FHWA Resource Center
Prestressed Concrete Committee for Economic Fabrication (PCEF)
PNW/PCI-WSDOT Joint Meeting
June 13, 2006
Meeting called to order by Jugesh Kapur at 8:05 AM. Jugesh Kapur and Millard Barney gave short introductory remarks. Specifically, Jugesh welcomed the attendees to the new home of the WSDOT Bridge and Structures Office at the Edna Lucille Goodrich Building in Tumwater. Jugesh also noted that this year's scheduled attendance of nearly 40 people was one of the largest ever, and was a sign of the high interest level in the discussions of the group.
Millard noted that R. B. Johnson Company had two representatives at this year's meeting, and that Patrick Sibborn, representing Encon, was a new attendee.
The meeting continued into the agenda items.
Jugesh Kapur summarized the personnel changes within the Bridge and Structures Office. Due to Jerry Weigel's retirement as State Bridge and Structures Engineer last August, Jugesh was selected as Jerry's replacement. Dick Stoddard is currently serving as Acting Bridge Design Engineer. Bijan Khaleghi is serving both as Acting Design Supervisor and as Bridge and Structures Office Concrete Specialist. As of July 1, 2006, Bijan will serve for six months as Acting Bridge Design Engineer, and Dick Stoddard will serve for six months as Acting Bridge Design Supervisor.
Jugesh noted that the office was actively working to fill vacant engineering positions in both Bridge Design and Bridge Preservation, and that three interns had been hired for the summer.
Al Gabo summarized the reorganization of the Materials Laboratory management. Al now serves as a Structural Assistant Construction Materials Engineer under Jim Walter as Construction Materials Engineer. Kyle Coffman has promoted into Al's former position as Supervisor of the Materials Fabrication Inspection Unit.
NAFTA Steel Component Requirement Legislation:
Barry Brecto offered a clarification on which projects fit under NAFTA's exemption from the conventional "Buy-America" requirements. If a project is a Direct Federal project, as normally designed by the FHWA office in Vancouver, WA, NAFTA applies, and the project is exempt from the "Buy-America" requirements. NAFTA does not apply to conventional Federal Aid projects, such as WSDOT projects with Federal match funding, and such projects fall under the "Buy-America" requirements. This status is not likely to change, as it has been emphasized by congressional actions.
ACTION: No further action on this item.
Review of Major WSDOT project’s:
Hood Canal Bridge, Evergreen Point Floating Bridge, Manette Bridge:
Patrick Clarke provided updates on these projects.
Pontoons for the Hood Canal Bridge are currently being constructed in Concrete Technology's dry dock facilities in the Port of Tacoma. The float-out of the first set of three pontoons is scheduled for October 2006.
The Evergreen Point Floating Bridge project consists of several components: an interchange near UW and the arboretum, west approach structures, concrete pontoons supporting elevated roadways, and east approach structures.
The UW/Arboretum Interchange and West Approach structures are currently going through structure type evaluations, and the structure type should be something that works well for both the mainline structures and the ramp structures. Prestressed concrete tub girders, of a special deep section appropriate for the 250 foot spans, are being considered for these structures.
The structures connecting the interchange to the Seattle mainland will feature 350 foot main spans. Structure types being considered are segmental box girder or steel tied arch.
The floating bridge will consist of twin 75 foot wide pontoons supporting an elevated roadway of prestressed concrete girders. The structure type for supporting the girders will be the subject of a later agenda item.
The East Approach structures will be a haunched concrete box girder, either conventionally constructed cast-in-place on falsework, or constructed as a precast segmental bridge. The end pier for the East Approach structure will serve a dual purpose as the floating bridge maintenance facility.
Construction of this bridge will require construction of a new separate dry dock facility. Sites for this new facility are under evaluation now. The construction contract for this new dry dock facility is scheduled for AD at the end of 2008. The construction contract for the pontoons is scheduled for AD at the end of 2010.
The Manette Bridge replacement project in Bremerton is now under design. Preliminary design efforts are helping to assist the Olympic Region Design PE Office as it works through the environmental permit process. The bridge elements remain as discussed at previous PNW/PCI-WSDOT meetings – haunched spliced precast concrete girders shipped to and post-tensioned on site, and supported on substructure consisting of precast concrete elements for columns and crossbeams. However, the alignment of the bridge has been revised so that five of the seven spans are on tangent and parallel to the existing bridge, and only the end spans feature minor curves for connection to the mainland. Funding is secure. The project is currently scheduled for a December 2007 AD Date, but this could be delayed pending completion of environmental permits.
