Thursday, October 22, 2020
Time: 8:30 AM – 12:00 Noon (EDT)
IBC 20-53: Walk Through the Eye of a Needle
Dan Fitzwilliam, P.E., T.Y. Lin International, San Diego, CA
Pedestrian bridge design is becoming more demanding and challenging as architects and engineers utilize the full measure of design ability available with current design software. This is particularly evident in the design of cable supported pedestrian structures. The innovative and creative concepts require a more detailed review of demands and specifically dynamic analysis of potential vibrations of the lightweight structures. The Scioto River Pedestrian Bridge is one such example of innovative pedestrian bridge design. The structure is a suspension bridge with cable support on one side of the deck and has a geometrically challenging pylon. Based on lessons learned from past cable supported pedestrian bridges, more in-depth analyses were developed for the design of this bridge. Additionally, to evaluate the fatigue performance of the supplied cables, a new fatigue testing regimen was required. The cable fatigue testing required by the project specifications included new testing parameters which are intended to verify the manufactured cables are fit for the unique demands from this structure. Design of tuned mass dampers for the lateral movements of the bridge will be presented. This presentation will review the analysis and design process for the more unique aspects of this suspension bridge. It will also cover the cable fatigue testing required, the testing process, testing issues and challenges and results. Design fabrication and testing of specialty equipment is reviewed and how these components impact project cost and schedule. The presentation will conclude with lessons learned during the design process.
IBC 20-54: Atwater Village Cable Stayed Equestrian Bridge
Dan Fitzwilliam, P.E., T.Y. Lin International, San Diego, CA
This will be the first cable stayed bridge in the city of Los Angeles and possibly the first cable stayed equestrian bridge in the world. With a very slender, light-weight deck and relatively heavy equestrian live loads, the bridge’s dynamic behavior was a major design consideration. In order to mitigate the potential for resonant vibrations during passage of groups of equestrians, a system of tuned mass dampers was designed for the bridge. The use of tuned mass damping of the superstructure to limit vibrations allow this bridge to use a span to depth ratio 130:1. The deck is divided into two pathways: a twelve foot wide pedestrian side with a hardwood deck and stainless steel mesh railings; and a twelve foot wide equestrian side topped with horse friendly rubber paves and a less transparent wooden picket railing system. The cable-stayed bridge type is also the first of its kind in Los Angeles. High-stressed cables are incrementally attached to the 125-foot-tall mast and configured in a fan pattern, creating a distinctive element in an otherwise homogenous landscape. To residents in the area, the bridge is a welcome enhancement to the amenities they already know exist. However, its visibility to drivers on Interstate 5 stokes the curiosity of commuters in neighboring communities and cities to come see the bridge, enhancing the opportunity for non-vehicular recreation and outdoor activity. As the first completed symbol of renewal and revitalization, the North Atwater Non-motorized Multimodal Bridge is a champion of community identity and civic pride.
IBC 20-55: New Pedestrian Cable-Stayed Bridge at University of Memphis
Roger Haight, Steven Lowinger, and Dennis Smith, WSP USA, New York, NY
The new pedestrian cable-stayed bridge at University of Memphis serves a long-standing need to connect increasing development on the south side of the campus with the north campus. This signature cable-stayed bridge, opened for the fall 2019 semester, has a 14-ft walkway and a span of 156 ft crossing over a main vehicular thoroughfare as well as an adjacent rail freight line and deltes at-grade crossings. The cable-stayed bridge comprises a leaning concrete two-pylon tower supporting the main span with backstays that transmit the bridge forces to the rear anchorage. The foundation for the pylon tower was designed to avoid uplift on the drilled shafts. The pylon towers are slender, only two ft wide based on the architect’s conceptual design, and accommodate the horizontal forces of the walkway deck along with live, wind, and seismic loads. Horizontal concrete corbels in the deck bear against the tower and transmit the force through horizontal bearings to the pylons; a shear block ensures transverse stability of the walkway. The deck profile and cross-slope were designed to shed water so that no scuppers or drainage downspouts were required above Southern Avenue or the railway. The walkway deck consists of precast panels on a steel edge girder-floorbeam framework with a cast-in-place overlay that provides composite action between the deck, edge girders, and floorbeams. The bridge design uses the European SETRA Guideline for dynamic behavior under the action of pedestrians. The bridge also includes a sweeping architectural railing for increased pedestrian safety over the rail line.
