Page 215 - Handbook of Civil Engineering Calculations, Second Edition

1.198 STRUCTURAL STEEL ENGINEERING AND DESIGN

2
2
4
3.13(3.40 – 2.77) – 0.581(3.40 – 0.053) 21.53 in (896.15 cm ). Then S x
4
3
3
21.53/4.60 4.68 in (76.69 cm ). This value agrees with that recorded in the AISC
Manual.
2
Then M f b S x 20,000(4.68)/12 7800 ft·lb (10,576 N·m); w 8M/L
2
8(7800)/13 369 lb/lin ft (5.39 kN/m).
6. Establish the value of f y for deflection determination
0.5
0.5
2
0.5
Apply (10,320t /f c )[1 – 2580/( f c g/t)] (H/D)( f c + f b )/f c – A
, or (113.8/f c ) (1 –
0.5
23.74/f c ) 1.084( f c + 20,000)/f c – 1.93. By successive approximation, f c 13,300
lb/sq.in. (91.7 MPa).
7. Compute the corresponding effective flange width for
deflection determination
0.5
0.5
0.5
Thus, b (10,320t/f c )[l – 2580/( f c g/t)] (10,320 0.105/13,300 )[l – 2580/
(13,300 0.5 108.7)] 7.462 in. (189.5 mm).
8. Locate the centroidal axis of the cross section having this
effective width; check the value of f c
2
Thus h 11.415 – 7.462 3.953 in. (100.4 mm); ht 0.415 sq.in. (2.68 cm ); A 313
2
3
3
– 0.415 2.715 sq.in. (17.52 cm ); H 8.670 in (142.1 cm ); y t 8.670/2.715 3.19
in. (81.0 mm); y b 4.81 in. (122.2 mm); f c (3.19/4.81)20,000 13,300 lb/sq.in. (91.7
MPa), which is satisfactory.
9. Compute the deflection
2
2
For the net section, I x 26.8 + 3.13(3.19 – 2.77) – 0.415(3.19 – 0.053) 23.3 in 4
4
(969.8 cm ). This value agrees with that tabulated in the AISC Manual. The deflection is
4
3
6
4
5wL /(384EI x ) 5(369)(13) (12) /[384(29.5)(10) 23.3] 0.345 in. (8.8 mm).
Related Calculations. New stadiums for football and baseball teams feature unique
civil engineering design approaches to steel beams, columns, and surface areas. Thus, the
Arizona Cardinals’ new football stadium in Glendale, Arizona, will have two Brunel
trusses supporting the roof of the stadium.
The Brunel trusses also support two transparent retractable panels that permit open-air
games in good weather. In inclement weather, the two panels can be moved together to
enclose the roof of the stadium. When the roof panels are closed the entire stadium can be
climate-controlled using the facilities’ air-conditioning system.
To further simulate outdoor conditions for the playing field, the entire 100-yard-long
(100 m) natural-grass field can be rolled outdoors. Then the natural grass can receive both
sunlight and rain to help the grass grow in a normal way. The field weighs some 9500
tons. It is moved outdoors on 542 wheels and has built-in drainage and watering piping.
Some 76 motor-driven steel wheels power the movement of the field into, and out of, the
stadium.
When the playing field is moved out of the stadium, other uses that do not require grass
turf can be made of the facility. Thus, concerts, circus performances, industry shows, con-
ventions, and the like, can be held in the stadium while the turf field is outdoors.
This structure is one example of the advancing use of civil engineering to meet the re-
quirements of today’s growing population. A sports stadium is leading the way to innova-
tive design concepts aimed at making people’s lives safer and more enjoyable.