Alaskan Way Viaduct:
Ron Lewis reported on this project. Legislative action this past session implemented a deadline for making a decision (now January 2007), stipulated a ceiling on WSDOT funding for the project, and stipulated that the City of Seattle would be responsible for all funding requirements above this ceiling. The City would also be fully responsible for any reconstruction of the seawall. As a result, structural alternatives to a tunnel have acquired new life, and the WSDOT Alaskan Way Viaduct team is actively reviewing seven elevated structure alternatives. Structure types for these alternatives include cable stayed suspension, extradoes suspension, precast concrete segmental, steel truss, steel box girder, and prestressed concrete girder. The goal is to maintain existing traffic operations and to reduce structure impact to the fullest extent practical. Tie-ins at the north and south ends of the project make staging difficult. Some alternatives retain, and others eliminate, the existing downtown core access ramps. The rating and review process will begin in July with the goal of selecting a preferred alternative by September 2006.
Jugesh Kapur reported on the status of the retrofit alternative that is being promoted by others. The promoters claim that such a retrofit is practical, can be completed under traffic, can extend the life of the structure 20 to 30 years, and can be achieved for under 1 billion dollars. T. Y. Lin has been hired to evaluate the feasibility of the proposal. Jugesh noted that such a retrofit would only address seismic deficiencies, and would not address the other structural and load rating deficiencies.
Jugesh also reported on the status of the existing viaduct. The viaduct is inspected in-depth twice annually, with the next inspection due in October. The viaduct as settled up to 4-1/2 inches at one particular frame. If the settlement reaches 5 to 6 inches, WSDOT is ready to go with a foundation retrofit project for this frame that includes micropiles.
Rich Zeldenrust reported on these DB projects. Kiewit/DMJM Harris is the DB for the Kirkland Phase 1 project currently underway. The other projects are planned for 2007 through 2011. Project scope for these projects has been dynamic because of current market conditions. The ultimate build-out scenario for the SR 520/I-405 I/C is currently estimated at 1 billion dollars. The ultimate build-out scenario for the I-90/I-405 I/C is also currently estimated at 1 billion dollars. The ultimate build-out scenario for the SR 167/I-405 I/C is currently estimated at 750 million dollars. Funding for the majority of the future I-405 Design/Build work is dependent on successful passage of RTD, in addition to funding from the Nickel and TPA gas tax funds. While 80 percent of the I-405 bridges are currently prestressed concrete girders, construction of flyover ramps at the major interchanges will require structures more appropriate for long spans.
Atkinson/CH2MHill is the DB for this project, and construction is currently underway. A major element of this project is the conversion of the Broadway I/C from the current NB left hand exit to a NB right hand exit (for general purpose lanes). The NB left hand exist will then be converted to an HOV exit. The project includes five new bridges and 18 widenings. Most of the bridges are prestressed concrete girders using the newer WF sections, along with steel plate girders for the longer flyover bridges. A separate City of Everett project for construction of a SPUI at 41st Street was added to this project by Change Order.
Other Major WSDOT Projects:
Dick Stoddard and Ron Lewis summarized the list of current bridge construction projects under design. Several projects located throughout the state were identified. The current dilemma now is finding engineers (in-house and consultant) to design the bridges and ensuring that the contractor market place can accommodate the work within the funding restrictions of the Nickel and TPA line item legislation.
Washington State Ferries:
Greg Trisko provided a brief summary of WSF construction activities. The WSF program calls for 1 billion dollars of facility construction over the next decade, including terminal construction or reconstruction at several locations. The projects will include more precast concrete construction than in the past.
Sound Transit Segmental Girder Project:
Bob Connelly of Bethlehem Construction and Patrick Malone of PCL Civil Constructors gave a presentation on the current segmental girder construction for this project. The project is providing a light rail link from Martin Luther King Way to 154th Street near Sea-Tac airport. Most of the elevated structure (168 spans of an average span of 120 feet) is being constructed by the "span by span" method of segmental construction using an overhead truss gantry. Locations crossing BNSF, I-5, and the Duwamish River (12 spans varying from 142 feet to 350 feet) are being built by conventional balanced cantilever segmental construction methods. Construction is underway for the "span by span" constant depth sections, and is due to begin shortly for the balanced cantilever sections.
ACTION: Status update of major prestressed girder projects at next year’s meeting.
Remarks by Don Nelson:
Don Nelson, Director of Environmental and Engineering Programs for WSDOT, was able to fit in a brief appearance at the meeting just following the Everett HOV discussion noted above. Don provided a brief summary of the current WSDOT program. The Nickel package is funding 21 active projects, with 61 projects yet to come. The TPA package is funding 8 active projects, with 63 yet to come. This is on top of approximately 500 conventionally funded projects. A primary concern gaining attention since the beginning of the year is the low number of bids, and the rapidly escalating costs, of bids being received for these projects. Don passed out a handout documenting the situation, and demonstrating that this is a nationwide phenomenon. Doug McDonald has been discussing this with the Governor and her economic advisors. The handout outlines some of the actions that WSDOT is taking at the current time.
