Revisiting Spanning the Gap

Three years ago, we created this blog post based on a technical support question we often receive about allowable fastener loads for ledgers to wood framing over gypsum board. Given that this is still a frequent question and a relevant topic, we decided to revisit the post and update it.

Drywall. Wall board. Sheetrock. Sackett Board? A product called Sackett Board was invented in the 1890s, which was made by plastering within wool felt paper. United States Gypsum Corporation refined Sackett Board for several years until 1916, when they developed a new method of producing boards with a single layer of plaster and paper. This innovation was eventually branded SHEETROCK®. More details about the history of USG can be found here.

No matter what you call it, gypsum board is found in almost every type of construction. Architects use it for sound and fire ratings, while structural engineers need to account for its weight in our load calculations. A common technical support question we receive is for allowable fastener loads for ledgers to wood framing over gypsum board.

Ledger over Gypboard

Ledger over Gypboard

One method to evaluate a fastener spanning across gypsum board is to treat the gypsum material as an air gap. Technical Report 12, General Dowel Equations for Calculating Lateral Connection Values, is published by the American Wood Council.

Technical Report 12

Technical Report 12

TR12 has yield limit equations that allow a designer to account for a gap between the main member and side member of a connection. With a gap of zero (g=0), the TR12 equations provide the same results as the NDS yield limit equations.

Technical Report 12 Yield Limit Equations[1]

Technical Report 12 Yield Limit Equations

The equations are fairly complex, but it should be intuitive that the calculated fastener capacity decreases with increasing gap. Engineers are often surprised to see a 40, 50, even 60% drop in fastener capacity with one layer of 5/8” gypsum board. So what else can you do?

Testing, of course! In So, What’s Behind a Screw’s Allowable Load? I discussed the methods used to load rate a proprietary fastener such as the Simpson Strong-Tie® Strong-Drive® SDS or SDW screws. To recap, ICC-ES Acceptance Criteria for Alternate Dowel Type Fasteners, AC233, allows you to calculate and do verification tests, or load rate based on testing alone. We develop our allowable loads primarily by testing, as the performance enhancing features and material optimizations in our fasteners are not addressed by NDS equations.

So to determine the performance of a fastener installed through gypsum board, we tested the fastener through gypsum board. This is easier to do if you happen to have a test lab with a lot of wood and fasteners in it. We did have to run down to the local hardware store to pick up gypsum board for the testing.

SDWS Over 2 Layer Gypboard

SDWS Over 2 Layer Gypboard

SDWS-Over-2-Layer-Gypboard-Failure

SDWS Over 2 Layer Gypboard Failure

A full set of allowable loads for Strong-Drive SDWH and SDWS are available on strongtie.com. The information is given as single fastener shear values for engineered design, and also screw spacing tables for common ledger configurations. As much fun as writing spreadsheets to do the Technical Report 12 calculations is, having tabulated values based on testing is much easier.

Fastening Systems

In the fastener marketplace, Simpson Strong-Tie stands apart from the rest. Quality and reliability is our top priority.


5 Steps to a Successful Soft-Story Retrofit

Last year, I gave a presentation at the annual National Council of Structural Engineers Associations (NCSEA) Summit in Orlando, Florida, titled “Becoming a Trusted Advisor: Communication and Selling Skills for Structural Engineers.” As this was a summit for the leaders of the structural engineers associations from across the country, I wasn’t sure how many people would find it valuable to spend their time learning about a very nontechnical topic. To my surprise and delight, the seminar ended up being standing-room only, and I was able to field some great questions from the audience about how they could improve their selling and communication skills. In the many conversations I had with the conference attendees after my presentation, the common theme was that engineers felt they needed more soft-skills training in order to better serve their clients. The problem, however, was finding the time to do so when faced with the daily grind of design work.

Structural Engineers In a Training for Seismic Retrofits

Presenting at the NCSEA Summit, I’m the tiny person in upper left hand corner.

When I started my first job as a design engineer at a structural engineering consulting firm straight out of school, I was very focused on improving and expanding my technical expertise. Whenever possible, I would attend building-code seminars, design reviews and new product solution presentations, all in an effort to learn more about structural engineering. What I found as I progressed through my career, however, was that no matter how much I learned or how hardworking I was, it didn’t really matter if I couldn’t successfully convey my knowledge or ideas to the person who really mattered most: the client.

Contractors discussing building plans with an engineer.

