We know many of you visit our website on a regular basis for product and technical information and to use our software, calculator tools and other web apps. If you haven’t visited strongtie.com recently, it has a new look and several new features, including enhanced search and browsing and a mobile-friendly design. Here are some of the new features and site improvements:
Update-to-date product information: If there is a new code report, catalog or product you will be able to find that information on our new website first. It has the latest product and technical information while retaining the same features and information you expect.
Enhanced search and browsing: You can now search for our products based on specific product attributes. Our enhanced search capabilities allow you to explore our collection of products by applying filters so you can quickly and easily browse and find the products that you are looking for.
Mobile-friendly: Our new site has a responsive design that allows you to view the site in any format. From large desktops to mobile devices, you can view our site in the office or while on the go.
Enhanced Visuals: We have added new and improved photographs, illustrations and graphics so that you can see our products in greater detail.
We hope the new website better serves your design and technical needs. If you have any suggestions, comments or feedback, please email us at email@example.com or leave a comment below.
This week’s post comes from Scott Fischer who is an R&D Engineer at our home office. Since joining Simpson Strong-Tie in 2006, Scott has worked on cast-in-place connectors to concrete. He helped develop the current testing criteria for cast-in-place concrete products and also performed the testing and code report requirements needed for these product lines. Prior to joining Simpson Strong-Tie, Scott worked for nine years as a consulting engineer. His experience includes the design and analysis of concrete structures, including post-tensioned slab design, concrete lateral systems and foundations. Scott is a licensed professional engineer in the state of California and received his bachelor’s degree in Architectural Engineering from Cal Poly San Luis Obispo.
How often do you get the opportunity to high five a co-worker in the office? Maybe it’s when you just worked through a really complex calculation, or finally figured out that tough detail. Whatever it might be, there are times when we should raise a hand and celebrate the hard work that we do. So when we recently relaunched the Simpson Strong-Tie Strong-Rod™ Systems website, which includes a link to our new Shallow Podium Anchorage Solutions, there were a few high fives going around the office. With that in mind, we want to share the latest developments and continue our anchorage-to-concrete blog discussions that began in May 2012, continued with a March 2014 post referencing the Structure magazine article on anchor testing, and more recently one discussing our release of anchor reinforcement solutions for Steel Strong-Wall® shearwall to grade beams.
Anchor Reinforcement Testing and Research Program
Simpson Strong-Tie has been studying cast-in-place tension anchorage and anchor reinforcement concepts extensively over the past several years. Designing an anchor solution in a thin concrete slab for a high anchor demand load while meeting the ductility provisions of ACI 318-11, D.18.104.22.168 is extremely challenging. A strong industry-need for a safe, logical, yet economical design solution, led to a cooperative research program between Structural Engineers Association of Northern California (SEAONC) members and Simpson Strong-Tie. Testing was initiated by a Special Project Initiative grant from SEAONC to members Andy Fennell, P.E. (principal at SCL) and Gary Mochizuki, S.E. (principal at Structural Solutions at the time, now with Simpson Strong-Tie). We completed the program with continued involvement of SEAONC members. This is the second time we have partnered with SEAONC on non-proprietary anchor bolt testing. The first partnership, on sill plate anchor bolts in shear, resulted in successful code change provisions (led by SEAONC) restoring the capacity of these connections to pre-ACI 318 Appendix D values.
This current research program has focused on non-proprietary anchor reinforcement detailing that increases the nominal breakout capacity of concrete slabs. The anchor design satisfies the seismic ductility requirements of ACI 318-11 Appendix D and also significantly increases design capacity for wind applications. The project goal was to provide a design solution for the industry with independently witnessed proof testing of the anchor reinforcement detailing and application of ACI 318-11 Appendix D design procedures. (Note: Appendix D is moved into a new Chapter 17 in ACI 318-14.)
