structure and is defined asPe(x) = [((Cs)/(()] w(x) vs (x)Eq. 6This load can now be applied to the structure in a fashion similar to the one inwhich the initial unit loading of po = 1 was at the beginning of the process. Now, though,the value of Pe(x) is substituted to determine displacement, shears, and moments due toearthquake loading.Like earthquake loading, wind loading offers a complicated set of loading conditionswhich must be met in order to provide a workable design. Although the problem ofmodeling wind forces is a dynamic one, with winds acting over a given time interval, theseforces can be approximated as a static load being uniformly distributed over the exposedregions of a bridge.The exposed region of the bridge is taken as the aggregate surface areas of all elements asseen in elevation. The loading on a bridge due to wind forces is specified by AASHTObased on an assumed wind velocity of 100 miles per hour.For conventional girder/beam type bridges this translates into an intensity of 50 poundsper square foot with the minimum total force being 300 pounds per foot. Trusses andarches require wind loads applies with an intensity of 75 pounds per square foot with theminimum total force of either 150 or 300 pounds per foot, depending on whether theaffected member is windward or leeward chord. The windward chord is that chordexposed to the prevailing wind and the leeward chord is located away from the wind.With regard to the superstructure, wind forces are applied in a transverse and longitudinaldirection at the center of gravity of the exposed region of the superstructure. AASHTOoffers a set of wind loading values for truss and girder bridges based on the angle of attackof wind forces. Conventional slab-on-stringer bridges, however, with span lengths lessthat or equal to 125 ft can utilize the following basic loading:* Wind load on structure:Transverse loading = 50 lb/ft (2.39 kN/m)Longitudinal loading = 12 lb/ft (0.57 kN...
