Welcome to our Structural Engineering Blog! I’m Paul McEntee, Engineering R&D Manager at Simpson Strong-Tie. We’ll cover a variety of structural engineering topics here that I hope interest you and help with your projects and work. Social media is “uncharted territory” for a lot of us (me included!), but we here at Simpson Strong-Tie think this is a good way to connect and even start useful discussions among our peers in a way that’s easy to use and doesn’t take up too much of your time. Continue reading
Engineered wood products have been used in wood-framed construction for many decades. Early forms of engineered wood include plywood as replacement for 1x wood sheathing and glu-laminated beams that could be fabricated in larger sizes with optimized material utilization. I-joists utilizing deep plywood webs and solid sawn lumber flanges solved the challenge of longer floor spans. Oriented strand board (OSB) eventually replaced plywood in the webs, while the innovation of laminated veneer lumber (LVL) became common in the flange material.
In addition to I-joists, structural composite lumber is widely used as a replacement for solid lumber. This could be for a number of reasons such as availability of longer lengths, straighter sections and higher strengths. Structural composite lumber (SCL) may be LVL, parallel strand lumber (PSL), laminated strand lumber (LSL) or oriented strand board (OSB).
Structural composite lumber has two faces. If the cross-section is rectangular, say 3½x5¼, the narrow face will show the edges of the SCL layers. In a square section, the face that shows the SCL layers is still referred to as the narrow face. Fasteners will have lower performance when they are installed in the narrow face of SCL. While this is not an issue for beams, Simpson Strong-Tie connectors such as post bases, column caps or holdowns may have reduced allowable loads when installed on the narrow face of SCL columns.
To support the use of Simpson Strong-Tie connectors installed on SCL post material, we have run many tests over the years. The reductions are published in the technical bulletins, T-SCLCLM13 (U.S. version) and T-C-SCLCLMCAN13 (Canada version). The reduction factors range from 0.45 to 1.0, and vary based on SCL material type – LSL, PSL, or LVL – and also by connector and fastener type.
It is important to understand the magnitude of the reductions. While narrow face installations may be unavoidable, engineers will need to specify the correct lumber and hardware combination to meet the design loads.
Share additional thoughts by leaving a comment.
In this earlier post, I shared the story of my brother-in-law indicating that he thought some of the connectors specified on a swim club project were “ugly.” The contractor and I were able to come up with some other options, but I guess I’m still upset with my brother-in-law for calling Simpson Strong-Tie® connectors ugly. I’ll have to walk into his office sometime and comment on the attractiveness of his financial audits. How pretty are those nonrecurring charges, unrealized capital gains and special purpose entities?
The shade structure at the cabana club looks awesome, by the way. While engineers may identify the powder-coated hardware as Simpson Strong-Tie, everyone else just thinks it looks safe and strong.
Not every use of connectors is going to be Michelangelo’s David, but Barclay Simpson loves artwork incorporating our products. So Simpson Strong-Tie was happy to work with Portland-based photographer Jim Golden to create a photograph of our connector products. We’re calling it our Genuine Connector Collection.
In addition to doing amazing portraits and still life photos, Jim likes to work with everyday objects to create something beautiful. He creates portraits of unique collections. The items from each of his collections may come from a different time or place. They tell a story about the evolution of a product: how the design has changed over the years and all of the different iterations of a product.
I am so excited because it is a special way for us to tell the Simpson Strong-Tie story. Barclay Simpson started off with one joist hanger in 1956. It is clear from the photograph that our portfolio of engineered connectors has grown significantly from that one joist hanger. There are nearly 100 connectors featured in the photo and that is still just a small sample.
Jim Golden not only knew about Simpson Strong-Tie and our products, he has actively used them for building decks, home renovation projects and creating things like skate board ramps. His passion about Simpson Strong-Tie is apparent by the meticulous care he took to arrange the products and create the final photograph.
Click here to watch a short video of Jim Golden in action with Simpson Strong-Tie connectors and subscribe to our YouTube channel to be notified of new video posts. You can also download digital wallpaper of the photograph so that you can have some industry art of your own to admire!
(And if you’re really a fan like me, ask your local sales rep for a poster.) We’d like to hear from you – tell us what you think of the new image and if you’ve ever used our products as art.
[Simpson Strong-Tie note: Shane Vilasineekul is the Simpson Strong-Tie Engineering Manager for the Northeast U.S. and one of our guest bloggers for the Structural Engineering Blog. For more on Shane, see his bio here.]
