Thanks to the Structural Engineers Association of North Carolina for inviting me to speak this past Friday at their annual conference in Charlotte. We had a great time discussing the basics of the Direct Strength Method for cold-formed steel design and its application to sheathed stud walls. Watch the recorded presentation and download example CUFSM files and design guide documents.
The Structural Stability Research Council (SSRC) Task Group (TG) 05 - Thin-Walled Structures is recruiting new members. Researchers, students, and practitioners are welcome to join by clicking here. We recently assembled a database of 700 cold-formed steel columns to aid ongoing research activities. You can gain access to the database if you sign up for TG05. We are also supporting the 2nd annual international cold-formed steel student competition.
We have developed an Excel spreadsheet that can predict the deflections, twist, roll angle, and internal forces in a curved beam as it is lifted with a crane. The spreadsheet can be used to study uncracked prestressed concrete girders with an initial sweep or intentionally curved steel girders. Check it out- U.S. Customary or Metric. My presentation to the TRB AFF30 Concrete Bridge committee can be downloaded here.
Check out our new metal building vehicular access door wind analysis software, 32 bit Windows, 64 bit Windows . It is still in beta form, so please give us feedback! All the supporting research reports and papers for this MBMA project can be read here.
For those of you who are RSS savy, click the Subscribe button above to follow this main page as a feed. With RSS, you'll know right away when I add new content.
We have started posting research videos to YouTube - experiments, simulations, … Hours of viewing enjoyment! Watch them here.
We presented two papers at SSRC in Pittsburgh, aka the city of bridges. The first paper provides engineering expressions that will allow engineers to predict the influence of flange-stiffened holes on their cold-formed steel studs and joists. The second paper calculates deflections and stresses in horizontally curved steel girders during a crane lift.
I presented on structural steel cold bending fabrication techniques (girders, beams, plates, HSS sections) at the TRB AFH70 Committee meeting today. The slides are posted here .
Our group recently completed a series of reports for the Virginia Department of Transportation documenting the bond strength and mechanical properties of corrosion resistant reinforcing steel, including stainless steel (N32, Enduramet 316LN,2205), MMFX2, and Zbar. The different bars had widely varying yield stresses and ductility which were shown to affect concrete crack width in service. Bond strength between the steel and concrete was most sensitive to relative rib area.
We continue to develop a simulation protocol for thin-walled ultra-high performance concrete members thanks in great part to our collaboration with Dr. John Bolander and his computational cement composites group at UC-Davis. Check out our latest model runs of uniaxial compressed thin concrete plates which in the near future will allow us to explore and quantify the structural limits of locally-slender UHPC members.
Members of our research group recently visited St. Louis. I gave a general overview of the Direct Strength Method for CFS beams with holes and presented a design example. Karthik Ganesan discussed proposed modifications to the LRFD resistance factor for cold-formed steel compression members. Tian Gao presented experiments on metal building vehicular access doors under hurricane-force wind pressures. The St. Louis Arch is beautiful, especially at night!
We had a great time at the SDSS conference in Rio de Jeneiro where we presented recent work on the cold-work of forming effect. Our paper includes a finite element example demonstrating that the increase in yield stress often accounted for in the design of cold-formed steel columns is at least partially negated by cold bending residual stresses and a shifted von Mises yield surface, i.e. the Bauschinger effect.
Several simplifying assumptions are made when designing for lateral wind drift of metal buildings. Recent MS graduate Maninder Singh Bajwa explored the implications of these assumptions with experimental work and computational studies led by Dr. Finley Charney. Base plate thickness was observed to play an important role in frame stiffness, and it was shown that wall girts can share lateral load between frames just as much as the roof diaphragm. The most unique part of this study is that we pulled on a real building (see pic to the right)!
Take the guesswork out of your concrete strut-and-tie models! We recently presented a paper at the fib congress in D.C. describing the use of truss topology optimization to identify the concrete truss model that most closely follows the elastic stresses in a concrete member. The visualization tool was written by Dr. Jamie Guest at Johns Hopkins University and is freely available.
I have created a new webpage for disseminating research publications, AISI reports, and design examples related to the extension of the AISI Direct Strength Method to structural members with holes. Much of this work will be presented and discussed this week at the NASCC Direct Strength Method Workshop and SSRC meetings in Orlando.
I am currently working with my friend and colleague Dr. Cheng Yu at the University of North Texas to developed simplified methods for predicting the elastic buckling properties of thin-walled structural components with stiffened holes. Click here to view our recent conference presentation in Orlando, FL.
My matrix structural analysis students (CEE 4404) recently completed their group projects. I have shared a few including a study of the Eiffel Tower, a 90 story building in Chicago, a precast concrete parking garage, and the New River Gorge bridge in West Virginia. Also, a group of students in my CEE 2804 class (Intro to Civil Engineering) wrote a compelling paper about how the civil engineering profession is intertwined with the socioeconomic status of Dubai. Please enjoy!
Undergraduate researcher Elaine Huffman recently completed a load test and 3D finite element analysis of the Ironto Wayside Footbridge, the oldest remaining metal bridge in Virginia located at the I-81N rest area in Ironto, VA. Read the final report.
We recently completed an experimental program where we studied the load-deformation response of a vehicular access door under simulated hurricane force wind pressures. Of particular interest were the forces transmitted to the door frame through special devices called wind locks. The wind lock forces often control the member size and connection details for a door frame in a metal building. Please contact Dr. Lee Shoemaker at the Metal Building Manufacturers Association for a copy of the report.
We have completed some preliminary research evaluating the LRFD resistance factor for cold-formed steel compression members. View the progress report and presentation given at the AISI COS meeting on 8/14/09 in Charlotte, NC.
Another new journal article is available online! This one presents simplified methods for predicting the local, distortional, and global buckling loads of cold-formed steel columns and beams with holes. The methods are currently being incorporated into the American Iron and Steel Institute (AISI)'s North American specification as part of the extension of the Direct Strength Method to CFS members with holes.
A new journal article is now available which summarizes a portion of my Ph.D. work (under the direction of Dr. Ben Schafer at Johns Hopkins University) where we developed simplified methods for predicting the critical elastic buckling stress of thin plates with general hole shapes, sizes, and spacings. Engineers can use these simplified predictions in lieu of full finite element analysis when designing locally slender structural components containing holes.
Ryan Bowen, a recent MS graduate of the group, has completed a report summarizing an experimental program where he measured the residual radius of curvature in cold-formed steel structural studs. The residual curvature is caused by plastic deformation as the sheet steel is wound onto a coil for transport. The curved steel sheet can result in residual stresses which are locked into CFS members as they pass through a roll-forming stand.
My new research website is up! I intend to to disseminate all kinds of fun information from this portal, including our research activities and my teaching efforts. Several of the links are still "under construction", so please do not fret if you click on a button and nothing happens. Happy surfing!