Author: Paul McEntee

A couple of years back we hosted a “Take your daughter or son to work day,” which was a great opportunity for our children to find out what their parents did. We had different activities for the kids to learn about careers and the importance of education in opening up career opportunities. People often ask me what I do for Simpson Strong-Tie and I sometimes laugh about how my son Ryan responded to a questionnaire he filled out that day: Q. What is your mom/dad's job? A. Goes and gets coffee and sits at his desk Q. What does your mom/dad actually do at work? A. Walks in the test lab and checks things When I am not checking things in the lab or sitting at my desk drinking coffee, I manage Engineering Research and Development for Simpson Strong-Tie, focusing on new product development for connectors and lateral systems. I graduated from the University of California at Berkeley and I am a licensed Civil and Structural Engineer in California. Prior to joining Simpson Strong-Tie, I worked for 10 years as a consulting structural engineer designing commercial, industrial, multi-family, mixed-use and retail projects. I was fortunate in those years to work at a great engineering firm that did a lot of everything. This allowed me to gain experience designing with wood, structural steel, concrete, concrete block and cold-formed steel as well as working on many seismic retrofits of historic unreinforced masonry buildings.

Lab Statistics – How Much Wood?

Like many people with desk jobs, I just have to get up and walk around every once in a while. Most of my walks are through our connector test lab at our home office in Pleasanton, California. The lab technicians install a lot of products for testing, so in addition to stretching my legs, I like to quiz them for ideas on things we can do to make installation faster and easier for our products.

During one of my walks this week, a lab technician was finishing up a rather extensive test setup that consumed a large quantity of lumber, screws, and truss plates. I asked him how it was going and he commented, “Testing isn’t exactly environmentally friendly, is it?”

Before I could even respond, he added, “I guess that’s just part of the price of building safer buildings.” I like the way he thinks.

So, What’s Behind A Screw’s Allowable Load?

This is Part 2 of a four-part series I’ll be doing on how connectors, fasteners, anchors and cold-formed steel systems are load rated. Read Part 1 and Part 1A.

These loads just can’t be right! Occasionally, I get this statement from engineers. This happens when they have been specifying commodity fasteners based on NDS load values and they get their first look at our higher screw values. Then the call comes in. They want to talk to someone to confirm what they are seeing is correct. I assure them the loads are right and give them this brief overview of how we got here:

Our first structural screw, the Simpson Strong-Tie(R) Strong-Drive(R) SDS, was originally load rated by plugging the bending yield strength and diameter into the NDS yield limit equations and using the load value from the governing failure mode. As later editions of the NDS modified the calculations and we did more testing, we found that the tested ultimate load of the SDS screw could be as much as ten times greater than the allowable load generated from the NDS equations.

So, What's Behind A Screw's Allowable Load?

This is Part 2 of a four-part series I’ll be doing on how connectors, fasteners, anchors and cold-formed steel systems are load rated. Read Part 1 and Part 1A.
These loads just can’t be right! Occasionally, I get this statement from engineers. This happens when they have been specifying commodity fasteners based on NDS load values and they get their first look at our higher screw values. Then the call comes in. They want to talk to someone to confirm what they are seeing is correct. I assure them the loads are right and give them this brief overview of how we got here:
Our first structural screw, the Simpson Strong-Tie(R) Strong-Drive(R) SDS, was originally load rated by plugging the bending yield strength and diameter into the NDS yield limit equations and using the load value from the governing failure mode. As later editions of the NDS modified the calculations and we did more testing, we found that the tested ultimate load of the SDS screw could be as much as ten times greater than the allowable load generated from the NDS equations.
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Soft-Story Retrofits

In February 2007 I had the opportunity to volunteer for a Soft-Story Sidewalk Survey for the San Francisco Department of Building Inspection. The purpose of the survey was to inventory buildings in San Francisco that appeared superficially to have soft or weak first stories. The volunteers were given a list of addresses to review and we recorded if the building was more than three stories tall, had five or more dwellings, and estimated what percentage of the ground level had openings in the walls. No structural analysis going on, just counting stories, mailboxes, doors and windows.

San Francisco soft-story structure. Photo credit: USGS. — San Francisco soft-story structure failure. Photo credit: USGS.

