Calculating the section modulus Home BCGBC4010A > Structural principles - Properties > Section properties Section properties Back Introduction Centre of area (centroid) Second moment of area (I) Calculating the moment of inertia (I) Changing to significant figures Comparing beam A and beam B Section modulus (Z) Calculating the section modulus Radius of gyration (r) Calculating the radius of gyration You do not have the Flash plugin. Calculating the section modulus To calculate the section modulus, the following formula applies: where I = moment of inertia, y = distance from centroid to top or bottom edge of the rectangle For symmetrical sections the value of Z is the same above or below the centroid. For asymmetrical sections, two values are found: Z max and Z min. To calculate the value of Z for a simple symmetrical shape such as a rectangle: where and y = This gives the formula for Z as: Note: The standard form of writing the value of Z is to write it as a number x 103 mm3, eg a value of 2,086 is written as 2.086 x 103. Calculating Z You do not have the Flash plugin. Please refer to the Text alternative for an explanation of this interaction. View the text alternative. (RTF 71 KB)
