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Project Details
STATUS

Completed

START DATE

10/01/15

END DATE

02/22/18

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

ABC-UTC

Researchers
Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

Co-Principal Investigator
Katelyn Freeseman

Acting Director, BEC

About the research

Accelerated Bridge Construction (ABC) has grown tremendously over the past several years, due in part to the maturation of new materials that have properties conducive to working in an ABC environment. In recent years, Caterpillar Inc. has developed several formulations of a cementitious material for building purposes called CEMPOSIT, which is a variation of macro-defectfree (MDF) concrete.

This material is unlike any cement-based material currently available and is much more closely related to various types of rubber—although with vastly different properties than rubber. These favorable properties include high strength (comparable to ultra-high-performance concrete), rapid early strength, extremely low permeability, and the ability to be extruded on-site to fit specific project needs.

The goal of this work was to assess important material characteristics of MDF concrete and to develop conceptual uses for the material with a specific focus on accelerated/robotic bridge construction. The findings from the material tests are presented, along with discussion of applicability for usage in the accelerated bridge construction field, in this report.

Project Details
STATUS

Completed

START DATE

10/01/17

END DATE

12/31/18

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

ABC-UTC

Researchers
Principal Investigator
Katelyn Freeseman

Acting Director, BEC

Co-Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

About the research

The effectiveness of cast-in-place joints and other connections are of critical importance for ABC projects. While high strength materials are being used for these in-field connections, there is a general lack of existing research regarding inspection of joint quality and performance prior to opening to traffic. While these joints are intended to be constructed quickly, poor quality performance/construction will be detrimental to the equally important longevity of construction.

This report evaluates the capabilities of existing nondestructive testing technologies that could be used to determine bond and joint strength between pre-formed deck panels and the cast-in-place joint strips, and other ABC components of interest. The results of the information collection will be used to assess the feasibility of various techniques for further implementation in QA/QC efforts relating to ABC projects.

Project Details
STATUS

Completed

PROJECT NUMBER

12-441, SPR RB19-014, SPR RB07-013

START DATE

03/18/14

END DATE

10/29/16

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC, NCWTS
SPONSORS

ABC-UTC
Iowa Department of Transportation

Researchers
Principal Investigator
Brent Phares

Bridge Research Engineer, BEC

Co-Principal Investigator
Travis Hosteng
Co-Principal Investigator
Terry Wipf

Faculty Affiliate

About the research

As accelerated bridge construction (ABC) has gained the attention of the bridge community, certain bridge types, such as integral abutment bridges, have seen limited use. Integral abutments eliminate the expansion joint from the bridge superstructure by rigidly connecting the superstructure and foundation. The integral abutment is therefore often large and heavily reinforced, which presents challenges for ABC projects.

This research investigated integral abutment details for use in ABC projects through mechanical splicing of the integral diaphragm and the pile cap. Two ABC details, the grouted reinforcing bar coupler detail and the pile coupler detail, were evaluated in the laboratory for constructability, strength, and durability. A typical cast-in-place detail was also constructed and tested as a baseline.

For the grouted reinforcing bar coupler detail, a plywood template was used to “match cast” the pile cap and the integral diaphragm. The template was simple to construct and resulted in the successful alignment of 17 spliced steel bars and grouted couplers over an 8 foot specimen. Though the grouting of two couplers was obstructed, more than adequate strength was created by the connection, and the crack width at the precast joint was comparable to that of the cast-in-place specimen.

The pile coupler reduced the number of spliced connections between the pile cap and integral diaphragm sufficiently to facilitate adequate construction tolerances. The splicing system worked well during construction, but the detail’s strength and durability was less than ideal. Several lessons were learned from these tests that could improve the structural performance of the pile coupler detail.

 

Project Details
STATUS

Completed

PROJECT NUMBER

17-628, 18-SPR-013

START DATE

08/21/17

END DATE

01/31/19

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC, NCWTS
SPONSORS

ABC-UTC
Iowa Department of Transportation

Researchers
Principal Investigator
Travis Hosteng
Co-Principal Investigator
Behrouz Shafei

Structural Engineer, BEC

Student Researcher(s)
Austin DeJong

About the research

The use of precast elements and prefabricated bridge segments along with accelerated construction techniques, known as accelerated bridge construction (ABC), has allowed for increased efficiency of construction, reduced safety concerns, and converted month-, or even year-, long closures into a matter of weeks, or at times, days. This tactic is growing in popularity within the bridge community, and research projects have been initiated to investigate how the construction of bridge elements can be expedited.

