2015 nascc session summaries -...

Student Name: Abhishek Kulkarni

e-mail: [email protected]

2015 NASCC Session Summaries:

1) 90 Seismic Design Ideas in 90 Minutes.

Speakers: James Malley, Degenkolb Engineers; Rafael Sabelli, Walter P Moore Engineers &Consultants; Pat Hassett, Hassett Engineering, Inc.

In this session the three highly esteemed structural engineers with experience in seismic design ofstructural steel buildings presented 90 design ideas for future projects. One of the primary ideasexplained was that of seismic joints. Structural fuse coupling beam provides great control over ductilityof a structure. The use of dampers (seismic isolation) is a major concept with many upcomingapplications providing great results in seismic design. The use of steel plate shear walls was anotheridea discussed. Also, a new research on sandwich plate shear walls at University at Buffalo wasexplained. Use of BRBF (Buckling Restrained Braced Frames) in seismic design was recommended asit helps in reducing base shear of a structure. Another idea discussed was that of making the weldstronger than the gusset plate, so that the latter is more ductile. Use of cast nodes was suggested insome complex connections. Use of PR moment frames and box shaped linked beams was suggested.Exterior diaphragms were recommended for box columns. HSS brace frame connections andcomposite shear walls were some of the ideas presented.

2) Follow the Load Path to Avoid Unfortunate Consequences.

Speaker: Carol Drucker, Drucker Zajdel Structural Engineers, Inc.

Load paths are essential to understand in structural analysis as well as connection design. In thissession, the most common mistakes made in assuming load paths and how they can be avoided wereexplained. The implications of following the incorrect load path in fabrication and erection were alsodiscussed. The session pertained to all levels of engineering experience. It highlighted the load pathsfor gravity and lateral systems for steel-framed buildings as well as load paths for connections.According to the speaker, the shortest load path is typically the best design choice. Force is attractedto stiffness in a structure and thus stiffness governs the load path. It is mandatory to have a close loopfor a load path and supervise the erection process. The larger member with more load should ideallybe continuous. It’s important to watch out for discontinuous columns as they pose complications inachieving a close loop load path. It’s a good practice to put axial loads on drawings for clearunderstanding of the design details. It’s important to understand the force redistribution and jointequilibrium to understand the load path in most structures. It was an interesting session and thespeaker talked right from the fundamentals to complex systems thereby giving the audience a clearunderstanding of the concept.

Andrew Roenker

2015 NASCC Session Summary

4/14/15

Fracture Critical Determination: Current and Future Practice, Part 1

This seminar was given by Dennis Mertz (University of Delaware) and Justin Ocel

(Federal Highway Administration). These two speakers were addressing the current method of

determining the fracture critical status of bridges. Fracture Critical Members are tension

members whose fracture would compromise the stability of the structure. The issue at hand is

that there is no single method of assessing FCM that is widely accepted. The biggest problem

involved in these members is that too many bridges are being deemed fracture critical. Both of

the speakers agreed that the current terminology and method needs to be changed. However, the

two speakers presented their own ideas on assessing the situation.

2015 NASCC Session Summaries Anne Schmid

Stability design for seismic loading, session number 62975

Geometric nonlinearity analytical method

This presentation was by a student of Wong’s on an analytical method for geometric nonlinearities.Moment frames are expected to undergo major deformation in an earthquake. ABAQUS is anappropriate software for large displacements, while SAP and Opensees are better for smalldisplacements. SSM (state space method) software gives a response similar to large displacementsoftware. In SSM you can choose which stiffnesses are activated. Applying damping can indicatewhether software-generated curves are unstable.

Guambo Biau (Johns Hopkins) – Wood sheathed cold formed steel shear wall

Biau presented a model to predict the lateral behavior of a shear wall. For a seismic load, you can lookin a table to find the fastener spacing, thickness, type of wood sheathing, which leads to calculation ofchord stud strength predicted by omega,0 to prevent buckling failure. There may be incompatibilitybetween a rigid board of wood and flexible steel framing. Chord stud buckling dominates the failure of ashear wall. Buckling is expected at and above 75% capacity of the studs.

David Padillo Llano (Virginia Tech)

Thin wall structures should include local buckling efficiently in models to find strength and stiffnessdegradation and energy dissipation. Low deformation responses are typical. The ABAQUS modelincluded varied local slenderness, shell elements, and damage initiation and evolution. Two modelingtechniques were used: including a spring, or dividing the structure into nonlinear segments.

The “backbone arm” and initial stiffness and displacement (a function of local slenderness) werediscussed. As energy dissipates, stiffness degrades from its initial value to zero. Chord studs andfasteners are modeled separately. Different failure occurs when local buckling is considered in themodel; there is a 22% strength reduction and a 54% displacement increase. Not including local bucklingoverestimates strength.

