How does your office approach the design of roof top screen walls?  They are all too common since they do well to hide roof top equipment or offer privacy on residential buildings.  However, in the past, they have not been explicitly addressed in the code. Some engineers use the provisions for roof top structures and equipment, others use solid freestanding signs, and some argument could be made for using the parapet provisions.  

In the November 2019 SE University session, Emily Guglielmo, SE, from Martin/Martin, presented Wind Loads on Non-Building Structures.  Emily reviewed the ASCE7 wind provisions for non-building structures, but also offered some guidance on non-building structures that are not specifically addressed in ASCE7.  She also provided some additional resources available to engineers to help fill in the gaps where the code may be silent on some situations.

Emily explained new language added to the commentary of ASCE7-16.  As you can see in the slide below, the commentary now makes it clear that screen walls should be designed in accordance with Section 29.5.1.

Using this new guidance from the code, the design of screen walls is now more explicit, however, an obvious follow up question would be whether shielding can then be considered for equipment surrounded by a screen wall.  Although each case is unique, Emily offered some guidance on this situation. Watch this short 3 minute video to hear Emily’s recommendation on the use of shielding on roof top structures.

Emily Guglielmo, SE, Martin/Martin

In November 2019, SE University welcomed Emily Guglielmo, SE, from Martin/Martin, to present Wind Loads on Non-Building Structures. In 2015, Emily designated Bridges to Prosperity (https://bridgestoprosperity.org/) for our SEU Speaker Inspires donation for the month, and she has chosen to do the same in 2019.

Emily said this about her choice, “Bridges to Prosperity believes that every person has a right to safe access and has engineered innovative, scalable approaches to act on that belief. As an engineer, it’s inspiring to see other engineers using their passion for the profession to implement real change in the world.”

Thank you, Emily, for helping structural engineers with your SE University session, and for your designation of Bridges to Prosperity as one of our SEU Speaker Inspires Organizations of the Month!

SE University began the SEU Speaker Inspires program in 2015 as a way to “pay it forward”, enabling our speakers to designate a charity/organization of their choice for SE University to make a donation to help improve our world.

The design of wall anchorage in tilt-up walls has been influenced most by past failures during seismic events.  While many failures were the result of cross-grain bending in wood roof designs, many problems were found also in steel structures, where the steel lacked the necessary ductility and overstrength required during an earthquake.  How do ACI and ASCE 7 address the design of wall anchorage to ensure these past failures are not repeated?

In the July 2019 SE University session, John Lawson, PE, SE, from Cal Poly – San Luis Obispo, presented Engineering Tilt-Up: Design Provisions Born from Past Experience. John reviewed how past failures have influenced current design practices and explained the implementation of current slender wall provisions and how to classify wall elements.  He also covered wall anchorage forces and how they get transferred into the diaphragm and potential issues with both steel and wood deck roofs. 

John noted during the session that even in regions where wind typically governs the building design, seismic can still govern in the case of the wall anchorage design force.  After noting past failures at the wall anchorage, the design force has been increased to maximum expected forces to ensure the connection can withstand the required ductility and strength required during an earthquake. Since the wall anchorage force is 3-4 times the ground acceleration, this design force can often exceed the design wind force, even though wind may control the design of the tilt-up wall panel.

John explained the process to determine the required design force for wall anchorage.  Watch the following 4 minute video to hear John walk through the wall anchorage design equation, including some valuable tips for this design process.

In October 2019, SE University welcomed Bruce Brothersen, PE, SE, from Vulcraft, and Walter Worthley, PE, SE, from Valley Joist, to present Retrofitting of Existing Buildings with Steel Joists.  Walt designated St. Jude Children’s Research Hospital (https://www.stjude.org/) for one of the SEU Speaker Inspires donations for this month.

Walt shared: “The St. Jude Children’s Research Hospital continues to provide exceptional care for children with cancer. Their work in helping patients and families deal with this disease, as well as help to find cures, continues to be an inspiration to every life they touch.”

Thank you, Walt, for helping structural engineers with your SE University session, and for your designation of the St. Jude Children’s Research Hospital as one of our SEU Speaker Inspires Organizations of the Month!

SE University began the SEU Speaker Inspires program in 2015 as a way to “pay it forward”, enabling our speakers to designate a charity/organization of their choice for SE University to make a donation to help improve our world.

