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Problem L - Periodic Loading

Steel E =29000 ksi, Poissons Ratio = 0.3 Pinned base All beam-column connections are rigid Joint Masses Lumped mass at joints C and D is 0.02 kip-sec2 / in Loading The load P(t), applied to joint C, is a periodic load. Three different loading cases (functions) are defined for P(t). The three loading functions, which have periods of 0.25, 0.50 and 1.00 seconds respectively, are shown in the chart and graph below. Assume 5% damping for all loading. | Problem L Periodic Loading Steel E 29000 ksi Poissons Ratio 0.3 Pinned base All beam-column connections are rigid Joint Masses Lumped mass at joints C and D is 0.02 kip-sec2 in Loading The load P t applied to joint C is a periodic load. Three different loading cases functions are defined for P t . The three loading functions which have periods of 0.25 0.50 and 1.00 seconds respectively are shown in the chart and graph below. Assume 5 damping for all loading. Time Time Time Note The period of Point Force Function 1 Function 2 Function 3 time functions 1 2 k sec sec sec and 3 is 0.25 0.5 a 0 0 0 0 and 1 seconds b 10 0.0625 0.125 0.25 respectively. c 0 0.125 0.25 0.5 d -10 0.1875 0.375 0.75 e 0 0.25 0.5 1 To Do 1. Verify natural period of structure is approximately 0.50 seconds. 2. Determine displacement at joint D for the three periodic functions. Note Our intent is that you try this problem on your own first. After you have solved it on your own you can step through our solution if desired. If you have problems trying to create the model then follow the steps in our solution. 1 Problem L Solution 1. Click the drop down box in the status bar to change the units to kip-ft. Kip-ft 30 2. 3. From the File menu select New Model From Template. This displays the Model Templates dialog box In this dialog box click on the Portal Frame template Portal Frame dialog box button to display the 4. In this dialog box Type 1 in the Number of Stories edit box. Type 1 in the Number of Bays edit box. Type 15 in the Bay Width edit box. Click the OK button. 5. Click the X in the top right-hand corner of the 3-D View window to close it. 6. Click the drop down box in the status bar to change the units to kip-in. Kip-in 30 7. From the Define menu select Materials. to display the Define Materials dialog box. Highlight the STEEL material and click the Modify Show Material button to display the Material Property Data dialog box. 8. In this dialog box Verify that the modulus of elasticity is .