Gulen Ozkula (University of California, San Diego)

Special moment frames are flexible, therefore inertia is needed to satisfy code. Shallow (like W14) ordeep columns are available that fit this requirement. Shallow members have to be heavier, but deepermembers are more economical. But deep columns have high width to thickness ratios and are prone tolocal buckling. A small radius of gyration means lateral torsional buckling is also likely. There has beenlittle research on the stability of deep columns. The test matrix was discussed: 25 W24 sections weretested to examine different slenderness ratios and to represent strong, weak, and biaxial bending.Different axial loads, low medium and high (at 20%, 40% and 60% of the nominal strength) were applied.More axial load resulted in less final strength and less energy dissipation. Local buckling occurred at theends. When web and flange requirements were violated, first local then global lateral bucklingoccurred. The strength, rotation capacity, energy dissipation all decreased when load was increased. Astockier column underwent more strain hardening. Dr. Uang established interaction parameters and


equations. Web buckling is dominant in more slender sections. The positive exponent that appearswhen all cases are considered is not a logical result, and they don’t know why it occurs.

Students connecting with industry

Carl Fosholt – BS in architectural engineering from Cal Poly in San Luis Obispo, works at Buro Happold,interested in steel, concrete, tension structures, working on 2017 Atlanta Falcon Stadium, speaking onbehalf of Erleen Hatfeld

Engineering is exciting and fun. Your kids and their kids will see your work. It looks big on site.Appreciate the product of your work. Strive to improve yourself. Seek those who can help. Keepdeadlines in mind and always keep a log of your questions and deadlines. Put yourself in situationswhere you are less comfortable to get a wide range of experience. Go to the site. Be clear on yourdeliverable and time frame. Budget time. Have a holistic view of tasks and how each thing is importantto the project. Focus on quality. Be an engineer your boss wants to go to. This helps you get interestingtasks and gain trust. Learn from your managers. Put yourself in your boss’s shoes. Speak up when youare overwhelmed and manage their expectations. Always ask questions and try to get constantfeedback. You have to ask for that feedback. Get licensed and get involved in industry. Go to seminarsand activities to learn and network and meet mentors to help you. Build your people skills. Learnmanagement and communication, interacting professionally. Practice public speaking. Buildrelationships. Do something nice every day. Find what excites you; this will make you a better engineer.What excites you about engineering?

John A Kennedy – BS Notre Dame, MS Missouri, has worked for Structural Affiliates International, asmall Nashville consulting firm, for 10 years: lots of healthcare buildings, schools

This talk is tailored to design consultants. The learning curve is steep starting out, but keeps going up.You never stop learning. It is important to have a mentoring environment. Look for this in interviews.Keep your calculations. Be fastidious and take notes even in informal meetings. Study drawings andstandard details for your office. Ask questions. Before you build in computer software, think about acantilever. Estimate dead and live loads. Lateral loads are not uniform, but do a uniform check. Keepschematics. Keep the loads, steel, wind, and seismic in a spreadsheet to understand the macro leveldesign. Then create a final model to account for openings, roof stuff, and back check against yoursimple model. Understand that your model is appropriate. With regard to paper drawings, there is adisconnect between school and practice. Learning programs gives an advantage. Drawings are notessupported by linework. Learn to sketch and write neatly because your drawings will be seen by others.Communication is writing emails and letters and reports and proposals every day. You are going tomeetings, making calls and site visits every day. Listen more and talk less in the beginning. You willlearn new terminology and be exposed to professionals. Take care to manage liability. Take pride in andenjoy your work.

Allan James Olson – BS Johns Hopkins, MS Cornell, MBA NYU, worked at Arup since 2007, for 8 years,has worked on structures for performing arts, rest stops, subway stations, airports, museums and


sculptures, works with famous architects, professor at the Columbia University graduate school ofarchitecture

He has had the opportunity to use structural principles on non-structures. Simple calculations arepowerful; so are rules of thumb. It is important to define orders of magnitude. This gives confidence.Write notes to your future self by annotating your calculations. Don’t use any old piece of paper. Youcan open excel and paste in relevant codes. Be effective, not just efficient. Understand what isimportant to the end user: rentable space? Flexibility? Communication is key. You have to be a talentedexplainer. This is underemphasized in school. Read literature. Draw something that works. Thearchitecture will pressure you to “make it work,” and you will want to please, but sometimes you mustsay no. Manage your liability. “Manage up”: anticipate what your boss wants. Guide your career.Learn to delegate and work in teams. Individual achievement is no longer the key. Lead people to theoutcome. Ask questions. Everyone knows you don’t know what you’re doing. Take a read on thementorship you see going on. Follow your instincts. If something doesn’t feel right, push the basics.You usually find something and you will sleep easier. Nothing is certain. We deal with expected valuesonly. Think twice about the five places in your answer. Realize where we can add value: this is theintersection between the arts and the sciences. If a computer can do your job, it will. Take charge ofyour career. Some people believe in the “just world hypothesis”, but you don’t just need hard work.You must also be seen by the right people and advocate for yourself.

