5.4. Examples

Try these first

1. 1.

   What is beam deflection?

   Hint

   Think about how a trampoline bends under weight.

2. 2.

   What does the modulus of elasticity indicate?

   Hint

   High E means less bending.

3. 3.

   What is the formula for calculating deflection at mid-span?

   • Δ = 5wL^4 / 384EI
   • Δ = wL^3 / 48EI
   • Δ = PL^3 / 3EI

   Hint

   Recall the context of mid-span deflection.

4. 4.

   True or False: An increase in modulus of elasticity will always decrease beam deflection.

   • True
   • False

   Hint

   Think about why stiffer materials bend less.

5. 5.

   A beam has a span of 3 m with a distributed load of 8 kN/m and E = 150 GPa, I = 200×10^6 mm⁴. Calculate the deflection.

   Hint

   Remember to switch to consistent units.

6. 6.

   Explain how an increase in moment of inertia would qualitatively affect deflection in real applications.

   Hint

   Think about how beams resist bending.