- Compute VDL and VLL+I at the support and at K
At the support F£>L = ^(0.25O x 74.5) = 9.31 kips (41.411 kN); IF = 0.251.
Consider that the load at the support is not subject to distribution. By applying the nec-
essary correction, the following is obtained: F1x+1 = 55.39(74.5 - 9.33)774.5 -
16(1.251)(0.23) = 43.85 kips (195.045 kN). AtK: VCDL = 9.31 - 12.70(0.250) = 6.13 kips
(27.266 kN); IF = 50/(61.8 + 125) = 0.268; P1x+1 = 36(1.268)(1.23) = 56.15 kips (249.755
kN); FLL+I = 56.15(74.5 - 12.70 - 9.33)774.5 = 39.55 kips (175.918 kN).
Select the shear connectors, and determine the allowable
pitch p at the support and immediately to the right of K
Assume use of %-in (19.1-mm) studs, 4 in (101.6 mm) high, with four studs in each trans-
verse row, as shown in Fig. 41. The capacity of a connector as established by AASHTO is
110</^2 (/c')^05 = UO x 0.75^2 (3000)^05 =
3390 Ib (15,078.7 N). The capacity of a
row of connectors = 4(3390) = 13,560 Ib
(60,314.9N).
The shear flow at the bottom of the
slab is found by applying q = VQII,
or g&L = 9310(16.90)(12.06 + 3.25)7
14,549 = 166 Ib/lin in (29,071.0 N/m);
^LL+I
43,850(50.70)(6.61 + 3.25)7
19,779 = 1108 lb/in^2 (7639.7 kPa); p =
13,5607(166 + 1108) = 10.6 in (269.24
mm).
Directly to the right of K: qfa -
6130(16.90)(16.89 + 3.25)721,793 =
FIGURE 41. Shear connectors.^96 lb/lin in (16,812.2 N/m); ?LL+I =
39,550(50.70)(10.70 + 3.25)731,414 =
890 lb/lin in (155,862.9 N/m); p =
13,560/(96 + 890) = 13.8 in (350.52
mm).
It is necessary to determine the allowable pitch at other sections and to devise a suit-
able spacing of connectors for the entire span.
- Design the weld connecting the cover plate to the W shape
The calculations for shear flow are similar to those in step 12. The live-load deflection of
an unshored girder is generally far below the limit imposed by AASHTO. However,
where an investigation is warranted, the deflection at midspan may be calculated by as-
suming, for simplicity, that the position of loads for maximum deflection coincides with
the position for maximum moment. The theorem of reciprocal deflections, presented in an
earlier calculation procedure, may conveniently be applied in calculating this deflection.
The girders are usually tied together by diaphragms at the ends and at third points to ob-
tain lateral rigidity of the structure.
singke
(singke)
#1