Andrew Hermiz – Lawrence Tech in SE Michigan, has worked for 3 years at Harley Ellis Devereaux inDetroit and presented at the steel conference on integrating technology in the office, active in theyoung members group of structural engineers in Michigan, current chair

Focus on broad coursework in school. This is useful when interacting with other engineers. A mastersdegree is the industry norm. It is a benefit to your marketability. Think about your career. The hiringenvironment has improved. Get ready for your first job. Make face-to-face meetings. Communicationis important. Technology can be distancing. Learn from your superiors – you don’t know what you don’tknow. Learn from your peers and anyone involved in the project. We all have the same goal andunderstand what others need from you. Turn to your resources. Someone has a design guide or projectto help you. Realize you have hit a wall and get help. Make an honest effort and don’t ask others to doyour work for you. Getting a PE, SE license is the most important step in your career. Continue youreducation. Attend webinars maybe during lunch and learn about architectural and mechanical systems.Make yourself easier to work with. Get involved in professional organizations. Take pride in your work.

Questions and Answers:

What are the common errors of entry level engineers? Entry level engineers forget about load path.They are thinking of individual pieces and not how to transfer load. Little connections and load pathconsiderations are a common mistake. Check analysis results against an estimate. Units could be asimple error from computers. Jumping straight to the model before doing hand calculations is acommon error.


What do entry level engineers do? There are two schools of thought: expose entry level engineers toeverything (standard details, software tutorials, meetings) or maybe some meaty design work rightaway. Speaker designed a work platform to hold lights. Another speaker breaks little pieces out andcreates “homework problems”. This takes a little extra time but is an investment that an engineer willmake in you. You could be doing researching on permits. Offer your help instead of waiting to be askedto do something you want to do. Your experiences all depend on the projects you get.

2015 NASCC Session Summaries

Fracture Critical MembersPresented by Justin Ocel & Dennis Mertz

Written by Chris Hahnel

This session focused on bridge design, and more specifically the evolution of theFracture Critical Members (FCM) design criteria. First, let’s address how the code currentlydefines what a FCM is. A fracture critical member MUST have all three of the followingrequirements: It has to be steel, it must be in tension, and is has to be non-redundant.However, a FCM is not the only thing that can cause a collapse. There are several other typesof members that could lead to the collapse of a bridge, but FCM’s are a special type. So, howdid we get here? In the mid 50’s and 60’s steel material, Inspection, and erection deficiencieswere all found which led to the fracture control plan. In 1965 the first fatigue provisions werereleased which had 9 detail categories. Not long after, in 1971 the first bridge inspectionrequirements were put into effect. The previously stated 9 design categories was a little bulky,therefore in 1974 revisions were published for fatigue design. These revisions were the resultof testing done at Lehigh University. The revisions reduced the number of design categoriesdown to 6. In 1977 & 78 the issue of non-redundant members was first addressed by firstarbitrarily modifying allowable fatigue stress for non-redundant members, but then laterbecame more stringent on base metal toughness. This was also the first time the term“fracture critical” was published.

The current design provisions first address FCM’s in article 6.6.1.2.3 where it states theFCM’s are always designed for an infinite life, no matter that the design life of the structure is.Also, 6.6.2 specifies material toughness, fabrication guidelines, and shop inspectionrequirements; the commentary implicitly includes a list of FCM’s. It is interesting to note, thewhile we have several requirements for FCM’s but the Eurocode says NOTHING about fracturecritical members! EN1990 Article 2.1 basically leaves it up to the engineers digression to beworried about certain members. ASHTO is not so lax, it is very prescriptive.

The code gives three ways of addressing redundancy: load path (3 of more mainmembers), structural (continuity of span or system), or internal (built up detailing). Also, in2012 the FHWA opened the door for in depth analysis being able to prove you have redundancyin your system and therefore getting exempt from FCM costs. This is huge if you can do so,because the big increase in cost for fracture critical is not the material cost but rather the legacycost of continual inspection.

In conclusion, fracture critical member is merely a label for members with a specialdesign procedure. It does not mean that the structure is going to collapse, jus that thestructure is more prone to do so.

2015 NASCC Session Summaries

Flexible Moment ConnectionsPresented by Clinton Rex

Written by Chris Hahnel

First, we should address something; a flexible moment connection is NOT an actual typeof connection. A partially restrained (PR) connection is however a real type of connection.Flexible moment connection, type 2 wind connection, and smart connections are all othernames that have been and a currently used by some people but they in the end are all PRconnections. So what defines a PR connection?

· They are not as strong (partial strength vs. full strength) and they are typically designedas partial strength.

· They are not as stiff as a fully restrained (FR) connection, meaning say an angle betweena column and beam does not stay square, it bends.