Significant Test Findings and Design Concepts
Anchoring to relatively thin concrete slabs introduces many unique challenges, so testing was bound to reveal some unique findings. The goal was to increase concrete breakout capacities and also satisfy the ACI 318 anchor ductility requirements with anchor reinforcement detailing. Here are some of the significant findings:
Relatively thin concrete slabs do not allow the placement of anchor reinforcement to drag the load down into a larger mass of concrete as shown in RD.5.2.9. Modified anchor reinforcement was required (Figure 2). The required area of anchor reinforcement is based on D.22.214.171.124(a) where the required area of anchor reinforcement exceeds the anchor steel strength, or 1.2Nsa < (nAsfy x 0.707). The 0.707 is for the 45 degree slope of the bars. The proof testing showed the horizontal leg development outside the cone and continuity through the cone adequately developed the anchor reinforcement.
ACI 318-11, D.4.2.1 states that when anchor reinforcement is provided, calculation of concrete breakout strength is not required. You know we love load path discussions, so where does the load go once it gets into the anchor reinforcement? The tests indicated that when the anchor reinforcement is provided, the concrete breakout area increases. This limit state is an extended breakout area past the anchor reinforcement bends that will form when that reinforcement is properly quantified and configured. The extended breakout is similar to multiple anchors loading the slab at each bottom bend of the anchor reinforcement. We have applied this concept to the calculations to evaluate extended breakout past the anchor reinforcement bends.
Let’s follow the load path some more. Once the anchor is connected to the slab, what is the slab bending capacity? The testing showed that to achieve the anchorage capacity, the slab must have an adequate amount of flexural reinforcement with anchorage forces corresponding to ACI 318-11, Section D.126.96.36.199 applied to the slab. Guidance from this section says to apply the anchor tension loads obtained from either design load combinations that include E, with E increased by Omega, or 1.2 x Nominal steel strength of the anchor (Nsa). If the anchors are not oversized, designing for 1.2Nsa should be the most economical solution. For wind applications, the slab Designer should consider the project specified design loads.
A vertical concrete block shear forming at the anchor bearing plate is possible if the anchor embedment is shallow and the anchor reinforcement is working to resist the initial anchor bolt breakout area. Our testing showed that this block shear is separate from Appendix D Pullout and is dependent on embedment depth, perimeter of the bearing surface and concrete strength.
For anchors with shallow embedment that have a double nut and washer, the concrete breakout can begin from the top nut, thereby reducing the effective embedment depth. To address this, we eliminated the top nut from our specified anchor assembly kit to insure the breakout begins from the top of the fixed-in-place plate washer.
The testing and modeling also allowed us to re-examine the appropriate bearing area for the plate washer, Abrg. The flat top surface of a nut is typically circular due to the chamfer at the points, so the resulting bearing area of the plate washer is circular extending out the thickness of the plate from the flat-to-flat dimension of the nut. For near-edge conditions, the side-face blowout capacity can be the controlling limit state and where the plate washer bearing area becomes more important.
Edge testing with anchor reinforcement details showed that the breakout area will spread out and begin from the anchor reinforcement bends, like the mid-slab. In a mid-slab condition, the breakout slope follows the 1.5:1 or 35 degree slope used in Appendix D. However for the near edge, we found that 1.5 x effective embedment (hef) from anchor reinforcement bends only holds true parallel to the edge. Due to eccentricities, the breakout angle from the anchor reinforcement bends into the slab (perpendicular to the edge) is steeper and a steeper 45 degree slope should be used.
The testing showed that even though we had cracks intersecting the anchor as it was loaded, the capacities exceeded uncracked assumptions. This is likely due to the flexural reinforcement running through the breakout cone providing continuity across the cracks. We’re still studying the effect of the flexural reinforcement, so for now we recommend assuming cracked concrete and providing a minimum of 4 – #5 flexural bars each way at anchor locations that require anchor reinforcement. Your slab design may require more flexural bars or they may already be there to meet other slab design requirements.
What Solutions Are Now Being Offered and How Do I Get Them?
