Rudi Seracino

Abstract: The NSF IUCRC for Integration of Composites into Infrastructure (CICI) is specialized at innovating advanced fiber-reinforced polymer (FRP) composites and techniques for the rapid repair, strengthening or replacement of highway, railway, waterway, bridge, building, pipeline and other critical civil infrastructure. The Center consists of West Virginia University (WVU) as the lead institution in the current Phase II, with North Carolina State University (NCSU), the University of Miami (UM), and the University of Texas at Arlington (UTA) as partner university sites. CICI is currently establishing an international site at the Center for Engineering and Industrial Development (CIDESI) in Queretaro, Mexico, through a collaboration between NSF and the National Council of Science and Technology (CONACYT) in Mexico. The primary objective of the Center is to accelerate the adoption of polymer composites and innovative construction materials into infrastructure through joint research programs between the university sites in collaboration with the composites and construction industries. In Phase III, CICI aims to broaden its scope of research in composites to include: 1) nondestructive testing methods; 2) manufacturing techniques, such as 3D printing; 3) inspection techniques, such as the use of drones with high resolution cameras; 4) in-situ modifications of infrastructure systems, resulting in enhanced durability and thermo-mechanical properties; and 5) cost-effective recycling of high value composites, enabled by the addition of CIDESI.

Sampson County Bridge No. 810003 is a three-span prestressed channel structure built in 1966 on Service Route No. 1933 across Branch Six Run Creek. Six channel beams (12 stems) were retrofit in November of 2020 using a prestressed mechanically fastened fiber reinforced polymer (MF-FRP) system. The retrofit was designed to restore prestressing forces lost due to corrosion of internal steel strands. The retrofit was intended as a temporary measure to keep the bridge open without lowered load postings while a bridge replacement could be designed, bid, and scheduled. Bridge 810003 is scheduled for demolition and replacement in late 2022 or early 2023. The proposed research aims to salvage the six retrofitted channel beams from Bridge 810003 that have been in-service for more than 21 months. In addition, the work proposes to salvage two additional control beams from the bridge that have not been retrofitted. Beams will be identified prior to bridge demolition, carefully removed from the bridge during demolition with the MF-FRP repair systems intact, trucked to Constructed Facilities Laboratory (CFL) in Raleigh, and tested to failure in the laboratory. Samples of the FRP material will be recovered from the tested beams and for material-scale tension testing. Concrete cores will be taken from the beams to determine the concrete compressive strength. The proposed experiments will capture the full response to failure of the retrofit beams, allowing for comparison to analytical predictions and evaluation of the effectiveness and durability of the retrofit. Predications of beam behavior will use the procedures developed as part of previous research project RP2018-16. As justified by the research results, edits to the existing design methods, installation procedures, inspection procedures, ratings spreadsheet, and standard details and specifications will be developed and proposed. This proposed research project presents a unique opportunity to evaluated the performance of in-service girders that cannot be replicated on new concrete girders.

The NCDOT has previously funded FRP related research projects through NC State University. RP2014-09 consisted of material characterization of Glass FRP reinforcing bars and Carbon FRP prestressing strand (of the same type to be used in the Harkers Island Bridge replacement), and the design, construction and destructive testing of full-scale 45 ft. long hollow core slabs commonly used throughout North Carolina. The design was consistent with the then current ACI440 and AASHTO design guide documents. The test results demonstrated that the flexural and shear performance of the all FRP-reinforced cored slabs was ????????????????equivalent??????????????? to that of traditional steel-reinforced cored slabs designed to current NCDOT standards. More recently, RP2018-16 developed an innovative rapid repair solution suitable for common prestressed concrete bridge elements, including cored-slabs and C-channel beams. The system is comprised of a prestressed mechanically-fastened FRP plate that restores lost prestress force in deteriorated bridge beams such that inventory and operating load rating restrictions may be removed enabling the bridge to remain in service until replacement is scheduled. In April 2019 this repair system was implemented on Bridge No. 380080 in Franklin County, and a second application was installed on Bridge No. 810003 in Sampson County in November 2020. While there are applications of FRP materials and systems in the repair or strengthening of existing concrete bridges in North Carolina, the Harkers Island Bridge replacement will be the first to fully replace all internal reinforcing and prestressing steel with FRP alternatives in a new construction. The Harkers Island Bridge will be among the largest applications of FRP in a fully FRP-reinforced new concrete bridge in the United States. The experience and long-term performance data collected from this bridge will contribute to the validation and future editions of ASTM standards, material and construction specifications, and design codes including those from AASHTO and ACI. Ultimately, the outcomes of this research project will lead to improved NCDOT design and construction of durable bridge infrastructure resulting in reduced maintenance and repair, longer service life, and cost-savings.

Hydraulic spread calculations dictate the number and spacing of deck drains and closed drainage system locations. Closed drainage systems require routine maintenance to function properly, but typically maintenance is not performed until the drainage system has failed, and problems become apparent. Current procedures for calculating hydraulic spread results in closely spaced bridge deck drains which present a construction challenge and requires regular maintenance during the life span of the bridge. Current drainage systems adopted by North Carolina Department of Transportation (NCDOT) routinely fail and are difficult to maintain. The main objective of this research is to update NCDOT??????????????????s guidelines for bridge deck drains design and investigate potential alternative drainage systems to be used by NCDOT in future bridge construction projects. Upon the completion of this research project, the research findings will provide NCDOT personnel with improved hydraulic spread calculations to reduce the number of bridge deck drains, which will reduce the initial construction cost, minimize maintenance expenditure, and improve the life cycle cost of the bridge drainage system.