IBC 20-56: Withdrawn
IBC 20-57: Two Girder System Redundancy Design Glen Road Pedestrian Bridge
Paulina Arczewska, Ph.D., P.Eng., and Augustin Yun, M.A.Sc., P.Eng., Morrison Hershfield, Burlington, ON, Canada
The Glen Road pedestrian bridge is a rigid frame three-span steel I-girder bridge with inclined legs and located in the City of Toronto, Ontario, Canada. In replacement of the original two girder system bridge, the City was seeking a structural replacement with a redundant system while preserving the original heritage values and aesthetics. In general two-girder systems are considered as a non-redundant structure without providing alternative load path as one girder failure leads to an entire system failure. However, implementation of two redundancy characteristics out of three such as alternative load path, structural redundancy, and internal redundancy in two girder system can provides quasi redundant system. Additional bottom flange cross frames are provided to meet these criteria. Alternatively a redundant system with three girders with two inclined legs can be considered without comprising the original aesthetics and heritage value of the bridge. This study is focused on the post-fracture serviceability investigation for the two systems using finite element analysis to provide a redundant system. The study includes analyses with a plastic hinge assumed at critical locations and evaluation of the structure load caring capacity for the post-fractured system with formed plastic hinge. In the both systems, the girder sections are redesigned until the redistributed load under post-fractured system can safely carry the applied dead and live loads until a necessary actions be taken. The two systems are compared for cost, constructability, maintenance and aesthetics and presented for the City’s further consideration.
IBC 20-58: Mon Wharf Switchback Pedestrian Bridge
Jason DeFlitch, P.E., and Larry Maher, SAI Consulting Engineers, Inc., Pittsburgh, PA
The Mon Wharf Switchback Pedestrian Bridge offers cyclists and pedestrians a fully-lit, ADA-accessible, non-motorized connection between the historic Smithfield Street Bridge and the Mon Wharf Landing trail. Constructino challenges included flooding potential and the the site being constrained by I-376 and the Monongahela River.
The structure is a 607 foot long by 12 foot wide two girder system with a concrete deck on a switchback configuration to minimize foundations and structure footprint. The girders were made continuous from Smithfield Street all the way around the switchback to greatly minimize the number of joints on the bridge.
Steel column bents with steel bracket cantilevers support both the upper and lower ramps. Foundations are supported by micropiles to reduce vibration on the existing brick-lined ALCOSAN line below and facilitate smaller equipment needed during construction. The girders were fabricated straight to reduce fabrication costs, and grade changes were accounted for by varying the deck haunch over the girders.
The bridge is comprised of six continuous 70 foot spans and a single 100 foot span. The single span passes below the Smithfield Street Bridge and allows foundations to be placed outside the limits of Smithfield Street avoiding interferences during construction. The last 66 feet of the bridge consists of a ramp on a pile-supported concrete footing and side walls.
For the City of Pittsburgh, the Mon Wharf Switchback contributes to the City’s growth and prosperity.
IBC 20-59: A Gathering Place for Tulsa – Taking The Midland Valley Trail Across Riverside Drive
Gregor Wollmann, P.E., HNTB, Blacksburg, VA; Ryan Woodward, COWI, New York, NY; Gavin Daly, HNTB, New York, NY
Opened in September of 2018, the Gathering Place is a spectacular 27-hectare (66 acre) public park located two miles from downtown Tulsa, Oklahoma and nestled along the eastern bank of the Arkansas River. This paper focuses on design and construction of a footbridge spanning across busy Riverside Drive to integrate the river into the park landscape. As part of the park development the highway itself was transformed into an iconic feature. To meet this challenge, architectural considerations took an important role in the selection of the structure type for the new crossing, leading to the choice of a single-span, post- tensioned concrete box girder bridge with trapezoidal cross section. With a clear span of 43.7 m (143.5 feet) and a depth of only 1.2 meters (4.0 feet) the structure is exceptionally slender. A unique integral foundation system allowed the elimination of bearings, expansion joints, and abutment retaining walls, thus creating the impression of the bridge growing organically out from the landscape. The paper touches briefly on the transformation of the urban environment with the development of the park and then discusses the challenges encountered during design and construction of the footbridge due to its great slenderness and unusual foundation system.
