Question

Help me with part D please! Show work and units!  

SE 1 -Homework 2.1 HW 2.1-3 due Thursday, December 4, 2018 1) You have a bookshelf that is 8 ft long and 1 ft deep, as shown in Figure 1. You can also see in Figure 1 that your cat, Timmy Shenko, is sitting exactly in the middle of the shelf. The shelf is made of wood (E1,500 ksi, ultimate strength 4,000 psi) and can be considered a simply- supported beam. Timmy can be modeled as a point load acting at L/2, and you estimate that he weighs 12 lbf. The weight of the engineering textbooks you keep on the shelf can be modeled as a distributed load, estimated to be 2.0 psf. The weight of the shelf itself can be modeled as a distributed load, estimated to be 1.25 psf. Since you are estimating these loads, you should multiply all dead loads by a factor of 1.2 and all live loads by a factor of 1.6 a. b. c. d. What are the reactions at the supports? What is the maximum moment in the shelf? Where does this moment occur? If the factor of safety in bending is 4, what must the height of the shelf be? Using the height that you determined in part (c), what is the maximum deflection of the shelf? Where does this maximum deflection occur? Use unfactored loads to compute deflection. 8' Figure 1 - Bookshelf with Timmy Shenko Table 1 - Bending Calculations for Simply-Supported Beams L-overall length w-point load, M = moment Max bending moment End Slope Max Deflection lcad per unit len WL 16EI WL 48EI WL 4 24EI 384EI

Answer 1