Design criteria for cracked-concrete masonry units are finally available for adhesive anchors.
It has been over 15 years since cracked concrete changed the way anchorage to concrete was qualified and designed. The ICC International Building Code (IBC) 2003 referenced American Concrete Institute (ACI) 318-02 Appendix D as a design provision for both cast-in-place and post-installed anchors into concrete. Appendix D was the first introduction of cracked concrete to designers. These design provisions required mechanical anchors to be qualified per ACI 355.2, which mandated testing of anchors in cracks. The Masonry Society (TMS) 405 has not addressed cracks in concrete masonry units since the code’s introduction to concrete in 2003. The Concrete and Masonry Anchor Manufacturers Association (CAMA) has taken on the task of introducing cracked masonry unit testing, qualification and design by updating Acceptance Criteria AC58. These criteria were developed to address the testing and qualification of adhesive anchors in grouted, hollow, and partially grouted concrete masonry units, as well as in brick masonry units.
Not all anchoring adhesives are created equal. There are important differences between acrylic-based and epoxy-based adhesive systems — differences that affect installation, gel and cure times, and anchoring performance. In the following post, Marlou Rodriguez, S.E., of Simpson Strong-Tie, lays out some of the comparative installation advantages of each system.
There are two common types of adhesives for anchoring threaded rod or rebar into concrete — epoxy-based systems and acrylic-based systems. What’s the difference? When should you specify one rather than the other? This blog post will help you understand the differences and guide you in choosing the best adhesive for your anchoring solution. Continue Reading
Simpson Strong-Tie engineering manager Brad Erickson, S.E., P.E., and Simpson Strong-Tie senior product manager Mark Kennedy, PMP, conducted an informative discussion of this new product solution. You can view the webinar in our Training Center and take a course to earn one hour of CEUs, PDHs and AIA LU/HSW credits. The course and webinar discuss installation steps, identify projects where FRCM would be ideal, and cite testing and industry standards associated with FRCM. Continue Reading
Designing post-installed anchorage near a concrete edge is challenging, especially since the ACI provisions for cracked-concrete anchorage went into effect. In the following post, one of our field engineers, Jason Oakley, P.E., explains how SET-3G™ and Anchor Designer™ software from Simpson Strong-Tie make it easier to design a ductile anchor solution.
Engineers often provide holdown anchoring solutions near a concrete edge to help prevent overturning of light-frame shear walls during a seismic (or high-wind) event. Sometimes a post-installed anchor must be used if the cast-in-place anchor was mislocated or misinstalled, or is located where a retrofit or addition is needed. Since the cracked-concrete anchorage design provisions went into effect more than a decade ago, it has been challenging for engineers to offer a near-edge post-installed anchoring solution. This is especially true for structures subject to earthquake loads in seismic design category (SDC) C through F. Simpson Strong-Tie’s new SET-3G epoxy is the first anchoring adhesive in the industry to offer exceptionally high bond-strength values that permit ductile anchorage in concrete near an edge. This blog post will cover a specific example that focuses on Chapter 17 of ACI 318-14 to design a threaded rod, anchored with SET-3G adhesive, used to secure a holdown located 1 3/4″ away from a single concrete edge (Figure 1). Continue Reading
The new FRCM Composite Strengthening Systems™ repair and reinforcement solution from Simpson Strong-Tie combines high-performance sprayable mortar with a carbon-fiber grid that creates a thin structural layer that repairs and strengthens without significantly increasing the structure’s weight or volume. FRCM stands for fabric-reinforced cementitious matrix. Its advantages are similar to those of FRP (that is, strength, low weight and ease of application), but it may also be used to repair, resurface, strengthen and protect in one application, along with providing greater resistance to heat and better long-term durability. Continue Reading
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.
The wait is over. The ACI 440.2R-17 Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures is now available. The following post will highlight some of the major changes represented by this version of the document.
It’s been a long road and countless committee hours to get from the last version of ACI 440.2R-08 to this document. While there are multiple smaller changes throughout the document, the most notable update is the addition of Chapter 13 – Seismic Strengthening.
The new seismic chapter addresses the following FRP strengthening scenarios:
Section 13.3 – Confinement with FRP
This section includes all of the following: general considerations; plastic hinge region confinement; lap splice clamping; preventative buckling of flexural steel bars.
Section 13.4 – Flexural Strengthening
The flexural capacity of reinforced concrete beams and columns in expected plastic hinge regions can be enhanced using FRP only in cases where strengthening will transfer inelastic deformations from the strengthened region to other locations in the member or the structure that are able to handle the ensuing ductility demands.
Section 13.5 – Shear Strengthening
To enhance the seismic behavior of concrete members, FRP can be used to prevent brittle failures and promote the development of plastic hinges.
Section 13.6 – Beam-Column Joints
This section covers a great deal of recent research on the design and reinforcement of beam-column joints.
This section provides many recommendations for FRP strengthening of R/C shear walls.