In seismic applications, a PR connection becomes a fuse for seismic energy dissipation if theconnection in ductile. This usually results in limited yielding of beams and columns. While inlots of practices the design of the connection is delegated out to the fabricator, the design of PRconnections cannot be given to the fabricator.

ASCE 7-10 defines provisions for the design of PR connections for seismic application. ASCE341-10 also address the use of PR’s, 6C outlines 4 requirements that must be met to be used inordinary moment frames (I didn’t have time to write these down). 6D says that you have toprove that the connection can resist 2 cyclic loads.

A common PR connection is the TSA style connection which includes a clip angle attachingthe beam to the column above and below the beam. However, this type of connection istypically limited by the number of bolts that can be placed in the angle. The prying force in theangles needs to be looked at and understood to fully estimate the strength of the connection.Typically, Fy is used for PR models, while Fu is now used for the prying force models. Technicallyboth are right; it is a question of strain.

An interesting approach to strengthening a PR connection is to consider a composite PRconnection. This connection takes into account the presence of a concrete slab above theconnection for added stiffness and strength. Lots of actual testing and finite element modelinghas been done in this area and empirical equations have been developed based on these tests.

2015 NASCC Session Summaries Derek MarucciGraduate Student

University of Cincinnati

Wednesday 4:30pm: Lessons I Wish I had Known Starting Out

Six young designers presented on lessons that they have learned throughout the courseof their careers that they wish they had known starting out. They suggested that engineers anddesigners learn about what resources are available to them from their companies and from theindustry and to become familiar with them. They also encouraged audience members to not beafraid to ask their employers for the things they need or would like to have, such as mentors,resources, or involvement with certain projects. Several presenters stressed the importance ofmaking sure the results from analysis programs make sense and to use hand calculations tocheck them. One presenter suggested annotating hand calculations with notes explaining whyyou made certain assumptions and why you used certain numbers so that it is easier to figureout what you were doing and why you did it if you have to go back and look through them inthe future. Several presenters also suggested trying to predict the results of analysis programsand then checking the output to verify that it is in line with what you were anticipating.

Thursday 8:00am: Stability Design of Steel Buildings

Lawrence Griffis from Walter P Moore presented the information available in the AISCSteel Design Guide No. 28 and gave an introduction to the Direct Analysis Method. Heexplained the advantages of using the Direct Analysis Method over the Effective Length Methodand the First Order Analysis Method. He explained the calculation and use of notional loads,and he also emphasized the effectiveness of the Direct Analysis Method to lead to moreeconomical beam-column proportions. He also talked about the complications anddiscrepancies associated with determining K factors and how the Direct Analysis Methodeliminates these discrepancies all together by not requiring a K factor. Lastly, he summarizedseveral examples that are available in the Steel Design Guide 28 that designers can use tobecome familiar with the Direct Analysis Method.

Thursday 10:00am: Looking Forward: Career Insights from Industry Professionals

Students Connecting with Industry Sessions –

Three speakers representing the design and construction industries presented on theinsights that each of them have learned in their careers. The concept that was stressed themost was to not be afraid to ask questions and/or to ask for help because your employerswon’t know that you need something or have questions unless you ask. They explained thatemployers know that you are going to have many questions when you are first starting out andto take advantage of this time to ask questions and learn as much as possible. They alsoreassured the audience that as a new/young engineer, we have something to bring to the table,

such as unbiased perceptions and fresh eyes that are able to recognize alternate solutions andmethods in resolving design issues. After the presentations, we went on a tour of the exhibithall and then we had an opportunity to meet and connect with industry experts and majordesign firms from across the country.

Thursday 3:00pm: Flexible Moment Connections

Clinton Rex from Stanley D. Lindsey Associates presented on the various details, designprocedures, and effects on building stiffness of partially restrained (PR) connections. Heexplained that PR connections used in seismic systems act as the fuse to deform and dissipateenergy during cyclic loading. He listed the advantages of PR connections over fully restrained(FR) connections as being greater constructability and less cost. He also referencedexperimental research completed by Dr. James Swanson on PR top-and-seat angle connectionsand the failure modes associated with these types of connections. He ended the presentationby stressing the importance of accounting for the stiffness and strength of PR connections inthe design and analysis of structural steel frames to account for their influence on buildingbehavior.

Friday 10:15am: Are the Results of My First or Second Order Analysis Correct?

Joshua Buckholt from Computerized Structural Design presented on properlyperforming Second order analyses with structural analysis software. He emphasized theimportance of checking that models are properly imported and checking to make sure that theappropriate attributes are transferred to the analysis model. He also emphasized checking tomake sure the correct section properties and material properties are specified and to makesure that the correct loads are properly applied to the structure. He suggested companiesdevelop an in-house checklist for their employees to help them avoid common pitfalls andmistakes in their models. He then explained how to benchmark software to accuratelydetermine if the software accounts for P-δ and P-Δ effects using the commentary to Chapter Cin the AISC specification.