Bruce Brothersen, PE, SE, Vulcraft

In October 2019, SE University welcomed Bruce Brothersen, PE, SE, from Vulcraft, and Walter Worthley, PE, SE, from Valley Joist, to present Retrofitting of Existing Buildings with Steel Joists.  Bruce designated City of Hope (https://www.cityofhope.org) for one of the SEU Speaker Inspires donations for this month.

Bruce shared: “Engineering is all about making the world better. Engineers are not alone in the pursuit. The City of Hope National Medical Center is making the world better through Cancer research, prevention and treatments. Just about everyone is effected by cancer, personally, family members or friends. We are honored to assist, in a small way, to give more hope to people effected by cancer.”

Thank you, Bruce, for helping structural engineers with your SE University session, and for your designation of City of Hope as one of our SEU Speaker Inspires Organizations of the Month!

SE University began the SEU Speaker Inspires program in 2015 as a way to “pay it forward”, enabling our speakers to designate a charity/organization of their choice for SE University to make a donation to help improve our world.

SE Solutions was pleased to recently present scholarships to three Purdue University Structures students to help defray the cost of their education. Harsh Bohra, Corey Beck, and Michael Walz were the recipients of the awards. This is the eighth year that SE Solutions has offered the scholarships.

From Left to Right, SE Solutions President, Brian Quinn, PE, Purdue University Students and Scholarship Winners – Corey Beck, Michael Walz,  and Harsh Bohra

Harsh Bohra, received his bachelor’s degree from the Indian Institute of Technology, Bombay in 2018 and will be completing his MSCE degree with specialization in Structural Engineering in May 2020. He has worked as an engineering intern at Baker Consulting Group and currently is a teaching
assistant for a structural analysis course. He is proficient in finite element modelling with geometric and material nonlinear imperfection analysis (GMNIA). His research focuses on formulating a new design method for evaluating the permissible differential settlement for above-ground storage tanks. Upon
graduation from Purdue, Harsh is determined to work on design of complex and innovative structures.

Corey Beck is from Indianapolis, Indiana. He received his Bachelor of Science in Civil Engineering from Purdue University in 2017 and intends to complete his MSCE at Purdue in May 2020. In between his undergrad and graduate work, Corey served as a bridge design engineer for Indiana’s Department of Transportation. Currently, he is working on developing a rapid assessment procedure for autonomously determining the seismic vulnerability of bridges throughout Indiana. Additionally, he hopes to use artificial intelligence software to help eliminate critical gaps in mineable information required to conduct this assessment. He chose civil engineering so that he could have the opportunity to understand, develop, and improve structures that would have a lasting impact on the well-being of communities throughout the nation, and hopefully one day the world. Upon graduation, Corey would like to find a job that allows him to be a design engineer but also investigate structural failures and deficiencies so as to better improve the built world. Ultimately, he hopes he can have the opportunity to work on innovative and challenging projects throughout his career.

Michael Walz received his BSCE from Valparaiso University in 2018. He is currently working on his MSCE at Purdue University and anticipates graduating in May 2020. At Purdue, Michael has been a teaching assistant for multiple classes and has enjoyed the opportunity to learn concrete, wood, and masonry design better through teaching it. After graduation, he hopes to work for a structural engineering firm in Chicago, working on new building design, renovations, and rehabilitation projects.

SE Solutions would like to congratulate each recipient and wish them future success in their fields of study as structural engineers.

In the immediate aftermath of the Northridge earthquake in 1994, steel buildings seemed to perform well. In the weeks to months following, however, extensive damage was found in special moment frame steel systems. As a result, FEMA allocated 10 million dollars to investigate, test and analyze materials, member connections, and structural systems in order to establish a better understanding of seismic structural systems, and recommend changes to building codes.   

In the September 2019 SE University session, James O. Malley, SE, from Degenkolb Engineers, presented Changes to the Seismic Design of Steel Buildings.  Jim reviewed how the damage caused to steel moment frames during the Northridge earthquake led to major changes in the design of steel structures.  Jim outlined the new overall design philosophy which aims to develop inelastic mechanisms within designated structural fuses to dissipate the majority of the earthquakes energy.  Jim also covered how seismic design requirements aim to satisfy this new design philosophy for the various structural systems.

During the session, Jim explained new language that was added in 2016 to AISC 341 in regard to columns that are common to intersecting frames.  Research showed that in high R factor systems where columns are shared by intersecting frames, the 100/30 rule may not be adequate, especially for low rise buildings.  Thus, language was added to ensure this potential simultaneous inelasticity is considered during design. In the 3 minute video below, Jim explains the reasoning for this code change. 

