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21 PREPUBLICATION COPYâUncorrected Proofs 3. HIGHWAY AGENCY EXPERIENCE WITH THE IBRC PROGRAM The first section below describes the use today of the technologies that were used in the statesâ IBRC projects. The best indicator of the impact of the program is the extent to which the technologies demonstrated in IBRC projects have been adopted in general practice. The subsequent sections describe IBRC technologies that have not been adopted, the influence of the statesâ IBRC experiences on acceptance and use of the technologies, the influence of standards and specifications on adoption of new technologies, and the influence of training requirements. EXTENT OF USE TODAY OF THE IBRC TECHNOLOGIES Information on the extent of use of the IBRC technologies by state highway agencies today was obtained from two sources, the interviews with the state agencies selected as case studies and the 2018 survey of state highway agencies conducted by the AASHTO Committee on Bridges and Structures. The AASHTO survey requested essentially the same data as the interviews, but had a broader distribution to all 52 states and territories. Table 3.1 is a summary of the responses from the states interviewed regarding their use of the IBRC technologies. (One of the 10 states did not respond to this question.) The table shows, for example, that all nine states that responded had implementation processes in place for HPC, SCC, and HPS, indicating that these technologies are fully implemented and are used regularly in appropriate situations, while most states are not using FRP deck elements (6 out of 9 states not using), FRP superstructure elements (7 of 9 not using), and FRP prestressing tendons (7 of 9 not using). A similar inquiry was made of state bridge engineers through the AASHTO survey. The results of this survey, combined with information from two states interviewed who did not respond to the AASHTO survey, are shown in Table 3.2. Forty states responded to the AASHTO survey, although some respondents did not respond to every question. The table shows, for example, that close to 90 percent of respondents are using externally bonded FRP reinforcement (32 out of 37 states that responded to the question) and ABC (33 of 37), and that approximately two-thirds are using HPC (28 of 42), SCC (29 of
22 PREPUBLICATION COPYâUncorrected Proofs 42), and HPS (26 of 37). Stainless steel rebar and cathodic protection anodes are each used by 61 percent of respondents (22 of 36). Table 3.3 summarizes the data describing use of IBRC technologies from the AASHTO survey and the state interviews. In the table, the technologies are listed in order of the number of states indicating that the technology is in use. The column headed âSpecifications or Standards Developedâ shows the total number of states reporting that they have agency- or state-developed, AASHTO, or other specifications and standards. The following technologies have been adopted into regular practice by the majority of respondents (that is, the majority use the technology and have developed specifications or standards for it): ABC. Externally bonded FRP reinforcement. SCC. HPC. HPS. Stainless steel rebar. Cathodic protection anodes. Neither the state interviews nor the AASHTO survey asked the states how frequently they used each technology, compared with alternatives. Thus, for example, among the states that reported using stainless steel rebar, the fraction of all rebar used that is stainless steel is not known.