One such element being investigated is the integral abutment. This structural connection for bridges was introduced to eliminate the need for expansion joints between the substructure and superstructure, where the presence of water and other deteriorating chemicals caused long-term and frequent maintenance issues. Due to this area needing to be heavily reinforced, congestion issues arise when attempting to apply ABC methods. In addition to the reinforcing congestion, the construction tolerances and weight of the integral abutments cause some problems for ABC projects.

These issues are the basis for this project, which was intended to investigate the use of mechanical couplers to splice the foundation elements to the superstructure elements of bridges while applying ABC techniques. Since this was a Phase II project, the methodologies and laboratory setup for evaluating the ABC connection details were the same as that of Phase I. From the results of Phase I, three connection details were developed for investigation in Phase II. Of which, two were a revised design of the two mechanical coupler connection details tested in Phase I, and the third was a new connection detail designed through the Iowa Department of Transportation (DOT) to be used on an upcoming bridge project.

With this project completed, further investigations about integral abutment connection details for ABC applications should be conducted to provide more literature on the subject. Such investigations would be further revisions to the designs of the connection details and field monitoring of real-world applications of the connections.

Project Details
STATUS

Completed

PROJECT NUMBER

ABC-UTC-2013-C3-ISU01

START DATE

07/01/17

END DATE

09/30/18

RESEARCH CENTERS InTrans, BEC, CMAT, CTRE
SPONSORS

ABC-UTC

Researchers
Principal Investigator
Alice Alipour

Structure and Infrastructure Engineer, BEC

Co-Principal Investigator
Jennifer Shane

Director, CMAT

About the research

Accelerated bridge construction (ABC) techniques are rapidly gaining acceptance as an alternative to conventional construction methods to reduce construction duration and minimize the impact of closures at the network level. There are different types of ABC, and each technique has its limitations and its own speed of completion. The choice of using ABC depends on a host of different factors, including the availability of capital funds for its implementation, its impact on the traveling public, and socio-economic considerations. While many states have implemented a multitude of different ABC techniques, the decision making process for choosing ABC over conventional construction, the costs of ABC, the type of ABC techniques used, and the associated timelines and incentives for faster completion are not clear.

This report aims to address this lack of clarity through a review of the available literature and interviews with a few states that have implemented ABC at different levels. It appears that the major factors impacting the timelines for ABC projects are the impacts the closures might have on the socio-economic aspects of the community. While most states acknowledge the importance of indirect costs, there is no mathematical formulation to account for these costs in the final decision making process. Most decisions are made based on qualitative input from the districts and discussions with the public. For the establishment of incentives, a procedure similar to that followed for conventional construction and that follows the Federal Highway Administration (FHWA) guidelines is suggested by most of the states.

Project Details
STATUS

In-Progress

START DATE

01/01/18

END DATE

02/29/20

FOCUS AREAS

Infrastructure

RESEARCH CENTERS InTrans, BEC
SPONSORS

ABC-UTC

Researchers
Principal Investigator
Behrouz Shafei

Structural Engineer, BEC

About the research

Link slabs have been gaining some attention in the bridge engineering community lately. The basic link slab concept is to add/include a thin slab at the ends of the decks of two adjacent spans, allowing the spans in a multi-span bridge to act as though they were simply-supported but in the absence of a (problematic) joint. The two most promising applications for link slabs appear to be in removing deck joints from existing bridges and in eliminating the use of joints in new prefabricated element bridges (commonly known as accelerated bridge construction) that require multiple spans.

To be successful, a link slab must allow the ends of the adjacent spans to both rotate and displace, as if the attached members were simply supported. The goal of this multi-part project is to develop design details and evaluate the behavior of link slabs in new and existing bridges.

The work to be funded by the Iowa Highway Research Board will focus on the use of link slabs in rehabilitation projects. The complementary/matching project, funded by the ABC-UTC, will focus on the use of link slabs in accelerated bridge construction projects. Both projects will leverage information learned regarding material selection/design as well as the behavior of specific connection details.

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