S C S  System

Testing

SCS System - Full Scale Testing

Full performance testing using large scale samples of the SCS System encompasses testing the uniqueness of our system to repair and strengthening timber piles and poles, with aspirations of achieving remediations of concrete columns. Our starting goal is to remediate and strengthen timber piles and poles, where present standard methodologies are most commonly used. There exist similar published testing studies performed for similar manufactured products; therefore, comparisons can be made as to the structural capabilities of similar products and the capabilities of the SCS System (see comparisons below). Providing superior test data of the performance of our system will be a benefit of improving our nation’s infrastructure and with the effectiveness of the time-saving installations, that will provide more infrastructure projects to be remediated and strengthened.  

Our laboratory testing focuses on fabricated similarly damaged timber piles in order to quantify and record the capabilities of the SCS System. Our system rehabilitates damaged timber piles and poles to exceed the original structural capacities of un-damaged piles. The SCS System has been designed as a value-engineered way to repair and strengthen existing columns using standard industry-accepted techniques, by reducing the cost of materials and installation time. The test paradigm is to perform tests in compression and true flexure capacities. All of the testing is being performed at the Constructed Facilities Laboratory at North Carolina State University.

 

SCS System Flexural Testing

The full-scale flexural testing of the SCS System for the isolated limited repair of timber piles has been completed. The testing scheme was developed to systematically test the flexural properties of timber piles and the components of the SCS System individually and together, thereby collecting a large array of comparable data to be analyzed. The thorough analysis of this data will take time, however, the initial applied load data and observations of the testing samples, provides additional criteria for the development of the testing scheme for additional flexural testing.

The full-scale flexural repair testing was composed of using 11” ø and 18’ long Southern Yellow Pine piles, that were turned to provide a uniform consistent diameter. The test controls were; one full section unaltered pile, one simulated damaged pile and one simulated damaged pile with only a limited GFRP jacket filled with epoxy grout. All of the SCS System enhanced pile specimens were installed on simulated damaged piles, limited to a 2’ long length, centered at the middle of the pile span, with either hourglass-shaped damage or a hollowed-out section.  

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The testing setup was designed as a four-point loading scheme, however, during the testing procedure, the loading scheme was modified to a three-point loading test setup, due to the extreme durability of the test specimens with the SCS System. The three-point loading configuration allowed for the ability to use greater concentrated test loads. The test setup used nylon straps connected to anchorages affixed to a strong floor, to restrain the ends of the piles. Two synchronized double-acting hydraulic rams with nylon straps were suspended from a steel frame to apply the vertical load force. Interior and exterior strain gauges were installed on the various elements in the SCS System to continually record the elements strains during the testing process. Various string potentiometers were attached along the entire test piles to record the pile deflection.

The failure location in all of the specimens, (including the specimens enhanced with the SCS System), were in the timber piles and NOT in the GFRP jacket, even though the maximum moment was at the center of each specimen.

 

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Test Results of the SCS System Achieved 3x the Flexural Capacity of a Full Undamaged Pile

OBSERVATIONS OF THE SCS SYSTEM FLEXURAL TESTING:

  • Even under high loads, none of the GFRP repair jackets enhanced SCS System failed. This consequence brings us to consider the incredible resilience of the SCS System jacket, mainly in the novelty of impact loading mitigation. This additional benefit of the SCS System could be very valuable in providing for the safety and security of critical infrastructure of timber piles and their structures. An impact testing program may be developed to provide useful data to support this considered attribute of the SCS System.​​

  • It was found that the developmental length of the SCS System was much less than originally considered. Observationally, it appears that only 5” may be required to achieve the full functionality of the system. Additional tests will be performed to establish the required developmental length beyond a damaged portion of the pile, thereby reducing the overall required length of the SCS System jacket and consequentially reducing the cost of the pile repair.

 

  • It was observed that the failure mode of the timber piles had two distinct types. The difference between the two types of failures was relevant to each test specimen. In the specimens that were enhanced with Continuity Connections with carbon fiber hoops, a snapping type failure occurred in the timber pile, beyond the jackets. Whereas all the other specimens and controls had breaking of the woodpiles.

 

DESCRIPTION OF PILE FAILURE TYPE 

a) Snapping of the wood fibers: where the full cross-section of wood fibers ripped apart simultaneously, thereby

    creating an almost vertical pile bifurcation in the timber piles.

b) Breaking of the wood fibers: where the wood fibers of the piles were pulled apart in a rapid sequential fashion, thereby creating a more diagonal or sheared separation in the timber piles.

