Category Archives: Tee Bending

Steel Lintels and the American Palace of Versailles

Can you imagine living in a home larger than the airplane hangar for a 747? Well David and Jackie Siegel are about to finish construction on their 90,000 square foot residence. David Siegel, the billionaire founder of Westgate Resorts, started construction on this mega-mansion in 2004 and after the financial crisis in 2008 had to take a hiatus from funding this build.  The home, which is just now coming to fruition, includes a 30 car garage, 2 movie theaters, and around 800 tons of structural steel.

The American Palace of Versailles

The house is modeled after the Palace of Versailles in France and features a copious amount of windows, around 2000 in fact. To match the Arched French windows and doors highlighted on the French Palace, the architects incorporated numerous French arches into the Florida residence.

When architects are designing a house with this many windows they must keep in mind a key component of construction, the lintels. A lintel is a structural horizontal block that spans the space or opening between two vertical supports. Lintels are not only load-bearing building components, they can also be decorative architectural elements.

Lintels can be made out of a variety of materials. Steel lintels are the most reliable and versatile. When using steel you have the option to use any number of different shapes. The shape and style of a lintel can be manufactured to best suit the building material and window style for your project. Frequently, lintels are made using curved steel angles, or rolled tees.  The design of the Siegel residence called for curved lintels over many of the windows and doors.  These specific lintels were used for structural support and for decorative purposes. The style shown here is made with curved steel and this is just one of many different types of metal lintels that are possible.

Curved Steel Lintel on the American Palace

Arched Lintels are also important for safety purposes.  Brick arches that are installed without lintels can be weakened over time and sometimes even collapse. Nobody wants to be around falling bricks and archways.  So whether you are building a home with 2000 windows or merely 2 windows, you should always consider which type of lintels you are using.

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Creating Close Tolerance Curved Steel Tees

Steel tees, especially larger tees, are produced by splitting a steel beam and then straightening or curving the two resultant tees to the required specifications. At times these specifications can require close tolerance work.
For example, WT12 x 27.5 steel tees were required to be rolled stem-out to an inside radius of 53ft 0.187in with 44ft 4in of outside arc and left untrimmed (with some extra material—for grip or pickup– at each end to be trimmed to length by the customer.)

The splitting tolerance was +/-1/8in; the rolling tolerance was +/-1/8in on the rise over 10ft. (Tighter than the 1/8 over 5ft AISC tolerance for straighness.) Beyond these tolerances, what was critical to the application was consistency of the outside radius measured at the tip of the stem and that the tees be as equal as possible.

Measuring the radius of a stem-out steel tee at the tip of the stem precluded using a chord and rise measurement. (The inside radius, of course, could be measured that way.) A special checking fixture was manufactured with an inside radius to match the specifications. The stem-out tee could then be set against the checking fixture to verify the dimensions. This fixture in fact mimicked the application of the curved tees: they are to be welded to the inside radius of curved plate. If the tees did not match up to the plate, the welders would have serious problems.

Other measures were taken to ensure accuracy and consistency. Special arrangements were made with the steel supplier to improve consistency in the height of the beams. The beams were checked before they were split into tees for any variation in height.

 

Measuring Consistency in the Height of the Beams Before Splitting and Rolling

Great care was taken to guarantee that the beams were split right down the center.

Beams Split Down the Center to Make Two Equal Tees

And then the rolling was done to the precise specifications and checked on the fixture.

Tees Rolled to Close Tolerances

Inspectors from the equipment manufacturer who will use these tees checked the first four rolled tees and approved proceeding with production.  As production proceeded, continuous checking was done to guarantee the required quality.

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Creating Straight or Curved Steel Tees

One of the structural steel shapes is the tee.  Tees can be supplied straight or curved.  The smaller sizes are produced in steel mills; the larger sizes are produced by splitting beams longitudinally.

