Kemper Memorial Arena, located in Kansas City, Missouri and designed by architect Helmut Jahn, is a steel space frame structure that established Jahn as an adventurous designer.
Designed for flexibility, the arena seats up to 18,000 people. The two tiers of seating are part of a concrete substructure. The metal walls and roof, suspended from giant trusses, form the superstructure. Teh two elements are independent. The three e xterior trusses that give the 325 x 424 foot interior a column-free enclosure are made of standard tube varying between 30 and 48 inches in diameter and 3/8 to 1 1/4 inches thick. These tubes are bolted together with internal tube stiffeners. the trusse s are 27 feet deep and set 153 feet on center. The substructure takes no vertical loads from the roof or exterior walls. Loads from the trusses are transferred to steel hanger angles out from the building, leading to pin connections that sit on concrete piles driven 60 feet into the earth.
The structure of the Kemper Arena was designed for maximum efficiency. The main structural pieces are three large triangular space frame trusses which span the entire 324 foot width of the building and provide support for the ceiling suspended from them.
The three dimensional triangular configuration of these trusses provides internal stiffness and wind resistance for the arena. These exterior trusses are located at 153 feet on center and are made up of steel tubes chosen by the architect and engineers
since the circular cross section would provide maximum buckling resistance with minimal material. The circular shape also has less wind resistance and less perimeter area- which meant less maintenance and dcreased ice formation than wide flange or box s
haped trusses. The circular shape also expressed the three dimensional character of space trusses very well. the joint details were developed to ease the fabrication and construction processes and therefore the amount of field welding was minimal. Uniq
ue bolted connections with internal tube stiffeners were developed and verified witha structural model test. The structural system weighs 23.5 psf and costs about $8.22/square foot.
Each truss member has only four contact points with the ground via pin connections. Each is a triangular structural member but instead of siz members touching the ground only four are needed due to the crossbracing from the triangle.
The walls of Kemper Memorial Arena are self supporting and consist of reinforced concrete which also supports the spectator seating down through their own foundations. From the photo it is evident that at no point do the walls touch the space frame which supports the roof.
Concerning the horizontal and lateral loading:
Since there are two different structural systems in use, it is necessary to distinguish between the two systems. The first system is that of the walls of the arena which resist lateral loads with their weight and because at ground level they are buried i
n an earth berm which provides for added stability. These walls are connected internally to the reinforced concrete seating structures which by nature of their weight and strungth add to the ability of the exteriour walls to resist lateral loads.
The second structural system, which is actually the primary structural system, is the set of three exterior trusses. These trusses resist lateral loads due to their rigid configuration. The three trusses achieve internal stiffness and wind resistance fr om their diagonal bracing with three inch rods on the bottom chords. The three dimensional configuration also helps achieve stiffness and wind resistance.
The circular cross section of the tube naturally provides maximum buckling resistance with minimal use of materials. Also the circular shape has minimal wind resistance and less perimeter area which means less maintenance and painting area. The main loa
ds that this building has to resist due to its loacation and use are wind loads, snow loads, dynamic loads from people and other dynamic loads from various uses of the facility.
Kaori Abiko and Jesse Emory
ARCH 461/561 Spring 1995
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