Computer analysis of a truss. The purpose of this study is to show that the magnitude of the joint displacements as well as the magnitude of the forces in members may control the proportions of structural members. For example, building codes typically specify maximum permitted displacements to ensure that excessive cracking of attached construction, such as exterior walls and windows, does not occur (Photo 1.1 in Section 1.3). A preliminary design of the truss in Figure P4.53 produces the following bar areas: members 1 through 4, 5 in.2 , and members 5 and 6, 2 in.2 . Also E = 29,000 kips/in.2 .

Case 1: Determine all bar forces, joint reactions, and joint displacements, assuming pin joints. Use the computer program to plot the deflected shape.

Case 2: If the maximum horizontal displacement of joint 4 is not to exceed 0.25 in., determine the minimum required area of the diagonal truss bars, members 5 and 6. For this case assume that the diagaonal members have the same areas, while all other truss members have cross sectional area of 5 in. 2 . Round the area to the nearest whole number.

Transcribed Image Text:

45 kips 0 2 6 3 5 1515 (4) 4 45 kips 20