Friday 2:45pm: Achieving Economical Long Spans with Composite Truss Construction

David Stevenson from Entuitive and Tim Verhey from Walters presented on the use ofcomposite trusses to achieve long spans in steel floor construction. Composite trusses are builtup of standard rolled members with shear studs on the top chord to provide composite actionwith the concrete. They listed the different types of truss configuration which include the PrattTruss (mainly used for shorter spans), the Warren Truss (mainly used for longer spans), and theModified Warren Truss (well suited for long spans and relatively lighter weight). They alsodiscussed how composite trusses have the advantage of accommodate mechanical andelectrical systems more efficiently compared to standard rolled shapes and castellated beams.

One issue with composite trusses that they revealed is that partial loading can be problematicbecause it can cause load reversal in the truss elements where tension members are loaded incompression and vice versa. At the end they suggested that engineers who employ compositetrusses in their projects utilize a Design Assist fabricator to provide input which will help tostreamline the fabrication process and minimize errors.

P a g e | 1Frida Petterson

NASCC 2015 Steel ConferenceStability Design under Seismic Loading Conditions – Thursday 8:00-9:30 am

In this session, four different papers on the seismic behavior of shear walls and connections werepresented. One of the papers were called OpenSees Simulation of Steel Column Axial Cyclic ResponseIncluding Local Buckling and this paper looked at the effects of local buckling as a limit state in thinwalled cold formed steel columns. The software Abaqus was used for the 22 models, each of which haddifferent slenderness and length. The models included imperfections and also damage initiation. Theproject found that the failure mechanism is local buckling when it is included, and without local bucklingthe failure of the fastener governs.

Another interesting paper was Observations from Cyclic Tests on Deep, Slender, Wide-Flange StructuralSteel Beam-Column Members, where the behavior of deep columns under seismic conditions wereinvestigated. Five different W24 sections were tested, with three different loading conditions for eachsection.

Looking Forward: Career Insights from Industry Professionals – Thursday 10:00-11:15 am

This session was presented by four professionals from different companies, both from design andconstruction industries. They talked about things they had learned during their careers. They mostlyspoke about how important it was to be able to communicate in a proper and clear way. Another thingthey all spoke about was how asking questions are the key to moving forward when you meet obstacles.It is better to ask the questions early on so that no unnecessary mistakes are made, and that employersknow that a new employee will have many questions. A quote from this session is: If it doesn’t challengeyou, it doesn’t change you.

Direct Connect – Thursday 1:00-2:30 pm

The direct connect session gave us students an opportunity to speak to multiple different companiesand understand what these companies had to offer. This session was interesting and gave a taste ofwhat it would be like to interview for different companies, as well as an understanding of what theprofessional life will be like.

Flexible Moment Connections– Thursday 3:00-4:00 pm

This session was about partially restrained (PR) connections. Different details and design procedureswere presented. The speaker explained that when the effect of the connection on the overall behavior isvery small, it can be neglected, but it cannot always be neglected. The connections becomes the fusesfor seismic energy dissipation so ductile connections are needed under such conditions. The benefit ofusing PR connections instead of fully restrained (FR) connections was less cost and betterconstructability.

P a g e | 2Frida Petterson

Follow the Load Path to Avoid Unfortunate Consequences – Friday 10:15-11:45 am

In this session emphasis was on how important it is to see the whole structure as a system and not justfocus on small concentrated parts, for example a connection or a single beam. The session started offwith some load path fundamentals. The speaker described how all loads will be transferred to theground through the shortest way, and that forces are attracted to stiffness. The session concluded witha short summary stating that it is important to provide a complete and efficient load path, and also toprovide sufficient strength and stability for load path.

T.R. Higgins Keynote – Friday 1:00-2:30 pm

In this sessions the award was distributed, and then a presentation by Chia-Ming Uang followed. Thetopic of his presentations was What Seismic Design Is All About. He spoke about important parts of theseismic design procedure, especially about how important the connection design is. He encouraged theaudience to be careful with detailing and welding so that the desired ductility would be reached, andalso about how important it is that the gusset plate of buckling restrained braces (BRB) does not failfirst. Finally, he also spoke about a project performed on the stability of deep columns, which was thesame project as described in the session Stability Design under Seismic Loading Conditions.

Stability of Angles, Channels, and Z-Shaped Members – Friday 2:45-3:45 pm

In this session three different speakers presented a paper each about three different research projects,all in the field of stability. The first one treated the buckling, post-buckling and strength behavior of thinwalled columns of angles with unequal leg length. This was then followed by a project on the strengthand buckling of cold-formed web/flange stiffened lipped channel columns. The last project was aboutexperiments on Z-shaped stub beam-columns.