A customer who is seeking steel tees for use in machinery and equipment or for use in construction would typically contact either a steel mill (if the quantity was sufficient, e.g. a truckload) or a steel service center which would stock structural shapes and sell in smaller quantities (e.g. as few as one piece.)

Some steel service centers have equipment to split tees.  Rotary shears, which work something like a can opener, split a beam into two tees.  The beams are typically split in the middle of the web, but also can be cut with unequal stems.  (What is left of the web is called the “stem.”)  When the material is too thick for a rotary shear (above, say, about 7/16in), a cutting torch is used to split the tees.

With either method, when the beam is split residual stresses are released, and the resulting tees relax into a shape curved in one or two planes.  The tees look like bananas and need to be straightened.

There are primarily two ways to straighten the tees:  ramming and rolling.  In the former case, a hydraulically powered ram pushes on the tee when the tee is held at two ends.  By repeatedly applying pressure along the length of the curved tee, it can be straightened.

A quicker and more effective way to straighten tees is with a three-roll section bender (also called a “profile bender,” or an “angle roll.”).  The curved steel tee is run through large rollers with smaller calibrating rollers until it is straight.  The process is faster than ram straightening and provides superior quality.  Mill tolerance for straightness of tees is 1/8in variation from straightness in ten feet.  Ram bending can achieve this tolerance.  With roll straightening, however, tolerances of 1/8in over 40 feet and longer can be achieved.

Stem-Up Split and Curved Tees

Most steel service centers do not operate section rollers and so it is common for them to send out tees to be split and straightened by companies who specialize in curving steel.  Such companies also curve tees to a specified radius for customers.  In some cases the “banana” tees can be fed into a section bender without previously being straightened.  The tees can be rolled stem in, stem out, and stem up depending on the application.  And tees as large as 18in can be curved these ways.

18in Stem-In Split and Curved Tees
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Built-up Curved Tees

Steel tees up to 22 x 142-1/2 can be curved stem in, stem out or stem up.  At times, however, either the stem is too large or the radius is too tight to roll a tee.  One solution is to fabricate a built-up tee.

For example, a customer wanted two tees with a 14in stem ½ in thick and with a 10in wide flange rolled to a 6ft 11in inside radius stem out.  Too tight to roll, this size tee to this radius could be made in two pieces.

Two pieces are burned out of 1/2in plate 13-1/2in wide cut to a 16ft 11-5/8in inside radius with 8ft of good arc measured to the outside. The other piece is a 5/8 x 10 flat rolled the easy way to a 6ft 11in inside radius.  This piece is then cut in half.  The resultant pieces are tacked together to make two tees.

Built-Up Curved Steel Tees

The end use is for lintels at a high-end housing project.

For more information on curved steel lintels, see the City of Chicago Building Code, Article 3, Section 326, Sub-Article 502.4.

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Straightening or Curving Steel Tees Made from Split Beams

20ft WT4 x 9 Split and Straightened to 1/16in Tolerance

One steel section that does not typically come as a profile from a steel mill is the tee section.  Except for small sections, steel tees are produced by splitting beams.  A rotary shear or a torch cuts the web of the beam to produce two tees.  The cut is usually down the middle of the beam but sometimes is done off center.

When the residual stresses of the beam are released by cutting it, the tees take the shape of a banana. If straight beams are required, then a straightening operation must be done.  One method is to press the beams in a cambering machine which restrains the steel section while being pressed with one or two hydraulic cylinders. Another method is to roll the beam sections on an angle roll (also called a section bender or profile bender).  The latter method tends to produce a straighter tee.

Stem In Tee with No Ripples

21in tees up to 80ft long with up to 1in web thickness can be produced.  The standard tolerance for tees is 1/8in over 5ft; with the right angle roll, the tolerance can be as precise as 1/8in over any length of tee. Tees 30ft long can be rolled to within 1/16in overall.

After beams have been split into tees, the tees can be curved with the stem in, the stem out, or the stem up, to both large and very tight radiuses and everything in between.  And again, to very precise dimensions.

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