Practice Problem 1 Find the distance of the centroid of the built-up section from the bottom and its centroidal moment of inertia along the x-axis. Properties of C180x15 channel. A = 1850 mm² tw = 5.3mm x= 13.8 mm Properties of W250x18 A wide flange and a channel have the following properties. Wide Flange Channel A = 18400 mm² A = 6430 mm² A = 2270 mm² bf= 101 mm tw=4.8 mm Practice Problem 2 A built-up section fabricated by attaching a C180x15 to a W250x18 shape with 15 mm rivets as shown. Determine the moment of inertia at the centroid of the built-up section. = 12 mm d=470 mm I=726x106 mmª ly = 93.6x106 mmª Ix=8.86x106 mm ly= 0.405x10 mm Ix= 22.4x10mm* d=251 mm tf= 5.3 mm FR = 138 MPa 5.31 251 N.A. I= 131x106 mmª ly = 3.4x106 mmª tw = 10 mm x=20 mm FB = 118 MPa 101 13.8 64.46 52.54 15.3 y=78.26 130.80 Check your answers against the Key to Corrections found at the end of this SAS. Write your score on your paper. Question: In Practice Problem 1 and 2, what will happen if another channel, of the same properties, is attached to the bottom of the wide flange? What will happen to the centroid of the built-up section? Can you just algebraically add the individual moments of inertia of the channels and the wide flange?

Standard units are also called SI units. SI units are used for measuring a physical quantity satisfying certain conditions. There are two types of units: fundamental units and derived units. Fundamental units are physical quantities that are independent,…