Blast Testing of Prestressed Concrete Girder Bridges:
Ron Lewis reported on the status of this effort. The project has now been divided into two phases. Phase 1 will be the testing for blast calibration of two individual deck bulb tee girders. Phase 2 will be the blast testing of bridges to be built using the prestressed concrete girders to be donated by Concrete Pre-mix Prestress Company (CPM) and Morse Brothers. Environmental issues continue to delay efforts to confirm a location for the test or tests.
ACTION: Status update at next year’s meeting.
Report of the FHWA Representatives:
Barry Brecto and Tim Rogers reported on current FHWA activities and programs. FHWA is now focusing on encouraging new ways for DOT's to conduct business. Applications for the Innovative Bridge Research and Development Program are due by August 2006. The Highways for Life Program (concerning accelerated construction for highway corridors) was also mentioned. The latest congressional funding package included a small earmark for high performance concrete construction.
Report of the ODOT Representative:
Craig Shike reported on the current ODOT construction program. 75 percent of the bridge design program is being managed by a Consultant (Oregon Bridge Delivery Partners – OBDP). The design work will be substantially complete in 2006, with construction to continue for five years. Craig noted that ODOT is encountering the same difficulties with bid results as is WSDOT, and has had occasions when projects have received no bids at all.
WSDOT Precast Prestressed Girder Designs:
Review of WSDOT Precast Girders:
Bijan Kahleghi provided an overview of the current status of the family of WSDOT precast girders. While still included in the family of girders, use of the conventional I girders is being sharply reduced in WSDOT designs due to the availability of the much more efficient WF series of girders. The girder design tables in Bijan's handout reflect the WSDOT practice of 0.6 inch diameter strands, with 7.5 ksi minimum at release and 8,5 ksi minimum at 28 days.
Use of Five Inch Cast-In-Place Slab instead of HMA for PCPS Members:
Use of precast prestressed (PCPS) members is being expanded with the addition of the 5 inch cast-in-place topping slab as a combination wearing course/composite section. Seven bridges in the upcoming SR 539 reconstruction project will use this structure type. Use of PCPS members and deck bulb tee girders with an HMA wearing course instead of the 5 inch cast-in-place topping slab is restricted to highways with ADT's of less than 30,000.
Use of Lightweight Concrete for Precast Concrete Tub Girders:
Bijan noted that the use of the precast concrete tub girders is limited by the weight limitation for transporting these girders to the project sites. Bijan suggested that use of lightweight concrete in these girders would be a factor in easing the shipping difficulties.
DeWayne Wilson noted that successful performance of LWC in this state has been inconsistent. While the 1950 Tacoma Narrows Bridge use of LWC has performed well, use at Biggs Rapids Bridge and Maple Street Bridge (Spokane) was not so successful. Use of LWC with epoxy-coated steel reinforcing bars may be a significant improvement, and recent experience with LWC for the Lewis & Clark Bridge Deck Rehabilitation project and the Hood Canal Bridge project has been very good.
An unavoidable restriction on the use of LWC is the availability of aggregate for such concrete. There are no pit sources of such aggregate in the Northwest, forcing the use of aggregate from Texas, Utah, California, and North Carolina, with associated higher costs.
Steve Seguirant noted that use of LWC would affect several girder design parameters, and that such design performance characteristics would have to be better defined before use of LWC could be conventionally used for girders.
Epoxy Coated Steel Reinforcing Bars for Deck Slabs:
Jugesh Kapur reported that current WSDOT policy is to specify epoxy-coated steel reinforcing bars for all horizontal layers of bridge deck slabs. This action is being taken due to the increased presence of cracks in bridge decks in recent years. The only bars exempted from the epoxy-coated policy are the hooks of the prestressed concrete girder stirrups, provided that these hooks are bent at 135 degrees.
Camber of Prestressed Concrete Tub Girders:
Bijan reported on the construction experience related to the use of prestressed concrete tub girders of the four Farwell bridges completed in 2005 for the North Spokane Corridor project. The Contractor requested, and received, approval for erecting the girders much earlier than the conventional 120 calendar days after casting. During placement of forms for the deck through the placement of steel reinforcement and concrete for the deck, it was noted that the girder camber was much less than predicted by design. Review of the situation concluded that the camber was reduced because of the early placement of construction loads on these girders.
