With Opening Day for the brand new Marlins Ballpark round the corner, I thought it would be only fitting to do a small write-up on one of the most interesting projects that I have worked on. The project is extremely dear to my heart and I should thank everyone at Bliss and Nyitray for providing me with an opportunity to work on this project and enough latitude to get creative, both in terms of the structural analysis and detailing.
My first opportunity to work on the ballpark was way back in September 2005, when I was about 4 months into my chosen profession as a Structural Engineer. Sadly, I worked only for a couple of months on the project before it got shelved. The project revived again towards the end of 2008, but I was busy working on another cool project [link in another post]. It was in March 2009 that I started working on the ballpark again. The design was substantially underway, but a lot of items pertaining to the support system for the retractable roof were in the process of being finalized. My first task was to study and optimize the track beams that carry the operable roof and design the monster SuperColumns, twelve in total (8 elliptical and 4 “tree” shaped ones).
I will digress a little to thanks the wonderful team members on the project and will apologize for not being able to single out all contributions, or else I will never finish. The design team comprised of a number of individuals (both young in age and young at heart). The significant credits list is below (and, in no particular order):
≡ Bart Wallis (“Bartman”): Principal-In-Charge, man behind many of the wonderful structural solutions and responsible for guiding the overall design. Enough said!
≡ Jim Ordija (“Jimb0”): Responsible for overall structural model, designed all stadia columns, point man for every day activity on the project both during construction.
≡Christian Martos (“Machine”): Designed/detailed every single beam on the project, often till dawn. “Not too bad” was/is his favorite line.
≡ Anantha Chittur (“Big A”): Responsible for all items pertaining to the track beam, super column, analytical modeling issues, shear walls, miscellaneous East canopy connections to track beam.
≡ George Khoury (“Are we done yet?”): Singlehandedly designed all the complicated foundation elements, responsible for the structural scheme and design of the complicated façade.
≡ Adam Rixey: Designed a lot of the foundations, beams, miscellaneous steel. Led the field team of inspectors and kept the contractors in check.
≡ Neal Benish (“Neal the Deal”): Along with Christian, spent the nights in the office designing the raker beams, North Ramp and other complex connections.
≡ Adriana Jaegerman (“Patchika”): Designed many of the complicated elements of the façade system.
≡ Sam Darrah: Led the field team after Adam decided that Hawaii was better than Miami. Formed a double-threat with partner-in-crime Matt P.
≡ Matt Poling (“Matty Matteo”): Designed miscellaneous elements on the stadium and chief rope-walker while inspecting the roof trusses at 200+ feet in the air.
≡ Jeff Peters: Primarily responsible for inspections on the SuperColumns and Track Beams, ensured that the contractors were kept in a tight leash. No-nonsense inspections and known to have tie-wire, other tools in his waist belt to help errant ironworkers.
≡ Lazaro Alfonso (“Laz”): Responsible for designing all plate girders supporting the canopies and other miscellaneous details.
≡ William Caycedo: Responsible for designing all the masonry elements, crazy slab on grade details, ramps etc.
≡ Pablo Garcia (“Matador”): Primary role was to generate presentable calculations for Bart’s design, which was often “back of the napkin”. Designed many of the masonry elements within the bowl.
≡ Raul Martinez: CAD/REVIT manager, the cog in the wheel for making sure that the drawings were drafted and sent for every single deadline.
Jasond Lorio, Spencer Whitehead, Jose Matallana, Florencia Braga: Thanks for the countless hours (days and nights) of drafting/modeling to pull together this project.
Other individuals that had significant role in the project:
Suhendi “Ken” Widjaja and Jason Linton (Inspections, shop drawing review)
Marilyn Rojas (keeping track of paperwork and answering countless phone calls for us.
A great team of engineers/architects/builders were also part of this monument. Thanks to all the members of the teams from Populous Architects, Hunt Construction Group, Baker Concrete, VSL Heavy Lifts, Uni-Systems, Walter P. Moore, RWDI Wind Enginers,ME Engineers, Schuff Steel, Canam Steel and to every single person who has worked on this project.
With the credits out of the way, here is a rundown of the interesting/challenging facets of the ballpark. Any large, complicated project will have a few memorable items. In fact, the complexity of the Marlins ballpark led to many unforgettable items.
Several schemes/options were studied to effectively support a *heavy* roof. My mentor, Bart Wallis, had a system figured out that would work: A concrete box girder on steroids. So massive was the void inside it that I could easily fit my cubicle across its width. The retractable roof structure would ride on rails supported by the track beams. Massive 36 inch diameter wheels, each powered by an individual motor provides traction for the roof. Each roof truss is supported by transporters which are then linked together.
There were stringent deflection limits on the track beam. If it deflected too much, then it would cause an overload on the giant transporters that carries the 8000 ton roof. Initial design was based such that it deflected no more than 1.5 inches at mid-span over spans as large as 150 feet. The structural design for the operable roof was done by Walter P. Moore (WPM) and the mechanization by Uni-Systems (UNI). There was constant exchange of information/analysis models between all parties in order to make sure everyone was within the tight design parameters. It was tough at times due to the fast-track nature of the project, but every step we moved forward was a step closer to having a brand new ballpark.