Simpson Strong-Tie Can Help
We recognize that specifying Simpson Strong-Tie® Composite Strengthening Systems™ (CSS) is unlike choosing any other product we offer. Leverage our expertise to help with your FRP strengthening designs. Our experienced technical representatives and licensed professional engineers provide complimentary design services and support – serving as your partner throughout the entire project cycle.
For complete information regarding specific products suitable to your unique situation or condition, please visit strongtie.com/cssor call your local Simpson Strong-Tie RPS Specialist at (800) 999-5099.
Join us live on July 25 for the second interactive webinar in the Simpson Strong-Tie FRP Best Practices Series: Advanced FRP Design Principles. In this webinar we will highlight some very important considerations during the FRP design processes. This will include topics such as the latest industry standards, proper use of material properties, and key governing limits when designing with FRP. Attendees will also have an opportunity to pose questions to our engineering team during the event. Continuing educations units will be offered for attending this webinar.
The primary benefit of fiber-reinforced polymer (FRP) systems as compared with traditional retrofit methods is that significant flexural, axial or shear strength gains can be realized using an easy-to-apply composite that does not add significant weight or section to the structure. Many times it is the most economical choice given the reduced preparation and labor costs and may be installed without taking the structure out of service. However, it is important to make sure the composite is properly designed following industry standards in order to ensure that it is the right product for the application.
To provide you with a better understanding of the topic, it’s important to dispel some common myths and misconceptions that you might hear about FRP:
I was driving under a concrete bridge one nice clear day in Chicago, and I happened to look up to see rusted rebar exposed below a concrete bridge. My beautiful wife, who is not a structural engineer, turned to me and asked, “What happened to that bridge?” I explained that there are many reasons why spalling occurs below a bridge. One common reason is the expansion of steel when it rusts or corrodes.
Fiber-reinforced polymer (FRP) composite systems can be used to strengthen walls, slabs and other concrete or masonry members in buildings and other structures. The case studies below show ways in which Composite Strengthening Systems™ (CSS) provide valuable solutions for strengthening buildings and other structures for our customers.
Residential Project in San Francisco
The homeowner for this project wanted to repair some spalling concrete on his concrete piers and also wrap the piers with FRP. We worked with the contractor and homeowner to design a cost-effective solution. This was a successful project for all involved, since the alternative was to jacket the piers with costly and unsightly steel jackets.
School Project in Argentina
The goal of the project was to analyze a standard design of approximately 400 schools in Argentina that were built in the 1980s and to make recommendations to retrofit the structures to meet current seismic code requirements. On analysis, it was found that columns were in need of shear reinforcement for the schools to meet the new seismic requirements.
Hospital Project in Butler, PA
The Engineer of Record on this project wanted to provide continuity across the slab construction joints, something which the existing rebar did not provide. We provided a design of Near-Surface-Mounted (NSM) laminates, which are installed in saw-cut grooves in the top of the concrete slab. This installation allows a flush finished surface, important for allowing the floor finishes to be installed on the slab.
Silo Project in Garden City, IA
The concrete silos on this project had spalling at the top portion, which caused a hazard at this site. After repairing the concrete, we provided a ring of carbon fabric to assist in keeping the top concrete of the silos solid for years to come.
Bridge Project in MN
MNDOT wanted to gain experience working with our CSS products on one of their bridges. We worked with their staff to design several types of strengthening solutions for bridge pier caps and columns. We then provided onsite installation training for the MNDOT maintenance staff to install the FRP products on the bridge.
We recognize that specifying Simpson Strong-Tie® Composite Strengthening Systems™ is unlike choosing any other product we offer. Leverage our expertise to help with your FRP strengthening designs. Our experienced technical representatives and licensed professional engineers provide complimentary design services and support – serving as your partner throughout the entire project cycle. Since no two buildings are alike, each project is optimally designed to the Designer’s individual specifications. Our pledge is to address your specific condition with a complete strengthening plan tailored to your needs, while minimizing downtime or loss of use, at the lowest possible installed cost.
Your Partner During the Project Design Phase
During the Designer’s initial evaluation or preparation of the construction documents, Simpson Strong-Tie can be contacted to help create the most cost-effective customized solution. These plans include detailed design calculations for each strengthening requirement and design drawings with all the necessary details to install the CSS system. Simpson Strong-Tie Engineering Services will work closely with the Design Engineer to provide all the necessary information required to design the system.
Why Use Our Design Services?
Assess feasibility studies to ensure suitable solutions to your application
Receive customized FRP strengthening solutions
Work with our trained contractor partners to provide rough-order-of-magnitude (ROM) budget estimates
Collaborate during the project design phase
Receive a full set of drawings and calculations to add to your submittal
Maintain the flexibility to provide the most cost-effective solution for your project
Gain trusted technical expertise in critical FRP design considerations
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/css or call your local Simpson Strong-Tie RPS specialist at (800) 999-5099.