- I am not entirely sure I follow but a 10' length of 1-1/2" angle iron is going to have a good amount of flex. Also critical is the metal properties, A36 (hot rolled) versus something like 1018 (cold rolled). Below is a simple way to get a good idea of the strength properties. It should also help you figure out the necessary bracing to strengthen up the frame.
Use a tape measure to find the depth and width of the angle iron bar, and the bar's total length (both angled sections). Take the force pushing or pulling on the angle iron and multiply it by 3 and the total length.
Square the depth and multiply it by two times the width of the iron. Divide the answer from Step 1 by the answer from Step 2. The result will give you the ability of your angle iron to resist breaking its angle, in units of Newtons per square meter.