Report D4.3. Field demo of bridge in Florida

Transcription

1 SEACON Sustainable concrete using seawater, salt-contaminated aggregates, and non-corrosive reinforcement Start date: October 1, 2015 Duration: 30 months Report D4.3 Field demo of bridge in Florida Author(s) Main Editor(s) Thomas Cadenazzi, Guillermo Claure and Antonio Nanni UM Due Date 01/31/2018 Delivery Date 02/21/2018 Task number 4.3 Dissemination level PU Project Coordinator Antonio Nanni, University of Miami, 1251 Memorial Drive Coral Gables, FL USA Date: 2/21/2018, Version: Tel: nanni@miami.edu 1 (15) Website:

2 Table of contents Preface 1 1 CFRP-PC 18 X 18 bearing piles 4 2 CFRP-PC/GFRP-RC 12 X 30 sheet piles 5 3 HCB Beams 6 4 GFRP-RC bent caps 7 5 Bulkhead cap and test blocks Inside the test blocks Green concrete pour Demolding activities and results 12 Date: 2/21/2018, Version: 1 2 (15)

3 Preface A special and innovative vehicular bridge is under construction in Homosassa, Florida. Even though nothing special can be noticed if driving around as a usual observer, there is a secret inside the structure. The FDOT District 7 Structures Design group designed this Bridge utilizing innovative Fiber Reinforced Polymer (FRP) materials with the support of the FHWA Every Day Counts and FDOT Invitation to Innovation programs. Additionally, this Bridge Replacement project is a demonstrator for SEACON. The 186-foot bridge features special Glass Fiber Reinforced Polymer (GFRP) bars and Carbon Fiber Reinforced Polymer (CFRP) prestressing strands. By using CFRP-PC Bearing Piles, CFRP-PC/GFRP-RC Sheet Piles, hybrid GFRP-RC sheet piles, Hybrid Composite girders, GFRP-RC bent caps, GFRP-RC bulkhead caps, GFRP-RC Traffic Railings and Approach slabs and a 63-foot long GFRP-RC gravity wall, the Department was able to virtually eliminate regular carbon-steel reinforcement on the bridge. This FDOT bridge replacement project is crucial as the corrosion of the steel reinforcement in the existing bridge has severely impacted the future reliability and safety of the bridge. The chloride-attack that has occurred over that last 63 years has resulted in loss of effective reinforcing steel, especially in the substructure. Having a bridge made in composite materials prevents this problem in the future. In addition, eliminating the need to shutdown of the bridge for future repairs is especially vital at this location since the bridge is the only way for vehicles to reach Homosassa Springs. After carefully considering all options, FDOT opted for composites primarily because of the high costs of maintaining traditional steel-reinforced bridge elements in the state s saltwater and wetland environments. In addition to their inherit resistance to corrosion, FRP-PC also exhibit high strength, elastic behavior and low stiffness material properties. This results in a material that is very effective in resisting the high loads that are applied to the structure from a mechanical stand point. An addition benefit is the extreme light weight of this material which is one of the great advantages brought the contractor on site, Astaldi Construction Corporation. The light unit weight of the material allows the contractor to use less labor and reduces transportation costs, and the low stiffness allows easy on-site cutting of bars to length. Date: 2/21/2018, Version: 1 3 (15)

4 1. CFRP-PC 18 X 18 bearing piles Halls River Bridge counts a total of 36 CFRP-PC piles. During Phase II of the construction project, eighteen (18) CFCC-prestressed concrete piles were cast at Gate Precast Company in Jacksonville, FL. In order to save time and avoid any delays, the contractor cast the production piles along with the test piles. The production pile lengths were as follows: 55 ft for end bent 1; 66 ft for bents 2 and 3; 70 ft for bents 4 and 5; and 64 ft for end bent 6. Piles cross section and elevation are shown in Figure 1. Figure 1 - Piles cross section and elevation The installation at the bridge site, from February 15 to June 28 (with the installation of the pile splices) was possible through steel cables wrapped around two points on the CFCC pile (Figure 2). Pile Driving Analyzer (PDA) sensors or strain transducers were attached to predrilled holes at the top of the pile to monitor pile capacity, blows per inch, and stresses in the pile. The piles were driven with an APE D30-42 single-acting diesel hammer at the lowest fuel setting. If the maximum allowable of 20 blows/in was reached, pile driving was stopped and the fuel settings were reduced. When the pile reached practical refusal, pile driving was terminated. Date: 2/21/2018, Version: 1 4 (15)

5 Figure 2 - CFRP pile installation Since the new structure replaces a 63-year old bridge, while driving piles, a seismograph was also used to monitor the vibrations on the existing bridge; the seismograph sensor was placed in a sand bag on top of the pile cap of the closest existing bridge. The maximum allowable vibration of the bridge is 0.5 in./sec. 2. CFRP-PC/GFRP-RC 12 X 30 sheet piles Among the 235 sheet piles that compose the seawall, there are 149 CFRP-PC/GFRP-RC 12 X 30 sheet piles and 86 Hybrid TCS-PC/GFRP-RC, in traditional carbon steel. Sheet piles in traditional carbon steel have been designed to be driven behind the seawall corridor, where not affected by the chloride attack of the Halls River Bridge waters. Figure 3 shows typical pile elevation view. Figure 3 Typical Pile Elevation View During the nine months of sea wall construction (from early April to December 2017), due to harsh soil conditions, the sheet pile wall needed to be re-designed. The new seawall involves an anchored/tieback bulkhead system for shallower embedment, using existing sheet piles and cutoffs for deadman Date: 2/21/2018, Version: 1 5 (15)