To accommodate future projects where the Contractor may desire to accelerate construction, the standard girder schedule tables in the bridge sheets now include a deflection dimension "D" at both 40 days and 120 days. However, Bijan noted that the "A" dimension for the girder pad is still based on a girder camber deflection at 120 days.
ACTION: Girder developments will be updated at next year's meeting.
Rick Brice reported on the ongoing updates to WSDOT supported computer program software. Non-composite sections can be analyzed with or without a non-composite deck. All programs have been updated to reflect the requirements of the 2005 LRFD Specifications. More details have been added to the program printouts to provide better ties of results to specific input. Girder camber and deflection calculations are now provided at 40 and 120 days. Strand debonding capabilities have been added.
Rick also reported on work in progress. This includes program updates to address the 2006 LRFD Interim Specifications, better accommodation of geometric affects of superelevation and curvature, and revision of longitudinal shear calculations. Long term issues include accommodating new traffic barrier shapes, moving file libraries to the internet for access by outside consultants using WSDOT girder design programs, and revising programs to accommodate design of multiple span girders in one file as opposed to the current requirement of a separate program file for each span and girder. Collaboration with Texas DOT is ongoing also for other program improvements.
Steve Seguirant asked if consideration was being given to revising the program to accommodate girder continuity. Rick responded that this is being considered.
ACTION: Update of new program developments at next year’s meeting.
Prestressed Concrete Girder Bid Prices:
Mike Bauer reported the recent policy, as of December 2005, of separating prestressed concrete girders from the conventional Superstructure lump sum bid item and listing the prestressed concrete girders instead as separate unit cost bid items, measured per linear foot. This step was taken as an attempt to get a better handle on costs for bridge superstructures. Based on raw cost data provided by Concrete Technology Corporation and others, new cost ranges were established for the entire family of WSDOT prestressed concrete girders, including fabrication, transportation, and erection. Experience to date has been limited because the change is so recent, but recent bids for the girder bid items have been in line with expectations.
During the ensuing discussion, it was reported that some local agencies were taking the step of procuring the prestressed concrete girders in advance of bridge construction, and then providing the girders directly to the Contractor at the time of bridge construction.
A question was asked about whether or not the allowance of Mexican cement into the US has had any affect on the market. The conclusion of the discussion was that this cement would probably be engulfed by the demand from the California, Southwest, and Southeast construction markets, and probably would not affect the Northwest market.
ACTION: Update market conditions and bid experience at next year's meeting.
Issues with Spliced Prestressed Concrete Girders:
Mark Gaines and Rich Zeldenrust led the discussion of a construction problem in Contract 6895, SR 240, I-182 To Columbia Center I/C, Bridge No. 182/14 Widening. This bridge involved post-tensioning of spliced prestressed concrete tub girders. During post-tensioning and grouting, excessive strand elongation and grout leakage from the closure forms at Pier 3 was observed. Upon removal of the closure forms, the blown out duct was discovered. The pier closure concrete was Class 4000 with 1-1/2 inch slump. The Contractor submitted a claim, contending that the concrete cover was too small.
Rich had completed specific hand calculations based on the construction sequence. While the calculations did show high stress, the calculated stresses were within the modulus of rupture for the pier closure concrete, provided that the concrete had been properly consolidated when placed.
The discussion then shifted to in-span girder splices. Bijan showed a suggested detail with taper flairs in the precast girder to accommodate the dimension difference between the 1 inch precast girder cover and the 2-1/2 inch cast-in-place closure cover. The precast fabricators uniformly panned the detail, noting that such localized and non-uniform form modifications would add significant cost and would represent a return to the "end block" days. Suggestions were offered to include the taper entirely in the closure, decrease the stirrup spacing in the vicinity of the closure, to place the closure at the location of the intermediate diaphragms, and to exaggerate the closure as a specific architectural feature.
Bijan concluded this discussion by showing a spliced girder construction scheme proposed for a bridge replacement project on I-5 in Lewis County. The lengths of the girder segments are meant to match the existing dimensions of the approach and main spans of the existing bridge being replaced. The proposal is to shift the existing truss spans to parallel alignments, shift traffic, erect the spliced girders using the existing piers as temporary falsework supports, complete construction of the bridge, and remove the existing substructure and detour bridges. The precast fabricators noted that the concept was feasible from a girder fabrication perspective, provided that the side forms were kept constant and that the additional girder depth was achieved by thickening the bottom girder flange alone. It was also noted that the tapered depth at the ends of the girders offered no structural benefit for this as a simple span structure, unless the girders were to be somehow rigidly connected to the end piers.
