When the deck from Problem 9.11 is raised off of the ground and installed on the side of a house, the two outer joists are reinforced and remain rigid, but the center joist bends under the load of the 130 lb person (standing in the same place), providing a flexible support at the plank center. If the joist is a 2 in (width) × 8 in (depth) simply supported redwood beam 10 ft long, loaded at its center, what is the reaction force on each of the three plank supports?
Problem 9.11:
A 1 in × 10 in plank on a redwood deck has L = 48 in long and supported on three joists that rest on the ground and so do not bend. The joists act as pin/roller supports for the plank. If a 130 lb person stands on the plank in the location shown, what is the reaction force on each of the joists?