6 anchor piles and modifying its nature from simply cantilevered to anchored structure. Deadman bulkheads are GFRP reinforced, while tie-back anchors are composed by stainless steel (SS) rods embedded in 4 perforated pipes for drainage reasons. Figure 4 shows the West sheet pile wall during construction. Figure 4 - Sheet Pile Wall 3. HCB Beams The superstructure is supported by using 45 Hybrid Composite Beams (HCB). These HCBs consist of an exterior FRP shell and lid that is sealed closed to provide the first layer of protection. The tension forces in the beams are primarily resisted by half inch diameter low-relaxation galvanized strands. These tension strands are set into the bottom of the FRP shell. The compression forces in the beam are resisted by a concrete arch within the FRP shell. The horizontal shear force is resisted by shear connectors that are embedded into the concrete arch on one end and extend up into the concrete deck to be poured on site. Carbon-steel reinforcing was used, instead, for the shear connectors. In order to increase the corrosion resistance of these steel shear connectors, the reinforcing was zinccoated. Figure 5 illustrates the beams exterior FRP shell with the low-relaxation galvanized steel tension strands on the left, and the complete product on-site set on the bent caps, on the right. Figure 5 - Hybrid composite girders Date: 2/21/2018, Version: 1 6 (15)

7 4. GFRP-RC bent caps Figure 6 GFRP bent cap cage installation As part of the substructure, six GFRP-RC bent caps were first assembled on site and cast with approximately 11 yd 3 of concrete each (Figure 6, top left and right). While vibrating the concrete, the use of a special rubber-tipped vibrator has revealed fundamental in order to protect the GFRP rebars and have a denser concrete with less voids to patch. The GFRP bar cages are tied using plastic ties and easily moved and placed with the help of a 6-ton tilt deck double axel trailer and a 230-ton crawler crane. Figure 6 shows the internal GFRP reinforcement, with a detail of the rubber-tipped vibrator on the bottom center, and the complete bent cap structure on the bottom right. 5. Bulkhead cap and test blocks The sea wall is composed by a total of 235 CFRP sheet piles. The following procedures and pictures only refer to the North-West side, where 35 sheet piles were installed, but the same method will be applied for all the four sections of bulkhead cap pours. Figure 7 shows the North West section of bulkhead cap, during GFRP rebar tying activities that took place on December 18-19, Date: 2/21/2018, Version: 1 7 (15)

8 Figure 7 - North-West Bulkhead cap reinforcement installation view Figure 8 - GFRP bulkhead cap cage Given the sheet piles cut-off to new elevation (due to the already mentioned sea wall re-design), the notch was not guaranteed in some of the interlocks between the piles. Thus, the designed configuration female-female guaranteed at the top of the sheet pile for a length of 12 inches, has been modified from the original plans to a male-female connection. For this reason, the transversal bar 5B1 has been laid down (see Figure 8 and 9), instead of running transversally into the designed interlock. Figure 9 GFRP Bulkhead cap tying Date: 2/21/2018, Version: 1 8 (15)

9 5.1. Inside the test blocks (Figure 10): Figure 10 Actual view inside test blocks Figure 11 Test block design view on the right and field configuration th l ft Test blocks are composed in cross-section by 6 bars #5 made of CFRP/GFRP/BFRP that interchange location along the different wall sections, following the below layout (Figure 12). Date: 2/21/2018, Version: 1 9 (15)

10 Figure 12 Test block rebars layout along the different wall sections In the field, due to construction means and methods, there has been the need to slightly modify the layout. A plastic chair has been set on the bottom of the test block in order to hold both bars in position V and VI. Due to the geometry reasons of the plastic chair and ease of installation, the 2 bottom bars were placed in a new position (see Figure 11, on the right). Figure 13 is an additional top view of the test block GFRP CFRP BFRP reinforcement. Figure 13 Top view of test blocks 5.2. Green Concrete pour: Figure 14 shows order confirmation along with technical data of the green concrete use for the bulkhead cap Date: 2/21/2018, Version: 1 10 (15)

11 Figure 14 Green concrete technical data Green Concrete Pour: Concrete pour of bulkhead caps, along with the test blocks, took place on Thursday Dec. 21, with 14.5 CY and additional 2 CY of green concrete ordered as back-up. Figure 15, 16 and 17 show the activities of concrete pumping and topping. Figure 15 Pumping wall 2A Date: 2/21/2018, Version: 1 11 (15)

12 Figure 16 Start pumping wall 3A After field-acceptance of the mix design characteristics previously shown, the concrete was poured through a 4 in. pump. Placement of concrete was aided by the rubber-tipped vibrator on site, already used for the previous concrete pours. Approximately 16.5 cubic yard (3 trucks) of green concrete were poured for the 3 sections of wall; After each wall section form was filled, the top was then smoothly finished Demolding activities and result Figure 17 Topping out wall 1A After 12 days, the forms were removed and the concrete stripped. Figures 18, 19, 20, 21 and 22 show the final product of bulkhead cap along with test blocks and SS tie-back anchors. Date: 2/21/2018, Version: 1 12 (15)

13 Figure 18 Wall 1A demolded and stripped Figure 19 Wall 1A complete Figure 20 Wall 3A complete, test block view Date: 2/21/2018, Version: 1 13 (15)

14 Figure 21 Wall 2A complete, test block view Figure 22 SS tie-back anchor rods carrying the sea wall load over the deadmen Figure 23 West Side sea wall active as of February 9, 2018 Date: 2/21/2018, Version: 1 14 (15)

15 After rip-rap placement, all the temporary structures and temporary sheet piles on West side were removed on February 9, Figure 23 the final product of the West side sea wall, with test blocks submerged in the Halls River waters. Date: 2/21/2018, Version: 1 15 (15)