ACTION: Bijan will review current practices and will recommend possible revisions to concrete cover and duct placement details.
Shipping Problems With Prestressed Concrete Girders:
Eric Shultz shared a construction problem he encountered during construction of Yakima River Bridge No. 24/2 under Contract 6933, SR 24, I-82 To Keys Road. Based on the bridge layout in effect at the time of design, the design of the W83G girders was stretched to the girder stress limits allowed for shipping, even though final stresses in place were easily accommodated. As it happened, the girders had difficulty achieving the specified concrete strength at strand release, and this created some problems. Were he to have the opportunity to start over, Eric would have revised the span arrangement of the bridge layout to avoid stretching the girder lengths to this extent.
Discussion ensued into the effectiveness of various methods for dealing with release and transportation stresses. Although external "king-post" systems offer visual comfort, such systems are now recognized to offer little practical effectiveness. The use of temporary prestressed strands in the upper flange of prestressed concrete girders is found to be much more effective.
ACTION: No further action on this item.
Problems With Girder Ends:
Girder End Cracking and Allowable Parameters:
Chuck Prussack asked if WSDOT noticed any ongoing problems with girder end cracking, and if there were any allowable parameters for such cracking. Bijan Khaleghi responded that WSDOT hadn't noted any shear cracking. Patrick Clarke noted that the original Hood Canal Bridge prestressed concrete girders did have cracking that resulted in corrosion of the girder reinforcement and prestressing strand. The girders for the Hood Canal Bridge Widening and Replacement addressed the situation by decreasing the stirrup spacing and increasing the concrete cover.
It was noted that cracks would generally be present at the time of girder removal from the casting bed, but that ongoing strand relaxation and eventual girder erection would allow and cause the cracks to close, and possibly be covered by pier diaphragm construction.
Rich Zeldenrust asked if, as girder lengths get longer and girder weights heavier, are cracks at blocking areas of increased concern? Steve Seguirant responded that such would be the case only for skewed girders. Bijan Khaleghi offered that a detail revision from a while back addressed this situation.
Bursting Zone Reinforcement:
Mark Gaines opened the discussion by noting that spliced girders of the same depth seem to be requiring increasing amounts of reinforcement based on code. Steve Seguirant responded that the formula in the code dictates unreasonable reinforcement requirements. Steve also noted that the current WSDOT I and WF girder webs are sized for #5 stirrups only. Bijan Khaleghi stated that the code does not work well for shallow depth girders, and that a proposal is being developed to revise the formula. Steve concluded that designers need to keep the stirrup reinforcement spacing at reasonable dimensions, and to recognize that shallow girders are not affected as much as deeper girders, even if the formula is unable to recognize this.
ACTION: No further action on this item.
Noise Barrier Wall Design and Detailing Issues:
Bijan Khaleghi and Patrick Sibborn were able to conduct their detailed discussions during the lunch break. Bijan provided a summary of the discussions and the likely followup actions.
The current WSDOT Standard Plans provide several different structure type alternatives for noise barrier walls, but construction is heavily dominated by one type - prestressed concrete panels on shaft foundations (with or without barrier face). Based on detail changes and improvements suggested by shop drawing submittals under contract, the Standard Plans and noise barrier wall specifications will be updated. Base plate dimensions will be revised. Anchor bolt material specifications will be revised to ASTM F 1554 Grade 55. The confusion of whether or not welded wire fabric is acceptable for precast concrete panel reinforcement will be clarified (it is for panels but not yet for pilasters). Patrick will submit details of WWF as pilaster reinforcement for Bijan to review and consider for approval.
Kyle Caufman asked about the acceptable tolerance for fit of the cone head reinforcement bar ends in the panel base plates - is a 1/16 inch gap acceptable? Bijan responded that the fit is supposed to be tight with no gaps. If a gap exists, then the panels are set up to rock back and forth under cyclic loading, and this is not acceptable.
Bijan noted that noise barrier wall design has not yet been elevated to LRFD status, and that it is still governed by the AASHTO Guide Specification which allows for load factor design or service load design.
ACTION: Bijan will update the Standard Plans to incorporate the approved revisions suggested by Patrick.
PCPS Members and Deck Bulb Tee Girder Issues:
JVI Vector Connectors:
Mark Gaines revisited this item from last year. This proprietary product had been used as the weld tie connector in a couple of WSDOT projects with PCPS members. Further investigation and review of the manufacturer's catalogue indicated that this product is generally used for parking garage construction and may not be appropriate for cyclic highway loading. Based on this research, this product will no longer be allowed for use as a PCPS member or deck bulb tee weld tie device.
