Dear All,
Table 4.18.3 suggests that Fm is the maximum of absolute value of Fm(x) as x varies from 0 to xa such that x is between 0 and xa. Now from figure 4.18.7 & 4.18.8, it can be seen that variation of Fm is droping with respect to xa so maximum Fm occurs at lower value of x. Hence can we take the value of Fm for lower xa ( say x=0.05 or so). If not then by what extend it will affect the results ?

Dear P08IP708,

What you are saying seems logical. But, it should be tested for a wider range of values. Those curves are only valid for nu* = 0.4.

PV Elite/CodeCalc uses the actual formula instead of the charts, so they can go for the extended range and are not limited to the charts.

But, it would be interesting exercise to find out at which value of x gives the biggest Fm.