{"title":"History and Development of UHPC Applications in New York State","authors":"Julianne M. Fuda","doi":"10.21838/uhpc.9668","DOIUrl":"https://doi.org/10.21838/uhpc.9668","url":null,"abstract":"","PeriodicalId":170570,"journal":{"name":"Second International Interactive Symposium on UHPC","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121820255","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Sritharan, L. Zhong, Enrique Rubio-Delgado, P. Hadl
As part of a recent UHPC bridge deck overlay project in Iowa, several mock-up bridge decks were cast with the overall dimensions of 8 ft (length) x 6 ft (width) x 9.25 in. (height). The construction of the slabs used a normal concrete base and varying thickness of UHPC overlay (i.e., 1.25 in, 1.75 in., and 2.0 in.). Each half of the overlay was placed first followed by the second half at a different time, replicating the lane-by-lane construction in the field. To ensure a robust joint between two adjacent lanes, different joint details were used. With the 2 in. UHPC overlay, an additional layer of reinforcement was included to investigate the strength gain associated with a reinforced UHPC overlay. In each case the last 0.25 in. UHPC was placed for the entire slab with reduced amount of steel fibers. In addition, a reference concrete slab was also cast. The mock-up slabs were then cut into 2 ft wide, 8 ft long strip and are being subjected to positive and negative flexural moment tests. A total of eight tests have been planned. The presentation will cover a summary of results from the tests and their performance under positive and negative moments. The presentation will conclude the influence of different UHPC overlay thickness, impact of different joint details, and strength gain resulting from incorporating reinforcement within the overlay.
{"title":"UHPC Bridge Deck Overlay — Impact of Key Design Variables","authors":"S. Sritharan, L. Zhong, Enrique Rubio-Delgado, P. Hadl","doi":"10.21838/UHPC.9712","DOIUrl":"https://doi.org/10.21838/UHPC.9712","url":null,"abstract":"As part of a recent UHPC bridge deck overlay project in Iowa, several mock-up bridge decks were cast with the overall dimensions of 8 ft (length) x 6 ft (width) x 9.25 in. (height). The construction of the slabs used a normal concrete base and varying thickness of UHPC overlay (i.e., 1.25 in, 1.75 in., and 2.0 in.). Each half of the overlay was placed first followed by the second half at a different time, replicating the lane-by-lane construction in the field. To ensure a robust joint between two adjacent lanes, different joint details were used. With the 2 in. UHPC overlay, an additional layer of reinforcement was included to investigate the strength gain associated with a reinforced UHPC overlay. In each case the last 0.25 in. UHPC was placed for the entire slab with reduced amount of steel fibers. In addition, a reference concrete slab was also cast. \u0000The mock-up slabs were then cut into 2 ft wide, 8 ft long strip and are being subjected to positive and negative flexural moment tests. A total of eight tests have been planned. The presentation will cover a summary of results from the tests and their performance under positive and negative moments. The presentation will conclude the influence of different UHPC overlay thickness, impact of different joint details, and strength gain resulting from incorporating reinforcement within the overlay.","PeriodicalId":170570,"journal":{"name":"Second International Interactive Symposium on UHPC","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131811595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The redecking of the Pulaski Skyway is the largest implementation of ultra-high performance concrete (UHPC) in North America to date. Approximately 90,000 m² (1 million ft²) of deck was replaced with precast concrete panels connected with field-placed UHPC, using a total volume of more than 5,000 cubic yards (3,800 cubic meters) of UHPC. The construction of the new deck took place over the course of four years in a temperate climate with hot summers and cold winters. The very large quantity of deck, the large volumes of field-placed UHPC, and multiple years of construction with all possible weather and temperature conditions created challenges to successful UHPC placement. This paper discusses the types of problems that arose and the solutions that were developed during the course of the redecking construction project. The problems included placement issues related to pumping, fiber segregation issues deriving from low ambient temperature, cracking due to early age loading, and underfilled pockets and joints due to leaking or blown-out forms. The distinct issues encountered are set out in detail, along with the solutions and the methods that were employed to find the solutions, with a discussion on the reasoning behind the selection made in each case. The information presented is intended to serve as a resource for engineers and construction inspectors undertaking UHPC joint fill projects, providing substantive explanations of the sort of UHPC construction problems that can arise and examples of means utilized to address them.
