International Bridge Technologies Inc.

San Diego, CA, United States

International Bridge Technologies Inc.

San Diego, CA, United States

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Soule B.T.,International Bridge Technologies Inc.
3rd International fib Congress and Exhibition, Incorporating the PCI Annual Convention and Bridge Conference: Think Globally, Build Locally, Proceedings | Year: 2010

The existing bridge across the Indian River Inlet in Bethany Beach, Delaware, has been plagued by extreme scour. The bridge is also located adjacent to the Atlantic Ocean, and is subject to the corrosive effects of the marine environment. Construction of a new bridge is underway under a design-build contract. The new design addresses the two key challenges of the site. First, the main span of the bridge is sufficient to keep the substructure out of the channel. Second, the bridge is highly resistant to corrosion. These requirements dictate a concrete cable-stayed bridge, incorporating a 950-ft main span. To produce a cost-effective bridge, the design includes several key innovations. The first is the configuration of the edge girders, which wrap around the pylons without monolithic fixity. This allowes the pylons to be vertical, with a transverse connection located at the foundations. The vertical, uninterrupted pylons are cost-effective, while the foundation connection mobilizes the lateral capacity of the foundation. The contractor developed a construction sequence that takes advantage of the unique access and profile. A significant portion of the bridge is constructed on falsework, using precast floor beams. Only the central two-thirds of the main span is erected with a traveler, accelerating the construction.


Birrcher D.B.,International Bridge Technologies Inc. | Tuchscherer R.G.,Datum Engineers Inc. | Bayrak O.,University of Texas at Austin
3rd International fib Congress and Exhibition, Incorporating the PCI Annual Convention and Bridge Conference: Think Globally, Build Locally, Proceedings | Year: 2010

A research study was performed to investigate the discrepancy in shear capacity calculated with strut-and-tie models and sectional models near the transition between deep and slender beams. Shear test data from a largescale experimental program and the literature (179 total tests) were analyzed. Inappropriately large discrepancies in shear strength calculated using the AASHTO LRFD (2008) strut-and-tie model and sectional shear provisions were found when the shear span-to-depth (a/d) ratio was near 2. The discrepancies were largely due to overly-conservative estimates of strength calculated with the strut-and-tie model provisions in AASHTO LRFD (2008). The discrepancies were greatly reduced with the use of strut-and-tie model provisions developed in this study that were largely based on fib (1999) recommendations.


Tuchscherer R.G.,Datum Engineers Inc. | Birrcher D.B.,International Bridge Technologies Inc. | Bayrak O.,University of Texas at Austin | Bayrak O.,Structural Engineering Laboratory
PCI Journal | Year: 2011

The overall objective of the research project summarized in this paper was to develop simple and safe design guidelines for deep beams. To accomplish the research objective and related tasks, a database of 868 deep-beam tests was assembled from previous research. In addition, 37 beams were fabricated and tested with the following cross-sectional dimensions: 36 in. × 48 in. (910 mm × 1220 mm), 21 in. × 75 in. (530 mm × 1910 mm), 21 in. × 42 in. (530 mm × The overall objective of the research project summarized in this paper was to develop simple and safe design guidelines for deep beams. To accomplish the research objective and related tasks, a database of 868 deep-beam tests was assembled from previous research. In addition, 37 beams were fabricated and tested with the following cross-sectional dimensions: 36 in. × 48 in. (910 mm × 1220 mm), 21 in. × 75 in. (530 mm × 1910 mm), 21 in. × 42 in. (530 mm × 1070 mm), and 21 in. × 23 in. (530 mm × 580 mm). These tests represent some of the largest deep-beam shear tests ever conducted. Based on an analysis of the database and the experimental program, the deepbeam shear provisions in Building Code Requirements for Reinforced Concrete (ACI 318-08) and AASHTO LRFD Bridge Design Specifications were found to be overly conservative. Thus, a new and simple strutand-tie modeling (STM) procedure was proposed for the strength design of deep-beam regions. The procedure is largely based on the fib structural concrete design provisions. It is more accurate than the STM design method in ACI 318-08 and AASHTO LRFD specifications but just as conservative. With the use of the proposed provisions, the design of deep beams is more efficient and reliable. As a result, implementation of the new design provisions into ACI 318-08 and AASHTO LRFD specifications is recommended.


Tuchscherer R.G.,Northern Arizona University | Tuchscherer R.G.,University of Wisconsin - Milwaukee | Tuchscherer R.G.,University of Texas at Austin | Birrcher D.B.,International Bridge Technologies Inc. | And 6 more authors.
ACI Structural Journal | Year: 2014

The objective of the study summarized in this paper was to develop simple, accurate, and conservative guidelines for the design of deep beams and discontinuity regions. To accomplish this goal, the authors compiled a database of 868 deep-beam shear tests from the literature and fabricated and tested 37 additional deep-beam specimens. The cross-sectional dimensions of the specimens that were tested included 36 × 48 in. (910 × 1220 mm); 21 × 75 in. (530 × 1910 mm); 21 × 42 in. (530 × 1070 mm); and 21 × 23 in. (530 × 580 mm). A comprehensive analysis of the database resulted in the following conclusions: 1) deep-beam shear design provisions of ACI 318-11 and AASHTO LRFD (2010) are overly conservative; and 2) the accuracy of existing design provisions can be improved without compromising their conservative nature. Accordingly, the authors propose recommendations to these methods to form an improved strut-And-tie modeling procedure. The transparently derived procedure is based on fundamental principles, current provisions, and experimental data. The authors recommend adoption of the proposed modifications into the ACI 318 and AASHTO LRFD provisions. An example problem illustrating the use of the proposed method is provided in the Appendix. © 2014, American Concrete Institute.


