The 2016 NFL season recently kicked off in September. With successful baseball and hockey teams, Chicagoans are hoping that the Bears will take home a few more wins this year. While we keep our fingers crossed for the Bears this season, we are flashing back to last April when Chicago proudly hosted the 2015 NFL Draft at the Auditorium Theatre.
The city was buzzing with fans supporting their football team during the draft. One popular spot was Pioneer Court, an open area along Michigan Avenue that housed 32 giant NFL team helmets during the draft for fans to take pictures with. Continue reading Giant Size NFL Helmets→
Because of its symmetrical nature, pipe can be bent to consistent radii with no distortion, but several things need to be taken into account in order to avoid rippling. In part one of this blog post, we discussed why rippling occurs and what material should be used to avoid it. Once the best material has been determined, a pipe bending company must use the right machine, tooling and methods in order to avoid distortion. Continue reading Pipe Bending Techniques to Avoid Rippling→
Rippling on the surface of a pipe is a somewhat common problem that occurs during bending operations. Learning about the reasons behind the rippling can help avoid this issue.
Ripples are caused by high levels of compressive force on the inside of a pipe or tube with thin wall thickness. Thicker pipe walls can withstand higher compressive forces on the inside of a bend without distorting or wrinkling. With custom rolled pipe, material on the outside of the bend stretches – this causes wall thinning. The material resists this thinning and as a result the outside surface of the bend wants to cave in. This causes the flawed profile shape we know as ovality or distortion. Continue reading How to Avoid Rippling when Pipe Bending→
Quite frequently, companies that bend and curve structural steel products find themselves working closely with either local or nationally known artists as well as architects for typical construction projects. There is a certain level of artistry involved in the bending and rolling process that makes the use of curved steel very desirable in public works of art. Continue reading Rolling Half Pipe for Pillars→
The sport of hockey has seen a rise in popularity over the last few years nationally, which can be attributed to the increased media presence of the NHL and hockey at the Olympics. At a very simplistic level of understanding, the goal of the game is for a player to hit the puck into a net Continue reading Pipe Bending in Pro Sports→
A 167’-7” tall, Verizon Wireless communications tower, atop Smelter Mountain in Durango, Colorado required a structural upgrade on its 3 existing tower legs. The tower had originally been built with 2” to 3” standard structural pipe as its supporting legs, but after years of cyclical wind loads it was determined that the existing tower legs needed a structural upgrade. In order to reinforce the tower’s legs, engineers devised a plan to weld pipe jackets to the outer half of the existing legs, which can be seen in the diagram below.
Pipe jackets are a common term for pipe split or halved into 180 degrees. They are commonly used for heat exchangers and or coils welded to the outside of tanks. For this project the split/halved pipes are referred to as 180deg cut pipe. Various size pipes were to be split into halves, from 3” to 5” XXH and then straightened in order to surround the outer half of the existing tower legs. The additional support from the reinforcing 180deg cut pipe increases the stiffness of the tower 12x from its original design.
The pipe was split into 180deg cut pipe by way of a gantry track plasma cutting system. The pipe is fixed in order to restrict its movement when cutting and once the torch strikes an arc the movement of the cutting head is automated to eliminate any deviation from the cut line. Due to residual stresses within the pipe, from its melting and manufacturing at the mill, the pipe springs and twists open once it is fully split. This is commonly known in the industry as the banana peel effect, and must be corrected by way of straightening. Most structural steel fabricators have the equipment to split the pipe through some sort of track cutting system, either flame or plasma, but it is the straightening of the halved pipes back to within, or better than, mill tolerance that is the challenging aspect of splitting pipe into 180deg cut pipe. For this, most fabricators seek out a bender/roller as they have the necessary equipment to bend, curve and straighten structural steel. With the proper tooling, a machine which is normally used for bending steel can also be used for the opposite, to straighten out existing curvature.