Are you finding it difficult to keep your fees competitive?
“Codes are becoming more complex.”
“Builders are demanding lower construction costs.”
“If I don’t allow this they will find an engineer who will.”
“Competition is stiffer.”
“New proprietary systems take too long to evaluate.”
“We have less time to do our job”
“Architects don’t give us enough to work with.”
“Other engineers are not doing it right.”
Working at Simpson Strong-Tie for 15 years, I have had the opportunity to speak with thousands of engineers and these are recurring themes. Some of these issues are way above my pay grade, but there may be something each of us can do to help keep our profession healthy.
A few years ago we had Susan Dowty from the California offices of S.K. Gosh speak at our SEA of Ohio conference. After her presentation, she stuck around to hear Steven Regoli from the Ohio Board of Building Standards. The gist of his presentation was that Ohio building officials don’t have the authority to reject sealed plans or even require calculations to be submitted unless there is clear evidence of a code violation. Midway through, a very lively discussion broke out between Susan and Steven about the responsibilities of plans examiners as they relate to structural design. On one side you have plans examiners who are licensed engineers and perform something akin to a peer review, and on the other side you have plans examiners with little engineering background that rely on the licensed engineer to ensure structural provisions are met. With some exceptions, the first view is held by many western states and the latter by many states in the South, Midwest and East Coast.
So how does this affect engineering fees? Well, when all it takes to collect a fee is a sealed set of structural plans, the temptation is there to cut corners in the design process and, in an increasingly competitive market, provide clients with a building that costs less to construct than one properly designed. I take pride in working in a profession that holds ethics in such high regard, but it only takes a few to give in and disrupt the market in a particular region. It seems like these “few” are gaining in numbers the last several years. Without proper checks and balances, this trend could continue.
So what can we do about it? I don’t think local government would be open to increasing the payroll for building departments to hire more engineers to review plans (building departments in Ohio saw some of the first and most severe cuts during the recent recession), but maybe we can help raise the bar for structural plan review. Steven Schaefer, the founder of Schaefer structural engineers in Cincinnati, decided years ago to take it upon himself to educate Ohio building departments on the fundamentals of structural engineering. He regularly presents at their meetings and has even created a guide to help plan reviewers look for proper load paths and lateral force-resisting systems. Next week he will be presenting four courses at their state conference and will be honored with an award for all his efforts over the years. We may not all be able to have the same impact, but most of us could spare a few hours each year to work with our local engineering association to reach out to building departments and offer training and support.
Leave a comment if you have some ideas on how to maintain our high standards, or better yet, share some successes you have seen in your area.
In January, our engineer Shane Vilasineekul wrote about his top ten mobile apps. Today we’re talking social media and how it can help you be better at your job. Now I know that the common notion of social media is that it is more of a place to goof off from work, but stay with me here. Think of social media as a place where people can meet. There is a big difference between bars versus a conference for professionals. While they are both places where people can meet in one spot, they perform different functions. Social media is the same way. It can be used for non-professional networking, but it can also be a helpful place where structural engineers can learn about new products, industry news and trends.
Here are ways that structural engineers can use social media:
Use Twitter for Industry Events and Trends: Twitter’s strongest point is its brevity. With a 140-character limit, tweets can really get to the point. Another reason that Twitter is useful is that it is often the social media platform where you see things unfold in real time. For example, you can search industry specific events and see tweets in live time and learn about the demonstrations and seminars your colleagues think are useful, the ones to skip, etc.
LinkedIn Is An Industry News Resource: LinkedIn is not just a place to show off your resume any more. LinkedIn is becoming a hub for industry news. Do you want to know what is going on with other structural engineers? You can join industry specific groups to share tips and ideas. It’s also good practice to follow companies and clients that you work with so you know when they launch a new product, promote a new project or even share their own social media content.
Subscribe to Blogs: Following structural engineering blogs like this one ensures that you never miss a beat about what other industry folks are saying. Subscribing to a blog post means that you can read all the content an industry blog has to offer all from the comfort of your inbox. Blogs also can cover day-of/breaking news that you can’t get from trade publications.
Facebook For Recommendations: While you may look at Facebook as a more family and friends zone, there is something to be said for interacting with fellow structural engineers on this platform. If you are friends with former classmates, you will find a bevy of articles that are helpful for you from an industry standpoint. You can also ask industry specific questions to your friends or ask for recommendations from people you know and trust. Following company pages opens up opportunities to give ideas for new products, learn new product uses, or even find out about new promotions and offers.
