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Hi Sean. In this case, and the doubly reinforced case, would it be correct to perform the last step of this solution by using Fst*z1 to calculate the design moment instead of the two compression forces?
Hey @Jomo_Ndirangu - to evaluate the moment capacity of the section, you can take moments about any point in the section depth - the position of the tension steel just happens to be the most convenient - but when you do take moments, must account for all forces that don’t pass through the pivot point,
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I noticed that for problems involving calculation of moment capacity, you tend to utilize the forces in the compression block. Whenever I use the tension steel forces, I obtain a slightly different answer. Was wondering what the difference could be caused by, hence my earlier question.
This is most likely just a rounding error. Remember that the section analysis is based on the idea that there must be horizontal force equilibrium in the section. So, in theory the forces are identical, so if there is a numerical difference in the moment capacities computed from the tension versus compression force, it’s just due to rounding…assuming the preceding calculation had no error.
S