Bijan Khaleghi showed a proposed revision to the keyway detail for PCPS members and deck bulb tee girders to open the top gap to 2 inches, to delete the grout, and to call for the keyway to be filled with the structural concrete. Mike Bauer noted that Standard Specification Section 6-02.3(25)N states that the Contractor need not fill the keyway with grout in situations where a cast-in-place concrete slab is placed on top. The precast fabricators uniformly expressed doubt that the keyway could be successfully filled with concrete under one operation - a 2 inch gap is not enough to ensure filling. It was suggested that opening the keyway up to a vertical sided 4 to 5 inch gap would be more constructable, and would not compromise the placement and cover for the adjacent stirrups.
End Skew Limitation for PCPS Members:
Bijan Khaleghi asked the group for comments about practical limits on skews for PCPS members and deck bulb tee girders. At one time, WSDOT had a policy limiting the skew to 30 degrees, but in recent years the Bridge Office has been making more and more exceptions up to 45 degrees. Steve Seguirant noted that skewed PCPS members would twist, but that deck bulb tees would have less of a problem at higher degrees of skew. Mike Johnson offered that their plant had produced PCPS members at 55 degree skew, but that girders at such higher degrees of skew required additional work at the bearings in order to provide full end bearing support. Mike had seen some projects where girders were produced at 30 degree skew, and then a cast-in-place closure was constructed to accommodate the higher skew in the field. Mike would prefer a 30 degree limit.
Concrete Strength and Strand Diameter:
Bijan Khaleghi inquired whether the current WSDOT design criteria for concrete strengths of PCPS members (6.0 ksi at release and 8.0 ksi at 28 days). The precast fabricators expressed concern about requiring such higher strengths for concrete with air entrainment. Mike Bauer pointed out that Standard Specification Section 6-02.3(25)B had been changed following discussions at last year's PCI meeting to delete the air entrainment requirement for all prestressed concrete girders, including the field cast closures for spliced girders. With no requirement for air entrainment, the strength requirements are not a problem.
Traffic Barrier Reinforcement:
Bijan Khaleghi noted that, with the addition of the 5 inch cast-in-place composite slab on top of PCPS members for WSDOT bridge designs, the need for the complicated details for the traffic barrier connection to the PCPS members was no longer necessary. The 5 inch cast-in-place composite slab is sufficient to accommodate the connection of the traffic barrier to the structure. As such, the previous details for connecting the traffic barrier to the PCPS members have been removed from the Bridge Office standard details. For projects where bare decked or HMA topped PCPS members are used, the barrier connection details will be dealt with on a project specific basis.
ACTION: Bijan will revise the keyway details to address the group's comments.
Use of Precast Arch members for Evergreen Point Floating Bridge Pontoon Superstructure:
Jesse Beaver showed the design concepts being developed for support of the elevated roadway on the pontoons. The conventional approach would be 60 foot spans with six columns across. An alternative approach that is being considered is to use precast concrete beams formed as open spandrel arch sections for a 90 foot span. The mid-arch cast-in-place key would coincide with the crossbeam. The concept as currently developed would require approximately 1,000 precast elements. Design challenges to be addressed include placement of the expansion joints and accommodation of the arch thrust forces.
ACTION: Update development of the concept at next year's meeting.
Alkali-Silica Reactivity (ASR) Testing and Mitigation Requirements:
Don Brouillard reported on the status of this ongoing issue. Based on the results of the completion last year of the six year review and related tests, the 2006 Standard Specifications in Section 9-03.1(1) have been revised to address the work of the outside consultant. Depending on the aggregate test used, and the expansion rate recorded, the mitigation measures vary, and are specified in the revised specification. Don noted that 85 percent of the 150 pits tested during the review were found to be OK.
Acceptance Testing performed by the Contractor - Requirements and Specifications:
Don Brouillard also reported on this issue. Due to the beginnings of Design-Build construction in this state, conventional WSDOT methods need to be adjusted or revised. The anticipated workload of conventional work and scheduled Design-Build work will require outsourcing of quality assurance (QA) testing. It appears that the model used by the precast industry for QA testing, where the process is defined as part of PCI plant certification, could be used as an outline for a revised process for Design-Build. Under this model, WSDOT would likely be performing periodic document checks and oversight of the process.
Fly Ash and Slag:
Mark Gaines reported on the current WSDOT position on use of fly ash and slag in concrete mixes. Due to the temporary closure of the Chehalis coal fired power plant, supplies of local domestic fly ash are insufficient for the current construction market. To address the situation, the Standard Specifications have been amended to allow the use of slag at a 1:1 substitution rate. Also, Contractor's will be allowed to submit alternative mix designs for WSDOT concrete classes that currently require use of fly ash. Chuck Prussack mentioned that CPM uses some fly ash from sources in Canada and Montana, but only when necessary and when available.
