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.

The system has been used successfully for more than 40 years with the first installations in 1971 still in service today. Our testing challenge was to evaluate the performance of the system under seismic loading. First we had to define what that means for this type of system and the types of structures it is used on. We settled on testing the cyclic bending capacity of damaged and repaired piles in a cantilever column condition. Timber pile systems are subject to a variety of types of damage. Marine borer attack at the waterline is a common occurrence, so we focused on that type of repair.

Extreme example of pile damage.
Extreme example of pile damage. Image credit: Simpson Strong-Tie.

Timber pile systems are typically braced by batter piles or X-bracing. The connections of the bracing system generally do not have enough capacity when the structure is subject to large earthquake displacements, so the piles are analyzed as a forest of cantilever columns. The test protocol we used is the cyclic CUREE protocol found in ASTM E2126.

Once we sourced the large diameter timber piles (harder than one might think), we wanted to simulate marine installation conditions as closely as possible. So we created a marine environment at the Tye Gilb test lab. The salt water conditioning tanks extend into the basement through two large access panels in the floor.

Conditioning tanks extend down into the basement of Tye Gilb.
Conditioning tanks extend into the basement of Tye Gilb. Image credit: Emory Monatague, Simpson Strong-Tie.

This enabled us to soak the piles before the repair, install the repair materials under water and condition the repair in salt water. Since the repairs are typically at the waterline, half the repair is under water.

Placing FX-70-6MP Marine Epoxy Grout.
Placing FX-70-6MP Marine Epoxy Grout. Image credit: Emory Montague, Simpson Strong-Tie.

The testing was performed on 16-inch diameter, 18-foot tall creosote-treated Douglas-fir timber piles. We chose creosote-treated piles to evaluate the influence of the treatment on the bond of the FX-70-6MP Marine Epoxy Grout to the wood pile. Creosote was the common treatment when these structures were built and is an oily liquid. Adhesion tests on treated and untreated piles showed no negative effects on the bond due to the creosote chemicals.

Once the repair has cured, the specimen is craned into place and clamped at the base to create a fixed base condition. The percentages you’ll hear called out in the video are related to the lateral displacement of the top of the pile. The 100% cycle is 5.4 inches in each direction and we’ll push it all the way out to more than 17 inches at failure.

Pile specimen during testing. Image credit: Joe Way, Simpson Strong-Tie.
Pile specimen during testing. Image credit: Travis Anderson, Simpson Strong-Tie.

The testing video is of a 25% cross section loss specimen repaired with a 5 ½ foot long jacket that extends 18 inches beyond the damaged area. There is a ½ inch annulus (space between the jacket and the pile) that is filled with the FX-70-6MP Marine Epoxy Grout. Enjoy the show!

Have you had the opportunity to work on a marine structure repair? Tell us about it by posting a comment.

– Paul

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.


Paul McEntee

Author: Paul McEntee

A couple of years back we hosted a “Take your daughter or son to work day,” which was a great opportunity for our children to find out what their parents did. We had different activities for the kids to learn about careers and the importance of education in opening up career opportunities. People often ask me what I do for Simpson Strong-Tie and I sometimes laugh about how my son Ryan responded to a questionnaire he filled out that day:

Q.   What is your mom/dad's job?
A.   Goes and gets coffee and sits at his desk

Q.   What does your mom/dad actually do at work?
A.   Walks in the test lab and checks things

When I am not checking things in the lab or sitting at my desk drinking coffee, I manage Engineering Research and Development for Simpson Strong-Tie, focusing on new product development for connectors and lateral systems.

I graduated from the University of California at Berkeley and I am a licensed Civil and Structural Engineer in California. Prior to joining Simpson Strong-Tie, I worked for 10 years as a consulting structural engineer designing commercial, industrial, multi-family, mixed-use and retail projects. I was fortunate in those years to work at a great engineering firm that did a lot of everything. This allowed me to gain experience designing with wood, structural steel, concrete, concrete block and cold-formed steel as well as working on many seismic retrofits of historic unreinforced masonry buildings.