The long and short of it is that, if you run your analysis with Eh, you have to go adjust all your support loads by Ec/Eh. If, instead, you run the analysis using Ec in all cases, you have to correct your terminal point loads by the ratio of Eh/Ec. Since this second approach requires you to do much less hand calculation, and a procedure is given in B31.1 Paragraph 119.10, this is what you should do. In B31.3, Paragraph 319.5, the analyst is specifically directed to calculate all support forces and terminal point reactions using Ec.

So I am not quite sure why you are asking this. You are being directed to calculate support loads using Ec. Fine, run your analysis using Ec. You are being directed to calculate terminal point loads using Eh. Fine, adjust the terminal point reactions as permitted by B31.1, Paragraph 119.10, equation 9. Note that, if you are using B31.3, you are not permitted (see 319.5) to use Eh for any reason other than to calculate the amount of required cold spring.

If you had spent half the effort reading the codes that you have spent asking other people to read them for you, you'd be done by now.