Archive for June 2011
Back to all posts
Crowd Effects and Fabricated Structural Steel?
Posted by Tom Klemens on June 16, 2011 at 8:45 AM.
Stunning 3D game quality graphics make MassMotion a highly effective visual communication tool easily understood by even the non-technical decision makers involved in large scale planning. OK, maybe it’s a stretch to post this information under the “Steel in the News” banner. But it’s just so doggone cool and we don’t have another convenient outlet to share this with you, so sit back and enjoy. If nothing else, click in the image to see a video clip of the program output and ponder that for awhile.
Developed by Arup, the design, planning and engineering firm, the new MassMotion software from Oasys precisely predicts pedestrian movement of crowds of hundreds of thousands of people with individual personalities and unique
agendas based on extensive human behavior research. More information is available at www.oasys-software.com.
Save the Date for SteelDay September 23
Posted by Tasha Weiss on June 15, 2011 at 10:44 AM.
Have you seen what the structural steel industry can do? It can be pretty amazing, and SteelDay is your opportunity to experience it firsthand. The industry’s largest educational and networking event returns for a third successive year. Hosted by AISC, its members and partners, SteelDay is a national event for those of you in the design and construction community to explore the structural steel supply chain firsthand.
Dozens of SteelDay event locations around the U.S. are already available to sign up for on SteelDay’s website at www.SteelDay.org.
Here is what you can expect to see at some of this year’s events:
- Steel Making and Recycling
- HSS (Hollow Structural Sections) Producers
- Steel Modeling and Detailing (BIM)
- Advanced Machinery and Robotics
New this year is a SteelDay sculpture competition in honor of AISC’s 90th year anniversary. AISC members are invited to get creative and enter the contest for a chance to win a trip to the 2012 NASCC: The Steel Conference, where the ultimate winner will be voted on by attendees and awarded a prize. Visit the competition’s website at www.aisc.org/Sculpture.aspx to find out more!
For detailed information on what this year’s SteelDay has in store, view AISC’s press release at www.aisc.org, here. Keep up with SteelDay updates, photos, and discussions by joining SteelDay’s fan page on Facebook and follow the SteelDay conversation on Twitter (www.twitter.com) @SteelDay.
Jacks ‘R’ Us
Posted by Ted Sheppard on June 14, 2011 at 2:17 PM.
Jacks come in all shapes and sizes. They are versatile tools. If you want to make small, very sensitive movements, there are jacks for that. If you want to lift 1,000 tons, there are jacks for that. From my perspective, jacks have evolved over time from my first field experience with jacks to my latest experience.
On my first bridge project we had screw jacks that would move wedges in and out to lift or lower what they were supporting. To assist in the sliding the wedges were usually greased. This meant that you too were greased after you handled them. Another problem with them was that you were on top of a falsework bent, and there wasn’t always enough room to get out to the end of the long handled crank that turned the screws. You could reach it, but you could not always exert enough power to move the wedges. On my first bridge this occurred. The bridge and a roadway were almost parallel, so we rigged a manila line down the falsework, over to a block attached to a tree on the river bank, and then fastened it to the trailer hitch on our foreman’s station wagon. He ran up and down the road a few times, and we got the bridge jacked. Fortunately it was not a large adjustment or we would have paid the foreman mileage.
I soon graduated to hydraulic jacks. These were much more reasonable, but not without their own problems. My first hydraulic jacks were water jacks with hand pumps. Yes, water jacks, and yes, in winter we added anti-freeze. And yes, even then they froze up. On my first water jack job, we had 500 ton capacity jacks. They were big and heavy. During the temporary closure of the arch ribs on the Niagara Arch Bridge, one of the jacks on my side of the river froze. We had to wrestle it out from under the falsework and put in our spare. A very big engineer from the home office, who loved being in the field, was handling the jacking on the other side of the river. He kept chirping into the radio, “I got mine,” or “This side is ready.” It was very cold, but I was steamed. We finally made it, and I didn’t lose my job. Patience really is a virtue.