{"title":"UHPC Joint Fill Construction Problems and Solutions on the Pulaski Skyway","authors":"Michael D. Mcdonagh, A. Foden","doi":"10.21838/UHPC.9629","DOIUrl":"https://doi.org/10.21838/UHPC.9629","url":null,"abstract":"The redecking of the Pulaski Skyway is the largest implementation of ultra-high performance concrete (UHPC) in North America to date. Approximately 90,000 m² (1 million ft²) of deck was replaced with precast concrete panels connected with field-placed UHPC, using a total volume of more than 5,000 cubic yards (3,800 cubic meters) of UHPC. The construction of the new deck took place over the course of four years in a temperate climate with hot summers and cold winters. The very large quantity of deck, the large volumes of field-placed UHPC, and multiple years of construction with all possible weather and temperature conditions created challenges to successful UHPC placement. \u0000This paper discusses the types of problems that arose and the solutions that were developed during the course of the redecking construction project. The problems included placement issues related to pumping, fiber segregation issues deriving from low ambient temperature, cracking due to early age loading, and underfilled pockets and joints due to leaking or blown-out forms. The distinct issues encountered are set out in detail, along with the solutions and the methods that were employed to find the solutions, with a discussion on the reasoning behind the selection made in each case. \u0000The information presented is intended to serve as a resource for engineers and construction inspectors undertaking UHPC joint fill projects, providing substantive explanations of the sort of UHPC construction problems that can arise and examples of means utilized to address them.","PeriodicalId":170570,"journal":{"name":"Second International Interactive Symposium on UHPC","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115831004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B. Abediniangerabi, S. M. Shahandashti, B. Bell, S. Chao, A. Makhmalbaf
Majority of building energy consumption is used to heat and cool enclosed spaces. An innovative ultra-high-performance fiber-reinforced concrete (UHP-FRC) facade system has the potential to reduce building energy consumption. The objectives of this research are (1) to analyze the heat and moisture transfer within the UHP-FRC facade panels, and (2) assess the energy performance of a proposed UHP-FRC facade system in comparison with conventional sandwich panel facade system in commercial building context (large office, medium office, and small office buildings). A transient hygrothermal analysis is conducted to investigate heat and moisture transfer within the UHP-FRC facade system and evaluate the risk of mold growth in internal layers of the facade system for different boundary conditions. A simulation-based building energy performance analysis is conducted to investigate the energy performance of the UHP-FRC panel system in the commercial building context (three DOE prototype commercial buildings are used as building context) in fifteen locations with different climate and weather conditions (45 scenarios). The results of the hygrothermal analysis showed that the UHP-FRC panel assembly’s performance is superior to the conventional panel regarding combined heat and moisture transfer. Although the result of building energy simulations showed that the energy savings of using the UHP-FRC panel depend on the building type and climate condition, in 44 out of 45 scenarios, the total energy savings were positive. It is expected that the results of this research help develop the next generation of high-performance energy-efficient facade systems using UHP-FRC.
{"title":"Assembly-Scale and Whole-Building Energy Performance Analysis of Ultra-High-Performance Fiber-Reinforced Concrete (UHP-FRC) Façade Systems","authors":"B. Abediniangerabi, S. M. Shahandashti, B. Bell, S. Chao, A. Makhmalbaf","doi":"10.21838/UHPC.9655","DOIUrl":"https://doi.org/10.21838/UHPC.9655","url":null,"abstract":"Majority of building energy consumption is used to heat and cool enclosed spaces. An innovative ultra-high-performance fiber-reinforced concrete (UHP-FRC) facade system has the potential to reduce building energy consumption. The objectives of this research are (1) to analyze the heat and moisture transfer within the UHP-FRC facade panels, and (2) assess the energy performance of a proposed UHP-FRC facade system in comparison with conventional sandwich panel facade system in commercial building context (large office, medium office, and small office buildings). A transient hygrothermal analysis is conducted to investigate heat and moisture transfer within the UHP-FRC facade system and evaluate the risk of mold growth in internal layers of the facade system for different boundary conditions. A simulation-based building energy performance analysis is conducted to investigate the energy performance of the UHP-FRC panel system in the commercial building context (three DOE prototype commercial buildings are used as building context) in fifteen locations with different climate and weather conditions (45 scenarios). The results of the hygrothermal analysis showed that the UHP-FRC panel assembly’s performance is superior to the conventional panel regarding combined heat and moisture transfer. Although the result of building energy simulations showed that the energy savings of using the UHP-FRC panel depend on the building type and climate condition, in 44 out of 45 scenarios, the total energy