With our newly launched Strong-Rod Systems webpages, you now go to the Shallow Podium Anchor link to find anchorage solutions. On the website, you will find anchor reinforcement detail drawings and design load tables with slab design recommendations. We’ll also be adding sample calculations, a guideline for selecting your anchor solutions, 3-D anchor reinforcement graphics and guidelines for addressing your condition if your installation is outside the scope of the current solutions that we offer. The anchor reinforcement is non-proprietary and is fabricated by the rebar supplier, but the configuration and placement is described in the details. In addition, you will see detailed information about the Simpson Strong-Tie Shallow Anchor Rod and Anchor Bolt Locator that is specified as a kit in the load tables. Note the absence of the top nut for reasons described above.
How Do We Specify It and Use It?
So now you know what is on the website but how do you put all these pieces together and apply them to a specific design? As a design professional, you will drive the bus on applying these details and design tables onto your drawings. Similar to specifying Strong-Wall® shearwalls or Strong Frame® moment frames, it just takes a little upfront coordination on your drawings. Typically, you’ll start with a slab key plan that shows the anchor bolt locations. You will need to know the design uplift forces from the light-frame structure above the slab and some basic project variables like specified concrete strength, slab thickness(es) and whether the structure is in high seismic or wind-controlled areas. Now you can choose the necessary design tables from the website by clicking on the individual design tables tab. Your key variables will help you select your specific table based on slab thickness, concrete strength, near edge, etc., and of course wind or seismic.
Once you have selected your design table, just match your project demand loads or your project-specified anchor bolt with the tabulated ASD or LRFD capacity to select the appropriate shallow anchor callout and reference detail that you can identify on the key plan. The detail callout from the table will send you to sheet SA1 where you will find the anchor reinforcement details and Shallow Anchor Kit recommended for your condition. As mentioned previously, the anchor reinforcement would be fabricated and bent by the rebar guys, but would follow these details. You can download the details shown on sheet SA1, place them on your construction documents and then coordinate them with your plans or schedules similar to how you might provide a shear wall schedule. The footnotes that accompany the tables provide important slab design information and other design and installation recommendations. You’ll soon be able to download the sample design calculations, use them as a tool to help follow the design procedure of the recommended details and submit with your project.
What if My Situation Does Not Fit the Details on the Website?
Though a great number of installations will be covered by these details and tables, there will be conditions that currently cannot be addressed with anchor reinforcement solutions. Installs that may be outside of the current scope could include: a demand uplift that’s too large, a slab that’s too thin, lower concrete strength, corner installs, double wood frame shear walls or two close anchors in tension. To address these conditions, we suggest alternatives like slight adjustment or reconfiguration of the shear walls, thickening slab edges, adding downturn concrete beams or extending the anchorage from above down into a cast-in-place wall or further extended down into the footing at ground level.
The joint SEAONC-Simpson Strong-Tie testing project has shown that anchor reinforcement details can greatly increase the breakout strength of concrete to support cast-in-place anchor bolts in concrete slabs. The testing also showed that the design provisions in ACI 318-11 Appendix D can be rationally applied to these anchor reinforcement details. The testing and Appendix D calculation approach are the basis of the details, load tables, graphics and application guides that can be found on our new Strong-Rod Systems webpages. We’re updating these pages as we create more content, so check back frequently. We look forward to working with you on your anchorage installation challenges and hope that some of these solutions will help you with projects you are working on today. How about a high five?
What do you think about these new anchorage solutions? Let us know by posting a comment below.
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.
Structures and connections can be designed either using Allowable Strength Design (ASD) method or Load and Resistance Factor Design (LRFD) method. In the ASD method, the allowable strength is calculated by dividing the nominal strength by a safety factor. In the LRFD method, the design strength is calculated by multiplying the nominal strength by the resistance factor. In design, the adjusted ASD design value is compared to a calculated load or stress. As long as the adjusted ASD design value exceeds the calculated load of stress, then the ASD design value is judged safe. In LRFD design, the nominal strength is equated to factored loads. If the factored strength is greater than the factored loads, then the design can be accepted. ASD is the more common method adopted in the professional world.
LRFD is relatively new to wood design. Prior to 2005, the National Design Specification for Wood Construction (NDS) was based on allowable stress design (ASD). In the 2005 edition, the American Wood Council incorporated Load and Resistance Factor Design (LRFD) into the NDS. To this day, most wood design in the US relies on ASD, but the use of LRFD is becoming more common. On the other hand, the steel design industry already uses the LRFD philosophy for design, and for that reason, design values for steel self-drilling tapping screws are offered in both ASD and LRFD.