I moved up to jacks that used hydraulic fluid with electrically driven pumps. We had to jack a 1,400 ton space frame that had been assembled on the ground 85 ft in the air. We used four jacking towers that swallowed the four bearing points. The concrete pylons were built inside our towers, and we then lowered the frame to its final position. Our pumps on this job could be adjusted so that the speeds were equalized at all four towers.
When I was at Tri State Steel Construction we had to raise the elevation of a bridge with a minimum delay to traffic. We used an electrical console to control 40 jacking points, and we raised each point simultaneously. We would go one full stroke, add temporary supports, “fleet” the jacks (see note below), and after the general contractor had placed a wedge of asphalt, we would go again. The temporary supports actually remained in the concrete of the new bearing pedestal.
I then moved on to strand jacks. When we were awarded the bridge over the Kanawha River in West Virginia, we had planned on using falsework in the river. Although this would have been permitted per the specifications, the U.S. Coast Guard asked if we could erect the bridge without falsework so that there would be no impediment to barge traffic. We looked at it and decided to erect the center span of the twin tub girder spans by using strand jacks. The center span was 450 ft long and the assembled girders weighed about 400 tons. We put a strand jack on each end of the side spans, assembled the girders on barges, floated them into position and jacked them into place.
You can see that large or small movements or lifts that weigh a few tons and as many as thousands of tons can be handled efficiently with jacks. The jacking systems today, just 10 years since my last retirement, can do marvelous things. You won’t get greasy, and the jacks won’t freeze up. When you are planning a job, if it is appropriate, consider using jacks.
Editor’s Note: We asked Ted to explain what it means to “fleet” the jacks for those who are not familiar with the term.
When a single, full-length stroke of the piston, does not give you the total lift distance required, you must fleet the jacks. This means, putting a temporary support under the piece being jacked, removing the jacking fluid to retract the piston, adding a shim or pipe piece to make up the difference for the movement of the first stroke, and then jacking again. This happens a lot on bridges where the space available is much less than that needed to jack up with one stroke. Some jobs require several cycles of jack, shim, retract, shim, jack, etc. If all the jacks worked exactly the same and all of the shims could be placed in the same time frame, you could do this to music. On the project described in this article, we did this at night. I wasn’t interested in singing; just getting to the hotel and climbing into bed.
Seeking Higgins Lectureship Nominations
Posted by Tom Klemens on June 13, 2011 at 9:40 AM.
Each year the T.R. Higgins Lectureship Award recognizes an outstanding lecturer and author whose technical paper or papers, published during the eligibility period, are considered an outstanding contribution to the engineering literature on fabricated structural steel.
Recent winners include Charles W. Roeder, James O. Malley, Donald W. White, Walterio Lopez & Rafael Sabelli, R. Shankar Nair, Ronald O. Hamburger, and Jerome F. Hajjar.
AISC encourages anyone involved with steel construction to submit nominations. Winners receive a framed certificate, which is presented at NASCC: The Steel Conference, and a $10,000 cash award.
This year nominations must be received by Monday, August 1. For more information from the AISC website, click here.
Steel Shots: Sculptural Steel
Posted by Tom Klemens on June 10, 2011 at 2:25 PM.
AISC member Capone Iron Corporation, Rowley, Mass., recently donated this AISC Steel Sculpture to the Worcester Polytechnic Institute, Worcester, Mass. In addition to providing a close-up look at common connections, this rendition of the sculpture also displays a clear coating system. Click photo to see the other side. (Photos by Bill Pascoli)
The AISC Steel Sculpture was originally created by Duane Ellifritt, professor emeritus at the University of Florida, as a visual teaching aid. It shows a variety of steel members and 20 or more commonly used connections. The first AISC Steel Sculpture was erected in 1986 and snce then more than 130 of the sculptures have been installed on campuses across the country, many fabricated and donated by AISC member companies. For more information, visit the Faculty and Students section of the AISC website.
Of course, steel is frequently the designer’s material of choice for more subtle works of art, especially in public settings where strength in combination with clean lines is important. Sometimes the scale is massive, as in the graceful lines of a bridge arching across a canyon. In other cases, steel is the medium for expressing delicate beauty, as in this ornamental connection detail.