savings were positive. It is expected that the results of this research help develop the next generation of high-performance energy-efficient facade systems using UHP-FRC.","PeriodicalId":170570,"journal":{"name":"Second International Interactive Symposium on UHPC","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121360425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Prestressed precast double-tee bridges are the most common type of bridges on South Dakota local roads. They are also common in the neighboring states. Nevertheless, longitudinal girder-to-girder joints of many of double-tee bridges are deteriorating after a few years of service mainly due to insufficient joint detailing. The conventional joint consists of discrete welded steel plates embedded in grouted shear key. Twenty joint rehabilitation detailing alternatives were developed, rated, and two joint details were selected for bridge system testing: (1) a continuous joint reinforced with wire mesh and filled with latex modified concrete (LMC), and (2) discrete pockets reinforced with steel bars and filled with ultra-high performance concrete (UHPC). A full-scale 50-ft (12.19-m) long conventional double-tee bridge was constructed and tested under AASHTO fatigue loads. Subsequently, the longitudinal joint of the bridge was rehabilitated using the two proposed details in which each detail was incorporated on one-half of the bridge length. Fatigue and strength testing of the rehabilitated bridge showed that the both proposed joint rehabilitation methods are structurally viable. However, LMC is not a durable material for this application due to prior-to-testing cracks pertaining to restrained shrinkage. Only UHPC should be used in either proposed rehabilitation details. A cost analysis showed that the rehabilitation cost of a double-tee bridge with the proposed UHPC pocket joint method is only 30% of the bridge superstructure replacement cost. The presentation highlights the detailing and performance of both conventional and rehabilitated double-tee bridges, and a summary of findings will be presented.
{"title":"Rehabilitation of Longitudinal Joints of Double-Tee Bridges through Full-Scale Testing","authors":"L. Bohn, M. Tazarv, N. Wehbe","doi":"10.21838/UHPC.9637","DOIUrl":"https://doi.org/10.21838/UHPC.9637","url":null,"abstract":"Prestressed precast double-tee bridges are the most common type of bridges on South Dakota local roads. They are also common in the neighboring states. Nevertheless, longitudinal girder-to-girder joints of many of double-tee bridges are deteriorating after a few years of service mainly due to insufficient joint detailing. The conventional joint consists of discrete welded steel plates embedded in grouted shear key. Twenty joint rehabilitation detailing alternatives were developed, rated, and two joint details were selected for bridge system testing: (1) a continuous joint reinforced with wire mesh and filled with latex modified concrete (LMC), and (2) discrete pockets reinforced with steel bars and filled with ultra-high performance concrete (UHPC). A full-scale 50-ft (12.19-m) long conventional double-tee bridge was constructed and tested under AASHTO fatigue loads. Subsequently, the longitudinal joint of the bridge was rehabilitated using the two proposed details in which each detail was incorporated on one-half of the bridge length. Fatigue and strength testing of the rehabilitated bridge showed that the both proposed joint rehabilitation methods are structurally viable. However, LMC is not a durable material for this application due to prior-to-testing cracks pertaining to restrained shrinkage. Only UHPC should be used in either proposed rehabilitation details. A cost analysis showed that the rehabilitation cost of a double-tee bridge with the proposed UHPC pocket joint method is only 30% of the bridge superstructure replacement cost. The presentation highlights the detailing and performance of both conventional and rehabilitated double-tee bridges, and a summary of findings will be presented.","PeriodicalId":170570,"journal":{"name":"Second International Interactive Symposium on UHPC","volume":"2014 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127439867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. de la Varga, R. Spragg, R. El-Helou, B. Graybeal
It is widely accepted that ultra-high performance concrete (UHPC) provides better mechanical and durability properties than high performance or conventional concrete. The high cementitious materials and fiber contents are key to its change in properties, making this type of material suitable for a wide range of structural applications. However, because of its very low water-to-cementitious materials ratio range (i.e, 0.18-0.22) compared to that of high strength and/or conventional concrete (typically higher than 0.30), this type of material can be more prone to autogenous shrinkage cracking. This paper will examine the shrinkage cracking propensity of several commercially-available UHPC materials compared to that of a typical high strength concrete, a conventional concrete, and a cementitious grout. A dual ring test will be used for this purpose, which offers the possibility to not only assess the tensile stress developed in the material due to restrained autogenous shrinkage, but also to estimate the stress reserve capacity of the materials (that is, how near the materials are to cracking). The results will help UHPC designers and end users better understand the cracking behavior of these materials under restrained conditions.