The published design values for Simpson Strong-Tie wood fastener products are in ASD format and the allowable loads are generally shown at a load duration factor of CD = 1.0. The reference design loads listed shall be multiplied by all adjustment factors listed in Table 10.3.1 of NDS 2012 to determine adjusted design values. The load tables are listed in ASD format because ICC-ES acceptance criteria, such as AC233 (Alternate Dowel-type Threaded Fasteners) and AC120 (Wood Frame Horizontal Diaphragms, Vertical Shear Walls, and Braced Walls with Alternate Fasteners), that are used to qualify structural wood screws do not address the development of LRFD values for wood screws. However, one can establish the nominal strength values for fasteners from reference ASD design values for use in LRFD format by following the instructions of NDS (2012), Table 10.3.1. Reference design values shall be multiplied by the format conversion factor KF as specified in Table N1 of NDS 2012. Format conversion factors adjust reference ASD design values to LRFD reference resistances. They are also multiplied by the resistance factor, Φ as specified in Table N2 and Time Effect Factor, λ as specified in Table N3.
For e.g., the table below lists the ASD allowable shear loads for SDWS screw in Douglas Fir-Larch and Southern Pine Lumber:
For the SDWS22300DB screw with a wood side member thickness of 1.5 inches, the allowable shear load is 255 lbs. with a wood load duration factor of CD = 1.0. To convert this to an LRFD load, refer to table 10.3.1 of NDS 2012 and Appendix N, Tables N1, N2 and N3. Per Table 10.3.1 we need to multiply the reference load with format conversion factor KF, resistance factor, Φ and time effect factor, λ From the Table N1, the format conversion factor KF for connections is 2.16/Φ. From Table N2, for connections Φ=0.65. Let us assume a λ of 1.0 from Table N3. The LRFD load is calculated by multiplying the allowable shear load with the factors above.
LRFD load = Allowable shear load (at a load duration factor of CD = 1.0) x KF x Φ x λ
LRFD Load = 255 x (2.16/0.65) x 0.65 x 1.0 = 551 lbs.
For steel self-drilling, self-tapping screws, the omega and resistance factors used for calculating ASD and LRFD loads are based on American Iron and Steel Institute (AISI) standard S100. For Simpson Strong-Tie steel self-drilling, self-tapping screws the load tables are listed in both ASD and LRFD format.
If the screw connection capacities are calculated based on tests, the ASD values are calculated by dividing the tested nominal strength which is the average of the ultimate strength values from all the tests with the safety factor, Ω. For LRFD load, the tested nominal strength is multiplied by a resistance factor, Φ. When tests are performed for evaluating the connection capacities, the safety factor, Ω and the resistance factor, Φ are evaluated in accordance with Section F of AISI S100. Simpson Strong-Tie derives the LRFD values for steel self-drilling, self-tapping screws in LRFD format because this is part of ICC-ES AC118 (Tapping Screw Fasteners). See evaluation report ICC-ES ESR 3006 for examples of ASD and LRFD design values for the same fastener products.
If the screw capacities are determined based on the calculated nominal strength, the ASD loads and LRFD loads are determined based on Section E4 of AISI S100. For e.g., the table below lists the ASD loads and the LRFD loads based on calculations for #14 x 1” screw.
From the table, for 33 mil (20ga) steel to 33 mil (20ga) steel shear connection, the calculated nominal shear strength is 600 lbs.
Nominal Strength = 600 lbs.
From Section E4, the safety and resistance factors for connections are:
Now that you know the basics of ASD and LRFD, make sure you choose the one best suited for your specific material and construction application. If you have ideas for which of our products you would like to see in ASD and LRFD loads, be sure to let us know!