   

  • It was observed that the Continuity Connections with carbon fiber hoops of the SCS System prevented the debonding of the wood to epoxy grout interface, by strengthening the wood fibers adjacent to the ends of the SCS System repairs. This lack of debonding emphasizes the unique behavior of the collateral effect of the system, which may affect the undamaged pile far beyond the area of repair.

Time-lapse video of Specimen #8 - Full SCS System - Peak Moment = 176.6 (k.ft)

Click here to see our time-lapse video of our flexural tests on YouTube.

SCS SYSTEM TESTING - CONCLUSION

The results of the SCS System limited pile repair tests have exceeded our expectations, as far as strength and complementary timber pile collateral effects. The initial test results are allowing us to refine the SCS System design for timber piles to lower the material costs and in turn the installation costs, thereby concluding that the SCS System is the most economical and most rapid system available to repair damaged piles. 


The tests performed prove incredible structural capabilities of the SCS System for timber repairs, and also provides evidence that the SCS System can move forward to the exciting advantage of Repairing, Strengthening and Protecting CONCRETE COLUMNS effectively, rapidly and less costly.

SCS System - Compression Testing

Testing the axial compressive strength values of the timber piles and fabricated simulated damaged timber piles provides information relevant to the actual forces of piles that are presently in service supporting buildings, bridges and marine structures. The results of these tests illustrate the enhanced value of repairing and strengthening diminished capacity timber piles using the SCS System in compression. 

The Constructed Facilities Laboratory at North Carolina State University is equipped with a Baldwin-Lima-Hamilton 1,000,000 lb. capacity, calibrated 4 post, hydraulic press. All specimens were tested to failure, providing maximum compression values and the individual strain gauge readings were recorded.

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Testing the axial compressive strength values of the timber piles and fabricated simulated damaged timber piles provides information relevant to the actual forces of piles that are presently in service supporting buildings, bridges and marine structures. The results of these tests illustrate the enhanced value of repairing and strengthening diminished capacity timber piles using the SCS System in compression. 

Four test specimens were fabricated using the SCS System, which included 15” diameter, 3/16” thick GFRP jackets with an integral T & G joint, 40” long. The GFRP jackets were centered on the simulated damaged piles, leaving 2” of timber pile exposed at the top and bottom. The GFRP jackets were enhanced with the installation of internal carbon fiber fabric “hoops” and Continuity Connections with carbon fiber laminates. Various sensors were installed on the GFRP jackets, carbon fiber hoops, and the Continuity Connections. The GFRP jackets were centered around the simulated damaged piles, leaving a 2” void annulus space between the jacket and the piles. No axial reinforcement was included in any of the samples for compression testing. 

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The 2” void annulus of control #3 and specimens #1, #2 and #3 were filled with a multi-purpose marine epoxy grout* and left to cure for 28 days before the samples were tested. The multi-purpose marine epoxy grout* was found to have intrinsic structural deficiencies. The overall compression values of the specimens were comparable, however, negligible strain values from the sensors on the various elements indicated that the transfer of compressive load to the SCS System enhancements was not viable and therefore, unreliable. 

Specimen #4- Included (2) carbon fiber hoops and Continuity Connections near the top and bottom of the FRP jackets and filled with marine epoxy grout** and left to cure for 14 days before the specimen was tested. The failure mode of specimen #4 was a rupture of the carbon fiber fabric hoop. The carbon fiber hoop ruptured at an impressive strain of over 9,000 mu, while the continuity connections remained intact.

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Photo courtesy of NCSU

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Specimen #5 - included (4) carbon fiber hoops and Continuity Connections equally spaced in the FRP jackets and filled with marine epoxy grout** and left to cure for 14 days before the specimen was tested. The failure mode of specimen #5 was again a rupture of the carbon fiber fabric hoop, while the continuity connections remained intact. The increase of axial compressive strength of the simulated damaged pile, was an astounding 920,000 lbs, a direct result of the installation of the SCS System carbon fiber hoops and Continuity Connection.

Most relevant data of these tests were the axial compressive strength values as summarized below:

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COMPARATIVE TEST

The Southern Plains Transportation Center has published a report, titled: “Rehabilitation of Deteriorated Timber Piles Using FRP Composites”, dated 12/30/17. The Southern Plains Transportation Center commissioned this study performed at the College of Engineering, Louisiana Tech University. This study documents compression tests of fabricated simulated damage woodpiles that have been repaired with three similar pile repair products, produced by reputable manufacturers, which are FRP jackets filled with underwater epoxy grout or underwater cementitious grout. The size of timber piles used, and the variability of fabricated simulated damage was similar to our tests; however, they are comparable based on the proportion of the pile diameter size of the control used in their tests. The published tests results indicate that when averaging the three manufacturers compression performance strength percentage above the undamaged timber pile control, the result was 11.9% with the single best performance result of a 37% increase above their control.