YouTube For Educational Videos: An educational video can be a lot more effective and useful than reading a paper. Seeing how a company does product testing may even take the guesswork from your own job. At Simpson Strong-Tie, we make videos for our YouTube channel so you can see our products in action whether it’s a test or even a DIY project.
I hope this blog post takes the guesswork out of social media for you. While these are some starter suggestions, the sky is the limit. What do you use social media for? Do you see professional benefits? Let us know in the comments section.
My wife and I have been attending a boot camp class for a little over a year now. We have a great coach who always varies the workouts and keeps things fun while really challenging us. He likes hip hop music, so that is what we listen to as we suffer through our squats, kettle bell swings and burpees at 5:30 in the morning. I really just told you that story so I could tell you another one.
Earlier this week I was talking to one of our younger R&D engineers about a test project and I responded to one of his questions with a quote from rap lyric. You have to throw humor into engineering meetings when you can. He laughed and then gave me a puzzled look and said, “I’ve never had a boss anywhere near your age who knew who Jay-Z was.” I try to take it as a compliment, but I think he was calling me old. He would also be surprised to know I have my own YouTube channel, mostly so I can post videos my daughter creates of herself making rainbow loom rubber band bracelets. I think my channel has zero followers.
Simpson Strong-Tie also has a YouTube channel where we have videos on a variety of topics relevant to designers, contractors and do-it-yourselfers. Be sure to check out a new video called “FX-70® Pile Repair Cyclic Testing” on the Simpson Strong-Tie YouTube channel. It gives an overview of the testing we did to support one of our new products, the Simpson Strong-Tie® FX-70® Structural Repair and Protection System. This video captures the industry’s first scaled, cyclic test of a repaired wood pile.
As you may recall, I wrote a post last September called Not Just a Connector Company describing how our Engineering/R&D team developed and performed the test protocol for this product. FX-70 is a part of our Repair, Protection and Strengthening Systems for Concrete and Masonry, which is the result of our acquisition of Fox Industries, Inc., in 2011.
FX-70, which has been used successfully for more than 40 years, uses high-strength fiberglass jackets and high-strength water-insensitive grouting materials to repair and protect wood, steel and concrete structural members.
We wanted to evaluate the performance of the system under seismic loading. And, the cyclic static test frame at our Tye Gilb Research Laboratory in Stockton, Calif., enabled us to fully test the system on 16-foot-tall wood piles.
The results of this test will provide structural engineers with real-world data to help them evaluate the FX-70 system as a potential solution to their structural repair applications.
Tell us what you think of the video and testing.
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.
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.
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.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 ⅝” 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.
The allowable loads for Strong-Drive SDWH and SDWS structural wood screws are provided in an engineering letter, L-F-SDWSHGYP13. 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.
This week’s blog was written by Branch Engineer Randy Shackelford, P.E., who has been an engineer for the Simpson Strong-Tie Southeast Region since 1994. He is an active member of several influential committees, including the AISI Committee on Framing Standards, the American Wood Council Wood Design Standards Committee, and the Federal Alliance for Safe Homes Technical Advisory Committee. He is vice-president and member of the Board of Directors of the National Storm Shelter Association. Randy has been a guest speaker at numerous outside seminars and workshops as a connector and high wind expert. Here is Randy’s post:
In my last blog post, I gave an overview of FLASH, the Federal Alliance for Safe Homes, and how Simpson Strong-Tie partners with them. Last November, FLASH held their Annual Conference. The theme of this past meeting was “15 Years of Stronger Homes and Safer Families,” and it was one of their best conferences yet.
One of the highlights of the conference was a viewing of the Center for Disease Control’s unique Zombie Apocalypse campaign. The idea is that preparing for disaster is very much like preparing for a zombie attack. While it was fun, it was also educational because it tied into FLASH’s mitigation methods too.
A very interesting panel on the first day of the conference dealt with how members of each generation handle things differently. A panel of Baby Boomers and Millennials (Generation Y) highlighted the fact that different generations had different ways of doing the same thing.
