The Bump at the End of the Bridge
The Bump at the End of the Bridge

Author: Jeong Bok Seo

Publisher:

Published: 2005

Total Pages:

ISBN-13:

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A number of recently constructed bridge approach slabs using an articulation at mid span and the wide flange terminal anchorage system have experienced settlement at their expansion joints. This problem is more commonly referred to as the bump at the end of the bridge. This study investigated reasons for the bumps and recommended ways to improve the current situation. To find out possible causes of the bridge approach slab problem, literature review, questionnaire survey, and a visual inspection for 18 Houston sites were conducted. Based on the results, two bridge sites in Houston, Texas, were selected for detailed investigation. An extensive series of laboratory and field tests were performed at each site. The main causes of bump at two study sites were compression of embankment soil and natural soil, and poor compaction of embankment soil. The finite-element computer program ABAQUS was used to evaluate behavior of the current approach slab design and of a possibly more effective design. The results show that the transition zone is about 12 m with 80 percent of the maximum settlement occurring in the first 6 m for a uniform load case and the optimum width of sleeper and support slabs is 1.5 m. A new approach slab which is 6 m long and has one span from the abutment to a sleeper slab was proposed based on accumulated data. It is designed to carry the full traffic load without support on the soil except at both ends; the support slab is removed and the wide flange is kept on the embankment side as a temperature elongation joint. The BEST device (Bridge to Embankments Simulator of Transition) was built to simulate the bump at the end of the bridge problem. It is a 1/20 [superscript th] scale model of the typical transition and the dimension was determined from dimensional analysis. Multiple BEST tests were conducted using a range of parameters and several influence factors were derived. A computer program was developed which uses the influence factors to predict the bump size from the beginning stage of embankment construction.

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.

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.

Identification of the Best Practices for Design, Construction, and Repair of Bridge Approaches
Identification of the Best Practices for Design, Construction, and Repair of Bridge Approaches

Author: David White

Publisher:

Published: 2005

Total Pages: 349

ISBN-13:

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Bridge approach settlement and the formation of the bump is a common problem in Iowa that draws upon considerable resources for maintenance and creates a negative perception in the minds of transportation users. This research study was undertaken to investigate bridge approach problems and develop new concepts for design, construction, and maintenance that will reduce this costly problem. As a result of the research described in this report, the following changes are suggested for implementation on a pilot test basis: Use porous backfill behind the abutment and/or geocomposite drainage systems to improve drainage capacity and reduce erosion around the abutment; On a pilot basis, connect the approach slab to the bridge abutment, change the expansion joint at the bridge to a construction joint of 2 in., use a more effective joint sealing system at the CF joint, and change the abutment wall rebar from #5 to #7 for non-integral abutments; and For bridges with soft foundation or embankment soils, implement practices of better compaction, preloading, ground improvement, soil removal and replacement, or soil reinforcement that reduce time-dependent post construction settlements.

Design and Construction of Bridge Approaches
Design and Construction of Bridge Approaches

Author: Harvey E. Wahls

Publisher: Transportation Research Board

Published: 1990

Total Pages: 56

ISBN-13: 9780309049054

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Includes case histories of the Dumbarton Bridge (San Francisco Bay, Calif.), the Rainier Avenue Embankment (Seattle, Wash.) and the Gallows Road Grade Separation (Fairfax, Va.)