Q&A About Advanced FRP Strengthening Design Principles

Our thoughts go out to everyone affected by Hurricane Harvey and this disaster in Texas. To help with relief efforts we are donating $50,000 to the American Red Cross Disaster Relief Fund. Employees at our Houston warehouse are safe and the employees from our McKinney branch will be doing as much as they can to help with relief efforts.

This week’s post was written by Griff Shapack, PE. FRP Design Engineer at Simpson Strong-Tie.

On July 25, 2017, Simpson Strong-Tie hosted the second interactive webinar in the Simpson Strong-Tie FRP Best Practices Series, “Advanced FRP Design Principles,” in which Kevin Davenport, P.E. – one of our Field Engineering Managers – and I discussed the best practices for fiber-reinforced polymer (FRP) strengthening design. The webinar examines the latest industry standards, proper use of material properties, and key governing limits when designing with FRP and discusses the assistance and support Simpson Strong-Tie Engineering Services offers from initial project assessment to installation. Watch the on-demand webinar and earn PDH and CEU credits here.

During the live webinar, we had the pleasure of taking questions from attendees during the Q&A session. Here is a curated selection of Q&A from that session:

While I see how you improve the flexural capacity of a beam, how do you increase its shear capacity to match new moment strength?

ACI 440.2R recommends checking the element for shear if FRP is used to increase flexural strength. U-wraps can be used to provide shear strengthening of a beam.

Are there any “pre-check” serviceability checks (deflection, vibration, etc.) similar to the ACI 440 strength check that you recommend when considering the use of FRP?

ACI 440.2R contains a few serviceability checks on the concrete, rebar and FRP that can be performed once you have designed a preliminary strengthening solution.

Are these strengthening limits for gravity loads only? What about for a seismic load combination?

Yes, the strengthening limits are just for gravity loading. Seismic loading does not require an existing capacity check as it is highly unlikely for the FRP to be damaged during a lateral event.

Did Simpson Strong-Tie perform load tests on FRP repaired timber piles?

We are currently testing our FRP products as applied to timber piles at West Virginia University. We have also implemented a full-scale testing program on damaged timber piles at our own lab using our FX-70® fiberglass jacket system.

Will any of your seminars cover FRP and CMU? Seismic applications?

Yes, these are topics we are considering for future webinars.

The 0.6 limit for compressive stress can be very limiting. Can this value be evaluated on a case-by-case basis? The Euro code allows higher limits on compressive stress?

Our designers will report this value, along with the section addressing this check from ACI 440.2R, to the EOR and discuss whether the EOR would like to proceed with the FRP strengthening on his or her project.

Which engineer (EOR or Delegated Engineer) is responsible for specifying the scope of special inspections?

We provide a draft FRP specification to the EOR to use in their final determination of the special inspection requirements for a project. It’s in the owner’s best interest to hire a qualified special inspection agency on an FRP installation project.

For complete information regarding specific products suitable to your unique situation or condition, please visit strongtie.com/css or call your local Simpson Strong-Tie RPS specialist at (800) 999-5099.

Learn more: Webinar – Introducing Fabric-Reinforced Cementitious Matrix (FRCM)

In this free webinar we dive into some very important considerations including the latest industry standards, material properties and key governing limits when designing with FRCM.

Continuing education credits will be offered for this webinar.
Participants can earn one professional development hour (PDH) or 0.1 continuing education unit (CEU).

YouTube Video of FX-70 Testing Shows Industry First

My wife and I have been attending a boot camp class for a little over a year now. We have a great coach who always varies the workouts and keeps things fun while really challenging us. He likes hip hop music, so that is what we listen to as we suffer through our squats, kettle bell swings and burpees at 5:30 in the morning. I really just told you that story so I could tell you another one.

Earlier this week I was talking to one of our younger R&D engineers about a test project and I responded to one of his questions with a quote from rap lyric. You have to throw humor into engineering meetings when you can. He laughed and then gave me a puzzled look and said, “I’ve never had a boss anywhere near your age who knew who Jay-Z was.” I try to take it as a compliment, but I think he was calling me old. He would also be surprised to know I have my own YouTube channel, mostly so I can post videos my daughter creates of herself making rainbow loom rubber band bracelets. I think my channel has zero followers.

Rainbow Loom iPod Case

My daughter Kira made an iPod case out of rubber bands.

Simpson Strong-Tie also has a YouTube channel where we have videos on a variety of topics relevant to designers, contractors and do-it-yourselfers. Be sure to check out a new video called “FX-70® Pile Repair Cyclic Testing” on the Simpson Strong-Tie YouTube channel. It gives an overview of the testing we did to support one of our new products, the Simpson Strong-Tie® FX-70® Structural Repair and Protection System. This video captures the industry’s first scaled, cyclic test of a repaired wood pile.

Testing a wood pile.

Testing a wood pile.











As you may recall, I wrote a post last September called Not Just a Connector Company describing how our Engineering/R&D team developed and performed the test protocol for this product. FX-70 is a part of our Repair, Protection and Strengthening Systems for Concrete and Masonry, which is the result of our acquisition of Fox Industries, Inc., in 2011.

FX-70, which has been used successfully for more than 40 years, uses high-strength fiberglass jackets and high-strength water-insensitive grouting materials to repair and protect wood, steel and concrete structural members.

We wanted to evaluate the performance of the system under seismic loading. And, the cyclic static test frame at our Tye Gilb Research Laboratory in Stockton, Calif., enabled us to fully test the system on 16-foot-tall wood piles.

The results of this test will provide structural engineers with real-world data to help them evaluate the FX-70 system as a potential solution to their structural repair applications.

Tell us what you think of the video and testing.

FX-70® Structural Piling Repair and Protection System

For complete information regarding specific products suitable to your unique situation or condition, please visit strongtie.com/products/rps/fx70 or call your local Simpson Strong-Tie RPS specialist at 800-999-5099.

Not Just A Connector Company

I write a lot about testing on this blog, from my first post about testing to the series I did on how we test different products (hangers, holdowns, fasteners). This week I’d like to highlight some unique testing we’ve been doing to support one of our new product lines. Simpson Strong-Tie® recently introduced our Repair, Protection and Strengthening Systems for Concrete and Masonry. The new product line is the result of our acquisition of Fox Industries, Inc. in 2011.

In the past, I’ve shared some of the more fun tests we’ve run, like the bowling ball test or 40 kip hangers. This week we’ll take a sneak peek at testing of the FX-70® Structural Repair and Protection System. FX-70 uses high-strength fiberglass jackets and high-strength water-insensitive grouting materials to repair and protect wood, steel, and concrete structural members. The system is primarily used on piles in marine environments.

Fx-70 installation on wood piles.

Fx-70 installation on wood piles. Image credit: Simpson Strong-Tie.

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