Building Codes Archives - Page 10 of 13 -

How to Safely Select Nail Substitutions for Connectors

A few days ago, I was speaking to a customer about an application using nail substitutions for a joist hanger installation. Her questions come up often, so I thought I would dedicate a blog post to some of the resources available that cover the use of different nails in connectors.

Designers and builders often wish to use different fasteners than the catalog specifies. The application could require short nails that don’t penetrate through the back of a ledger or they want to use screws or sinker nails for easier installation. The Wood Connectors Catalog provides multiple options for alternate nailing for face mount hangers and straight straps on page 27.

The load adjustments for alternate fasteners cover substitutions from a common diameter of 16d to a 10d, or a 10d to an 8d. Multiple different replacement lengths are also covered, with reduction factors ranging from 0.64 to 1.0.

It is important to remember that double shear hangers require 3” minimum joist nails. Short nails installed at an angle in double shear hangers will not have adequate penetration into the header.

Fastener - Double Shear — Fastener – Double Shear

Pneumatic nail guns used for connector installation are commonly referred to as positive placement nail guns. These tools either have a nose piece that locates connector hole, or the nail itself protrudes from the tool so that the installer can line the nail up with the hole. Most positive placement tools do not accept nails longer than 2½”, so framers using these tools will want to use 1½” or 2½” nails. To accommodate installers using pneumatic nails, we have a technical bulletin T-PNUEMATIC. This bulletin provides adjustment factors for many of our most common embedded holdowns, post caps and bases, hangers and twist straps.

The question of nail size also comes up when attaching hangers to rim board, which can range from 1” to 1¾”. The adjustment factors in C-2013 don’t necessarily apply with rim board, since the material may be thinner the length of the nails used. We also have a technical bulletin for that application – T-RIMBDHGR.

Several of the reduction factors are the same as those in the catalog. Testing of hangers with 10dx1½ nails on 1” OSB or 1¼” LVL did not do as well, however. We observed that once the nails withdrew a little bit under load, they quickly lost capacity. For that reason, we recommend full length 10d or 16d nails on those materials.

Understanding that alternate fasteners are available for many connectors can help you pick the right fastener for you application. When you specify a connector, it is important to also specify the fasteners you require to achieve your design load.

What are your thoughts? Visit the blog and leave a comment!

Know Your Code

I attended a CFSEI and Steel Framing Alliance webinar last week entitled Specifying Cold-Formed Steel: Finding and Avoiding Pitfalls in Structural General Notes and Architectural Specifications. The presenter was Don Allen, P.E., from DSi Engineering, LLC, and he focused on issues specifically related to design and specification of cold-formed steel (CFS) in contract documents.

Wings or No Wings?

Guest blogger Jeff Ellis, engineering manager

While the title of this blog post might remind you of the tasty turkey dinner you enjoyed on Thanksgiving, it’s actually a question regarding a shear wall component’s effect on performance. What type of fastener do you use to attach wood structural panel sheathing to cold-formed steel (CFS) framing, and what is the effect on a shear wall assembly?

Wood Structural Panel Sheathed CFS Framed Shear Walls.( Image credit: Don Allen, DSi Engineering)

Structural sheathing is most commonly attached to CFS framing with self-piercing or self-drilling tapping screws, power driven pins, and adhesives.

The AISI North American Standard for Cold-Formed Steel Framing – Lateral Design standard (S213) specifies using either #8 or #10 self-tapping screws (depending on the assembly) that comply with ASTM C1513, and have a minimum head diameter of 0.285” or 0.333”, respectively.

It’s worth noting that you cannot verify ASTM C1513 compliance by simple inspection. While screw dimensions are easy to measure, other features such as hardness, ductility, torsional strength, drill drive, and thread tapping cannot be evaluated in the field or by visual inspection. It’s prudent that a Designer and jurisdiction expect a screw manufacturer to validate its product’s compliance with ASTM C1513. This can be done through test reports by an accredited test lab and evaluation data, or by an evaluation report published by an ANSI-accredited product certification entity such as ICC-ES or IAPMO UES.Continue Reading

2013 Buildings At Risk Summit Focused on Individual and Community Safety, Resiliency

The Structural Engineers Association of Northern and Southern California hosted the third annual Buildings At Risk ǀ Earthquake Loss Reduction Summit in Los Angeles on October 8 and in San Francisco on October 15. Robust panel presentations and discussions presented by professionals from diverse yet complimentary fields targeted a mixed audience of building owners, architects, engineers, government officials, insurance representatives, and financial industry representatives.Continue Reading

Why Your NDS Nail Calcs Could Be Wrong. . .And What You Can Do About It

This week’s post was written by Bob Leichti, Manager of Engineering for Fastening Systems. Prior to joining Simpson Strong-Tie in 2012, Bob was an Engineering Manager covering structural fasteners, hand tools, regulatory compliance and code reports for a major manufacturer of power tools and equipment. Prior to that, Bob was a Professor in the Department of Wood Science and Engineering at Oregon State University. He received his B.S. and M.S. from the University of Illinois, and his M.S. and Ph.D. from Auburn University.

When test results don’t make sense, we start by eliminating causes of the problem. When our withdrawal test values came up low, we checked the load cell calibration, the specific gravity of the wood, the nail dimensions, even the units – everything was correct. So why were the nail withdrawal values so low? More wood, more nails, more tests – same results. Ultimately, we concluded that the withdrawal resistance of stainless-steel, smooth-shank nails is not well described by the withdrawal function in the 2012 NDS, section 11.2.3, equation 11.2-3.Continue Reading

City of San Francisco Implements Soft-Story Retrofit Ordinance

The city of San Francisco is a unique construction environment that is 98% built-out with little new residential construction. Protecting the existing structures is particularly imperative to save the character of the city and maintain the population base by preventing a major migration out of the city after a large seismic event.

