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FRP COMPOSITE STRUCTURES IN THE US INLAND WATERWAYS
8th International PIANC-SMART Rivers Conference Pittsburgh, PA, September 20, 2017 FRP COMPOSITE STRUCTURES IN THE US INLAND WATERWAYS PRESENTED BY: Piyush Soti Graduate Research Assistant Dr. PV Vijay Assistant Professor Dept. of Civil & Environmental Engineering West Virginia University
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Background & Introduction
Objective Design, Manufacturing, Field implementation FRP Wicket Gates FRP Miter Blocks FRP Recess Protection Panels Conclusions & Recommendations
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Background: FRP Composites
FRP composites are emerging as a solution for both rehabilitation and new construction. The advantages with FRPs are: high strength/stiffness to weight ratio resistance against corrosion, moisture, chemical attack excellent durability, low thermal expansion enhanced fatigue and wear resistance FRPs offer potential for construction or repair of critical components of navigation systems at a reduced cost and greater durability.
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Background: Navigation Infrastructure
The inland navigation system serves as a backbone to the nation’s economy carrying an equivalent of 51 million truck trips each year. Many hydraulic locks and dams have not been updated since 1950s and have exceeded their design life. The American Society of Civil Engineers (ASCE) has rated the nation’s inland waterways infrastructure as D-. US Army Corps of Engineers spends almost 73% of their budget in repair and rehabilitation of current lock and dam facilities.
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Introduction Hydraulic structures are prone to severe corrosion and deterioration. Corrosion leads to expensive repairs/maintenance, closure, and in some cases replacement of the hydraulic structures. Traditional steel and timber used in navigation infrastructure deteriorate within years of service and require costly and periodic repair. The USACE requires more than $13 billion by 2020 to keep navigation infrastructure functioning without additional damages. Due to budget cuts associated with the use of traditional materials, the USACE is exploring the use of FRP composites.
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Objective To engineer waterway structures with noncorrosive FRP composites to prevent extensive in-service maintenance and replacement. Wicket gates Miter blocks Recess panel
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DEVELOPMENT OF FRP WICKET GATES
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Introduction: Wicket Gate
It is a movable dam that can be raised in times of low water. It is generally constructed of steel or iron frame with timber leaf. It is hoisted into position with a gantry operated crane without utilizing any hydraulic cylinder. Wickets are hinged just below their center point & held in an upward position with a prop which slides into a hurter track.
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Deterioration of a timber wicket gate
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Forces on wicket gate The gate was analyzed in operating, resting, and lifting positions. Position Prop force kN (kip) Shear force on gate section, kN (kip) Bending moment on gate section, kN-m (kip-ft) Operating (with tail water) 93 (20.9) 46.3 (10.4) 30 (22.1) (without tail water) 102.3 (23) 40.9 (9.2) 27.7 (20.4) Resting Lifting 132 (29.6) 165.4 (122) Wicket gate in operating position
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FRP wicket gate section
A FRP section 1.17m (46”) x 216mm (8.5”) was selected with flange thickness of 13.3 mm (0.523”) and web thickness of mm (0.4”). MI of a selected FRP module was 39,250.6 cm4 (943 in4). In addition, two steel plates were embedded inside face sheets to enhance moment of inertia, reduce deflection and buoyancy. 9.5 mm thick steel plate
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Bending of FRP wicket gate
FRP wicket gate was loaded in a 3-point bending with a span of 4.57 m and a central load of 89 kN. The max. deflection and tensile strain were14.81 mm and 978 µε, respectively. The gate was fatigue tested at ( kN) for 50,000 cycles and 3-point bending was performed with a load of 89 kN. The max. tensile strain was 975 µε as compared to 978 µε before fatigue loading. The strain energy absorption capacity of the gate was not reduced after fatigue.
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Field Installation Four FRP wicket gates were installed in Mississippi River at Rock Island lock and dam, Illinois, USA in Fall 2015. They are performing well without any signs of deterioration. About 2/3 the cost of timber gates on a first cost basis and expected life > 50 years (timber gate is ~15 years).
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DEVELOPMENT OF FRP MITER BLOCKS
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Introduction: Miter Blocks
Miter blocks are installed in lock gates to form a watertight seal between two gate leaves during closure. They are made of solid steel with a cross-section of mm x 63.5 mm and lengths up to 13 m Blocks have to withstand: wet-dry cycles, corrosive elements, mitering forces, and freeze-thaw effects. compressive stress of 9.65 MPa through its mitering surface 10,000 cycles of opening and closing operations in a year. Corrosion of steel blocks have been the cause of gate misalignment and potential lock closure.
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Design of FRP miter blocks
Designs-A, and-B were fabricated using off-the-shelf FRP shapes. Design-C was fabricated by bonding laminates and Design-D was manufactured by VARTM process. Based on poor performances under compression and fatigue, Designs-A and -B were eliminated and design-C was eliminated due to its complexity in fabrication. Solid FRP section (design-D) was selected as a potential miter block for additional testing. Design-C and Design-D
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Compression and Fatigue Testing on FRP Block
FRP miter blocks were subjected to compression in all directions. The values were 379 Mpa (55 ksi), 214 Mpa (31 ksi), and 165 Mpa (24 ksi). Blocks were also tested in fatigue with a load range of kN for 500,000 cycles and showed no signs of cracking. Testing of these blocks showed that they have higher than required strength, stiffness, and ductility properties.
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Performance of FRP Miter Blocks subjected to Water Immersion
Depending upon the height of the lock gate, FRP miter blocks can be subjected to not only moisture but also to water pressure. FRP miter blocks were cut to smaller lengths and few specimens were coated with an epoxy, while others were not coated. Both coated and uncoated specimens were kept in a container filled with water at NTP and inside a water chamber pressurized to 15.5 MPa .
