made: the integral connection between the approach slab and the bridge appears to function well with no observed distress at this location and no relative longitudinal movement measured between the two components; the measured strains in the approach slabs indicate a force exists at the expansion joint and should be taken into consideration when designing both the approach slab and the bridge and the observed responses generally followed an annual cyclic and/or short term cyclic pattern over time; the expansion joint at one side of the approach slab does not appear to be functioning as well as elsewhere; much larger frictional forces were observed in this study compared to the previous study.

Field Testing of Integral Abutments
Field Testing of Integral Abutments

Author: Robert E. Abendroth

Publisher:

Published: 2005

Total Pages:

ISBN-13:

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The objectives of this research program were to evaluate the state-of-art for the design of prestressed-concrete (PC), integralabutment bridges; to validate the assumptions that are incorporated in the current-design procedures for these types of bridges when they are subjected to thermal-loading conditions; and, as appropriate, to revise and improve the current-design procedures for this type of a bridge, as that design relates to the thermally-induced displacements of the abutments and the thermally-induced forces in the abutments and abutment piles. Two, skewed, PC girder, integral-abutment bridges in the State of Iowa were instrumented over a two-year period to measure structural behavior. Longitudinal and transverse displacements and rotation of the integral abutments, strains in the steel piles and in the PC girders, and temperature distributions were recorded throughout the monitoring period for both bridges. The coefficient of thermal expansion and contraction for the concrete in core specimens that were taken from 20 bridge decks and from several PC girders was experimentally measured at the 100%-dry and 100%-saturated conditions. The longitudinal displacements of the integral abutments correlated well with the recorded change in the bridge temperature. Total, longitudinal, pile strains exceeded the minimum, specified, yield strain of the steel for both bridges. Longitudinal strains in the PC girders were well within acceptable limits. The experimental data were used to calibrate and refine finite-element models of both bridges. Discrepancies were not fully explained for the differences between the predicted and measured, thermal expansion of the bridge and vertical rotations of the integral abutments.

Drilled Shaft Manual: Structural analysis and design for lateral loading by
Drilled Shaft Manual: Structural analysis and design for lateral loading by

Author: Lymon C. Reese

Publisher:

Published: 1977

Total Pages: 244

ISBN-13:

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Drilled shafts have been used on a limited scale for many years as an alternative to driven piles in a variety of foundation problems. However, uncertainty about the behavior of the drilled shaft has forestalled widespread adoption. The subject package, by Dr. Lymon C. Reese of the University of Texas, is intended for use by bridge engineers, geotechnical engineers, and builders of pile foundations. The manual contains rational procedures and practical guidelines for the design and construction of drilled shaft foundations. Volume I presents a rational design procedure for drilled shafts under axial loading and includes guidelines on construction methods, inspection, load testing, specifications, and cost estimates. Volume II presents alternative methods for computing the response of the shaft to lateral loading and presents the structural design of the shaft for axial and/or lateral loading.