The Community Action Plan for Seismic Safety (CAPSS) was a San Francisco Department of Building Inspection 10-year-long study started in 1998 to study earthquake risks in San Francisco and develop suggestions for mitigating loss of life and property damage from future earthquakes. I once worked as a volunteer on a sidewalk survey to inventory soft-story buildings as part of CAPSS. The key recommendations of CAPSS evolved into the CAPSS Earthquake Safety Implementation Program (ESIP), which has 50 tasks that will be implemented over the next 30 years.

One of those tasks includes the Mandatory Soft-Story Retrofit Program, which Mayor Ed Lee signed into law on April 18, 2013 at the annual commemoration of the 1906 San Francisco Earthquake. The law requires wood-framed buildings that:

Were built prior to 1978
Are three stories or more and,
Have five or more dwelling units

to be evaluated and brought into compliance. The city sent notices to building owners on September 15. It’s estimated that there are between 4,000 and 10,000 structures that fall under the program.

23rd Short Course on CFS Structures: October 15-17 in St. Louis

Simpson Strong-Tie is sponsoring the 23^rd Short Course on Cold-Formed Steel Structures hosted by the Wei-Wen Yu Center for Cold-Formed Steel Structures (CCFSS). The course will be held on October 15-17, 2013 at the Drury Plaza Hotel at the Arch in St. Louis, MO.

This course is for engineers who have limited or no experience designing with cold-formed steel (CFS), as well as those with experience who would like to expand their knowledge. Lectures will be given by industry-recognized experts Roger LaBoube, Ph.D, P.E., and Sutton Stephens, Ph.D, P.E., S.E. The course is based on the 2007 and 2012 AISI North American Specification for the Design of Cold-Formed Steel Structural Members with the 2010 Supplement (AISI S100-07/S2-10 and S100-12) and will reference the Cold-Formed Steel Design (4^th Edition) text.

Topics include design of wall studs, floor joists, purlins, girts, decks and panels. For more information and to register, visit the CCFSS website.

– Jeff

TED Talk – Michael Green: Why We Should Build Wooden Skyscrapers

I have been following TED Talks for a few years now. Like most websites I have on my “to visit” list, I couldn’t tell you how I found them. It may have been a link on some other website, or a friend on Facebook, or maybe linked on another blog somewhere. What is TED? I’ll steal from their website:

TED is a nonprofit devoted to Ideas Worth Spreading. It started out in 1984 as a conference bringing together people from three worlds: Technology, Entertainment, Design. Since then its scope has become ever broader. Along with two annual conferences — the TED Conference and TEDGlobal — TED includes the award-winning TED Talks video site, the Open Translation Project and TED Conversations, the inspiring TED Fellows and TEDx programs, and the annual TED Prize.

New content is posted on TED every day, so I often miss cool stuff. Thanks to one of our Canadian engineers for pointing out a talk by architect Michael Green, who makes a case for why we should build wooden skyscrapers. I did a previous post about the Timber Tower Research Project that Skidmore, Owings & Merrill LLP did for a 42-story wood framed building. Mr. Green makes the case for taller wood structures from an environmental standpoint and carbon dioxide output of concrete and steel versus wood.

The 12 minute video is worth a listen. The TED Blog post is here: Why tall wooden buildings must be our future: a visual essay by Michael Green.

– Paul

What are your thoughts? Visit the blog and leave a comment!

Hurricane Sandy Rebuilding Strategy

I confess that I listen to a lot of pop music while driving to work, mostly because I forget to change the station after dropping the kids off. It can be slightly embarrassing if I drive with a coworker and I’m tuned into the “all Bieber, all day” station when I start the car.

On Monday, I was without kids and managed to hear several news stories on NPR about Hurricane Sandy. Transcript of one story is here and the NPR blog post about it is here.

The Hurricane Sandy Rebuilding Task Force released a report titled Hurricane Sandy Rebuilding Strategy. The report has 69 recommendations ranging from complex, such as setting minimum flood elevations that account for projected sea level rise, to relatively simple, such as states and localities adopting and enforcing the most current versions of the IBC® and IRC®.

The recommendations cover energy, infrastructure, sanitation, water, fuel supply, internet, transportation, and too many other things to list. But if I had to pick one word to summarize the report, it would be:

Resilience: The ability to prepare for and adapt to changing conditions and withstand and recover rapidly from disruptions.

Regardless of whether the natural disaster is high wind, earthquake, flood or fire, there has been a shift in public policy over the past decade to emphasize resilience. Resilience is a cycle. It begins with mitigation before the disaster. Some examples of mitigation that have appeared in this blog:

Seismic Retrofit of Unreinforced Masonry (URM) Buildings

Soft-Story Retrofits

Building a Storm Shelter to ICC-500 Design Requirements

Designing new buildings with specific performance targets is a form of mitigation as well. Resilience continues with response after the disaster, and then short and long-term recovery plans to reduce the time between disaster and recovery.

Have recent natural disasters such as Hurricane Sandy changed the way you are designing? Let us know by posting a comment.

– Paul

What are your thoughts? Visit the blog and leave a comment!

Breaking News: Simpson Strong-Tie® Strong Frame® Special Moment Frame Testing Today

Today the NEES-Soft project has begun testing the steel Simpson Strong-Tie® Strong Frame® Special Moment Frame as a retrofit option for soft-story buildings at the NEES outdoor shake table facility at UC San Diego. The testing is focused on validating the FEMA P-807 design procedure, which attempts to create a least-cost retrofit solution by only retrofitting the garage areas of problem buildings.Continue Reading