The effect of gravitational wave is like tidal forces?
It depends what you mean by "very strong". 

The announced first detection (14th September 2015) was considered a very strong signal and that still only stretched the 4 km detector arms by less than the width of a proton (a tiny particle inside the nucleus of an atom). This wave would have no effect on a person.

You could hypothesis a stronger wave that would stretch and squish a person, I'm not sure what effect this would have but there are no objects in nature capable of producing waves this strong, even something as close as our sun becoming a supernova wouldn't be that strong, so it will never happen in real life.