John Lawson, PE, SE, Cal Poly – San Luis Obispo

In July 2019, SE University welcomed John Lawson, PE, SE, from Cal Poly – San Luis Obispo, to present Engineering Tilt-Up: Design Provisions Born from Past Experience.  John designated The Land Conservancy of San Luis Obsipo County (www.lcslo.org) for the SEU Speaker Inspires donation of the month.

John shared that he made this selection because: “I love this local organization as it preserves important open space and natural habitats while developing an educational outreach program called Learning Among the Oaks for elementary school children that fosters leadership and stewardship.”

Thank you, John, for helping structural engineers with your SE University session, and for your designation of The Land Conservancy of San Luis Obispo County as our SEU Speaker Inspires Organization of the Month!

SE University began the SEU Speaker Inspires program in 2015 as a way to “pay it forward”, enabling our speakers to designate a charity/organization of their choice for SE University to make a donation to help improve our world.

AISC’s Steel Solutions Center frequently receives questions related to welding in situations that are not ordinary or where special fixes are needed after something has gone wrong.  To address these questions and other welding dilemmas, special care was taken in Design Guide 21: Welded Connections (Second Edition)  to expand upon Special Welding Applications. Enhanced since the First Edition, the Design Guide now includes a chapter on Problems and Fixes which addresses commonly encountered problems with practical advice to solve the issues.

In the August 2019 SE University session,  Duane Miller, PE, from The Lincoln Electric Company, presented Introducing Design Guide 21: Welded Connections (Second Edition).  Duane covered some unique requirements for special welding applications, suggested potential solutions to frequently encountered problems associated with welded construction, and reviewed the approach used in AWS D1.1 to address unusual situations and the role of the EOR.

Duane began by offering 10 tips to avoid pitfalls with welding on in-place embed plates as covered in Chapter 14.14 of Design Guide 21.  Welding to in-place plates can cause cracking of the surrounding concrete due to expansion or distortion of the heated steel.  

The following tips can minimize the heat effects from welding:

1. Use embed plates that are ½” [13mm] thick.

2. Select steel grades and thicknesses for which preheat of the embeds will not be required.

3. Arrange anchorage elements away from the locations where field welds will be required.     

4. Design embed plate assemblies to resist distortion.

5. Design the field welded connection to allow for the smallest weld size possible.

6. Provide a perimeter gap between the edge of the embed and the concrete.

7. Allow the concrete to dry and cure before field welding.

8. Avoid overwelding in the field.

9. Control interpass temperature.

10. Test critical assemblies with mock ups.

Additional consideration should be taken when welding to stainless steel embed plates, as stainless steel distorts significantly more than carbon steel, thus making these tips more critical to the success of welding to stainless steel embeds.  Welding to galvanized steel is addressed in Chapter 14.2 and the concepts covered there would apply to galvanized embed plates as well. Using these tips will minimize many of the issues that can arise when welding to in-place embed plates.

James O. Malley, SE Degenkolb Engineers

In September 2019, SE University welcomed James O. Malley, SE, from Degenkolb Engineers, to present Changes to the Seismic Design of Steel Structures.  Jim designated the Earthquake Engineering Research Institute (EERI) Learning from Earthquakes (LFE) Endowment Campaign Fund (http://www.learningfromearthquakes.org/) for the SEU Speaker Inspires donation of the month.

Jim shared: “I selected this fund because EERI’s LFE program made a very significant impact on my career and those of many others by providing earthquake professionals from all disciplines with the opportunity to work together at the site of major earthquakes and share those experiences with the entire earthquake community. The EERI LFE program has made important and lasting contributions to improved understanding of the impacts created by earthquakes and has directly led to many significant advances in seismic design. The LFE endowment fund will guarantee that these contributions will continue for decades to come.”

To learn more about this endowment fund visit http://www.learningfromearthquakes.org/images/EERI-LFE-Endowment-Case-Statement-V10.pdf.

Thank you, Jim, for helping structural engineers with your SE University session, and for your designation of the Earthquake Engineering Research Institute (EERI) Learning from Earthquakes (LFE) Endowment Campaign Fund as our SEU Speaker Inspires Organization of the Month!

SE University began the SEU Speaker Inspires program in 2015 as a way to “pay it forward”, enabling our speakers to designate a charity/organization of their choice for SE University to make a donation to help improve our world.