A monster track beam needs an able ally, one who can carry its weight down all the way to the ground. That’s where the Super Columns come in. Each of these interior columns were elliptical in shape, measuring 15 feet long and 8 feet wide and towering 125+ feet above the ground (for a layman, that’s an equivalent of a 10 story building). Reinforcing details were worked out to ensure maximum efficiency and ease of construction. In order to simplify construction, the contractor (Baker Concrete) had built a template to fit the reinforcing bars.
There are four “tree” or “inverted tripod” columns at the entry plaza that carry the entire weight of the roof when it is in open position. Modeling them for analysis was just as complicated as building it right. Well, it was probably easier to model :). These tree columns went through several rounds of fine tuning, with each one requiring re-analysis between us, WPM and UNI. The columns were so massive that they *each* needed about 85-100 trucks of concrete (900 cubic yards).
The original design was for a cast-in-place box girder. However, the logistics/construction sequencing meant that the super columns and track beams had to be built prior to the stadium construction. These columns towered above the neighborhood, prompting Brent Musburger to question if they were building an overpass at the old Orange Bowl site. He was right in some ways, except it was overpass for the moving roof and not cars/trucks.
Building the track beams on shoring/scaffolding was not viable from a timing/logistics standpoint. It was decided that these beams would be precast on the ground and then lifted into place using a strand-jacking system. Some of the track beams weighed as much as 1400 tons. It was a balancing act…..the load of each beam lifted was balanced by two others sitting on the ground. The days/nights prior to the beams being lifted into place were one of the most nervous moments in my life. VSL Heavy Lifting and their wonderful team of engineers pulled it off without too many issues.
A lot of people will believe that there are only twelve super long-span trusses on this project, ones that carry the roof. But there is a 13th. This truss spans between the North and South Track beams, across the width of the ballpark, enabling the East Canopy to look as glorious as it does with breathtaking views of Downtown Miami. There are three large operable doors, which run on tracks.
The beauty of this truss, conceived by Bart, is that it provides the lateral stability for the roof system allowing slender 36 inch diameter columns, 80 feet tall to work structurally. Conventional designs would have required massive columns, thereby killing the architect’s visions of minimal impact to the views. The trusses are connected to the ends of each track beam with connections that carry forces in all imaginable directions. Designing the connection was extremely tricky, even more trickier was detailing it so that everything fitted perfectly 130 feet up in the air. I had a lot of fun designing it. It was hard getting used to the order of magnitude of forces that we was dealing with. If ever you get a chance to walk on the East Concourse level, take a moment to look up and you will see what I have been describing.
This is a masterpiece. It is a cantilevered slab that is supported on ellipitical columns, almost giving a feeling of being free-standing. My buddy, Neal Benish, really deserves all the credit for designing and detailing a Bart Wallis special. The key to being able to build it was the attention to detail given, working closely with the contractor to ensure that there was a synergy between how he wanted to build it and how we wanted it to behave once completed.
These are essential parts of any stadium structure. These beams cantilever enormous distances, helping to support the seating units and providing the views needed. This stadium is very unique in the sense that there is hardly a 90 degree corner or a typical detail. Each raker beam differed from the other, albeit slightly that every single one had to be designed and detailed. Some of them had really odd shapes due to architectural constraints. There is one that is famous among the team, the Pterodactyl. Once you see the shape of this beam, located in right field, you will know what I am talking about.
There are a few unsupported, floating stairs on this project, again near right field. The construction team was a little scared to build it and had our field representatives (Sam and Matt) drop their business cards on the stair landing during the concrete placement. This was in the event that if it collapsed, they would know who to call :). Thankfully, the cards are still in the landing.
CURTAIN WALLS and GLAZING:
Another striking aspect of this ballpark is its façade system. Populous Architects have often been criticized of designing “boring” stadiums. This one takes stadium architecture to a whole new level. This was a detailing exercise beyond compare, rather a nightmare, to two of my colleagues George Khoury and Adriana Jaegerman. A look at the façade and its simplicity from the exterior will hardly tell you volumes about how complex its supporting system is.
Last but not least, kudos to the WPM and UNI team of engineers who helped design and mechanize the massive roof structure over the ballpark which *only* weighs a mere 8000 tons. It is not easy to design a roof that spans over 550 feet in a hurricane-prone region with wind speeds in excess of 146 mph. A complex system of individual pieces was put together in a way that made it easy to build, pleasing to the eyes and extremely efficient. It is a real shame that people won’t be able to get up close to it like the design team did, to appreciate the minute details and the thousands of man hours that went into designing it. If it were up to me, I would have created a viewing gallery all the way up on my track beams to enable people to get a bird’s eye view.
It is never easy to put into words and describe every detail that has gone into this masterpiece. Only the design team knows the real effort and dedication that has gone into designing a stadium that will entertain the South Florida baseball fans for many, many years to come. A good coverage on the roof’s mechanization is here. In the video is a good friend Andrew “Drew” Agosto from UniSystems.
On April 4th 2012, the world will get a glimpse of the stadium on prime time. As every single fan enjoys the game of baseball, we engineers will be counting down to the start of the hurricane season and waiting for a real-time test of our design.