Design, Part 2
Time: 8:30 AM – 12:00 Noon (EDT)
IBC 20-60: Press Brake Formed Tub Girders Prove Successful in Project with Challenging Site Constraints
Karl Barth, Ph.D., West Virginia University, Morgantown, WV; Greg Michaelson, Ph.D., Marshall University, Huntington, WV
Press-brake-formed tub girder is a new technology for short span bridge applications. In 2009, the Federal Highway Administration (FHWA) challenged the North American steel industry to “develop a cost-effective short span steel bridge with modular components which could be placed into the mainstream and meet the needs of today’s bridge owners, including Accelerated Bridge Construction (ABC).” The press-brake-formed tub girder system consists of modular galvanized shallow trapezoidal boxes fabricated from cold-bent structural steel plate. The concrete deck is recommended to be precast on the girder and the modular unit can be shipped by truck to the bridge site. However, the bridge can be successfully employed using deck options. The system utilizes standard plate widths and is optimized to achieve maximum structural capacity, with most of the steel in the bottom flange and increased torsional stiffness. It is a closed system, since the girder is closed at the bottom. It is versatile for multiple-deck options.
Most recently researchers from West Virginia University and Marshall University worked on a 5-girder bridge application that was successfully constructed outside of Ranger, WV. The roadway profile incorporated both skew and super-elevation demonstrating its efficiency in situations with various challenging site constraints.
During this project the authors conducted monitoring of the girder fabrication, deck casting and UHPC closure pours during key phases of production, developed rating tools suitable for incorporation in various state DOT rating and inspection applications, and conducted physical testing and subsequent relevant analytical modeling during both erection and live-load.
IBC 20-61: Design and Construction of the SR 22 Bridge Replacements
David Klyce, P.E., RK&K, LLP, King of Prussia, PA; Kamlesh Ashar, P.E., Pennsylvania DOT, Allentown, PA
As part of the US 22 corridor improvement project in Allentown, Pennsylvania, PennDOT Engineering District 5-0 replaced the severely deteriorated dual Route 22 bridges that span over the Lehigh River, Dauphin Street, the historic Lehigh Canal, and railroads while maintaining the high volume of traffic on Route 22 and all roadway, rail, and recreational boating traffic passing underneath throughout construction.
The existing adjacent 678-foot long, six span and a 516-foot long, four span bridges with fracture critical steel two-girder and floorbeam superstructures carried a total of four traffic lanes. They were replaced with two pairs of wider consecutive dual bridges having prestressed concrete superstructures to carry a total of six lanes. The 640-foot length, five span western dual bridges cross the river and the RJ Corman railroad while the eastern 530-foot length, four-span dual bridges cross the canal, Dauphin Street, and Norfolk Southern railroad.
The new continuous span superstructures pushed the design of prestressed concrete PA Bulb-Tee girders to the limit by using 160-foot maximum length spans. Splayed girders were used to flare the deck width for a variable width ramp acceleration lane on the structure. Deep, drilled foundations were used to construct tall, reinforced concrete hammerhead piers for the new structures in challenging karst bedrock conditions.
Construction of the $30 million-dollar bridge replacement project reached substantial completion in September, 2019. This presentation will highlight the unique challenges and lessons learned during both design and construction from the perspective of the designer, contractor, and the owner.
IBC 20-63: Innovative Design Techniques and Materials Benefit the New High Rise Bridge over Southern Branch of the Elizabeth River
Gregory Shafer, Ali Ghalib, Ph.D., P.E., and Daniel Warren, P.E., Parsons, Baltimore, MD
The new High Rise Bridge over the Elizabeth River provided many unique design challenges. These include significant vessel impact loads with a highly skewed navigation channel and soft alluvial soils, long precast prestressed girders with simple spans of nearly 200 feet, new requirements for wind loads on girders during construction, and innovative corrosion free prestressing in the piles. At 85’-4” wide the new 6110 foot structure is designed for six lanes of traffic with approach spans of prestressed concrete girders of up to 196 feet made continuous for live load and a three-span continuous composite plate girder unit with a 250 foot navigation span. The long prestressed girders are susceptible to instability during transportation and handling requiring special precautions for safety during construction.
All piers are founded on prestressed concrete piles with 66” diameter cylindrical piles near the navigation channel and 36” square piles elsewhere. Corrosion-resistant stainless steel prestressing strands and corrosion-free carbon fiber reinforced polymer (CFRP) were used for piles exposed to chlorides. The brittle nature of these materials required new design approaches to ensure adequate strength and ductility. This is the first use of CRFP strands on piles of this size in the U.S. Vessel impact was a controlling force in design of the piers at the navigation channel. The skew of the navigation channel complicated evaluation of design forces. The deep soft alluvial soils are subject to significant scour and increased the demands on the load transfer which was evaluated using non-linear soil-structure interaction analysis.