2015 NASCC Session Summaries Himneet Singh

1. 90 Seismic Design Ideas in 90 Minutes

Speakers: James Malley, Rafael Sabelli, Pat Hassett

In this session, 3 Structural Engineers presented 90 seismic design ideas. Basic concepts of design invarious lateral force resisting structures were covered. Ideas were presented to show how small changesin details can help in resisting lateral forces. The session was helpful in brushing up the basic concepts inseismic design and to pay attention to some ideas which are not conventionally used.

2. Follow the Load path to avoid Unfortunate Consequences

Speaker: Carol Drucker

The session focused on determining the load path for design. The speaker ventured into commonmistakes made in assuming the load paths and how they can be avoided and also, the impact of thewrong load path. Case studies were presented highlighting the importance of knowing the load path.Load paths in Connections was also covered.

2015 NASCC Session Summaries Ken Orloff


Speakers: Dennis Mertz, University of Delaware; Justin Ocel, Federal Highway Administration

Moderator: Bill McEleney, NSBA

This seminar focused on the current federal policy and future practices regarding fracture criticaldetermination. According to the Federal Highway Administration, “a fracture critical member isa steel member in tension, or with a tension element, whose failure would probably cause aportion of or the entire bridge to collapse.” This definition is not very specific and leads toconfusion as to what really is a fracture critical member. Many bridges are inaccurately beinglabeled as fracture critical based on the vague definition currently being used. Special inspectionis required for such bridges and is creating a high demand on the bridge owners. Research isbeing performed in order to better determine the definition of fracture critical and assessing theredundancy of structures. During this seminar, the speakers looked at several bridge failures inorder to help describe the fracture critical members. A total fracture control plan has beendeveloped and is often illustrated as a three legged stool. The three parts, or legs, of the planinclude fabrication and shop inspection, material and design, and field inspection. Before thetotal fracture plan was developed, the design of tension members was based entirely uponyielding. As the speakers noted, the goal of the fracture control plan is to prevent brittle fracturesof non-redundant tension members and tension components.

2015 NASCC Session Summaries Martin Butler

Thursday

8:00 Fracture Critical Determination: Current and Future Practice, Part 1

10:15 Student Session, Looking Forward: Career Insights from Industry Professionals

1:00 Student Session, Direct Connect

Friday

10:15 Follow the Load Path to Avoid Unfortunate Consequences

1:00 T.R. Higgins Keynote

2:45 Stability of Angles, Channels, and Z-Shaped Members


The history behind the fracture critical designation was reviewed at the beginning of thissession, including some events which suggest greater system reliability than is accounted for currently.This session contained some disagreement about whether the fracture critical designation is as all agood thing. Both sides had some solid points. The opposed to the current designation side pointed outthat generally the failures were from brittle steel not used in modern design or poorly done welds andinspection may not have prevented this. True, though the dire results of a member properly given theFCM designation failing still probably warrants some special examination whether or not the catalyst forthis designation was a failure of this type or something unrelated. Theoretical and empirical workbehind the concern of FCM is robust enough that its continued use is fine. Because this session was part1 of 2, and the second part was during the student session I missed what was sure to be the interestingbits.

Stability of Angles, Channels and Z-Shapes

The buckling and post buckling behavior of cold formed angles, channels and zee shapedmembers were discussed in turn. The angle examination was prompted by Ojalvos continuum modelwhich uses the cross sectional centroids to predict buckling which gave higher values than the Wagnerhypothesis which uses the shear center. The torsional mode is better represented using the shearcenter and for such significantly asymmetric members the torsional mode dominates for short orintermediate lengths. Testing of some members in uniaxial compression and finite element modeling ofangles with both shell and solid elements found that the Ojalvo hypothesis over-predicted criticalbuckling loads and the currently used DSM curve should probably be continue to be used.

The cold formed channel study was precipitated by a study by Kumar showing that the DSMcurve currently used under-predicted strength. This study did more column sizes and also did notlaterally restrain the numeric models which gave values closer to the curve. Including more data pointsmade the appearance of the curve being over-conservative diminish.

2015 NASCC Steel Conference Philip Niekamp

Summaries:

1. Design and Stability of Connection Elementsa. Speaker – Bo Dowswell, ARC Internationalb. This session focused on considerations for local stability of the connection components

and covered:i. Double-coped beamsii. Rectangular gussets

iii. Coped connection plates (for horizontal bracing)c. Connection Stability Requires

i. Simplifying Assumptionii. Dividing into smaller elements for analysis

iii. Model connection elements like beams or columnsd. Use Section F11 from AISC 360-10 and assume Flexure for rectangular beam elementse. Low Length-to-Depth ratios cannot use My/I (i.e. connection elements)f. Double Coped Beam: Lb = c and Cb = [3+ln(Lb/a)]g. Connection Design = Ultimate Strength Design

h.

i.


