6.3. Concepts in Structural Design

Try these first

1. 1.

   What are the three primary considerations in structural design?

   Hint

   Think of the acronym SEC.

2. 2.

   What does LRFD stand for?

   Hint

   Recall the method name used to design structures.

3. 3.

   What does the acronym SEC represent in structural design?

   • Strength
   • Economy
   • Comfort
   • Safety
   • Economy
   • Comfort
   • Safety
   • Serviceability
   • Economy

   Hint

   Think about the key objectives of design.

4. 4.

   True or False: LRFD involves applying load factors greater than unity to service loads.

   • True
   • False

   Hint

   Consider how LRFD enhances safety.

5. 5.

   A structural engineer is designing a beam that will be subjected to a dead load of 50 lb/ft and a live load of 40 lb/ft. If the load factors for dead and live loads are 1.2 and 1.6 respectively, what is the factored load the beam needs to resist?

   Hint

   Apply the load factors to each load type.

6. 6.

   An architectural student needs to create a realistic load combination for a design that includes snow and wind influences. If the dead load is 30 lb/ft, the wind load factor is 1.5, and the snow load factor is 1.2, illustrate a reasonable load combination.

   Hint

   Remember to weigh both the loads by their factors before combining.