Contractors discussing building plans with an engineer.

How can an engineer be most effective in explaining a proposed action or solution to a client? You have to be able to effectively sell your idea by understanding the needs of your client as well as any reasons for hesitation. The importance of effective communication and persuasion is probably intuitive to anyone who’s been on the sales side of the business, but not something that occurs naturally to data-driven folks like engineers. As a result of recent legislation in California, however, structural engineers are starting to be inundated with questions from a group of folks who have suddenly found themselves responsible for seismically upgrading their properties: apartment building owners in San Francisco and Los Angeles.

Imagine for a moment that you are a building owner who has received a soft-story retrofit notice under the City of Los Angeles’ Ordinance 183893; you have zero knowledge of structural engineering or what this term “soft-story” even means. Who will be your trusted advisor to help you sort it out? The City of Los Angeles Department of Building and Safety (LADBS) has put together a helpful mandatory ordinance website that explains the programs and also offers an FAQ for building owners that lets them know the first step in the process: hire an engineer or architect licensed in the state of California to evaluate the building.

Simpson Strong-Tie Structural Engineer Annie Kao at a jobsite.

Checking out some soft story buildings in Los Angeles. The Los Angeles Times has a great map tool.

I’ve had the opportunity to be the first point of contact for a building owner after they received a mandatory notice, because it turns out some relatives own an apartment building with soft-story tuck-under parking. Panicked by the notice, they called me looking to understand why they were being forced to retrofit a building that “never had any problems in the past.” They were worried they would lose rent money due to tenants needing to relocate, worried about how to meet the requirements of the ordinance and, most importantly, worried about how much it was going to cost them. What they really wanted was a simple, straightforward answer to their questions, and I did my best to explain the necessity behind retrofitting these vulnerable buildings and give an estimated time frame and cost that I had learned from attending the first Los Angeles Retrofit Resource Fair in April 2016. With close to 18,000 buildings in the cities of San Francisco and Los Angeles alone that have been classified as “soft-story,” this equates to quite a number of building owners who will have similar questions and be searching for answers.

To help provide an additional resource, Simpson Strong-Tie will be hosting a webinar for building owners in the Los Angeles area who have received a mandatory soft-story retrofit notice. Jeff Ellis and I will be covering “5 Steps to a Successful Retrofit” and helping to set a clear project path for building owners. The five steps that Simpson Strong-Tie will be recommending are:

  1. Understanding the Seismic Retrofit Mandate
  2. Partnering with Design Professionals
  3. Submitting Building Plans with the Right Retrofit Product Solutions
  4. Communicating with Your Building Tenants
  5. Completing Your Soft-Story Retrofit

We encourage you to invite any clients or potential clients to attend this informative webinar, which will lay the foundation for great communication between the two of you. As part of the webinar, we will be asking the building owners for their comments, questions and feedback so we can better understand what information they need to make informed decisions, and we will be sure to share these with the structural engineering community in a future post. By working together to support better communication and understanding among all stakeholders in retrofit projects, we will be well on our way to creating stronger and more resilient communities!

For additional information or articles of interest, there are several resources available:

3 Hot Tips for Structural Engineers Who Want to Earn Education Credits and Stay Sharp

Written by Minara El-Rahman in collaboration with the Simpson Strong-Tie Training Department.

Do you ever get so busy that you can’t keep up with the training opportunities that are available? We have previously shared online resources and webinars that are available to structural engineers, but did you know that you can take advantage of Simpson Strong-Tie regional training centers that offer complimentary workshops and classes about proper specification, product installation and inspection of connectors and structural systems? Here are some tips on staying current with your training.

Simpson Strong-Tie training courses and webinars are focused on improving building standards and the overall safety of structures. With eight training centers across North America, Simpson Strong-Tie provides hundreds of complimentary classes to engineers, architects, builders and code officials each year. In fact, we have trained more than 24,000 participants online and in-person in 2016 alone.

“The workshops are very interactive,” explained Charlie Roesset, Director of Training for Simpson Strong-Tie. “Depending on the course, students may have the opportunity to view product samples or take part in product testing and installations.”

Tip #1 Make Training Offerings Work for You

If you specialize in a specific discipline, look for courses that are targeted to your area of interest or expertise. Simpson Strong-Tie courses include a broad range of topics from anchor system installation and engineered wood frame construction to seismic and high-wind design. We also incorporate the latest building-code updates and industry trends into our training curriculum. No matter where you are in your professional career, we offer a course that’s right for you. There are introductory courses as well as more advanced workshops for repeat and seasoned attendees.