In this case, a 3-Roll section bender with a special tooling setup was used to straighten the pipe and it was straightened to 1/8” over 10ft of length. After the 180deg cut pipes were straightened, they were bundled and sent to a galvanizer. The halved pipes were then hot dip galvanized for corrosion protection after installation. The galvanized reinforcing pipe jackets were then shipped to a terminal in Durango, Colorado where they were staged for pickup once the steeplejacks were ready for installation.
Structural Engineers Association of Illinois (SEAOI) gives out an award every year to a project it feels helps encourage engineering education and advances the art and science of structural engineering. Loyola’s recently constructed Institute of Environmental Sustainability (IES) won the “Best Project” award given out by SEAOI for the Excellence in Structural Engineering Awards Competition. The judge commented that “the winter garden is an elegant curved glass enclosure with a minimized amount of structure to allow unobstructed views. The environmentally responsible IEC integrates academic and residential components of university to create space for an exciting and delightful whole student experience”.
The crown jewel of IES is the winter garden. The winter garden is a 3,100 square foot urban agricultural greenhouse. The structure is designed using nine elliptically curved trusses that are made out of 8” SCH 80 pipe connected to 5” SCH 40 pipe though a triangular cross section configuration of a double top chord and single bottom chord system. The design of the continuously curving trusses helps minimize the amount of structure needed to hold up the glass curtain wall skin. The top roof portion of the greenhouse incorporates pipes curved to a very large 250ft radius to help maximize sunlight in the winter garden’s growing area while at the same time try to produce minimal glare to surrounding buildings. Also there is a tight 12 ft radius 90 degree bend at one end that goes down into an S shaped curve. This curvature in the steel pipe trusses design helps with passive ventilation. When you walk into the building you will notice the temperature. You are in an unconditioned environment that is not heated or cooled. The winter garden is shaped to assist natural ventilation with open end windows at both ends of the trusses. This unique curved shape of the winter garden also facilitates rain water harvesting. Water falling on the curved roof easily flows into a 3,000 gallon cistern located on the first floor. The water is then reused in the greenhouse operations for irrigation, landscaping and for flushing the toilets located off the lounge.
In the greenhouse there will be two aquaponic systems. There are also two vertical farming installations where food crops are grown for harvest on a wall mounted lattice structure. The ecological system will grow fish and produce for food. Students taking courses in related fields will work to identify what to grow in these systems and how to process them for market. Students maintaining these gardens will sell the produce at Loyola’s famers market and through the Engrained Café. The IES is an innovative and interactive learning environment that demonstrates how students can participate actively within, as well as help to create a living/learning green community.
Innovative Design in Engineering and Architecture with Structural Steel (IDEAS2) awards are sponsored by the American Institute of Steel Construction in recognizing projects where structural steel has been utilized in an innovative manner. This year the winners were chosen from nearly 100 submissions from architectural, engineering and construction firms throughout the U.S. This year Circuit of the Americas (COTA) Observation Tower won in the category for projects less than $15 million. The COTA is a 3.4 mile motor racing circuit, the first purpose-built F1 track in the U.S. that is located just outside of Austin TX. The land mark 251 foot tall observation tower was designed by Miro Rivera Architects to give spectators unrestricted views across the racetrack’s twisting bends. The platform (which has a glass floor) provides a 360 degree panorama view of the circuit and has a capacity for 10,000 spectators.
The circuit of the Americas observation tower won the award because it combines creativity, economic and technical achievement through the use of structural steel. The observation tower is very creative in how it uses a veil like structure made out of 18 bright red closely spaced HSS 8.625” OD structural pipe that are curved running down the full height of the tower. The pipes act as a canopy for both the platform and the stage below. The design of the curved pipes was inspired by the visual imagery of sports cars and movement. The red pipes running along the tower mimic the streaks of lights trailing racecars at night time. While ostensibly an architectural feature, the veil also serves as an outrigger column for lateral load resistance via a series of struts and rods that connect it to the main tower. The tower contains approximately 385 tons of steel. The observation tower also had a technical achievement through the use of fully connected Tekla Structures program.
