Page 328 - Civil Engineering Formulas

BRIDGE AND SUSPENSION-CABLE FORMULAS 261

TABLE 10.5 Ratio of Moduli of Elasticity of
Steel and Concrete for Bridges

f c for n E s
concrete E c
2.0–2.3 11
2.4–2.8 10
2.9–3.5 9
3.6–4.5 8
4.6–5.9 7
6.0 and over 6

where w channel length, in (mm), in transverse direction on girder flange; and
B cyclic variable 4.0 for 100,000 cycles, 3.0 for 500,000 cycles, 2.4
for 2 million cycles, and 2.1 for over 2 million cycles.
For welded studs (with height/diameter ratio H/d 4):
Z r d 2 (10.47)

where d stud diameter, in (mm); and
cyclic variable 13.0 for 100,000 cycles, 10.6 for 500,000 cycles,
7.85 for 2 million cycles, and 5.5 for over 2 million cycles.
Required pitch of shear connectors is determined by dividing the allowable
range of horizontal shear of all connectors at one section Z , kip (kN), by the
r
horizontal range of shear S , kip per linear in (kN per linear mm).
r

NUMBER OF CONNECTORS IN BRIDGES

The ultimate strength of the shear connectors is checked by computation of the
number of connectors required from
P
N (10.48)
S u

where N number of shear connectors between maximum positive moment and
end supports
S ultimate shear connector strength, kip (kN) [see Eqs. (10.1) and (10.2)
u
that follow and AASHTO data]
reduction factor 0.85
P force in slab, kip (kN)