Training participants receive a certificate of attendance with professional development hours (PDHs) at the end of each workshop, and may earn continuing education units (CEUs) and/or learning units (LUs) by completing additional requirements. Simpson Strong-Tie is a registered education provider with a number of industry organizations and associations including CSI, BIA, ACIA, AIBD, ICC, AIA* and IACET**.

Tip #2 Find Trainings That Are Current

Do your research to find workshops and online courses that are regularly updated to reflect changes within the industry. For example, we have regular trainings that focus on the new seismic retrofit ordinances in various municipalities on the West Coast (such as Los Angeles’ Soft-Story Retrofit Ordinance) and others on high-wind design and construction in the Southeast. Our trainings are tailored to your design needs based on your practice’s location.

Full-day workshops typically run from 8:00 a.m. to 4:00 p.m. Classes are often tailored toward specific audiences types to ensure that the training is appropriate and effective. Many courses are team-taught by registered engineers to provide in-depth technical expertise in the subject matter. While much of the instruction is technical in nature, many real-life examples and hands-on demonstrations are provided to help all attendees fully understand the material presented.

Tip #3 Hear What Other Structural Engineers Have to Say

Training

It is always a good sign when others in your field have good things to say about the courses they have taken. Below are some comments past participants have said about our training offerings:

Fred B., S.E., an engineer from Las Vegas, NV, has been a regular attendee of Simpson Strong-Tie workshops. He says the training keeps him informed of topics relevant to his industry and is a great way to keep up with his professional development hours. “Some of the courses offered by other groups are just not that interesting and they can be quite expensive. Simpson programs are interesting, hands-on and free. It’s the whole package.”

Bob N., an engineer from Richmond, VA, wrote, “Keep up the good work; I have found your seminars to be well done, pertinent, and useful. We also specify a lot of your products because of the training and the fact that you have an excellent product line.”

Kathy P., an engineer from Somerville, TX, shares: “You guys are so great! You teach well and keep it interesting. . . . . You support the industry to the benefit of everyone, not just your bottom line, and you make educational credits cost effective. Thank you, thank you, thank you!”

Sign up for a workshop and find out more about Simpson Strong-Tie training programs, including our latest online courses, by visiting www.strongtie.com/workshops.

* Simpson Strong-Tie is registered with the American Institute of Architects, Continuing Education System (AIA CES) as a provider of AIA Learning Units (AIA LUs).

** Simpson Strong-Tie is accredited by the International Association for Continuing Education and Training (IACET) and is authorized to issue the IACET CEU.

 

 

Ten Apps for Engineers

Shane Vilasineekul

Guest blogger Shane Vilasineekul, engineering manager

When Simpson Strong-Tie began supporting the use of iPads by employees, it was about the same time my Blackberry contract was expiring, so I decided to go all-in with Apple® and get an iPhone® 4s and an iPad®. Since mobile devices will not replace the heavy lifting required from most engineers’ computers, I wanted to find some apps that complemented my PC use and made me more efficient when I was away from my desk.  After reading reviews and trying out a few, I eventually came up with a list of apps that I recommend. None were developed for engineers, but they are the ones I use most often. Let me know what you think of these or any of your favorites that I missed.

DropBox

DropBox

Google Drive

Google Drive

1. File Sharing Apps: My initial search was for a way to share files between my Apple devices and my PC. Since there is limited space in the free cloud services, I use two: Dropbox (free) for work files and Google Drive (free) for home files. Install the apps on your mobile devices and the software on your computers, create and log into your account, and you are ready to access/modify/share any of these files on any device. Both of these apps are seamlessly integrated into many other apps.

Notability

Notability

2. Organization: I am not the most organized person, so I wanted an app that would help me keep track of my many notes. After trying a few different ones, I settled on Notability ($3). I can take handwritten or typed notes, insert a picture of things like a jobsite photo or a paper handout, draw a sketch, or even insert an audio recording. Best of all, I can organize the notes in folders within the app and also back them up as PDF files to Dropbox.

SlideShark

SlideShark

3.  Presentations: I regularly give PowerPoint presentations, so I started using an app called SlideShark (free) and got hooked. It is simple and remains true to the look of the original PowerPoint program. With the current version, I can access files on my DropBox account, play embedded videos, and use my iPhone as a remote when my iPad is connected to a projector. Although I still present with my trusty laptop most of the time, SlideShark is also great for practicing a presentation on a mobile device anywhere you find yourself with a few spare minutes.