{"title":"Shrinkage Cracking Propensity of UHPC","authors":"I. de la Varga, R. Spragg, R. El-Helou, B. Graybeal","doi":"10.21838/UHPC.9695","DOIUrl":"https://doi.org/10.21838/UHPC.9695","url":null,"abstract":"It is widely accepted that ultra-high performance concrete (UHPC) provides better mechanical and durability properties than high performance or conventional concrete. The high cementitious materials and fiber contents are key to its change in properties, making this type of material suitable for a wide range of structural applications. However, because of its very low water-to-cementitious materials ratio range (i.e, 0.18-0.22) compared to that of high strength and/or conventional concrete (typically higher than 0.30), this type of material can be more prone to autogenous shrinkage cracking. This paper will examine the shrinkage cracking propensity of several commercially-available UHPC materials compared to that of a typical high strength concrete, a conventional concrete, and a cementitious grout. A dual ring test will be used for this purpose, which offers the possibility to not only assess the tensile stress developed in the material due to restrained autogenous shrinkage, but also to estimate the stress reserve capacity of the materials (that is, how near the materials are to cracking). The results will help UHPC designers and end users better understand the cracking behavior of these materials under restrained conditions.","PeriodicalId":170570,"journal":{"name":"Second International Interactive Symposium on UHPC","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132221351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The I-95 Willington Viaduct in Wilmington, Delaware is a sixty-simple span steel multi-beam bridge scheduled to undergo major rehabilitation in 2021. Work will include substructure repair, deck overlay replacement, and transverse bridge deck joint replacements. The owner, the Delaware Department of Transportation (DelDOT),is investigating the concept of removing fifteen (15)failing transverse bridge deck joints via Ultra High Performance Concrete (UHPC) link slabs. Similar applications recently completed by the New York State Department of Transportation (NYSDOT)suggests that the UHPC material is performing adequately with suitable crack spacing control to prevent moisture and chloride penetration within the depth of the link slab. The NYSDOT application was based on using the link slab over elastomeric expansion bearings (i.e., at Exp.-Exp. locations).DelDOT is exploring the use of the NYSDOT approach to extend the application of UHPC link slabs at superstructure locations with different support conditions, i.e., Fix-Fix, Exp.-Exp. and/orFix-Exp.Analytical3-D non-linear computer models of the superstructure were developed to determine the structural response of the UHPC link slab with different support conditions. Results of the computer models have shown that the UHPC link slabs can be considered for use beyond just the Exp.-Exp. conditions and may extend the use of this detail to more structures. The UHPC link slab proposed by DelDOT has the potential to accelerate the rehabilitation process, reduce future maintenance costs,and increase bridge deck durability. In addition to the benefits of lower future maintenance due to the removal of the transverse bridge joints, UHPC link slabs can also be considered an Accelerated Bridge Construction (ABC) technique due to the time and cost savings compared to traditional full joint replacement.
{"title":"Modeling UHPC Link Slabs for the Wilmington Viaduct Bridge Rehabilitation Project","authors":"Loai F. El-Gazairly, David A. Nizamoff","doi":"10.21838/UHPC.9710","DOIUrl":"https://doi.org/10.21838/UHPC.9710","url":null,"abstract":"The I-95 Willington Viaduct in Wilmington, Delaware is a sixty-simple span steel multi-beam bridge scheduled to undergo major rehabilitation in 2021. Work will include substructure repair, deck overlay replacement, and transverse bridge deck joint replacements. The owner, the Delaware Department of Transportation (DelDOT),is investigating the concept of removing fifteen (15)failing transverse bridge deck joints via Ultra High Performance Concrete (UHPC) link slabs. Similar applications recently completed by the New York State Department of Transportation (NYSDOT)suggests that the UHPC material is performing adequately with suitable crack spacing control to prevent moisture and chloride penetration within the depth of the link slab. The NYSDOT application was based on using the link slab over elastomeric expansion bearings (i.e., at Exp.-Exp. locations).DelDOT is exploring the use of the NYSDOT approach to extend the application of UHPC link slabs at superstructure locations with different support conditions, i.e., Fix-Fix, Exp.-Exp. and/orFix-Exp.Analytical3-D non-linear computer models of the superstructure were developed to determine the structural response of the UHPC link slab with different support conditions. Results of the computer models have shown that the UHPC link slabs can be considered for use beyond just the Exp.-Exp. conditions and may extend the use of this detail to more structures. The UHPC link slab proposed by DelDOT has the potential to accelerate the rehabilitation process, reduce future maintenance costs,and increase bridge deck durability. In addition to the benefits of lower future maintenance due to the removal of the transverse bridge joints, UHPC link slabs can also be considered an Accelerated Bridge Construction (ABC) technique due to the time and cost savings compared to traditional full joint replacement.","PeriodicalId":170570,"journal":{"name":"Second International Interactive Symposium on UHPC","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134426795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many early-day overpass bridges across the highway in the State of Maryland were designed as multiple simple-span bridges with either steel or prestressed concrete girders. Maryland Transportation Authority (MDTA) plans to upgrade those