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Seismic Testing at UBC

Background: Each test specimen was subjected to the VERTEQ-II synthetic regenerated earthquake acceleration record Telcordia Technologies. Each record was applied at each test with consistently increasing amplitudes.


OCTAFORM CONCRETE FORMING VS TRADITIONAL FORMING

The seismic test was conducted on Octaform’s concrete forming system + PVC liner in 2007 by the University of British Columbia’s Department of Engineering.

The test was led by one of the foremost global experts in earthquakes and seismic research, Dr. Carlos Ventura.

With more than 30 years of experience, Dr. Carlos Ventura is the Director of the Earthquake Engineering Research Facility at UBC, as well as a Fellow of the Engineering Institute of Canada, thanks to his exceptional contributions to engineering.  Dr. Ventura has authored more than 450 publications and combines over 30 years of research.

The objective of these tests was to determine whether the Octaform Stay-in-place Concrete Formwork with PVC Liner protects a reinforced concrete structure against cracking and spalling during a severe earthquake and if the lateral load capacity of the wall is affected by the Octaform PVC liner.

Octaform’s wall system was dynamically tested at the earthquake engineering research facility at UBC on April 10th on April 19th of 2007. The dynamic loads were conducted by placing both a traditional concrete wall and an Octaform Formwork Wall on shaking tables and subjecting them each to prescribed earthquake expectations to verify their existing performance under severe shaking. The Octaform Wall was subjected to prescribed simulated ground motions at different intensities on a shake table in order to determine its performance under dynamic loads in comparison to the traditional concrete wall specimen. The test began by placing a lateral load of 450kN on both the traditional concrete wall and the Octaform Wall.

Prior to Dynamic testing, an initial flexural hairline crack was immediately observed in the cast-in-place control wall.  The crack was due to the surcharge weight of 44.6 kilonewtons. The Octaform wall was specimen was unaffected.

Cast-in-Place Control Wall Specimen – Test Results:

The dynamic loading test started with the test wall utilizing the synthetic regenerated earthquake acceleration methodology – VERTEQ-II to record at 25%. No damage was observed. When the amplitude of the earthquake was increased to 75% a crack developed immediately on the test wall. No additional damage was observed at 100%.

At VERTEQ-II x 200% the cast-in-place control wall specimen failed. The subsequent spalling of the concrete occurred, the wall became unstable and the specimen collapsed out of the plane.  Cables were used to protect the lab from damage, but the results represent a complete structural collapse.

Octaform Wall Specimen – Test Results:

Testing was conducted on the Octaform wall at records with amplitudes of 25%, 50%, 75%, 100%, and 200% with no observable damage. The amplitude was eventually increased successively to VERTEQ-II x 250% without any significant damage. Some < 2 mm cracking was eventually observed – non-structural and likely not enough to result in leakage. Owners would also have added assurance of leak protection due to the integral and highly ductile watertight liner (tested to exceed 140′ / 43 m head pressure).

The dynamic loading test confirmed that Octaform protects reinforced concrete structures against spalling during even the most severe earthquakes.

In fact, the machine was pushed to its absolute maximum limits with no discernible effect on the Octaform wall.

The results of the dynamic test clearly show by comparison with the traditional concrete structure that the Octaform system had significantly greater lateral load capacity, was completely protected against spalling, and showed almost no cracks after being subjected to the limits of the testing equipment.

In fact, according to Dr. Ventura, our technology tested well beyond any other system.

The likely reason for this is a combination of composite behavior of the inner strands of PVC connectors and added moment tolerance from these as well as containment of the concrete reducing spalling at the hinge and other zones of potential failure. More finite element analysis is being pursued currently and ongoing study.

Octaform Test Wall
Octaform System vs. Control Test Wall (Painted White to View Cracks)

 

Here we see our system being tested at the University of British Columbia’s test facility in 2007. Walls were subjected to cyclic loads applied through a lateral force along the top.

The Octaform retrofitted wall reached a shear resistance of 450kN at Verteq II x 250%. This placed well above all other strategies.  Octaform experienced minimal hairline cracks and no sudden failure.

A complete paper was authored by Jose Centeno, Devin Sauer, Felix Yao, P. Eng. and Dr. Carlos Ventura, P. Eng. copies are available on request.

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OCTAFORM PROVIDES IMPROVED SEISMIC PERFORMANCE

The Octaform Stay-in-place concrete forming system keeps concrete intact and increases load capacity and hardness. That is proven concrete performance, backed by science!

  • 39-60% increased load capacity
  • 41-66% increased hardness

“We are very excited about the potential for Octaform to offer improved resilience in critical infrastructure in seismic zones. This study showed the difference between a catastrophic failure of traditional cast-in-place versus the ability to not only stay in service but tolerate significantly higher seismic loads.

Additionally, Octaform’s PVC panels are lab-tested to be watertight to 68 p.s.i (140′ / 43 m of head pressure). Due to the ductility of PVC: increased structural integrity of the Octaform hybrid system due to composite effect and lateral confinement leads to minor cracking under severe earthquakes (VERETEK x 250%). This results in a reduced leakage risk from a containment vessel.”

– Dr. Mehdi Bagheri, Octaform