Due to the tight 10 month time frame from owner approval to race day, the complex tower structure design had to be conveyed to the fabricator so they could erect the canopy without confusion. Generally in the steel fabrication construction industry paper drawings are delivered to the steel fabricator to interpret and build, but this case they were able to bypass this step and print shop drawings directly from the model. To increase efficiency and reduce cost of bending each 8 inch steel pipe to the architects initial drawings the program helped work with a bender roller to break large radii into segments. There were a total of 70 curved 8” sch 40 pipes that start out at a tight 96” centerline radius and then get a slightly looser 360” radius before opening up to a large 1,349” radius at the bottom of the tower. The fabricator worked directly with a detailing service to electronically transfer the model into detailed fabrication shop drawings that showed the pipes in different curved sections. The construction manager, Austin Commercial, estimated that the integrated delivery process saved three months over a more conventional process. COTA is more than just a racetrack; it has become a major economic driver in Central Texas. On their website they state that from October 2013 to September 2014, COTA brought in $900 million to the Austin metropolitan area ($731 million for events and $166 million attributed to operations). During that time COTA hosted six motorsports, 18 concerts, 110 track rentals and other events that helped create 9,100 jobs through annual activities and operations.
The city of Chicago has prepared for the media spotlight this weekend as the NFL has moved its annual draft events from New York to the heart of the Midwest this year. Tourists and locals alike can visit Grant Park to take part in a number of activities as part of the “Draft Town” built up specifically for this event. While the draft itself is taking place at nearby Roosevelt University, the free fun takes place in the park. Events include a flag football festival, Super Bowl museum, football celebrity autographs, and even a lightshow at the famous Buckingham Fountain, as the city changes the colors on the fountain to represent the NFL team which is currently on the clock waiting to draft.
While visiting Grant Park, many patrons will have the chance to view some of Chicago’s finest examples of curved steel. Always a tourist attraction, the nearby Millennium Park is an extension of Chicago’s Grant Park and contains the famous Cloud Gate sculpture and Pritzker Pavilion. Cloud Gate, or “The Bean” as it is affectionately known, displays a 3/8″ thick curved stainless steel façade that has been polished to a mirror finish. The complex topological curved steel surface required computer and robotic assistance to create properly. The plates were fabricated so precisely that no on-site cutting or filing was necessary when lifting and fitting them into position to be welded together.
Nearby Pritzker Pavilion features both a curved stainless steel band shell with a ribbon like effect, as well as curved arches made from rolled pipe which varies in diameter from 12 to 20 inches. The curved pipe trellis allows for an open lawn structure to support the speaker system and has become very popular for local music and film events. The use of curved steel pipe was preferred by designer Frank Gehry over the alternative of using vertical columns or pipes to support the speakers as it worked together with the curved band shell more aesthetically.
Often, in the bending and rolling industry, we see requests which push the limitations of tube bending. This can occur in both large and small pieces. Sometimes a project may have been designed without considering the physical effects curving has on the material. In these cases, design plans can occasionally be evaluated and modified with the knowledge of an experienced steel bender.
One of the most common examples in tube bending where material shape and size needs to be evaluated is tube cross-section deformation. If you were to be rolling flat material to form a cylinder, the plate rollers are designed to sandwich the material between the rolls, completely and evenly supporting all material under the same stress levels. Even when curving angles, rolling equipment can use dies of different shapes in order to brace the material on the interior and exterior faces, so that pressure is applied evenly. However, when rolling a tube or pipe, the fixed bending dies of the rolling equipment can only form around and support the exterior of the material. This leaves the center of the tube open, and more vulnerable to deformation due to uneven pressure. Tubes can experience concavity, or even changes in overall height or width on particularly difficult bends.
This happens as a result of the rolling dies pressing inward on the tube walls. The reverse pressure from the die on the opposite side of the material also pushes back, but the force does not carry through the hollow space of the tube equally, leading to issues of concavity and the resulting shift in material causes height and width shrinkage/growth if severe enough.
An available option to counteract these efforts is to increase the wall thickness of the tubing to help in lessening distortion issues. In the event that material is architecturally exposed tubing, sometimes any deformation is unacceptable, and in those cases, further accommodations or changes may be required to the design to find an alternative.