Designing buildings and dealing with construction has always been a satisfying career for me. It is challenging to design a complete structural system, coordinate with the other consultants and create a clear set of construction documents for the contractor. Throughout my career, I’ve occasionally had a few panicked “Uh oh!” moments. I hope I’m not alone in admitting those happen. These typically occur far away from work when something prompts me to think about a project. I might see concrete being placed, then question whether I remembered to change the reinforcing callout on a mat slab I had just designed. I can’t stop thinking about it until I get back in the office to check.
I had an “Uh oh!” moment a few days after I started work at Simpson Strong-Tie. We have a training plan I call Catalog 101 where new engineers meet with each engineer who is an expert for a given product line. After I had met with our experts on holdowns, concrete anchors and engineered wood products, it was on to top-flange hangers (and my “Uh oh!” moment).
After learning a lot of things I didn’t know about hangers, we moved on to available options for some of our top-flange hangers – sloped, skewed, sloped and skewed, sloped top-flange, and offset top-flange. I learned that some hanger options get full load, some have small reductions and others large reductions. For example, the GLT with an offset top-flange gets 50% of the table load.
I had recently designed a project and specified a bunch of GLT hangers with offset top-flanges. I hadn’t noticed there was a reduction for this modification; I just thought it was really cool that Simpson Strong-Tie had a hanger that worked at the end of a beam. Minor panic set in until I could check my calculations. Fortunately, the beams at the framing conditions that required offset hangers had half the load of the typical beams, so the hanger was okay even with the load reduction.
The Wood Construction Connectors Catalog has a Hanger Options Matrix that makes it relatively simple to see which options – sloped, skewed, concealed, welded – are available for each hanger. The pages following the options matrix have more detailed information about size restrictions and load reductions associated with each option. It can be somewhat tedious to sift through all of the options and apply the reduction factors, so I always recommend using the Simpson Strong-Tie Connector Selector® software to do the work for you.
Connector Selector software allows you to input you geometry and loads and returns a list of connectors that meet those requirements, including any reductions due to modifications. Connector Selector is a desktop application, which needs to be downloaded and installed on your PC. Engineers have indicated they like the functionality of Connector Selector, but wished the input was more intuitive and preferred it as a web application.
I’m happy to say we listen, and the new Simpson Strong-Tie Joist Hanger Selector web app is available now. The easy-to-use interface enables users to quickly select the connection details and print out results. You can access the app from any web browser without having to download or install special software. The allowable loads are automatically calculated to reflect reductions associated with modifications – no more “Uh oh!” moments for me (at least with hangers).
Give the new Joist Hanger Selector web app a try and let us know what you think. We always appreciate your feedback!
Designing my first building was truly a learning experience. I remember one event in particular when I determined the required thickness for a steel column base plate. That day I wrote “1.5-inch thk. min.” on my calc pad and months later while out walking the job, I got to see that 1.5-inch thick plate in the flesh. Let me tell you, it was much thicker and heavier in-person than on my calc pad. This eye-opening experience – the realization that what you’re designing isn’t just a word or a number, but rather a physical object with width, height, length and weight – is something every structural engineer goes through early in their career. Designing something on paper doesn’t convey those physical properties very well.
Although there is no replacement for hands-on experience, technology has certainly come a long way in bridging the gap. Building Information Modeling (BIM) has grown significantly and is pushing to become the industry standard. It allows all parties involved to generate a 3D virtual model with objects drawn to scale and precisely placed. By collaborating and designing within a digital environment, multiple groups like contractors, builders, and structural engineers can coordinate project changes on the fly and head off any potential conflict.
Engineers commonly use 2D and 3D analysis software such as ETABS®, STAAD.Pro or RISA, to model, design, and export structural components’ actual dimensions to commonly used BIM software, like Revit®. Simpson Strong-Tie provides a number of 2D component details and 3D model families for Revit, allowing for accurate representation of each connector, Strong Frame® moment frame or ATS run within the building model. This type of visual representation provides users with an immediate sense of scale and understanding of how it will look and fit within the structure. It’s as close to the real thing as you’ll get.