23 PR E PU B L IC A T IO N C O PY â U nc or re ct ed P ro of s T A B L E 3 .1 P re se nt U se o f I B R C T ec hn ol og ie s, C as e St ud y St at e H ig hw ay A ge nc ie s Te ch no lo gy C ur re nt S ta tu s o f T ec hn ol og y Sp ec ia l P ro vi si on s o r S pe ci fic at io ns N ot in U se D ev el op in g Im pl em en ta - tio n Pr oc es se s I m pl em en ta - tio n Pr oc es s i n Pl ac e N ot A pp lic ab le A ge nc y- D ev el op ed A A SH TO O th er C on cr et e H PC 0 0 10 0% (9 /9 ) 0 89 % (8 /9 ) 11 % (1 /9 ) 0 SC C 0 0 10 0% (9 /9 ) 0 10 0% (9 /9 ) 0 0 U H PC 0 56 % (5 /9 ) 44 % (4 /9 ) 11 % (1 /9 ) 67 % (6 /9 ) 11 % (1 /9 ) 22 % (2 /9 ) FR P Ex te rn al ly b on de d FR P re in fo rc em en t 0 22 % (2 /9 ) 78 % (7 /9 ) 0 78 % (7 /9 ) 33 % (3 /9 ) 22 % (2 /9 ) FR P de ck e le m en ts 67 % (6 /9 ) 11 % (1 /9 ) 22 % (2 /9 ) 33 % (3 /9 ) 11 % (1 /9 ) 11 % (1 /9 ) 11 % (1 /9 ) FR P su pe rs tru ct ur e el em en ts 78 % (7 /9 ) 11 % (1 /9 ) 11 % (1 /9 ) 33 % (3 /9 ) 11 % (1 /9 ) 0 11 % (1 /9 ) FR P re ba r 33 % (3 /9 ) 33 % (3 /9 ) 33 % (3 /9 ) 33 % (1 /9 ) 22 % (2 /9 ) 33 % (3 /9 ) 22 % (2 /9 ) FR P pr es tre ss in g te nd on s ( st ra nd o r b ar ) 78 % (7 /9 ) 0 22 % (2 /9 ) 44 % (4 /9 ) 22 % (2 /9 ) 0 11 % (1 /9 ) C or ro si on C on tro l T ec hn ol og ie s C on cr et e re in fo rc em en t Lo w -c hr om iu m st ee l r eb ar 11 % (1 /9 ) 22 % (2 /9 ) 67 % (6 /9 ) 0 44 % (4 /9 ) 56 % (5 /9 ) 11 % (1 /9 ) G al va ni ze d re ba r 44 % (4 /9 ) 22 % (2 /9 ) 33 % (3 /9 ) 11 % (1 /9 ) 22 % (2 /9 ) 22 % (2 /9 ) 22 % (2 /9 ) St ai nl es s s te el re ba r ( so lid o r c la d) 22 % (2 /9 ) 11 % (1 /9 ) 67 % (6 /9 ) 11 % (1 /9 ) 56 % (5 /9 ) 33 % (3 /9 ) 22 % (2 /9 ) C oa tin gs a nd A no de s M et al liz in g 22 % (2 /9 ) 11 % (1 /9 ) 44 % (4 /9 ) 22 % (2 /9 ) 44 % (4 /9 ) 0 0 C at ho di c pr ot ec tio n an od es 11 % (1 /9 ) 22 % (2 /9 ) 67 % (6 /9 ) 0 67 % (6 /9 ) 0 0 G al va ni c pr ot ec tio n 22 % (2 /9 ) 11 % (1 /9 ) 67 % (6 /9 ) 11 % (1 /9 ) 56 % (5 /9 ) 11 % (1 /9 ) 11 % (1 /9 ) O th er IB R C T ec hn ol og ie s H PS 0 0 10 0% (9 /9 ) 0 44 % (4 /9 ) 56 % (5 /9 ) 11 % (1 /9 ) A B C 0 11 % (1 /9 ) 89 % (8 /9 ) 0 10 0% (9 /9 ) 22 % (2 /9 ) 11 % (1 /9 )
24 PREPUBLICATION COPYâUncorrected Proofs TABLE 3.2 Present Use of IBRC Technologies, AASHTO Survey Respondents and Interviewed Highway Agencies Technology Name Currently Using Technology Special Provisions or Specifications Not Applicable Agency/State- Developed AASHTO Other Concrete HPC 67% (28/42) 18% (6/33) 73% (24/33) 3% (1/33) 6% (2/33) SCC 69% (29/42) 23% (8/35) 71% (25/35) 3% (1/35) 3% (1/35) UHPC 45% (19/42) 47% (15/32) 34% (11/32) 3% (1/32) 16% (5/32) FRP Externally bonded FRP reinforcement 86% (32/37) 16% (5/31) 71% (22/31) 3% (1/31) 13% (4/31) FRP deck elements 24% (9/37) 74% (23/31) 23% (7/31) 0 3% (1/31) FRP superstructure elements 14% (5/37) 83% (25/30) 13% (4/30) 0 3% (1/30) FRP rebar 46% (17/37) 52% (17/33) 33% (11/33) 12% (4/33) 3% (1/33) FRP prestressing tendons (strand or bar) 16% (6/37) 84% (26/31) 10% (3/31) 3% (1/31) 3% (1/31) Corrosion Control Technologies Low-chromium steel rebar 25% (9/36) 61% (19/31) 23% (7/31) 10% (3/31) 6% (2/31) Galvanized rebar 25% (9/36) 62% (20/32) 31% (10/32) 3% (1/32) 3% (1/32) Stainless steel rebar (solid or clad) 61% (22/36) 36% (12/33) 55% (18/33) 6% (2/33) 3% (1/33) Metallizing 36% (13/36) 47% (15/32) 50% (16/32) 3% (1/32) 0 Cathodic protection anodes 61% (22/36) 45% (15/33) 52% (17/33) 0 3% (1/33) Galvanic protection 42% (15/36) 52% (17/33) 42% (14/33) 3% (1/33) 3% (1/33) Other IBRC Technologies HPS 70% (26/37) 24% (8/34) 32% (11/34) 41% (14/34) 6% (2/34) ABC 89% (33/37) 11% (4/35) 69% (24/35) 11% (4/35) 11% (4/35) NOTE: Tabulations include information from the AASHTO survey and from two interviewed state highway agencies that did not respond to the AASHTO survey. SOURCE: AASHTO Committee on Bridges and Structures 2018 Annual State Bridge Engineers Survey and interviews with state highway agencies conducted for the committee. Technologies that have been less widely adopted include