This summer, AISC invites its members to create their own small sculptures of steel to help celebrate SteelDay, which is September 23. There is no fee to enter the SteelDay Sculptures contest, and it is open to all AISC full and associate members.
For contest details, including information about the fabulous grand prize, click here, or go to www.aisc.org/sculpture.aspx.
[revised June 16]
Engineering Journal Call For Papers
Posted by Tom Klemens on June 9, 2011 at 8:15 AM.
AISC is always looking for Engineering Journal articles on interesting topics pertinent to steel design, research, and fabrication methods. We are especially seeking technical articles with practical applications in the steel industry. If you have a new idea or an improvement on an old idea, please submit a paper to AISC for publication in EJ. Contact Keith Grubb by sending email to firstname.lastname@example.org for more information.
The latest edition of Engineering Journal can be viewed online at www.aisc.org/ej, where downloadable author guidelines are also available.
One Week Left to Pre-Order Bridge Calendar
Posted by Tom Klemens on June 8, 2011 at 8:25 AM.
A discounted pre-production price of just $12 is available through June 15, 2011, for the 2012 Chicago Loop Bridges Calendar. The calendar features high quality photos printed on 100 lb premium gloss paper and is 11 in. by 17 in. when open. To preview the calendar, including the cover and each month’s featured bridge, go to www.chicagoloopbridges.com/calendar12.ht
While on the site, check out notes for a walking bridge tour (”Two Miles - Eighteen Bridges”), now available in a mobile version.
Entries Sought for BIM Awards Program
Posted by Tom Klemens on June 7, 2011 at 8:14 AM.
The Tekla North American BIM Awards program is now open and accepting model entries. The awards program is divided into three categories: BIM, steel, and concrete. There is no fee to enter, and the entry deadline is July 1, 2011.
Online voting will be open to the public from July 12-28. The results of that voting will be provided as input to the jury of leading BIM experts who will select the North America winning entries. All winners in the North American program will be automatically entered into the Tekla Global BIM Awards competition, where winners will be decided by a jury of leading BIM experts inside and outside Tekla.
Winners of the North American awards program receive one Tekla Structures Viewer license and two tickets to the Tekla North American User Meeting 2012, in addition to a trophy and website publicity.
Complete program information is available on the Tekla website by clicking here.
To view the 2010 entries, including winners, start here and follow the links to each category.
Wind Effects on Buildings - June 9 Seminar
Posted by Tom Klemens on June 6, 2011 at 10:03 AM.
The CCHRB (Chicago Committee on High Rise Buildings) offers its Seminar on Wind Induced Building Movement: The State of Art Measurement, Mitigation and Accommodation on Thursday, June 9, at the Harris Bank Auditorium in downtown Chicago.
This half-day seminar begins at 8 a.m. and will cover four important topics related to wind induced building movement:
1) actual measurement vs predicted movement;
2) human response to building movement;
3) methods of mitigation of movement; and
4) methods of accommodation of movement.
Registration, which includes a continental breakfast, is $125 for members of CCHRB or co-sponsoring organizations, including AISC, and $150 for non-members. Register online at the seminar registration page here.
Steel Shots: Backgouging
Posted by Jennifer Jernigan on June 3, 2011 at 4:12 PM.
Backgouging in preparation for welding often is more visually dramatic (i.e., sparky) than the welding itself.
Gouging is a process where you remove steel instead of the opposite where you “weld-in” the steel. Gouging is frequently used in the shops to make full-penetration welds and also is used for removing faulty welds or welds that need to be redone. When it is done from on the back of a weld, it is called backgounging. (Click to see a little sketch of what full-penetration welding entails in case you’re not that familiar with it. I’m a visual person and it usually helps me to draw something out.) In our shops we have welding machines that when you flip a switch, they turn into gouging machines.
A plate blocks the view of the actual gouging process in this photo. That plate is referred to as a wind block. It blocks the wind from interrupting the process of heating up the steel and blowing it off, aka backgouging. The wind block is welded to a “skid” that is used to set the steel beam on and keep it raised off the ground. Even at this angle you can see that the man is wearing his grinding shield to protect his face from the steel that is flying off as it is being removed.
Meet the MSC contributing web editors.