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.
Simpson Strong-Tie is sponsoring the 23rd 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 (4th 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.
I’m excited to share some tips on getting more involved with the structural engineering community. There are many organizations and industry associations related to structural engineering that it can feel daunting to try to meet all of the key players and make a name for yourself.
I have a really unique and fun job at Simpson Strong-Tie as a field engineer for our light-frame construction products, which include connectors, fasteners, and lateral systems. As a field engineer, I spend most of my time out on the road visiting engineers, architects, building officials, contractors, and others who need technical assistance using our product lines. While this means I spend a good chunk of time in SoCal traffic, I do get to talk to lots of different people working on projects ranging from small home remodels that might be using our new Strong-Frame® special moment frame to huge multi-family housing projects with several thousand units.
I also make sure to attend as many industry association functions as I can, because these are the best places to network and meet other professionals. There are many great organizations, including the Structural Engineers Association, which has chapters all over the United States. The California chapters have very strong participation. I also suggest getting involved in other industry organizations that include people outside of the profession, such as building officials, inspectors, contractors, builders, and architects. These people play an integral part in the construction industry and it’s important to understand their role and importance in supporting structural engineering.
Steel Deck Institute (SDI) is hosting a “Designing With Steel Roof Deck” webinar on October 23 and November 13 at 11 a.m. EST. The webinar is intended to expand participants’ knowledge of steel roof deck by introducing them to the benefits, manufacturing processes, shapes, properties, and finishes of this product. The basis of the presentation is SDI’s new Roof Deck Design Manual, which will be provided to participants. Various roof deck design considerations will be explored as well as an overall coverage of fasteners and industry construction practices.
CANAM/United Steel Deck and Vulcraft will be presenting. Simpson Strong-Tie will be moderating the webinar and providing two PDHs (0.2 CEUs) for participants. Click here to sign up for one of the webinars.
I write a lot about testing on this blog, from my first post about testing to the series I did on how we test different products (hangers, holdowns, fasteners). This week I’d like to highlight some unique testing we’ve been doing to support one of our new product lines. Simpson Strong-Tie® recently introduced our Repair, Protection and Strengthening Systems for Concrete and Masonry. The new product line is the result of our acquisition of Fox Industries, Inc. in 2011.
In the past, I’ve shared some of the more fun tests we’ve run, like the bowling ball test or 40 kip hangers. This week we’ll take a sneak peek at testing of the FX-70® Structural Repair and Protection System. FX-70 uses high-strength fiberglass jackets and high-strength water-insensitive grouting materials to repair and protect wood, steel, and concrete structural members. The system is primarily used on piles in marine environments.
Fx-70 installation on wood piles. Image credit: Simpson Strong-Tie.
Around Christmas, the Engineering Department does a white elephant gift exchange. We have no idea who framed this picture and wrapped it up the first time.
Several of our lab technicians (plus a product manager) are posing for the camera, and obviously trying to flex while sucking their bellies in during a concrete pour to test our SSTB(R) anchors. The tradition has it that if you end up with this picture, you hang it on your wall and re-gift it at next year’s gift exchange – so there it is, on the wall in Engineer Dustin’s office. The trick has become wrapping it so that nobody recognizes that it is the picture frame.
Speaking of concrete, between our test labs in Addison, Ill., Stockton and Pleasanton, Calif., we test a lot of concrete. We will certainly be doing a lot more testing to continue to support our new Repair, Protection and Strengthening Systems for Concrete and Masonry product line. But I will ask the lab technicians to keep their shirts on.
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.
I worked several summer internships while in college, and as an employer I find them to be mutually beneficial. Companies are able to complete tasks they haven’t had time for, and students gain valuable work experience. I have been lucky to have two very good engineering interns this summer. In the spirit of having interns do my work for me, I thought it appropriate to have Robert write a blog post this week. Robert will be finishing up his degree in Architectural Engineering from Cal Poly San Luis Obispo this winter. Here is what Robert wrote about what it’s like to be an engineering intern:Continue Reading
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:
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.
One of the first projects I worked on when I got out of school was the Mexican Heritage Plaza in San Jose, California. It was a 200,000 square-foot facility with a theater, classrooms, art gallery and gardens. It was my first time using ETABs and SAFE for the building frame and mat slab designs, and there was no graphical interface. Text file input – those were the days! I learned how to detail bolted and welded steel connections, and then I got to enjoy every junior engineer’s first right of passage – reviewing shop drawings. It was eye-opening to learn that a detailer needed to translate all the dimensions, size call-outs and typical details into exact measurements down to the sixteenth of an inch for every single member, bolt, and hole.
I am sure I spent too much time reviewing them and checking that all the numbers added up. Photocopying E-size drawings was more expensive than a junior engineer’s time back then, so before I hand copied my mark-ups over to five sets of drawings, I reviewed them with my manager. She circled the high-strength anchor rods for the special moment frames and wrote “Too short – recheck.” I pointed out that I had checked the grout pad, base plate and washer thickness to make sure the anchor rods extensions were long enough to fully thread the nuts on (they just worked). She told me that high-strength anchor lengths were always too short. It didn’t make sense to me at the time, but I marked up the drawings and sent them off. More on this later.
Common specifications for steel anchor rods used for concrete anchorage are ASTM A307, A449 and F1554 Grades 36, 55, 105. Some of these anchor rods have specifications appropriate for welding. According to AISC Design Guide 21 on Welded Connections, “unless the supplier of the anchor rod can provide assurance that the compositional limits of ASTM A36 have been achieved, weldability of F1554 Grade 36 should be investigated”. Both ASTM F1554 Grade 55 and ASTM A307 provide supplementary requirements for welding applications in Section S1. The S1 requirements limit the percentage of carbon equivalent permitted for the metal alloy. Where welding is required designers should specify F1554 Grade 36 with the compositional limits of ASTM A36 or F1554 Grade 55 ordered with supplementary requirement S1. ASTM A307 specified with supplementary requirement S1 can be ordered for anchor rods where welding is required.
Threaded Rods
There is a blend of art and science in the manufacturing of high-strength steel anchor rods (ASTM F1554 Grade 105, A325 and A449). Like a pastry chef, creating a perfectly baked soufflé with the correct ingredients and temperature, modern day blacksmiths achieve a balance of strength and ductility characteristics for anchor rods through controlled quenching and tempering treatments. The rapid cooling of metal through quenching increases toughness and strength, but it often increases brittleness. Tempering is a controlled reheating and cooling of the metal which increases ductility after the quenching process. Precise control of time with the application of temperature during the tempering process is critical to achieve an anchor with well-balanced mechanical properties.
Coupler Nuts
AISC does not recommend welding of high-strength anchor rods including, but not limited to, ASTM F1554 Grade 105, A325, and A449. The heat input from welding can alter the physical properties and other elements from the weld metal are introduced altering the metal alloy for high strength anchors. Similarly, quenched and tempered steel used to fabricate high strength nuts or couplers is also not suitable for welding.
Now let’s get back to my first steel project. We asked the steel detailer to recheck the anchor rod lengths, and they added 1” of extension above the top of concrete and shipped the assemblies with 16-gage steel templates attached with double nuts. Several templates were damaged in shipping so the contractor fabricated new ones. Somewhere in the process of swapping out templates and reattaching them with double nuts, the anchor rods were set 1” too low. Since the detailer added 1”, everything fit perfectly. And I understood why high-strength anchor rods could never be too long.
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Steel Deck Institute (SDI) is hosting a 