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Performance of FRP Miter Blocks subjected to Water Immersion (Contd.)
After 60 days, specimens were tested for moisture absorption. The application of a resin coat on cut specimens helped in reducing the absorption of moisture. The application of pressure resulted in an increase of % moisture ingress. Wet FRP blocks were tested in compression and were found to be lower but still above service requirement values.
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Field Installation FRP blocks were installed by bolting them to the existing lock gate at Hiram M. Chittenden Locks, Washington, USA in summer 2015. Workers were able to handle light-weight blocks and install them with ease. Solid FRP block cost about $500 per meter length. With an expected service life of 50 years for FRP blocks, there will be savings in terms of materials, labor, equipment, and others.
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DEVELOPMENT OF FRP RECESS PANELS
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RECESS PROTECTION PANELS
Recess panels are located in the upper lock approach and are used in many navigational structures. They are used to protect the recess areas in the lock chamber from barge impact damage to lock walls. The panels protect the recess area in the lock that allows the emergency gate to rise when miter gates are inoperable. Current panels are 12” thick and made of welded 12WF45 steel I-beams, angles, and plates. Current steel recess panels are heavy to lift and corrode in a short time requiring regular corrosion resistant surface coatings.
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DEVELOPMENT OF A FRP PANEL
The panels are supposed to be designed to withstand a barge impact load which when calculated required over 100 foot-kip section. Currently available off-the-shelf shapes are explored to develop FRP panels. Doubling 4” x 6” rectangular tubes FRP SUPERDECK of 12”x 8” SUPERPILE of 12” diameter and 0.5” wall thickness Doubling 4” low-profile FRP composite cellular modules
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DESIGN OF A FINAL FRP RECESS PROTECTION PANEL
Based on 4 different configurations evaluated, hexagonal deck was the best shape in terms of energy absorption. Crushing failure and moment capacity of the single FRP superdeck at a clear span of 96” was 48.4 kip and 96.8 ft- kip, respectively. It was made with 12 FRP superdecks and edge steel channels. In the field, the impact force from the barge is distributed to several beams of the FRP panel system, thus carrying significantly higher loads.
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FABRICATION OF FRP RECESS PROTECTION PANELS
Twelve pultruded FRP superdecks and hexagonal shear keys were assembled by adhesive bonding. FRP panel was housed in steel channel sections to facilitate smooth angles for ship and barge impacts. Following the panel assembly, top surface was coated with 0.375” thick impact resistant polyuria resin. Final dimension of the panel was 9’10.5” x 11’10”.
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TEST RESULTS ON FRP RECESS PANEL
The first test was performed with the application of load through 6” x 6” plate, placed at the center of the seventh hexagonal FRP beam. For 30 kip of applied load, the maximum deflection at center was 0.27” and the maximum bottom tensile strain was 880 micro-strains. Load applied (6” x 6”)
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LOAD DISTRIBUTION FACTORS
When the 30 kip load was applied longitudinally on the center beam with 24” long and 48” long spreader, the applied load was distributed to other beams. Tables below show around 80% of the load being distributed to all other beams. 30 kip load with 6x24 plate longitudinal Beam no. Def (in) LDF LDF (%) 1 0.032 0.027 2.66 2 0.045 0.037 3.75 3 0.059 0.049 4.91 4 0.077 0.064 6.41 5 0.11 0.092 9.16 6 0.165 0.137 13.74 7 0.257 0.214 21.40 8 9 10 11 12 30 kip load with 6x48 plate longitudinal Beam no. Def (in) LDF LDF (%) 1 0.031 0.028 2.77 2 0.044 0.039 3.93 3 0.057 0.051 5.09 4 0.073 0.065 6.52 5 0.103 0.092 9.20 6 0.153 0.137 13.66 7 0.229 0.204 20.45 8 9 10 11 12
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LOAD DISTRIBUTION FACTORS (CONTD.)
When 60 kip load was applied transversely with center on 7th beam using 24” and 48” long spreader, the applied load was distributed to other beams of the panels. Tables below show more than 85% of the load being distributed to all other beams. 60 kip load with 6x24 plate transverse Beam no. Def (in) LDF LDF (%) 1 0.052 0.024 2.36 2 0.079 0.036 3.58 3 0.103 0.047 4.67 4 0.142 0.064 6.43 5 0.209 0.095 9.47 6 0.35 0.159 15.86 7 0.389 0.176 17.63 8 9 10 11 12 60 kip load with 6x48 plate transverse Beam no. Def (in) LDF LDF (%) 1 0.05 0.023 2.35 2 0.08 0.038 3.76 3 0.107 0.050 5.02 4 0.148 0.069 6.95 5 0.228 10.70 6 0.313 0.147 14.69 7 0.328 0.154 15.40 8 9 10 11 12
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Conclusions and Recommendations
FRP wicket gates, miter blocks, and recess protection panels were successfully developed as replacements to conventional material-based structures with adequate safety factors against bending, shear, and fatigue. These structures were lighter, cost effective, easily fabricated and installed in the field. Regular monitoring and inspection of field implemented FRP structures will help in understanding their long-term performance, effectiveness, and durability for their mass implementation in hydraulic infrastructure.
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Acknowledgments This Work is Sponsored by USACE and the work is carried out by the WVU-CFC, Department of Civil and Environmental Engineering, Statler College, West Virginia University. Manufacturing coordinated and carried out in partnership with Composites Advantage Inc., Creative Pultrusion Inc., and Fiber Tech Inc. Discussions and field cooperation from all the Engineering and maintenance staff of USACE at their headquarters and various locations are sincerely acknowledged.
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Questions? Thank you!
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