9012 - 59.16(4.73)
2
= 12,916 in
4
(53.76 dm
4
); Sb = 879 in
3
(14,406.8
cm^3 ); Sts = 570 in^3 (9342.3 cm^3 ).
- Transform the composite
section, with cover plate
included, to an equivalent
homogeneous section of
steel; compute the
section moduli
In accordance with AASHTO, the ef-
fective flange width is 12(6.5) = 78 in
(1981.2 mm). Using the method of an
earlier calculation procedure, we see
that when n = 30, y = 78/76.06 = 1.03
in (26.162 mm); y'b = 19.42 + 1.03 =
20.45 in (519.43 mm); y'ts = 17.92 -
FIGURE 40. Transformed section. 1.03 = 16.89 in (429.006 mm); yt'c =
16.89 + 6.50 = 23.39 in (594.106 mm);
/ = 12,802 + 9072 - 76.06(1.03)^2 =
21,793 in^4 (90.709 dm^4 ); Sb = 1066 in^3
(17,471.7 cm^3 ); Sts = 1,290 in^3
(21,143.1 cm^3 ); Stc = 932 in^3 (15,275.5
cm^3 ).
When n = 10: y = 7.22 in (183.388 mm); yb = 26.64 in (676.66 mm); y'ts = 10.70 in
(271.78 mm); J^ = 17.20 in (436.88 mm); I= 27,950 + 9191 - 109.86(7.22)^2 = 31,414 in^4
(130.7545 dm^4 ); Sb=ll79 in^3 (19,320.3 cm^3 ); Sts = 2936 in^3 (48,121.0 cm^3 ); Stc = 1826
in^3 (29,928. lcm^3 ).
- Transform the composite section, exclusive of the cover plate,
to an equivalent homogeneous section of steel, and compute the
values shown below
Thus, when n = 30, yb = 23.78 in (604.012 mm); yt's = 12.06 in (306.324 mm); /= 14,549
in^4 (60.557 dm^4 ); Sb = 612 in^3 (10,030.7 cm^3 ). When n = IQ 9 yb = 29.23 in (742.442 mm);
y;s = 6.61 in (167.894 mm); /= 19,779 in
4
(82.326 dm
4
); Sb = 677 in
3
(11,096.0 cm
3
).
- Compute the dead load carried by the noncomposite member
Thus,
Ib/lin ft N/m
Beam 150 2189.1
Cover plate 51 744.3
Slab: 0.54(6.75)(150) 547 7982.8
Haunch: 0.67(0.083)(150) 8 116.8
Diaphragms (approximate) 12 175.1
Shear connectors (approximate) 6 87.6
Total 774, say 780 11,383.2
- Compute the maximum dead-load moments
Thus, M^L = (
1
/ 8 )(0.250)(74.5)
2
(12) = 2080 in-kips (235.00 kN-m); M£L = (
1
A)
(0.780)(74.5)
2
(12) = 6490 in-kips (733.24 kN-m).
