CROSBY KEMPER ARENA, KANSAS CITY, MISSOURI, USA

When large column free spaces are required, the structure of the building is a major element in the design. A good example is provided by this arena which has a roof supported by three huge triangular space trusses. The three space trusses spanning 324ft are completely self-supporting. The enclosure is set within the space truss structures and is made up of metal panels which are separated by wide joints.

The space trusses are 27ft high and made of mild steel tubes of 48in diameter and up to 1¼ in thick for the top chords, 36in and up to 1 in thick for the bottom chords and 30in and up to 1⅝ in thick for the web members. The top chord carries a maximum working load of approximately 2500 tons (2260 tonnes). This huge compressive member is restrained against buckling by the inclined web members. At bottom chord level, cross bracing is provided in each bay by two steel rods of 3in diameter. The space truss has great rigidity and strength against vertical, horizontal or twisting forces. Suspended below the space trusses by hangers, are secondary roof trusses, generally at 54ft centres, the space truss panel length. They are 9ft deep, decreasing to 4ft 6in deep over the 45ft central parts between trusses. The space trusses are positioned so that they all have approximately equal loads on them from each side. For the two end trusses, the load from one side includes the weight of the wall cladding, it being partly supported by the roof, as well as the roof weight itself. Joists 4ft 5in deep at 9ft centres span the 54ft between the roof trusses and in turn, support the roof decking. To give the roof surface a certain amount of stiffness in its own plane, bands of cross-bracing are provided over the 45 ft central parts between the trusses, going in an east-west direction, and on the east and west sides of the building, going in a north-south direction. The wall cladding panels are generally 15ft 6in by 9ft and supported by mullions at 15ft 6in centres, in turn supported by cross beams and then by columns at 18ft centres. The columns are suspended from the perimeter roof beams so that the cladding panels move with the roof, except the lower band of panels at the four corners whose mullions are supported on the ground.

Notes:

mild steel низкоуглеродистая сталь

restrained adj. связанный, защемлённый

working load рабочая нагрузка

Ответьте на вопросы к тексту

1. How is column free space for this arena provided?

2. What are the dimensions of the space trusses?

3. Which member of the space truss resists compressive forces?

4. How are secondary roof trusses positioned?

5. What are the differences in the loading of the space trusses?

6. How is stiffness of the roof surface provided?

7. What are the features of the wall cladding?