In comparison, the Compression Test performance of the SCS System strengthened a simulated damaged pile by 613%, to result in an 88.9% increase in axial load capacity ABOVE a full, undamaged timber pile.

*The multi-purpose marine epoxy grout was purchased from a major manufacturer and delivered to the Constructed Facilities Lab (CFL). The materials packaging indicated that they were very near the expiration date. Upon opening the epoxy containers for installation, the catalyst was found to be severely oxidized. Laboratory tests of this material were performed (CFL) and the resultant 28-day values for the compression strength were lower than the manufacturer’s datasheet by 10% and the splitting tension was 20% lower than the manufacturer’s datasheet

 

**We informed the multi-purpose marine epoxy grout manufacturer of the CFL material testing results and the manufacturer provided fresh multi-purpose marine epoxy grout, which was again tested. This material was not oxidized. Laboratory tests of this material were performed (CFL) and the resultant 7-day values for the compression strength and the splitting tension strength was closer, but did not reach the capacities of the manufacturer’s datasheet

 

 

A relatively new type of test was implemented to test the strain of joining plates and pockets of the Continuity Connection, installed in a GFRP SCS System jacket. The testing paradigm was performed by two of the authors of “Influence of geometry and fiber properties on rupture strain of cylindrical FRP jackets under internal ICE pressure” Sadeghian, P., Seracino, R., Das, B., & Lucier, G., was perfected at the Constructed Facilities Lab (CFL) at North Carolina State University.

 

The Ice Test consists of a special fabricated steel frame that retains and constricts the cylindrical test specimen. The test specimen is prepared with various positioned internal strain gauges and is filled with water. The water-filled specimen is placed in a freezer at -20-degrees Fahrenheit, and as the water converts to ice, the expanding ice exerts a continuous uniform pressure to the inside of the test specimen where the strain gauges record the strain and time until failure. 

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Continuity Connection - Strain Test

Phase l

Photo courtesy of NCSU

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The resulting average of the strain gauge analysis after the tests indicate that the Continuity Connection sustained a maximum strain of 5,000 microstrain, equating to a shear stress of approximately 11,400 lbs., which far exceeds the maximum yield capacity of a #3, grade 60 reinforcing bar. With these exciting test results, we continually improve the design of the Continuity Connection to increase the capacity of the connection.

Photo courtesy of NCSU

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Continuity Connection Strain Test -

Phase ll

 

Our Continuity Connection Strain Test – Phase l, using the Ice Test method produced fantastic results, however, there is always room for improvement. We modified the height of the sample by reducing the GFRP jacket exposure to the expanding ice. By doing so, we were able to record more precise stains on the Continuity Connection. This test modification allowed us to observe areas of the connection where improvements could be made. 

We tested additional samples with various enhancements to increase the bonding capabilities of the connection. These enhancements were intuitive and simple adjustments to the already well functioning system. The latest test series of the enhanced Continuity Connection was an incredible success. The tests resulted in an increase in the shear stress of the connection to over 12,000 microstrain, more than doubling our previous yield capacity. 

These phenomenal results far exceed the requirements for repairing and strengthening timber piles and poles, and positions the Continuity Connection, as an integral part of the SCS System, to repair and strengthen concrete columns and beyond.   

 

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Photo courtesy of NCSU

 

We are very proud to have joined the following:

Center for the Integration of Composites into Infrastructure  - (CICI)

    

Part of the NSF and IUCRC:

 

National Science Foundation  - (NSF)

Cooperative Research Program  - (Industry-University Cooperative Research Program IUCRC)

 

Testing the full SCS System will be performed at:

 

NORTH CAROLINA STATE UNIVERSITY TESTING 

Constructed Facilities Lab (CFL) 

North Carolina State University

Acknowledgments

Full performance testing is being performed under the supervision of Dr. Rudolf (Rudi) Seracino, Professor and Associate Head for Undergraduate Programs at North Carolina State University and Dr. Gregory Lucier, Research Associate Professor and Laboratory Manager at the Constructed Facilities Laboratory.

INNOVATIONS

The information on this website is for general information purposes only. Nothing on this or associated pages, documents, comments, answers, emails, or other communications should be taken as official advice for any individual project or situation. 

CONTACT

1622 Walter Street, Suite A

Ventura, California 93003

(805) 665-4014

inquiry@warstoneinnovations.com

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Structural Column Strengthening Test