overpass bridges with link slab connections since joint failures are common problems of bridges in the United States. Unlike continuous bridges without expansion joints over the superstructure, link slab can be used to eliminate these desk joints by making the deck continuous while keeping girders as simple spans. Ultra-High-Performance Concrete (UHPC) is one of the candidate materials of link slab in this prototype upgrade project. In the link slab connection study, bearings under the steel girders are designed to allow both rotation and longitudinal movements, thus minimizing the negative moments transferred between spans and the forces imparted to the connection. It is expected that if any cracking were to occur in this detail, it would be tightly spaced and would limit any water ingress to the structure elements below. In order to evaluate the performance and detect cracks caused by bending of UHPC material, wireless strain gauges are used during the third point bending test in the material lab. However, considering the field condition, these same wireless strain gauges are supposed to function normally when they are embedded both under the wearing surface and above steel girders. In this study, strain gauges are improved by attaching on thin steel plates then installed before concrete pouring. By calibrating with several types of strain gauges that attached to the surface, strains measured by the embedded strain gauges attached on steel plates could closely represent the true strains. The lab test also includes cyclic loading to simulate moving loads in the field. By assigning cyclic bending load based on the third point bending test, the ultimate failure signals from strain gauges and the ductile performance of UHPC in the field could be verified. With these experiments, several finite element analyses of the pilot bridge had done and those results are critical in the field monitoring for link slab system condition assessment.
{"title":"Performance of Proto-type UHPC Link Slab on a MDTA Overpass Steel Bridge","authors":"Yifan Zhu, Kuang-yuan Hou, Naiyi Li, C. Fu","doi":"10.21838/uhpc.9729","DOIUrl":"https://doi.org/10.21838/uhpc.9729","url":null,"abstract":"Many early-day overpass bridges across the highway in the State of Maryland were designed as multiple simple-span bridges with either steel or prestressed concrete girders. Maryland Transportation Authority (MDTA) plans to upgrade those overpass bridges with link slab connections since joint failures are common problems of bridges in the United States. Unlike continuous bridges without expansion joints over the superstructure, link slab can be used to eliminate these desk joints by making the deck continuous while keeping girders as simple spans. Ultra-High-Performance Concrete (UHPC) is one of the candidate materials of link slab in this prototype upgrade project. In the link slab connection study, bearings under the steel girders are designed to allow both rotation and longitudinal movements, thus minimizing the negative moments transferred between spans and the forces imparted to the connection. It is expected that if any cracking were to occur in this detail, it would be tightly spaced and would limit any water ingress to the structure elements below. \u0000In order to evaluate the performance and detect cracks caused by bending of UHPC material, wireless strain gauges are used during the third point bending test in the material lab. However, considering the field condition, these same wireless strain gauges are supposed to function normally when they are embedded both under the wearing surface and above steel girders. In this study, strain gauges are improved by attaching on thin steel plates then installed before concrete pouring. By calibrating with several types of strain gauges that attached to the surface, strains measured by the embedded strain gauges attached on steel plates could closely represent the true strains. The lab test also includes cyclic loading to simulate moving loads in the field. By assigning cyclic bending load based on the third point bending test, the ultimate failure signals from strain gauges and the ductile performance of UHPC in the field could be verified. With these experiments, several finite element analyses of the pilot bridge had done and those results are critical in the field monitoring for link slab system condition assessment.","PeriodicalId":170570,"journal":{"name":"Second International Interactive Symposium on UHPC","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121185021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Megan Vos, E. Torres, Raid S. Alrashidi, K. Riding, Trey Hamilton
One of the major barriers to the use of UHPC (ultra-high performance concrete) in the precast industry is the high cost relative to conventional concrete. Often, the properties of UHPC are not fully utilized throughout a member. One solution is to create a hybrid member with UHPC in zones of high or unpredictable stresses while filling the rest of the section with a conventional concrete. Constructing such a member will require innovative techniques to achieve a successful bond between the two different materials. This paper is unique in that it investigates the bond behavior when both materials are in the fresh state. Several specimens of 2 × 2 × 17 inches (50x50x431 mm) were fabricated for direct tension tests. These specimens were fabricated with half UHPC and half SCC (self-consolidating concrete). The interface between the two types of concrete was perpendicular to the tensile force so that the bond was in direct tension. All materials were placed immediately after mixing and were separated by a removable barrier. Time dependency of the bond strength was controlled by removing the barrier at different times after placing. The quality of the bond strength between fresh UHPC and fresh SCC was compared to the tensile strength of the SCC. The results were used to determine a maximum allowable time by which both concretes can be combined while maintaining an acceptable bond strength.