MyScript Calculator

MyScript Calculator

4. Calculator: I was shocked to find that my iPad didn’t have a built-in calculator app. I tried a few free ones, but never really liked them. Then MyScript Calculator (free) came out last year, which solves handwritten equations like the one shown in the icon. Now I look for reasons to use it. It won’t ever replace my TI-85, but I am not sure I want it to.

 

iBooks

iBooks

iBooks Shelf

iBooks Shelf

5. Reference Guides: I like the idea of having electronic versions of my codes and referenced standards all saved in my iPad. Some of the PDF files I purchased allow me to save them in iBooks (free); others shown in the screenshot are just covers. On a side note, ICC has all of their codes online, broken into sections (as opposed to a single PDF). It’s great for sending links of specific code language to people that don’t own the code.

GoodReader

GoodReader

6. Editor Apps: There are tons of PDF editing apps out there. I asked around to see what other engineers use and decided on GoodReader ($5). I have been pretty happy with it, mostly using it to mark up PDF files I am reviewing.

 

PhotoSynth

PhotoSynth

7. Photos: When out on a jobsite, there is no better way to capture information than with a picture. But when everything can’t fit inside the viewfinder, PhotoSynth (free) is a great tool to capture the surroundings. Immersive 360° images  can be posted online, shared, or viewed within the app. Here are links to a couple of mine: Hurricane Sandy, Columbus Test Lab.

SnapSeed

SnapSeed

8. Photo Editing: While on the topic of photos, I use Snapseed (free) whenever I need to edit them. It is simple and intuitive, but powerful enough to get the job done.

 

 

Scanner Pro

Scanner Pro

9. Scanner Pro ($3) turns your camera into a scanner. Take a picture of a paper document, then locate the corners of the paper within the app and turn it into a PDF file that scales and stretches it to look like a scan instead of a snapshot.

 

Paper

Paper

Sketchbook Express

Sketchbook Express

10. Sketch Apps: My favorite apps for sketching a new connector idea, illustrating a concept or just doodling, are Paper (free) and SketchBook Express (free). Paper is more free-form and natural, while SketchBook has more tools and provides more precise control. They are free, so give them both a try.

*Apple, the Apple logo, iPhone and iPad are trademarks of Apple Inc., registered in the U.S. and other countries.*

Is Designing with Wood Easy?

In college, I spent some of my free time either attending seminars or reading about high profile structural engineering projects. These projects tend to be noteworthy due to their massive scale or their use of innovative construction technologies (often both). Taipei 101 is 508 meters tall, and used to be the tallest building in the world. The Burj Khalifa has surpassed it as not only the tallest building in the world, but as the tallest manmade structure at 828 meters.

 I never thought I would design the world’s tallest buildings, but I did think it would be cool to work on some mid-rises. I never did. My design firm didn’t do that type of work – which looking back, was a good thing for me. We worked on a lot of everything, including commercial, industrial, multi-family and mixed-used projects. The variety of projects meant designing with all the major building materials, including concrete, steel, masonry, and wood. Reviewing my project portfolio and thinking about what was really satisfying to work on, the projects that stand out most were wood-framed.

Continue reading

What’s Most Important To You As A Structural Engineer?

I am attending the 2012 SEAOC-SEANM Convention in Santa Fe, New Mexico this week. I did not realize that Santa Fe is the oldest state capitol in the U.S., first inhabited by Spanish settlers in 1607, and then settled by Don Pedro de Peralta in 1609-1610. The Palace of the Governors, built in 1610, served as the main government building in Santa Fe for nearly 300 years. The current capitol building, known as the Roundhouse, is the only round state capitol building in the U.S. Our airport shuttle driver used to be a tour guide, so we learned a lot on the drive in.

St. Francis Cathedral, Santa Fe. By Bill Johnson, 2005. Licensed under Creative Commons, some rights reserved.

The first session I attended today was a discussion of recent earthquakes. James Mwangi Ph.D, PE, Associate Professor of Architectural Engineering at Cal Poly, discussed his project to develop sustainable reconstruction practices for masonry and concrete structures in Haiti following the 2010 earthquake. Then Joe Maffei, Ph.D, SE, talked about lessons learned about concrete wall design from the 2010 Chile earthquake.

Continue reading