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I need to find the effective length of a column (kl) from this chart which can be found in the "design of concrete structure" By Dr. Arthur Nilson.chart

the question states "if Psi top is 1.5 and the bottom joint is a firm (fixed) joint what is k? if the column is braced" what I don't know is if the joint is fixed should I take Psi as 0 or infinity? this is a diagram of the column

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You should take $\psi=0$, typically for fixed braced concrete column, design aids set the bottom as zero flexibility.

Common sense then tells us that if we have a column with top and bottom fixed; it has 2 inflection points at 1/4 length of the column from the bottom and top. Hence we get K= 1/2, which is as shown on this chart.

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