2. Flexible Moment Connectionsa. Speaker – Clinton O. Rex, Stanley D. Lindsey and Associatesb. Flexible partially restrained moment connections are used for low to mid rise buildings

and design procedures must consider the effects on building stiffnessc. The use of Flexible Moment Connections is a more rigorous and conservative application

of PR moment connection concepts.d. Of critical importance is the determination of the moment–rotation characteristics of

the connection to be used. The frame is loaded step-by-step, along the curve, with aparticular load case and sequence.

e. Plastic Limit Theorem states that a load computed on the basis of an equilibriummoment distribution, in which the moments are nowhere greater than Mp, is less thanor equal to the true plastic load. The actual shape of the connection curve is notrelevant in Flexible moment connections; only its plastic moment capacity is a factor.

f. In addition to strength, frame stability for second order effects must be checked.g. Prying Action is an important factor in FMC


3. The XTB-Extra High Strength Bolta. Speaker – NSSB-MISAb. The XTB high strength structural bolt has a 200ksi tensile strength and is available as a

twist-off type tension control bolt assembly and as a heavy hex bolt assembly.c. This session covered design aids, connection design comparisons, and cost comparisons

d.

e.f. The Stress concentration factor of XTB thread profile is approximately 60% of

conventional (A325/A490) thread profileg. Twist-off bolt installation verification was performed at Virginia Tech by Michael Woodh. Turn-of-nut installation verification was performed at the University of Cincinnati by

Philip Niekamp

i.

2015 NASCC Session Summary Prabhanjan Wagh

90 Seismic Design Ideas in 90 minutes

Speakers: James Malley, Degenkolb Engineers;

Rafael Sabelli, Walter P Moore Engineers and Consultants;

Pat Hassett, Hassett Engineering, Inc.

Moderator: John Kennedy, Structural Affiliates International, Inc.

This session was delivered by three highly esteemed structural engineers withdecades of combined experience in seismic design of structural steel buildings. Theytalked briefly about various basic concepts in design of lateral force resisting systemssuch as steel plate shear walls, coupled shear walls, composite coupling beams, steelframes etc. It is very interesting to know that how some of the small details in designcan help to achieve the desired performance of the system to resist lateral forces.This session really helped me to brush up my knowledge in seismic design ofbuildings.

My experience at the North American Steel Construction Conference (NASCC)

By John Morganstern

4/02/15

The North American Steel Construction Conference (NASCC) in which I and two othermembers of the University of Toledo Structural Engineers Association of Ohio (UT-SEAoO)attended was held at the Music City Center in Nashville TN this year. The conference issponsored by the American Institute of Steel Construction (AISC) and provides a greatnetworking opportunity for anyone involved in steel design, construction, fabrication anddetailing. There is also a special event tailored to students at the conference entitled StudentsConnecting with Industry Sessions (SCIS), in which students like myself have the opportunity tospeak with and get to know young engineers in the field of Structural Engineering. The SCISalso has a Direct Connect session in which students get an opportunity to speak one-on-one withmany company representatives ranging from structural design firms to contractors, fabricators,manufactures and detailers.

When I and the two other members of UT-SEAoO, Zebadiah Hites and Souvik Mazumder,arrived at the conference on the evening of Wednesday March 25th we were amazed at theenormous size of the Music City Center. The building spanned several blocks long and a blockwide through downtown Nashville with columns supporting an open interior area of about 80ft tothe ceiling above. After we found the check in desk and got our ID badges we toured the openexhibit hall in which dozens of companies ranging from steel design firms to computer softwaredesigners/detailers, fabricators and contractors had booths in which to showcase and display theirproducts and services. At the exhibit hall we also meet with one of the engineers who organizedthe SCIS and is the President and founder of SE University, Brian Quinn. Throughout theNASCC dozens of technical informational sessions open to all whom wished to attend wereoffered on a walk-in basis. The sessions were run by engineers and other individuals with anarray of technical knowledge in their field that ranged from steel truss design to updates onseismic code provisions for steel construction.

The SCIS started on Thursday morning March 26th and ran into the afternoon until about2:30pm. The SCIS had over 200 students attending from universities all across the country. Atthe start of the SCIS all the students were seated in a large banquet hall and then several youngengineers gave brief presentations on their experiences as a Structural Engineer. They also gavehelpful important tips on how to be successful as a structural engineer in the industry. Some ofthe tips included how it is important to always ask questions if you are unsure about anythingyou are working on and to get out of your comfort zone every once in a while by maybe visitingthe site in which something you designed is being built. After the young engineers gave theirpresentations a box lunch was served to all the students then we moved out into the main hall fora short tour of the Music City Center. After the tour we arrived back in the main hall to sign in

for the Direct Connect event. The Direct Event allowed us to speak one-on-one with many of thetop fabricator, contractor and design firm company representatives, even including the presidentin many cases. This was an excellent opportunity to network and tell my story to several of thetop companies in the industry including Drucker Zajdel Structural Engineers, L.A. Fuess &Partners and Meyer, Borgman & Johnson.