{"title":"Evaluation of Bond Strength of Joints in Hybrid UHPC and SCC Members","authors":"Megan Vos, E. Torres, Raid S. Alrashidi, K. Riding, Trey Hamilton","doi":"10.21838/UHPC.9659","DOIUrl":"https://doi.org/10.21838/UHPC.9659","url":null,"abstract":"One of the major barriers to the use of UHPC (ultra-high performance concrete) in the precast industry is the high cost relative to conventional concrete. Often, the properties of UHPC are not fully utilized throughout a member. One solution is to create a hybrid member with UHPC in zones of high or unpredictable stresses while filling the rest of the section with a conventional concrete. Constructing such a member will require innovative techniques to achieve a successful bond between the two different materials. This paper is unique in that it investigates the bond behavior when both materials are in the fresh state. Several specimens of 2 × 2 × 17 inches (50x50x431 mm) were fabricated for direct tension tests. These specimens were fabricated with half UHPC and half SCC (self-consolidating concrete). The interface between the two types of concrete was perpendicular to the tensile force so that the bond was in direct tension. All materials were placed immediately after mixing and were separated by a removable barrier. Time dependency of the bond strength was controlled by removing the barrier at different times after placing. The quality of the bond strength between fresh UHPC and fresh SCC was compared to the tensile strength of the SCC. The results were used to determine a maximum allowable time by which both concretes can be combined while maintaining an acceptable bond strength.","PeriodicalId":170570,"journal":{"name":"Second International Interactive Symposium on UHPC","volume":"437 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122480482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The widespread, growing interest in the United States in using ultra-high performance concrete (UHPC) in engineered structures is being hindered by a lack of structural design guidance relevant to this class of materials. The material characteristics that form the foundational inputs for existing reinforced concrete design specifications do not represent the behaviors that can be attained with UHPC; therefore, using existing design guidance results in inefficient, overly costly structures. The U.S. Federal Highway Administration has embarked on an effort to develop the needed design guidance for bridges. This document, which will be in the form of a guide specification and will supplement the AASHTO LRFD Bridge Design Specifications, is being coordinated with the relevant subcommittee of the AASHTO Committee on Bridges and Structures. The guide specification will define UHPC, present threshold mechanical and durability properties, define material models, and provide design guidance for flexure, shear, and other critical performance metrics. Both prestressed concrete and mild steel reinforced concrete elements will be covered. This paper discusses the framework for the guide specification and provides insight into key aspects that have been investigated and drafted to date.
{"title":"Development of an AASHTO Guide Specification for UHPC","authors":"B. Graybeal, R. El-Helou","doi":"10.21838/UHPC.9708","DOIUrl":"https://doi.org/10.21838/UHPC.9708","url":null,"abstract":"The widespread, growing interest in the United States in using ultra-high performance concrete (UHPC) in engineered structures is being hindered by a lack of structural design guidance relevant to this class of materials. The material characteristics that form the foundational inputs for existing reinforced concrete design specifications do not represent the behaviors that can be attained with UHPC; therefore, using existing design guidance results in inefficient, overly costly structures. The U.S. Federal Highway Administration has embarked on an effort to develop the needed design guidance for bridges. This document, which will be in the form of a guide specification and will supplement the AASHTO LRFD Bridge Design Specifications, is being coordinated with the relevant subcommittee of the AASHTO Committee on Bridges and Structures. The guide specification will define UHPC, present threshold mechanical and durability properties, define material models, and provide design guidance for flexure, shear, and other critical performance metrics. Both prestressed concrete and mild steel reinforced concrete elements will be covered. This paper discusses the framework for the guide specification and provides insight into key aspects that have been investigated and drafted to date.","PeriodicalId":170570,"journal":{"name":"Second International Interactive Symposium on UHPC","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129532792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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