Reference no: EM131747346
1. Structural beams are to be placed at 8 ft. on center under a reinforced concrete floor slab. If they are to support a service dead load D = 65 psf of floor area and a service live load L = 100 psf of floor area, determine the factored uniform load per foot which each beam must support.
2. Select the lightest C section that will safely support the service tensile load PD = 65 kips and PL = 5o kips. The member is to be 14 ft long and is assumed to have two lines of holes for ¾ inch f bolts in the web. Assume that there are at least three holes in each line 3 inches on center. Use A36 steel.
Select a standard threaded round rod to support a factored tensile load of 72 kips (service tensile load = 50 kips) using A36 steel.
3. Determine the critical buckling load for a 22ft W12 x 50 using the Euler equation. E = 29,000 ksi. Proportional limit = 36,000 psi. Assume simple ends and maximum permissible L/r = 200.
4. Determine the fcPn and Pn/Wc for W12 x 120 with KL = 26 ft, using the AISC Specification and Fy = 40 ksi.
A W10 section is to be selected to support the loads PD = 85 kips and PL = 140 kips. The member, which is to be 20 ft long, is fixed at the bottom and fixed against rotation but free to translate at the top. Use A992 steel.
For the beam shown, determine wn using A992 steel and the plastic theory.
5. A built-up steel beam consists of a ¼ in x 12 in web, and 3/8 in x 4 in top and bottom flanges. The member has the compression flange fully braced, therefore the moment capacity, fMn, using LRFD method was calculated to be 103.4 ft.k using Fy = 50 ksi steel. During design it was thought that the factored moment, Mu, was 100 ft.k, but after the member was fabricated it was found that the actual design moment, Mu, should have been 130 ft.k. A brilliant and resourceful young engineer suggested adding a ¼ in x 6 in cover plate to the bottom flange of the member to increase its capacity. Compute the new moment capacity, fMn, and state whether or not it will safely support the design moment, Mu = 130 ft.k.
6. Determine the nominal flexural strength of the following welded shape: The flanges are 7/8 inch x 12 inches, the web is 3/8 inch x 60 inches, and the member is simply supported, uniformly loaded, and has a span length of 40 ft. Lateral support is provided at the ends and at midspan. A572 Grade 50 steel is used.
A plate girder must be designed to resist a service load bending moment of 2400 ft.k consisting of 25% dead load and 75% live load. The total depth of the girder will be 73 inches, and continuous lateral support will be provided. Use Fy = 50 ksi and select a trial cross section. Assume that the moment includes an accurate estimate of the girder weight.
7. Design a base plate of A36 for a W12 x 65 column (Fy = 50 ksi) that supports the loads PD = 200 kips and PL = 300 kips. The concrete has a compressive strength f'c = 3 ksi, and the footing has the dimensions 9 ft x 9 ft.
8. Design a moment-resisting base plate to support a W14 x 120 column with an axial load Pu of 620 kips and a bending moment of 225 ft.k. Use A36 steel with Fy = 36 ksi and a concrete footing with f'c = 3 ksi. fcFp = 3.32 ksi.