At the close of Direct Connect and SCIS Souvik, Zebadiah and I attended a few technicalsessions before heading out to Broadway St in downtown Nashville for dinner. For Friday on the27th we spent the day attending various technical informational sessions that we found interestingand insightful. These sessions also allowed us to network with more structural engineers gainingnew knowledge and insight on solving technical issues. We left Nashville for the Toledo areaSaturday morning on the 28th. Souvik, Zebadiah and I had to miss a few classes at UT to attendthe NASCC conference, but overall found the experience to very helpful and rewarding. I plan toattend the 2016 NASCC conference next year in Orlando FL.

John MorgansternUT-SEAoOPresident419-704-0700

Lessons Learnt at North American Steel Construction ConferenceNASCC-2015Souvik MazumderGraduate student

It was big opportunity for me to attend AISC’s North American Steel Construction

Conference (NASCC)-2015 held at Music City Center in Nashville, Tennessee with two

members of University of Toledo Structural Engineers Association of Ohio (UT-SEAoO) John

Morganstern and Zebadiah Hites. This 3- day event was a networking platform where steel

detailers, fabricators, erectors, manufacturer, engineers, educators and students got scope to meet

each other and hone their professional knowledge.

On the first day we had to register at the conference and we got our ID badges. Then we

met one of the organizer of Students Connecting with Industry Sessions (SCIS) as well as

President and founder of SE University, Brian Quinn. After that, we met some software

developing companies like Bentley, SDS/2 and some equipment manufacturing company like

Python in the exhibition hall who were exhibiting their products. On the second day we attended

one session called Students Connecting with Industry Sessions (SCIS) where some remarkable

Structural Engineering professional from reputed company like Arup, Buro Happold shared their

valuable experience which will certainly assist us in future professional career. This session also

had an event called “Direct Connect” where we got opportunity to meet various representatives

of well-known Structural Engineering companies. In this session, I discussed about my doubts

with representatives of few companies and I got some good advices as well as helpful

information from them. On the second as well as third day, we attended some technical sessions

as per our individual requirement and gained technical knowledge. For example, I have attended

one session related to “Direct Analysis Method” where I have cleared my doubt related to

Notional Horizontal Load and Direct Analysis method.

In a nutshell, the conference has helped me to meet some outstanding Structural

Engineering professionals as well as to gain knowledge from the technical sessions where some

outstanding engineers and faculties shared their knowledge and experience. I am really looking

forward to attend next conference in Orlando, Florida in 2016.

Finally, I would like thank AISC and SEAoO for the funding to help with expenses and I

highly appreciate their effort to encourage students to participate in this kind of event.

Zeb Hites

Hello I am Zeb Hites a student at the University of Toledo and a member of the UT SEAoO

student organization. Though your generosity I was able to attend the North American Steel

Construction Conferences. I am a forth semester sophomore in the civil engineering program and this

was my first year attending this conferences. This made much of the conferences very new to me and

gave me the opportunity to learn a lot about steel design, construction, erection and production. I am

planning on pursuing a graduate degree in civil engineering with a focus in structural design. Some of

the sessions I was able to attend gave me a good idea of my future careers and the projects that I could

be assigned to.

I attended this conference with two others from the university, John Morganstern and Souvik

Mazumder. We arrived at the exposition hall Wednesday night and received our name badges and

toured the exhibit hall. It was late now due to the drive down so be retired to our hotel at prepared for

the next day. Thursday was the day that had the most opportunities for the students attending the

conference. This was the students connecting with industry session (SCIS) during this I was able to hear

from four practicing engineers that gave their advice for the students and graduates looking forward to

their careers. In the later part of the session that was an opportunities to meet and network with several

companies that are looking to hire.

Friday was our main day to tour the exposition hall learn from seasons. The exposition hall had

many large companies that are involved in the structural steel industry. There was tooling companies

such as Peddinghaus; design software makes like Autodesk, and Bentley. All of the exhibitions where

welcome to questions and offered educational software that is very helpful. I have been able to

associate myself with some main stream programs like Rivet by Autodesk. The sections that were

offered could suit anyone’s interest. One of the sessions that I attended was talking about large truss

design and manufacturing. It started by discussing the basics of truss design and application. This helped

me to understand trusses and what there limitations are. The later potion of the session then talked

about four case studies where large trusses where used in varies ways. It ended with a question and

answer part.

This was a very good education experience that I would recommend to anyone looking at

pursuing a career in the civil structural engineering field. I hope to be able to attend this conference

again in the future and I hope that SEAoO is able to continue their support of this trip. I would like to

end by saying thank you to the members of SEAoO and how much I appreciate what you are able to do.

2015 nascc session summaries -...

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