Strengthening of shear walls and diaphragm-to-wall connections has started on Little Tokyo Towers (see photo 1) located in downtown Los Angeles, CA. This senior–living residential facility was built in 1975. Structural analysis by Tuan and Robinson Structural Engineers showed that some modest strengthening was required to improve the building’s lateral system performance in the event of an earthquake.
Project Snapshot Series Part 2: Historic Theatre Retrofit Using FRP
Structural renovation work continues on an historic, 1920s-era theater in Hollywood, California. This major renovation will improve the structural performance of the building and help ensure that theatergoers and building occupants are safe in the event of a major earthquake. We are excited to share a second update on this project that focuses on the use of fiber-reinforced polymer (FRP) for strengthening the theater’s roof diaphragm. Continue Reading
Mechanical Anchors: Screw vs. Expansion: — Which Is Right for Me?
Not all post-installed mechanical anchors are created equal. There are key differences between screw and expansion anchor types — differences that include how they gain their holding strength, installation requirements, and overall anchor performance. In the following post, field engineers Todd Hamilton, Chris Johnson and Derek Gilbert compare the two anchor types.
Simpson Strong-Tie and Structural Technologies Offer Workshop on Seismic Strengthening Solutions for Concrete, CMU and URM
Did you know that Simpson Strong-Tie offers free education and training to the structural engineering and building industries? On May 18, 2022, a team of Simpson engineers and technical sales reps, in conjunction with Structural Technologies, hosted a workshop in Portland on fiber-reinforced polymer (FRP) and fabric-reinforced cementitious matrix (FRCM) seismic strengthening solutions for concrete, reinforced masonry and unreinforced masonry structures. The workshop educated engineers on how Composite Strengthening Systems™ (our FRP and FRCM solutions) can be used to strengthen structural concrete and masonry elements in their projects. This was our first workshop event since COVID restrictions were placed, and we were excited to host the industry again.
Masonry Reinforcement and Concrete Strengthening with Composites
This week’s post comes from Brad Erickson, who is the Engineering Manager for the Composite Strengthening Systems™ product line at our home office. Brad is a licensed civil and structural engineer in the State of California and has worked in the engineering field for more than 17 years. After graduating from Cal Poly, San Luis Obispo with a B.S. in Architectural Engineering, he worked for Watry Design, Inc. as an Associate Principal before coming to Simpson Strong-Tie. Brad is the Engineering Manager for Composite Strengthening Systems and his experience includes FRP design, masonry and both post-tensioned and conventional concrete design. While not at work, Brad enjoys spending time carting his three kids around to their competitive soccer games and practices.
Have you ever had a concrete or masonry design project where rebar was left out of a pour? Chances are, the answer is yes. Did you wish you could solve this problem by putting rebar on the outside of that element? That’s exactly what Simpson Strong-Tie Composite Strengthening Systems™ (CSS) can do for you and your project. In effect, composites act like external rebar for your concrete or masonry element. Composites can be used in similar configurations to rebar but are applied on the exterior surface of the element being strengthened.
The initial offering in our CSS line is our fiber-reinforced polymer (FRP) product group. An FRP composite is created by taking carbon or glass fabric and saturating it with a two-part epoxy which, when cured, creates the composite. Together, the weight of the fabric and the number of layers in the composite determine how much strength it will add to your concrete or masonry element.
Another form of FRP composite is a precured carbon laminate. The carbon fibers are saturated in the manufacturing facility and are attached to the structure using CSS-EP epoxy paste and filler, an epoxy with a peanut butter–like consistency. We also carry paste profilers (pictured below) that help contractors apply the proper amount of paste to a piece of precured laminate.
Of course, before any concrete or masonry reinforcement project can succeed, proper surface preparation is of the utmost importance. Without a good bond with the substrate, a composite will not be able to achieve the intended performance. Concrete voids must be repaired, cracks must be injected and sealed, and any deteriorated rebar must be cleaned and coated. Prior to composite placement, the surface of the substrate must be prepared to CSP-3 (concrete surface profile) in accordance with ICRI Guideline No. 310.2. Grinding and blasting are the most common surface-preparation techniques.
The following are just a few applications where composites can be used for concrete and/or masonry retrofits. The orange arrows show the direction of the fibers in the fabric – in other words, the direction in which the composite provides tension reinforcement.
This is a summary of the basics of composites and their installation on strengthening projects. As composites are not yet in the design codes in the United States, the American Concrete Institute has produced 440.2R-08: Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures. This guide has numerous recommendations for using fiber-reinforced polymer systems to strengthen your concrete or masonry construction.
If you would like more information about FRP design, you can learn the best practices for fiber-reinforced polymer (FRP) strengthening design during a recorded webinar offered by Simpson Strong-Tie Professional Engineers. We look at FRP components, applications and installation. We also take you behind the scenes to share the evaluation process informing a flexural beam-strengthening design example and talk about the assistance and support Simpson Strong-Tie Engineering Services offers from initial project assessment to installation.
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).
For complete information regarding specific products suitable to your unique situation or condition, please visit strongtie.com/rps or call your local Simpson Strong-Tie RPS specialist.