Kyle Field at Texas A&M S
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Form Functio n NEWS & INFORMATION FROM HAM+ILTON FORM FALL 2014 Project Profile Kyle Field at Texas A&M Heldenfels Enterprises Steeped in tradition, home to the 12th man and known The $450 million redevelopment is being done in two phases. for its raucous fans - renovating an iconic stadium such The first phase began in November of 2013. It consisted of as Kyle Field can be a daunting task, but Populous has replacing the entire lower east side deck, including lowering done their fair share of iconic designs, and this one is no it seven feet to bring the fans closer to the field, and the exception. The overall vision is to enhance the game day building of a new south end zone. experience by adding more public areas, plazas and gather- ing spaces. Fans will have more seating options including After a break in construction to play the 2014 season, suites, loge seating and an exclusive club area. Seats placed phase two will begin after the Aggies play their last home close to the field and a canopy over the seating areas will game in November. Phase two consists of replacing the not only provide shade from the hot sun, but will help entire west side of the stadium and will be completed in contain the noise level, keeping Kyle Field one of the August of 2015. When completed, the stadium will grow most intimidating stadiums for visitors. from 82,600 to a seating capacity of 102,512, with 12 seats reserved and kept empty in memory of the Aggies lost in the bonfire tragedy of 1999. The subcontractor for the structural precast is Heldenfels Enterprises, Inc. in San Marcos, Texas.The project was especially significant for Heldenfels, not only because of its size, but because several employees are former Texas A&M students, including owners Fred and Gil Heldenfels and VP & Chief Estimator Kurt Schriefer. (continued inside) “The Kyle Field Redevelopment project presented a demand- ing schedule as well as some unique design challenges. In typical Hamilton Form fashion, they were responsive to our needs and quickly improvised solutions that helped us stay on schedule.” – Fred Heldenfels, President and COO Project Profile Kyle Field at Texas A&M, continued The project calls for more than 2,400 precast pieces. H amilton Form worked closely with Heldenfels to identify the number of forms needed for the project, and which forms could be multi-purposed to cast several products. The between season construction schedules made timing critical. The majority of the forms are double risers, with some tub forms. Due to the number of unique riser configurations, multiple forms were needed. Most of the forms are 55 feet in length, longer than typical stadia forms. The tub form for the loge box seating was notably unique. The overall form was 56’-1” long with a 5’-9” deck that pushed the overall form width to 12’-2 ”, This two tier tub form is 52’-8” long and has a 5’-9” deck that pushed the making it one of the largest stadia forms Hamilton Form has overall width of the form to 12’-2”, one of largest stadia forms ever shipped ever shipped. from Hamilton Form. 56’ double riser stadia form Double stadia riser with 12” stems and deck strand in the lower tread Adjustable Stadia Form for McLane Stadium To cast the stadium, Hamilton Form developed a single, highly adjustable double stadia riser form. The package included several risers, fillers and two different back pans. Heldenfels produced approximately 185,000 feet of risers for the stadium; including single and double risers, in the same form. Formwork Baylor Bears – McLane Stadium Heldenfels Scores another Texas Stadium Wh ile many college stadiums are expanding to capacities of 100,000 and more, Baylor University’s new stadium in Waco, Texas seats 45,000; 5,000 less than the old stadium built in 1950. The new stadium is on 93 acres with a pedestrian bridge connecting it to the campus. The site on the Brazos River includes boat slips for “sailgating” around the stadium. The stadium has a canopy to provide shade from the Texas sun and open concourses to allow for airflow throughout the stadium. Heldenfels Enterprises secured the contract for the precast for the stadium. To produce the risers, Hamilton Form developed an approach that allowed Heldenfels to cast all of the risers in a single, highly adjustable form. The form - work included several fillers, risers and two different back pans. In all, ten different products were cast in the same base form; including both double and single risers. Technically Speaking Last Issue we discussed detensioning strand and its effects on the concrete product, and the form. To complement that Pretensioning Self-Stressing Forms discussion, this article discusses pretensioning. Know your limits Allow for movement Self-stressing forms are designed to resist both the hydrostatic forces Proper installation requires the form to be anchored at centerline of concrete and the compressive forces applied to the form by with the remainder of the form clipped down with slide connections prestressing. Longitudinal stiffeners, the form skin, and in some to resist uplift. This is critical because as the strands are tensioned, circumstances compression bars, are used to resist the prestressing the compressive force from prestressing causes the form to shorten. forces when designing a self-stressing form. The size, location, and When the form shortens, it must be allowed to move longitudinally. number of stiffeners and compression members are determined The center of the form should be anchored so that it shortens in both based on the amount of prestress force the form is designed directions instead of allowing it to “walk” or move in one direction. to resist. If the entire form is anchored or welded in place, movement will be At the end of the bed, a jacking plate bears against the end of the restricted. This can cause the form to buckle under load, damaging form. Holes drilled through the jacking plate allow strand to pass the form and creating a dangerous situation. through. The jacking end of the form is stiffened since this is where the prestress load is introduced. Our engineers design forms based on Measure the movement the amount and placement of prestressing force as specified by the When pretensioning, it is important to measure the amount of form customer. The first rule in pretensioning is: Never Exceed the Capacity movement in order to properly calculate strand elongation. Put a of the Form. reference mark on something stationary at the end of the form in an unloaded condition. After you fully tension, measure the difference Balance the load between the reference mark and the end of the form. Record the When prestressing, it is critical to balance the prestressing load being movement, and do it every time you tension until the plant is satisfied applied to the form. This helps protect your form from eccentric load - that the maximum movement by strand pattern is understood. ing that can cause serious form damage. First, make sure the jacking Checking form movement on a periodic basis will help to ensure plate is evenly bearing against the form, then balance the load being that form movement is always being used in stressing calculations. applied to the form by paying attention to the following: Keep a log book with form movement history to help you understand variables such as strand patterns, temperature, bed set-up and other • Ease the form into tension by symmetrically loading the form. factors that affect shortening. Move from side to side and up and down so that the load is being evenly applied. Form shortening is not something that can be predicted with a formula. The type of form, conditions and your processes are unique. The only • In general, you should tension the lower strands first, then way to know how much movement is taking place is to measure it. move upward in an ascending pattern. Keep up with maintenance • When tensioning a double tee, tension a few strand in one stem, Finally, you should regularly inspect the form connections and anchor then move to the other stem, tensioning this stem with the same bolts. Make sure connections are clean and free of any concrete designated number of strand. Moving side to side in an upward build-up. Check the form level. Make sure shims are still in place, manner will ease the form into full loading and also allow for free if not, replace them. movement of the form as tensioning is completed. • When tensioning a dual, triple or quad pile form, use the same logic as a double tee. Partially tension one side, then, move side to Stay safe side and upward to reach full loading. As you know, strand tensioning activities are very dangerous. • If you need to cast only one side of a dual cavity piling form, A tremendous amount of force is placed on each strand and you may need to partially stress the side not being used to help in turn high stresses are induced to the strand. If a strand balance the loading on the form. fails, the failure is instantaneous and can cause damage and great bodily harm. • If you have a triple pile form and need to pour only one cavity, use the center cavity not one of the side cavities so that you do Tensioning strand requires strict safety procedures to keep not eccentrically load your form. workers out of the line of strand during tensioning. Make sure all equipment is properly functioning and safety alarms, • Never pour one side of a dual form and not the other without signage and flaggers are properly positioned.