Design against fluctuating load mcq

In this chapter, all the required design loads are determined according to three design codes:

1. CSA S6-14
2. AASHTO LRFD-14
3. CSA S6-66

For the scope of this project, only dead loads and live loads are calculated, assuming other loads such as:snow loads, wind loads and seismic loads are trivial for the design.

Calculations are carried out for steel and prestressed concrete girder bridges.
The dynamic load factors for a bridge design code are calculated based on the 75 year mean maximum loads.
The analysis is performed for single trucks and for two trucks (side by side).
Dynamic loads are lower for heavier trucks and also lower for two trucks.

For fluctuating loads at points with stress concentration, the best approach is to design to avoid all localized plastic strain. In this case, K fshould be applied to both alternating and midrange stress components.

1) Impact load:

1. Suddenly applied load with a velocity is called as impact load

Different operations performed under impact load are blows of hammer, punching operations, etc 2) Fluctuating load:Load varying in magnitude and direction are called as fluctuating loads.
Parts subjected to fatigue failure must be designed for fatigue failure.