Question

What is the deflection of a W12x30 16 ft long with a distributed load of 2k/ft? Include the weight of the beam. a) 0.027in b) 0.055in c) 0.434in d) 0.832in

Answer 1

Answer:

correct answer is  option C)

Explanation:

W 12 x 30 section of the beam dimension

Value of   E = 29000 ks i/in²

               I = 238 in⁴

weight of beams per length =  30 lbs/ft = 30 × 10⁻³ ks i/ft = 2.5 × 10⁻³ ks i/in.

distribution load = 2 k/ft  = 1/6 k/in

L = 16 × 12 = 192 inch.

deflection due to distributed load = $\dfrac{5}{384}\dfrac{wl^4}{EI}$

                     = $\dfrac{5}{384}\times \dfrac{192^4}{6\times 29000\times 238}$

                     = 0.427 in.

deflection due to self weight = $\dfrac{wl^4}{48EI}$

                                           = $\dfrac{2.5 \times 10^{-3}\times 192^4}{48\times 29000\times 238}$

                                           = 0.01025 inch

total deflection = 0.427 in.+  0.01025 inch

    total deflection   = 0.4375 in

correct answer is  option C)