UHPC and FRP rebar. The UHPC technology was developed toward the later stages of the IBRC program; research to further develop the technology has continued since that time. The Iowa Department of Transportation constructed the first UHPC bridge in the United States in 2005 with support from the IBRC program. The objectives of the project included advancing the state-of-the-art in concrete bridge construction technology, developing experience in using advanced materials, and developing recommended design procedures. The bridge was constructed as a 110-ft simple span bridge with a three-beam cross section. According to a state report on
25 PREPUBLICATION COPYâUncorrected Proofs the project, âThe design of the beam was a challenge for the staff involved because of lack of approved specifications.â The investigators report that this issue was addressed with the assistance of standards developed in France and research completed at the Massachusetts Institute of Technology (Bierwagen and Abu-Hawash 2005, 8). This project illustrates that the UHPC technology was still new in the last years of the IBRC program. Nonetheless, nearly half of respondents (19 of 42) indicated current use of this technology, suggesting that implementation of the technology is progressing. The quantities and frequency of use of UHPC by these states were not determined in the survey or interviews. The use of FRP rebar has not been as widespread as use of stainless steel rebar. Barriers to implementation indicated in the state interviews include unavailability of the material and challenges with the field application, including handling difficulties and inability to field-bend the FRP rebar. Respondents also noted that corrosion-resistant materials such as stainless steel and low-chromium steel rebar provide sufficient performance characteristics and have similar costs. As a result, there was not a clear benefit to using FRP rebar instead of the other technologies to balance the increased field implementation challenges. However, FRP rebar is being used in a significant number of states (17 of 37 responding).
26 PREPUBLICATION COPYâUncorrected Proofs TABLE 3.3 Summary of IBRC Technology Use by States Technology Currently Using Technology Specifications or Standards Developed ABC 89% (33/37) 91% (31/35) Externally bonded FRP reinforcement 86% (32/37) 87% (27/31) SCC 69% (29/42) 77% (27/35) HPC 67% (28/42) 82% (27/33) HPS 70% (26/37) 79% (27/34) Stainless steel rebar (solid or clad) 61% (22/36) 64% (21/33) Cathodic protection anodes 61% (22/36) 55% (18/33) UHPC 45% (19/42) 53% (17/32) FRP rebar 46% (17/37) 49% (16/33) Galvanic protection 42% (15/36) 49% (16/33) Metallizing 36% (13/36) 53% (17/32) Low-chromium steel rebar 25% (9/36) 39% (12/31) Galvanized rebar 25% (9/36) 38% (12/32) FRP deck elements 24% (9/37) 26% (8/31) FRP prestressing tendons (strand or bar) 16% (6/37) 16% (5/31) FRP superstructure elements 14% (5/37) 17% (5/30) SOURCE: AASHTO Committee on Bridges and Structures 2018 Annual State Bridge Engineers Survey and interviews with state highway agencies conducted for the committee. IBRC TECHNOLOGIES THAT HAVE NOT BEEN GENERALLY ADOPTED As Table 3.3 indicates, present use of galvanic protection, metallizing, low-chromium steel rebar, and galvanized rebar among the states is limited. It should be noted that the need for corrosion control technologies varies by region. Southern states generally have lower rates of corrosion due to the reduced need to use deicing chemicals that can cause accelerated rates of corrosion. Moreover, satisfactory experience with epoxy-coated rebar, together with adoption of stainless steel rebar for some applications in the majority of responding states, may diminish the need for other forms of corrosion-resistant rebar solutions.