Roy B.C.,Consulting Engineering Services India Ltd. | Tassin D.M.,International Bridge Technologies Inc.
Long Span Bridges and Roofs - Development, Design and Implementation | Year: 2013

A need for capacity augmentation for the Vivekananda Bridge across River Hooghly connecting the twin city of Kolkata and Howrah, in the vicinity of Dakshineshwar, near Kolkata, was felt and the initiative started with a techno-economic feasibility study. The initiative further developed into the largest BOT project in the bridge sector in India which promoted by an international consortium. In this process, the designs were carried out accommodating various concerns, both technical, like river regime and constructability and non-technical, like environmental issues, land acquisition and resource mobilization. It was taken on concession for a period of thirty years, including three years for construction. The facility was thrown open to public on July 4th 2007, within the time frame and ost. The paper describes the process of conceptualization all through to implementation, realization and operation and maintenance.


Birrcher D.B.,International Bridge Technologies Inc. | Tuchscherer R.G.,Northern Arizona University | Huizinga M.,Thornton Tomasetti | Bayrak O.,University of Texas at Austin
ACI Structural Journal | Year: 2013

An experimental study was performed to examine current code requirements for minimum web reinforcement of reinforced concrete deep beams. Twelve full-scale tests were conducted in which the shear span-depth ratio (a/d) was 1.2, 1.85, or 2.5. At each a/d, the quantity of web reinforcement was the primary variable. Web reinforcement ranged from 0 to 0.3% in the vertical and horizontal directions. The compressive strength of concrete of the test specimens ranged from 3200 to 5000 psi (22 to 34 MPa). Diagonal cracking loads, diagonal crack widths, and failure shears were recorded for each test. The results indicated that a larger quantity of web reinforcement was needed to adequately restrain the width of diagonal cracks than to provide adequate deep beam shear capacity. Based on the strength and serviceability results, a minimum web reinforcement of 0.3% in each orthogonal direction was recommended for deep beams. Copyright © 2013 American Concrete Institute.


Tuchscherer R.G.,Northern Arizona University | Birrcher D.B.,International Bridge Technologies Inc. | Bayrak O.,Environmental and Architectural Engineering
American Concrete Institute, ACI Special Publication | Year: 2012

An experimental study was conducted in which 37 reinforced concrete deep beam specimens were tested. The specimens are some of the largest deep beams ever tested in the history of shear research. The data from the experimental program and from a database of 179 deep beam tests in the literature were used to assess the accuracy and conservatism of the strut and tie modeling provisions of ACI 318. In addition, the effects of the following variables were evaluated: distribution of stirrup legs across the web, triaxial confinement via concrete surrounding CCC and CCT nodal faces, quantity of web reinforcement, member depth, and a/d ratio. Based on the experimental findings of the study, suggested improvements to the ACI 318 STM provisions are discussed in this paper.


Tuchscherer R.G.,Northern Arizona University | Birrcher D.B.,International Bridge Technologies Inc. | Bayrak O.,University of Texas at Austin
ACI Structural Journal | Year: 2016

The objective of this study is to reduce the discrepancy between strut-and-tie modeling and sectional shear strength predictions at an a/d near 2. To accomplish this objective, the authors compiled and analyzed a database of 905 deep beam shear tests; 868 were gathered from the past literature and 37 were tested by the authors as part of a recent experimental investigation. Based on the results of the investigation and an analysis of the database, the authors identify the contributing causes of the discrepancy and recommend improvements to current shear provisions. The strut-and-tie model (STM) procedure proposed by the authors in a separate paper provides a uniform level of conservatism at the transition region between deep beam and ACI 318-11 sectional shear provisions. Copyright © 2016, American Concrete Institute.


Tuchscherer R.,Datum Engineers Inc. | Birrcher D.,International Bridge Technologies Inc. | Huizinga M.,Thornton Tomasetti | Bayrak O.,Environmental and Architectural Engineering
ACI Structural Journal | Year: 2010

The purpose of the testing program described in this paper was to evaluate the benefits of triaxial confinement that occurs when the loaded area of a strut-and-tie model (STM) is surrounded by concrete on all sides. To achieve this goal, five full-scale beams were fabricated and tested at the Ferguson Structural Engineering Laboratory in Austin, TX. Specimens were tested with a span-depth ratio (a/A) of 1.85. Two ends of each beam were tested, resulting in a total of 10 tests. Eight tests were conducted on beams with a 21 × 42 in. (530 × 1070 mm) cross section, and two tests were conducted on beams with a 36 × 48 in. (910 × 1220 mm) cross section. The primary experimental variables were the size of the load- and support-bearing plates and the amount of web reinforcement. Based on the results of the testing program, it is recommended that the permissible nodal stresses of an STM be increased for nodes triaxially confined by concrete. Copyright © 2010, American Concrete Institute. All rights reserved.


Salonga J.,International Bridge Technologies Inc. | Salonga J.,University of Toronto | Gauvreau P.,University of Toronto
Journal of Bridge Engineering | Year: 2014

This article presents a comparative study of 55 concrete arch bridges built over the last century. For each bridge considered in the study, section properties and geometrical ratios were determined and compiled into a database. These data were used to identify empirical trends related to important attributes such as proportions, stiffness, slenderness, and efficiency. These trends were then expressed as functions of span length. The database and empirical trends together provide a unique and comprehensive quantitative characterization of the state of the art of concrete arch bridges. By situating new design concepts within the trends compiled by this study, designers of arch bridges can gain insight into the implications of specific design decisions with regard to structural behavior and efficiency and will have a quick and reliable means of estimating the nature and extent of the effort required for validation. © 2013 American Society of Civil Engineers.

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