CIVIL ENGINEERING FORMULAS

262 CHAPTER TEN

At points of maximum positive moments, Pis the smaller of P 1 andP 2 ,
computed from

(10.49)

(10.50)

whereAceffective concrete area, in^2 (mm^2 )
fc28-day compressive strength of concrete, ksi (MPa)
Astotal area of steel section, in^2 (mm^2 )
Fysteel yield strength, ksi (MPa)

The number of connectors required between points of maximum positive
moment and points of adjacent maximum negative moment should equal or
exceedN 2 , given by

(10.51)

At points of maximum negative moments, the force in the slab P 3 , is com-
puted from

(10.52)

whereAsrarea of longitudinal reinforcing within effective flange, in^2 (mm^2 );
andFyrreinforcing steel yield strength, ksi (MPa).

Ultimate Shear Strength of Connectors in Bridges

For channels,

(10.53)

wherehaverage channel-flange thickness, in (mm)
tchannel-web thickness, in (mm)
wchannel length, in (mm)

For welded studs (H/d4 in (101.6 mm),

(10.54)

ALLOWABLE-STRESS DESIGN FOR SHEAR IN BRIDGES

Based on the AASHTO specification for highway bridges, the allowable shear
stress, ksi (MPa), may be computed from

Fv (10.55)

Fy

3

C

Fy

3

Su0.4d^22 fcEc

Su17.4h

t

2 

wfc

P 3 AsrFyr

N 2 

PP 3

Su

P 2 0.85fcAc

P 1 AsFy