Science Buddies: "Ask an Expert"

Can the increasing length of an I-beam's flanges or horizontal beam, affect the strength of the I-beam?

Yes changing any aspect of the cross section of beam will change it strength. Some elements have more effect than others though.

The answer depends on your definition of strength. The width of the flanges affect the bearing surface area so if your strength test involves going to a failure point where the bearing points go plastic, the width will matter. If your strength test involves twisting the beam, the width of the flanges will make a huge difference if the thickness of the flanges is constant.

You need to look up the various definitions and test methods for measuring beam strength. Engineers often use designs where the ends of the beam are pocketed (constrained) to increase the failure load capacity. Beams where the bearing points are not constrained will fail sooner than constrained end points. The last time I went searching for this kind of information, there were a large number of good sources online.