IBC 20-64: Development of Design Charts for Transverse Vertical Shear in Shear-Connected Precast Concrete Box Beam Bridges Subjected to AASHTO Truck Loading
Hosam Sennah, Reza Kianoush, and Khaled Sennah, Ryerson University, Toronto, ON, Canada
Accelerated Bridge Construction include precast box beams that can be assembled side-by-side with closure strips between them. Literature review revealed that transverse vertical shear force, Vy, to design the closure strip between adjacent boxes due to AASHTO truck loading is yet unavailable. This paper utilizes the orthotropic plate theory to conduct a parametric study on shear-connected box beams to obtain reliable Vy values to design the shear keys in the form of design charts.
IBC 20-66: A Simplified Calculation Method of Flexural Strength Calculation for CFST Composite Truss Bridge
Yinping MA, Yongjian Liu, Lei Jiang, and Mampiandra N. H. Zafimandimby, Chang’an University, Xi’an, Shaanxi China
The concrete filled steel tubular (CFST) composite truss bridge is comprised of the concrete deck and CFST truss which has advantages of high flexural stiffness and strength, better performance on assembly construction. However the failure mode of this type of bridge varies due to the weakness at the joint area, thus causing it becomes difficult to give prediction on the flexural strength of bridge during the design stage. This paper first summarized the typical failure modes of the CSFT truss girder based on existed specimen tests. Then the simplified calculating method was presented including the failure modes judgement and flexural strength calculation by the comparing different component efficiency coefficients. This method could take the joint failure and truss member failure both into consideration. Afterwards, the presented method was applied on the practical bridge engineering while the corresponding overall bridge finite element model (FEM) was also developed in ABAQUS. Finally the eigenvalues of different loading stages were extracted from simplified method and FEM and the comparisons were made. The results shown that the presented calculating method can give an accurate and rapid prediction on the failure mode and flexural strength of the CFST composite truss bridge. The simplified method established the capacity relationship between the joints and truss girders which also can greatly simplify the design process of the CFST composite truss bridge.
W07: What’s New in Steel Bridge Design;
Brandon Chavel, Ph.D., P.E., National Steel Bridge Alliance, Rocky River, OH; Mike Grubb, P.E., M.A. Grubb & Associates, Wexford, PA; Tony Ream, P.E., HDR, Pittsburgh, PA; Don White, Ph.D., Georgia Institute of Technology, Atlanta, GA
Time: 8:00 AM – 12:00 Noon (EDT)
This workshop will introduce attendees to new topics in steel bridge design, while also reinforcing some best practices in steel bridge design, fabrication, and erection. The workshop will present new and revised guidelines available from NSBA, AASHTO/NSBA Steel Bridge Collaboration, and FHWA for steel bridge design; preferred details for efficient and economical fabrication and construction; and a discussion on the use of weathering steel and various coatings. Additionally, a major focus of the workshop will be on steel bridge related updates in the AASHTO LRFD BDS 9th edition, including revised code provisions for typical steel design along with an introduction to the new methodology and associated provisions for the design of non-composite steel boxes based on recent FHWA funded research. These new non-composite steel box provisions that are generally applicable, conceptually unified, and clearly documented and illustrated, will lead to more economical and effective use of non-composite steel box-section members in bridge construction. These provisions accommodate a wide range of cross-sections including slender and longitudinally stiffened plates. The provisions and the theory behind them will be discussed in the workshop as well as a few examples showing their implementation. The workshop will provide attendees with a good base for what is new in steel bridge design, and provide them with information that can directly apply back in the office.
W14: BIM for Bridges and Structures: Changing the State of National Practice
Brian Kozy, Ph.D., P.E., Michael Baker International, Linthicum, MD; Ahmad Abu-Hawash, Iowa DOT, Ames, IA; Tom Saad, FHWA, Matteson, IL; Connor Christian, HDR, Minneapolis, MN; Joe Brenner, WSP, Lancaster, PA; Julie Rivera, HDR, Chicago, IL
Time: 10:00 AM – 12:00 Noon (EDT)
This workshop is intended to be an open forum where the AASHTO and FHWA will share its vision for development and deployment of national standards for Building Information Modeling (BIM) for Bridges and Structures, and provide explanation of recent accomplishments and ongoing work. BIM based engineering and construction provides an opportunity to be better, faster, more visualized, and reduce errors and conflicts in project development, construction, and asset management. Establishment and acceptance of national BIM standards will provide a common digital exchange format that ideally all software tools would adopt both now and in the future. AASHTO and FHWA intends to work with all the stakeholders in forums such as this to greatest extent possible and create an initial set of BIM standards that could be turned over to industry for long-term ownership and management. This workshop will include reporting and discussion on two recent FHWA research efforts plus the State Pooled Fund Project TPF 5(372).