27 PREPUBLICATION COPYâUncorrected Proofs FRP deck elements, FRP prestressing tendons (strand or bar), and FRP superstructure elements are the IBRC technologies used today by the smallest number of the responding states. According to the interviewed states, barriers to implementing these FRP technologies include: High cost of the material. Insufficient benefits to justify additional costs. Poor performance in some initial projects. Difficulty implementing technology in the field. Lack of an industrial base to provide qualified construction contractors and support for inspection and maintenance. Lack of available standards and design and materials specifications. The interviews indicated that the most common reason that FRP decks and superstructure elements were not being implemented was that the benefits of these technologies did not justify the additional cost. Poor performance of the materials in the field was also identified as a reason that further implementation of the technology was not pursued. Examples provided included difficulty with maintaining a suitable driving surface on FRP deck sections, poor field performance due to detailing, and the lack of inspection and repair guidelines for these materials. An example of a project from the IBRC program that used technologies that have not been widely adopted is the Rollins Road Bridge in New Hampshire, one of the interviewed states (Bell and Bowman 2007). This project included a bridge deck constructed with HPC and FRP grid reinforcing, as well as a structural health monitoring system installed during the time of construction. The monitoring system was used originally to verify the design assumptions and study the structural behavior of the deck, in particular the FRP grid reinforcing (Bell and Sipple 2010). The monitoring system was later used in load testing the bridge to verify the field performance of the new technology. The current NBI condition rating of the bridge deck of the Rollins Road Bridge is 7 (good). The bridge was constructed in 2000; the current
28 PREPUBLICATION COPYâUncorrected Proofs condition of the bridge deck is typical for a bridge with 18 years of service, indicating that there was not a performance problem with the deckâs FRP grid reinforcing. New Hampshire has not adopted into regular practice the FRP technology evaluated during the Rollins Road Bridge project. The barriers to implementation identified in the state interview included a lack of adequate standards and specifications, difficulty handling the material in the field, and high cost. Implementation of structural health monitoring has been very limited in the state due to its cost and limited utility for most common highway bridges, according to the interview. The HPC used in the Rollins Road Bridge has been adopted into regular practice. Adoption of HPC is generally motivated by the low permeability qualities of the material, which are believed to extend the service life of bridges. It was also noted in the interviews that clad stainless steel rebar has not been adopted for use by selected states. Several of the interviewed states indicated that during planned IBRC projects that included clad stainless steel rebar, the material was unavailable and had to be replaced with an alternate material such as solid stainless steel rebar. It was additionally noted that the clad rebar is susceptible to exposure of the overclad carbon steel core caused by damage to or cutting of the bars. Such exposure would significantly affect the corrosion resistance of the rebar, reducing the benefit of the technology. INFLUENCE OF IBRC EXPERIENCE ON ACCEPTANCE AND USE The interviewed states were asked how their experience with the IBRC projects influenced the use or nonuse of IBRC technologies. Generally, the interviews indicated that the IBRC program had an influence on the acceptance and use of the technologies included in the program. The means of influence included providing the motivation to try a new technology, mitigating the risk associated with new technologies, and assisting in the development of standards and specifications for new technologies. In several instances, an IBRC project was a stateâs first experience with a technology that the state eventually adopted as part of regular practice. Interviewed states reported that the funding provided by the IBRC program motivated the trial of new technologies. For example, in Texas, where project decisions are generally made at the district level,
29 PREPUBLICATION COPYâUncorrected Proofs the availability of funding to support the implementation of a new technology helped convince the district to try a new technology. Some states indicated that they had prior interest in a new technology, and that availability of IBRC funds was effective in accelerating implementation of the technology. An example identified by the Iowa Department of Transportation is the Mackey Bridge replacement project (120th Street over Squaw Creek in Boone County), an IBRC project that used ABC technology, including full-depth precast deck panels and precast superstructure and substructure components, all constructed with HPC. The bridge won the 2007 Precast/Prestressed Concrete Institute (PCI) Design Award for best owner-designed bridge. An article in a 2009 department publication that described the project reported: âABC reduces construction time, minimizes traffic disruption, improves safety, reduces environmental impacts, enhances constructability, and improves quality and life-cycle costs.â The article stated that "Iowa DOT officials used this research to determine the feasibility of using precast-concrete bridge components to accelerate construction for future projects in the stateâ and reported that the use of ABC was increasing, with several projects each year using the technique (Abu-Hawash et al. 2009, 8). Interviewed states also reported that the funding provided by the IBRC program mitigated the risk of trying new technologies in the field, encouraging trials. Successful initial projects led to further use and implementation. For example, the success of a Virginia IBRC project constructed with lightweight HPC deck and girders (Ozyildirim and Gomez 2005) led to a recommendation for use of the technology for construction of decks and beams. As of 2016, the use of lightweight HPC is required for all bridge decks in Virginia state projects. STANDARDS AND SPECIFICATIONS It was the consensus of the interviewed states that lack of standards and specifications was generally a barrier to implementation of new technologies. It was noted that the development of standards and specifications requires field experience with the technology. However, there is sometimes a reluctance to try a new technology when standards and specifications are not yet developed. Institutional resistance to