See the link below for an interesting summary of Baby Boomers, Gen X and Gen Y:
One highlight of the first afternoon of the conference was the RenaissanceRe Challenge. The challenge involved two teams of university students who had a chance to present their idea for projects to help Florida citizens confront wind events. The winning team of the challenge would receive a $20,000 scholarship. The team from Florida International University presented their idea for “Aerodynamic Intelligent Mitigation.” This consisted of a retrofittable element that is placed around the edges of a roof that has been proven to reduce uplift forces on the roof. Meanwhile, the team from the University of Florida, the Miti-Gators, countered with their idea for a cell phone “app” that would evaluate the wind resistance of a house. The idea would be that any prospective homebuyer could evaluate a home they were considering purchasing to see how wind resistant it would be compared to other homes. This is important because in Florida, 70% of homes were built before the Florida Building Code was adopted. In the end, the Miti-Gators won the scholarship.
Being a building-code nerd, the definite highlight of the second day was the panel discussion about building codes. Here are some of my favorite key takeaways:
- The building code is the first opportunity to ensure that buildings are built properly. Mitigation is the second opportunity.
- Legislators need to mandate adoption, consumers need to demand use, enforcers need to ask for adequate funding, and builders need to understand.
- So little attention is given to building departments and enforcers, more attention is given to the fire department and local police.
- Building codes originated due to disasters. We need to change the purpose of codes from safety to resiliency. We need to worry about what will happen to the building stock for years to come, not just the first cost today.
- The insurance industry has found that where codes are scientifically sound, consistently enforced, and implemented across communities, the return in investment in building codes is large.
- Building codes are one of the cornerstones of effective mitigation. There are not many other places where you can make a change that will have an effect in perpetuity.
- Building codes are an expression of society.
- Building code adoption is the battle between making buildings safe and the increased costs to the builder and developer. The builder does not get the long-term benefits that the owner does.
- The 800 pound gorilla is public policy: The risks people face are being masked by pandering politicians. Public policy interferes with the message that people need to understand their risk. The way to help people understand their risk is through the marketplace setting rates for insurance.
- A distorted market deprives consumers of proper pricing signals that can encourage dangerous behavior.
- Preparedness will not become a part of society until it is profitable
- The difference between natural hazards and natural disasters is that nature causes the hazard, and human behavior causes the disasters.
- Education of the public is the answer. Owners must be taught to overcome the thought that “This natural disaster MIGHT happen, but I know that if I spend the money to prepare now it WILL cost me, so I’ll take the risk.”
- People need to understand that “Disasters don’t just happen to the other guy.”
Finally, in the conclusion, “Building codes work; they save lives; stay the course; we’re making a difference.”
I couldn’t have said it better my self.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.*
What are your thoughts? Visit the blog and leave a comment!/p>
A few days ago, I was speaking to a customer about an application using alternate fasteners 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, C-2013 provides multiple options for alternate nailing for face mount hangers and straight straps on page 22.
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.
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!
Happy New Year! This week’s blog was written by Branch Engineer Randy Shackelford, P.E., who has been an engineer for the Simpson Strong-Tie Southeast Region since 1994. He is an active member of several influential committees, including the AISI Committee on Framing Standards, the American Wood Council Wood Design Standards Committee, and the Federal Alliance for Safe Homes Technical Advisory Committee. He is vice-president and member of the Board of Directors of the National Storm Shelter Association. Randy has been a guest speaker at numerous outside seminars and workshops as a connector and high wind expert. Here is Randy’s post:
As part of our mission to “help people build safer structures economically,” Simpson Strong-Tie works with many non-profit groups around the country, including the American Red Cross, Habitat for Humanity, and the National Storm Shelter Association. Another group we work with is FLASH, the Federal Alliance for Safe Homes.
The mission of FLASH is “Strengthening homes and safeguarding families from disasters of all kind.” FLASH recently celebrated its 15th year, and Simpson Strong-Tie has been right there with them for most of those years.
Creating the StormStruck® Experience
Perhaps the biggest outcome of our work with FLASH is our partnership in “StormStruck: A Tale of Two Homes®, located at INNOVENTIONS in Epcot® at the Walt Disney World Resort. StormStruck is a fun, interactive 4D experience that teaches visitors the steps they can take to protect their homes and families during severe weather. Visitors experience a storm and its effects on the “house” they are sitting in, and then decide how to best rebuild to resist the next storm. StormStruck has been seen by almost 800,000 people in the past year, and more than four million since opening in 2008. If you visit EPCOT®, be sure to head over to INNOVENTIONS East to see our exhibit. Continue reading