Use of Evaporation Reducers:
Mark Gaines indicated that WSDOT had concerns about the use of evaporation reducers, based on the verbiage in the product literature for one particular product (Confilm) that was being promoted. Since that time, two other products have been found that appear to be acceptable. CPM has now included these two other products in their latest plant approval package. Confilm is still not approved for use.
Review of Concrete Strength Requirements at Strand Release and 28 Days:
Bijan outlined the current WSDOT policy for concrete strength requirements for prestressed concrete girders. The current policy is 6.0 ksi maximum at strand release and 8.0 ksi maximum at 28 days for PCPS members and deck bulb tee girders, and 7.5 ksi maximum at strand release and 8.5 ksi maximum at 28 days for all other prestressed concrete girders. The general consensus was that these strength requirements were acceptable. Mike Wachter remarked that some Design-Build contracts are requiring concrete strengths at strand release higher than 7.5 ksi. Rich Zeldenrust offered assurance that the WSDOT I-405 design team is aware of current WSDOT design policy.
Acceptable Methods for Cooling Concrete during Hot Weather:
Chuck Prussack asked if WSDOT had any concerns about use of nitrogen as a method to cool aggregate. Don Brouillard was unaware of any concerns. Mark Gaines felt that use of the method should be documented as part of the annual plant review submittal, so that WSDOT would have an opportunity to give it a more serious review.
ACTION: The fly ash situation will continue to be monitored throughout the year. The Materials Laboratory will continue work on developing appropriate specifications revisions to accommodate Design-Build construction.
Self-Consolidated Concrete (SCC):
Mark Gaines provided an update on this topic. WSDOT is allowing SCC for specific precast concrete elements, most recently for precast reinforced concrete three sided structures fabricated by Utility Vault. Mark reported that the SCC used by Utility Vault did not include any viscosity modifier additives (VMA's), that Utility Vault tested the concrete mix by constructing a demonstration section, and that no settling out of aggregate was observed.
The primary concern is with the use of viscosity modifier additives (VMA’s), the types and amounts of admixtures used, and the possible long term affects on the longevity of the concrete. A material specification for VMA is still under development and is at least a year away. Mark indicated that WSDOT would be open to considering use of SCC in prestressed concrete girders, but that this would have to be on a project by project basis, at least initially.
Both Steve Seguirant and Bijan Khaleghi expressed concerns regarding the long term performance of SCC cast prestressed concrete girders with respect to elasticity, creep, shrinkage, durability, and reliability. Bijan was concerned that it might be difficult to achieve concrete strengths above 5.0 ksi. However, Al Gabo mentioned that a state precast panel fabricator has been getting 7.0 ksi for structural earth wall precast panels.
It was suggested that a "flowable concrete" with no VMA's, perhaps similar to that used by Utility Vault, would be worth investigating as a way of gaining some of the benefits of a flowable concrete while still maintaining use of a concrete mix with properties and performance that we are all familiar with.
ACTION: Continue discussion at next year’s meeting.
Issues With Submittals and Problem Resolution Process:
Review of the Resolution Request Protocol and WSDOT Fax Resolution Process:
Kyle Caufman outlined a change to the FAX resolution protocol that has been discussed internally within WSDOT and approved for implementation. The change is to add a line requiring identification of, and concurrence of, the WSDOT fabrication inspector assigned to the project. The concurrence can be verbal or written, but must be indicated on the form.
Discussion ensued on acceptable methods of transmitting this form. Distribution by e-mail under e-mail text or as a PDF attachment are acceptable methods, provided that all of the information established in the FAX form is included, and that the established WSDOT protocol for distribution is followed.
The form is intended for use for WSDOT projects, but does have value as providing a format for a useful tool for Local Agency projects and Design-Build projects. It was suggested that use of this form, or a similar form, and the protocol for its distribution, should be an item of discussion at any pre-construction meeting held for Local Agency and Design-Build projects.
Update on Repair Procedures for Large Voids and Rock Pockets:
Mark Gaines noted that recurring rock pockets in bottom flanges of prestressed concrete girders is a growing concern. Large size rock pockets are not covered by the repair procedures included as part of the annual plant approval package, and each occurrence should be addressed by the FAX resolution process.
The challenge is for Local Agency and other non-WSDOT administered projects, when those administering the project generally do not know how to handle such repair approvals. It was suggested that this topic be an item of discussion at any pre-construction meeting held for such non-WSDOT administered projects, so that a protocol can be established at the beginning of the project. If the precast fabricator has a specific repair procedure they prefer to use for rock pocket repairs not already covered by the annual plant approval package, such specific repair procedures should be submitted to the Project Engineer as a project specific submittal at the beginning of the project.