A collapsed house in San Francisco from the 1989 Loma Prieta earthquake. Photo credit: Adam Teitelbaum, AFP, Getty Images. — A collapsed soft-story in San Francisco from the 1989 Loma Prieta earthquake. Photo credit: Adam Teitelbaum, AFP, Getty Images.

Tell Us Your Genuine Story for a Chance To Win!

You may have noticed that the cover of our new 2013-14 Wood Construction Connectors Catalog features the word GENUINE. What do we mean by Genuine Simpson Strong-Tie Connectors? It’s really based on our roots and our founder Barclay Simpson, who made his very first connector for a customer in 1956. Barc believed in doing whatever it took to help the customer succeed.Today, helping the customer remains our number one priority. Whether that’s being on a jobsite to help with a product installation, spending endless hours on R&D and product testing or making sure our products get to our customers on time. This is what we promise to do everyday, and we do it genuinely.Continue Reading

Corrosion: The Issues, Code Requirements, Research and Solutions

When you hear $452 billion, what comes to mind? Perhaps the annual state budgets of California, Texas, Florida or New York? Maybe the combined net worth of Bill Gates, Larry Ellison, or the Walton Family? While those would be good guesses, I bet you didn’t think of corrosion! According to a May 2012 Congressional Briefing hosted by NACE International and ASM International, corrosion-related costs are a staggering 3.1% of the U.S. GDP, which is more than the individual budgets of those states above, and the combined net worth of the top 15 people listed on the Forbes 400: The Richest People in America.

Corrosion of metallic surfaces is an electrochemical process typically involving an anode, electrolyte and a cathode. An anode is a metal zone which loses electrons when exposed to an electrolyte, an electrolyte is a non-metal electrical conductor, and a cathode is the zone where an oxidizing agent (e.g., oxygen) gains the electrons. While there are many different forms of corrosion (e.g., pitting, intergranular, wet storage stain, etc.), and various sources of causes (e.g., treated lumber, moisture level, temperature, atmosphere, air quality, etc.), other factors such as exposure related to time of wetness are equally important. In a study presented in Dr. X.G. Zhang’s book Corrosion and Electrochemistry of Zinc, time of wetness is 50% greater near the top of a structure compared to the bottom, leading to greater corrosion.

Load Testing, Last Day To Enter Our Contest, And Happy Holidays!

With all of the frenzy that happens before (and during) the holidays, I won’t be doing full blog posts this or next week. But, I did want to remind you that this Thursday (12/20) is the last day to enter our “Creative Uses of Our Product” contest. We’ll post our five winners to the blog next week.

This week will be a short snapshot into what we were doing yesterday. We are always testing products and usually the only people who stop by to watch the tests besides the lab technicians are an R&D engineer and occasionally the product manager. As valuable as testing is, the simple day-to-day stuff just doesn’t generate much excitement – crushing bowling balls is fun and gets a crowd, but we save that for orientation classes.

Taking Wood-Framed Construction to New Heights

When I had more hair and less of it was gray, I worked on a project as an assistant engineer doing the calculations for a mixed-use building in San Jose, California. Final design consisted of four stories of wood framing over a concrete podium slab and another level of below-grade parking. At that time, my firm had designed many two- and three-story residential buildings, but common thinking was you switched to steel or concrete for taller structures because of perceived limitations in wood-framed construction.Continue Reading

Vote For Your Favorite “Creative Use of Our Product” Photo For A Chance To Win!

In my previous life as a building designer, I occasionally saw some creative installations of Simpson Strong-Tie products. These usually came in the form of an RFI where the contractor was asking for forgiveness for a misinstallation. However, this week’s post pays tribute to the creativity and ingenuity of our customers. The following photos are some of my favorite interesting applications and creative uses of our products. Some are purely utilitarian, which describes most of the aftermarket automotive uses. Others have a unique beauty while solving a problem or filling a need. Some are truly works of art and the rest are just plain silly. I hope you enjoy them as much as I do.

Tell us which picture is your favorite by posting a comment, or tell us about an interesting application or creative use for Simpson Strong-Tie products you’ve seen. We’ll be awarding five commenters with a Simpson Strong-Tie Prize Pack via random drawing (one entry per person, please). Details and rules here.