Lecture 3 Flashcards
ADTT
Average Daily Truck Traffic defined by Table 4.3
The AASHTO pedestrian load on bridge sidewalk is
.075 ksf
If load is applied to the bridge restricted to pedestrians and bicycles then the load will be
.085ksf
Railing must be deigned to withstand
.050 ksf both transversely and vertically
railing must also be deigned to handle a _____load.
.2 kip
The deck overhang cantilever on the outside girder is designed for uniform ine load of
1 kip/ft located 1’ from curb
The gravity load for design truck is outlined in
AASHTO A3.6.1.3.3
The force on the truck Fr equation is defined as
m*V2/ r
the multiple presence factor should be applied to the force of a braking truck
True
the braking force shall be taken as______of the axle weights of the design truck or the design tandem placed in all lanes
25%
Forces considered under lateral load
Fluid forces
Seismic Forces
Ice Forces
What are the forces considered that cause deformation
Temperature
creep and shrinkage
settlement
Temperature range for steel or aluminum
0-120F for moderate
-30-120F for cold
Temperature range for concrete
10-80F for moderate
0-80 for cold
The effect of creep and shrinkage can have an effect on structural…
Strength
Fatigue
Servicability
Settlement occurs due to
Elastic and Inelastic deformation of the foundation
What are som collision loads to consider in the dsign
Vessel
Rail
Vehicle
The total factored force effect “Q” shall be taken as
Σ ηγQ
η
Load modifier specified in article 1.3.2
γ
The number of design lanes should be determined by taking
w/12
Live load force effect shall be determined by considering each possible combination of number of
number of loaded laned multiplied by a corresponding multiple presence factor
Front axle weight of HL-93 design truck
8 Kip
Rear axle weight of HL-93 design truck
32 Kip
Distance between rear axles of design truck
14 to 30 feet
Design lane load shall consist of
uniformly distributed load of .64Klf
The tire contact area shall be
20” Wide 10” Long
LLDF
Live load distribution factor
The effect of forces tending to overturn a structure shall be calculated as a vertical upward wind load equal to
.020 ksf for strength III
.010 for service IV
Influence Function
A function that represents the load effect at a point in the structure as a unit action moving along a path or over a surface
