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Problem C - Truss Frame

Steel Frame E =29000 ksi, Poissons Ratio = 0.3 All steel members are L4x4 angles, Fy = 36ksi Base is pinned Diaphragms Concrete diaphragms are 8” thick with a unit weight of 150 pcf Model as rigid diaphragm at Levels A and B Additional dead load at each diaphragm is 50 psf Live load at each diaphragm is 100 psf To Do Size steel members for DL + LL using AISC - ASD89 Determine the first three modes of vibration | Problem C Truss Frame Steel Frame E 29000 ksi Poissons Ratio 0.3 All steel members are L4x4 angles Fy 36ksi Base is pinned Diaphragms Concrete diaphragms are 8 thick with a unit weight of 150 pcf Model as rigid diaphragm at Levels A and B Additional dead load at each diaphragm is 50 psf Live load at each diaphragm is 100 psf To Do Size steel members for DL LL using AISC - ASD89 Determine the first three modes of vibration Level B Level A Typical Elevation All four sides are the same 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 C Solution 1. Click the drop down box in the status bar to change the units to kip-ft. Kip-ft 30 2. From the File menu select New Model. This displays the Coordinate System Definition dialog box. 3. In this dialog box Select the Cartesian Tab. In the Number of Grid Spaces area type 0 in the X direction edit box. In the Number of Grid Spaces area type 0 in the Y direction edit box. In the Number of Grid Spaces area type 0 in the Z direction edit box. Click the OK button. 4. From the Draw menu select Edit Grid. to display the Modify Grid Lines dialog box. 5. In this dialog box Verify that the X option is selected in the Direction area. Type 7 in the X Location edit box and click the Add Grid Line button. Type 10.5 in the X Location edit box and click the Add Grid Line button. Select the Z option in the Direction area. Type 25 in the Z Location edit box and click the Add Grid Line button. Type 37 in the Z Location edit box and click the Add Grid Line button. Click the OK button. 6. Click in the window titled X-Y Plane @ Z 0 to make sure it is active. The window is highlighted when it is active. 7. Click the xz 2D View button to change the view to an X-Z elevation. Note that the title of the window changes to X-Z Plane @ Y 0. 2 Figure C-1 Initial Grid