30 PREPUBLICATION COPYâUncorrected Proofs exploring new technologies in the absence of standards and specifications was also identified as a barrier when existing practices are considered adequate. It was noted by several states that IBRC funding provided the motivation and resources to develop the specifications necessary to conduct a trial for a new technology. In addition, IBRC trials served as a means of developing standards and specifications. Standards for welding procedures for HPS were developed by Pennsylvania. California developed FRP specifications before the initiation of the IBRC program, but experience gained through the stateâs IBRC projects contributed to improvement of the specifications. Iowa noted that several states had pooled funds to support the development of UHPC standards and specifications following the initial testing of the technology during the construction of a UHPC bridge in an Iowa IBRC project, as previously described. It was also noted by several of the selected states that there is a willingness to try new technologies on an experimental basis without fully developed standards and specifications, if sufficient research and background information is available. Development of the supporting standards and specifications is required to move the technology from experimental use to practical implementation. Respondents also noted that industry and vendors sometimes assist with providing initial data for developing a specification. Several states indicated that the funding from the IBRC program contributed to the research and testing needed to develop standards and specifications for new technologies. For example, California had several IBRC projects focused on constructing a bridge entirely from FRP materials. Although the construction of the bridge was never realized, California Department of Transportation personnel reported that the fundamental testing and development that occurred during the IBRC-funded projects contributed to the implementation of FRP technology. A second example is the application of HPS in the state of Pennsylvania. According to the interviews, the IBRC program funding motivated the development of new welding procedures for using HPS (Kaufmann and Pense 2000). The Pennsylvania Department of Transportation subsequently constructed two bridges that used HPS with funding from the IBRC program. Today, the use of HPS is
31 PREPUBLICATION COPYâUncorrected Proofs commonplace, as indicated in Table 3.3, and the welding procedures developed during the research have been adopted nationwide. Several states interviewed reported that IBRC projects provided the field experience necessary to validate and improve standards and specifications that were in the development stage. For example, the Bridge Street Bridge in Southfield, Michigan (MI-1999-02)2 was constructed in 2001 with partial funding from the IBRC program. The bridge girders were reinforced using pretensioned FRP tendons and posttensioned FRP composite cable (Grace et al. 2002). The Bridge Street Bridge was the first concrete vehicular bridge constructed with FRP as its principal structural reinforcement. This project was awarded the Harry H. Edwards Industry Advancement Award by PCI. The overall project included an experimental effort aimed at developing and verifying design rules (Grace and Singh 2003; Grace et al. 2003). The project also included field testing to verify the in-situ performance of the technology. The project provided the opportunity to test standards and specifications that incorporated prestressed FRP reinforcement in bridge structures, which were under development, and led to further use of the technology based on the successful experience and the projectâs verification of the specifications and standards. The state responses shown in Table 3.3 indicate that standards and specifications have been developed and adopted for those IBRC technologies that are commonly used today. For example, more than three-fourths of respondents indicated that there are specifications or standards developed for ABC, externally bonded FRP reinforcement, SCC, HPC, and HPS. INFLUENCE OF TRAINING REQUIREMENTS Responses in the state interviews indicated that training requirements had not been a significant barrier to implementing most of the IBRC technologies. Respondents noted that entirely new materials such as FRP required training to implement the technology in the field and that lack of training for these technologies 2 Identification number assigned to the project by FHWA (FHWA n.d.a). The number indicates the state that received the award and the year in which funds were awarded.
32 PREPUBLICATION COPYâUncorrected Proofs had sometimes hindered implementation. New technologies that improved existing materials, such as HPC and SCC, required less training and training generally was not a barrier to implementing these materials. It was reported that industry sources were sometimes used for training on FRP materials. However, because the materials were often unique to the supplier of the material, there was little opportunity to develop training regimes that could be broadly utilized. Conversely, industry sources assisted in providing training for materials such as HPC and SCC. For example, the Portland Cement Association has contributed to developing specifications and training for HPC, according to the interview respondents. Several states reported that training of contractors was a challenge in implementing new technologies. Contractors had little experience with the new materials or processes. The consequences in some instances were poor construction quality or contractor resistance to including innovative technologies in construction bids due to the increased risk. It was noted that in some cases, fabricators were motivated to implement some new technologies because of the potential to improve the quality and ease of fabrication (for example, SCC.)