The NCDOT is in the process of deconstructing the 56 year old Bonner Bridge. This deconstruction provides an opportunity to evaluate the aged girders of the bridge and to compare their performance to load rating calculations. Such a comparison will provide a better understanding of the accuracy and assumptions associated with prestressing losses and will allow for refinements to the load rating procedures. This project focuses on a complete performance evaluation of the Bonner Bridge girders including full-scale load testing of 9 of the 61 ft. by 45 in. deep AASHTO Type III girders. The load testing will be conducted in the Constructed Facilities Lab (CFL) located at North Carolina State University. The research will provide recommendations for updates to the NCDOT Structures Management??????????????????s Manual guidelines. These assessments will also include directly evaluating the current amount of stress (after losses) in the girder prestressing steel; the condition, strength and stiffness of the concrete materials; and the location and extent of damage and repair of the girders.

The purpose of this research is to assist the NCDOT Traffic Management Unit (TMU) and the Value Management Office (VMO) in assessing issues regarding the construction of Diverse, Modern, and Unconventional Intersections and Interchanges (DMUII). Assessing the constructability of these emerging DMUII is a new area of study that has not yet been previously explored. Therefore, this research will identify factors affecting construction projects prior to construction and develop a schedule and cost payout model (based on prior NCDOT projects) that identifies problems related to expenditure, schedule, and obstruction of traffic during construction.

Integral abutment (IA) bridges may provide many advantages over conventional bridges during construction and subsequent maintenance. NCDOT has been designing various types of IA bridges. Unlike conventional bridges, IA bridges do not have expansion joints within the bridge deck or between the bridge deck and supporting abutments. Expansion joints and bearings in a conventional bridge are costly, and leaking joints cause deterioration of girders and bearings ?????????????????? leading to potential?????????ly unsafe conditions and high maintenance and repair costs. Besides cost savings related to construction and maintenance, IA bridges also provide superior performance during extreme loading events, such as earthquake and blast loading, and are being built at an increasing rate in the United States. NCDOT began utilizing integral abutments in 2006. Since that time, NCDOT has provided varying guidance and details for integral abutments, but the overall performance of each detail has not been documented. Because IA bridges are built without expansion joints, thermal expansion and contraction must be accommodated by movement of the abutments. Thus, significant forces can develop in the bridge structure, abutments, piles, and soil surrounding the bridge substructure. The magnitude of these forces and response of the IA bridge to them is strongly dependent on the stiffness of the bridge structure, pile foundations, and soil. If the piles and soil are too stiff, large unwanted forces/stresses may develop in the bridge. On the other hand, if the backfill is relatively flexible and the embankment and foundation soil is stiff, unwanted yielding of the piles may occur at the bottom of the abutment. The fact that the soil response is strongly dependent on moisture content, which can vary significantly both seasonally and over the life of the bridge, results in unexpected problems. NCDOT reported that components of their integral abutments have been removed, added, or revised to address construction and maintenance problems without monitoring the influence of the revisions. Evaluation of these revisions is needed and recommendations for updates provided, as required.

Precast double tees with thin stems are a widely used and highly successful floor member in parking structures and other buildings. Frequently, the end supports are dapped such that the bottom of the double tee is level with the bottom of the inverted tee or ledger beam on which it is supported. The dapped connection detail is especially important at crossovers between spans in parking structures because the overall structural depth and floor-to-floor height need not be increased where the double tee is supported by an inverted tee beam. Double tees with dapped ends are typically 24??????????????? to 30??????????????? deep and often carry parking loads, however, much deeper tees (48???????????????) are becoming more common due to the heavier loads and longer spans needed in data centers and other specialty structures.

Bridge column repair has been studied for some time with several established techniques for repair for shear and confinement critical columns. Recent research at NC State has demonstrated the feasibility of repair of heavily damaged bridge columns, including those suffering buckling and fracture of reinforcement, through the use of ???????????????Plastic Hinge Relocation??????????????????. That research led to the development of a set of repair techniques using both conventional and advanced materials. The research described in this proposal aims to further advance the techniques that have been developed, while identifying others that may lead to a more efficient repair design. The specific objectives of the research described in this proposal are to: (1) Experimentally verify the behavioral mechanisms developed in the prior study; (2) Investigate options for simplifying the repair process through alternative connections between adjoining members; (3) Evaluate alternative forming options for the repair region; (4) Study the use of rebar couplers for fractured bars; and (5) Evaluate residual drift limits within the context of complete bridge structures. The above will be accomplished through large scale tests that will take advantage of columns already constructed and tests as part of a different research program. In addition, the residual drift computational study developed in Phase 1 will be further developed to evaluate its performance for more complex bridge systems. Recommendations will consist of additional repair technique alternatives that can be implemented into the design guide developed during Phase 1. It is worth noting also that although the focus of this project is on earthquake induced damage, the repair techniques developed will also be applicable to the repair of other forms of damage, including environmental deterioration such as steel reinforcement corrosion and ice flows.

A precast concrete sandwich panel is typically comprised of a rigid foam core with a layer of concrete on each face. A wythe connector bridges the insulating core and joins the concrete wythes structurally. Traditionally, solid zones of concrete or steel ties have been used as wythe connections, however, these methods are thermally inefficient. The thermal bridging created is significant, and more thermally efficient wythe ties are needed. Enter a wide variety of proprietary FRP wythe connectors on the market. Carbon fiber grid is one option for wythe connection in precast concrete sandwich wall panels that is both thermally and structurally efficient. The system has been tested extensively under static and cyclic loads. It has not been tested as extensively for creep deformation over time. The experimental plan includes loading several small wall panels with full-scale cross-sections for long durations. Standard ????????????????push specimens??????????????? will be used and will be tested prior to loading (control specimens) and after sustained loading for 1 year. Various levels of sustained loading will be selected at percentages of the ultimate loads sustained by the control samples.