While I’m not 100% certain what you call a Strut grid (different countries different terminology) but it you are referring to hanging any cable trays, bus duct or other weighty items from the ceiling. I do not recommend hanging anything from the ceiling tile grid as it is not secure and normally is not designed to hang weight from. You really need the services support system to be hung independently from the structural slab or room system above the ceiling to allow independence from the movement in the ceiling grid. Usually this is not a difficult task and often cost less rather than having to reinforce the ceiling grid. All thread or hanger rods connected to the mains structure thought the ceiling tiles and attached to the cabling tray etc. Might not look so pretty but certainly more secure and longggggg lasting.