Suggestions for Changing From Paper Submittals to Electronic Submittals:
John Olk briefly described the efforts of the Bridge Office to take more advantage of electronic methods of working drawing submittals, and to reduce the amount of hard copy transmittals via courier or mail. Bridge Office Construction Support now has a scanner, and is now able to electronically return working drawing submittals with review comments via e-mail. As of June 2006, 80 percent of all construction support transmittals are being processed electronically via e-mail. The resolution of the PDF file need not be of "high-definition" quality, but it does need to be legible. A 300 by 300 resolution is suggested.
ACTION: No further action on this item.
NCHRP and WSDOT Research Projects:
Jugesh Kapur reported on the status of several ongoing NCHRP projects. The project attempting to extend the span range of deck bulb tee girders is behind schedule. The lead researcher has moved from University of Alaska to University of Tennessee, and the submittals received thus far have been incomplete and do not give much confidence for the results.
The project for simplifying live load distribution factors is in better shape for completion, but the results are not promising. Test results indicate that the distributed loads are 10 to 15 percent higher than specified by current specifications. The WSDOT position is that the "simplified" factors are too conservative, and that the reliance on interpreting multiple graphs for factor values is inappropriate in this electronic age. The results of this study are being presented for implementation by AASHTO.
Texas is conducting a study on blast affects on bridges.
Development of a new seismic code is nearing completion It is likely that this new code will be implemented as a guide specification, as a means of getting it out there for use while not forcing reluctant Midwestern states to use it now.
UW Accelerated Bridge Construction Project:
Work is progressing on this study of use of precast elements for bridge construction. One selected method will be tested. The precast elements will utilize debonded reinforcing bars for connection of the various elements in the field.
UW Prestressed Girder Camber Project:
This project will be measuring the camber deflections and prestress force losses for one of the newly constructed bridges in Contract 6933, SR 24, I-82 To Keys Road.
PCI Producers and Bridge Committee Meetings:
Chuck Prussack had 30 copies of a manual just published by PCI for Repair of Bridge Girders.
Steve Seguirant and Bijan Khaleghi serve together on an LRFD subcommittee. Minimum reinforcement is the current hot topic.
AASHTO Annual Meeting:
Jugesh summarized the significant ballot items for the upcoming AASTHO meeting. The "simplified" shear design code being presented is deemed too conservative by the West Coast DOT's, but it is likely to pass. WSDOT will continue to follow the current existing code. The new seismic code will likely be implemented as a guide spec in 2007, as mentioned above in the NCHRP discussion. Dr. Chuyuan-Shen Lee of Bijan Khaleghi's design unit will be checking two bridges using the new code.
AASHTO LRFD Design Items, T-10, Bridge Design Manual:
Bijan Khaleghi and Steve Seguirant summarized items under discussion by the LRFD and T-10 subcommittees. Topics include interface shear, continuity of multiple span prestressed concrete girder bridges, column resistance factors, and simplified shear design.
Bijan reported that the new WSDOT LRFD Bridge Design Manual was distributed last fall, and is now in use. An update is scheduled to come out shortly.
ACTION: Report on current NCHRP Panel status at next year’s meeting.
Design Awards and PCI Journal Awards:
Bijan Khaleghi reported that the South 317th Street Over I-5 Bridge built under Contract 6757 has been submitted to PCI for consideration for award, as a unique use of prestressed concrete tub girders for a "Texas T" bridge for HOV ramp access to the adjacent park and ride lot.
Steve Seguirant mentioned that an article written about over-reinforcement of tee beams under the initial LRFD code, and published in the PCI Journal, received awards both from PCI for the biggest contribution for research, but also from ASCE (T. Y. Lin Award).
ACTION: Award status update at next year’s meeting.
Delinquent Agenda Items:
Horizontal and Vertical Curved Precast Girders:
Bijan Khaleghi and Patrick Clarke asked the group for input concerning the use of curved prestressed concrete girders, with applications at locations such as the UW vicinity interchange with the reconstructed SR 520.
Patrick Clarke also inquired as to whether any of the precast fabricators had forms, or knew of availability of forms, for construction of various architectural barriers such as constructed for the 4th Avenue bridge in downtown Olympia. Chuck Prussack mentioned that CPM had constructed the precast barrier elements for the rehabilitated Monroe Street Bridge in Spokane, but offered that most architectural barriers tend to be so project specific as to preclude use in subsequent projects.
The meeting was adjourned at 3:25PM.