That’s all fine and dandy for large commercial and multi-family residential projects with big budgets and complicated structural, mechanical and electrical systems, but what about single-family residential and smaller budget projects where a full building model might be cost prohibitive or simply unnecessary? Engineers may still use one of the analysis programs mentioned earlier, but may only model one particular frame or wall within the building. For simpler beam or column calculations, Excel spreadsheets and programs like Enercalc and CFS can provide quick solutions, but without an accurate visual representation.
Simpson Strong-Tie has developed several free stand-alone and web-based programs that help designers translate from calculation to physical product. The Anchor Designer™ Software has a visual interface that automatically updates when the user changes anchor configuration, base plate size or footing dimensions. The Strong Frame® Selector can provide an ordinary or special moment frame design in minutes, then export the design to AutoCAD® and generate an accurate elevation with the click of a button.
Paul mentioned in an earlier blog post how not that long ago he upgraded one of his PCs to a whopping 8 megabytes of RAM. With many computers now coming with 8 gigabytes out of the box, the hardware to run these resource-intensive programs is readily available. As technology continues to evolve, I see BIM and similar software becoming the benchmark for all types of design. When design software can convey tangible properties in a process that was formerly very intangible, it becomes an invaluable tool, especially to structural engineers just starting out.
What tools or software do you use to help convey your design’s physical properties?
Upcoming Web Seminar – Frame of Reference: Steel Moment Frames Explained S.K. Ghosh Associates, Inc. is offering a seminar April 22, 2014 from 9:00 am to 11:30 am PST. The seminar will address design and detailing requirements for ordinary and special moment frames designed per the 2012 International Building Code. The presenter is Simpson Strong-Tie Southwest Branch Engineer Damon Ho, M.S., P.E. Details about the seminar and complete speaker biography can be found here.
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.
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.*
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.
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.
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.
The first post I ever wrote for this blog was But I Don’t Design Cold-Formed Steel… I talked about how limited my initial experience was with cold-formed steel and how I was forced to learn it on the job when projects required it. During the webinar, I winced a few times recalling my first CFS project when Don mentioned why you should not do certain things — and they were things I used to do.
Referencing the “most current edition” of a standard was something I remember doing in our general notes, and the webinar mentioned why it is important to verify that specified reference standards are correct for the governing building code for the project. I first designed under the 1994 Uniform Building Code, and then used the 1997 UBC for many years after that. The Uniform Building Code was almost self-contained in that it covered gravity, seismic, and wind load requirements in Chapter 16, and then each of the material chapters had most of the design requirements in the code.
A significant change in the International Building Codes has been removing many of the design requirements and simply referencing the appropriate design standards. Whereas the UBC had methods for calculating wind loads, the IBC simply refers you to ASCE 7 for wind loads. Similarly, Chapter 19 of the 1997 UBC had many pages of concrete design requirements. Now, the 2012 IBC has just a few pages referencing ACI 318 and then makes several amendments to it.
A couple of years ago, my brother-in-law asked if I could stop by the swim club where he is a board member. He was overseeing a construction project to upgrade the buildings and patio covers, which involved dry-rot repairs and the addition of Simpson Strong-Tie® connectors to create a continuous load path. He wanted me to meet with the contractor and make some suggestions for alternate connectors. The as-built conditions didn’t work for the specified connectors at a few locations, and there were some spots where he thought the connectors were “ugly.” I’m probably in the minority on this, but I think shiny galvanized steel connectors are just beautiful. So the “ugly” comment stung a little bit.
Once I got over my hurt feelings, I grabbed my Wood Construction Connectors catalog, aDeck Connection and Fastening Guide, and a few other fliers and technical bulletins that I thought might be helpful and drove across town to meet them. With literature in hand, we were able to come up with ways to work around the more difficult areas, and also select some more aesthetically pleasing architectural connectors at prominent locations. I thought we were done, and then the contractor had a few more questions on anchoring that I needed an Anchoring and Fastening Systems Catalog to look up some information on – and I didn’t have one! I managed to muddle through with my smartphone and find the information online, but couldn’t help but think that there had to be a better way to access design information when you are out of the office.
The better way has arrived in the latest version of the Simpson Strong-Tie® Literature Library mobile app. It was just launched this month and is much more comprehensive than the first version. There are several new features that I wanted to highlight for you.