Here to find out how to get glass breaking (like when wheatley smashes you down the elevator, and the tube breaks the glass chamber you're in in the glados chamber) and destruction (like in the introduction room where wheatley smashes the room through obstacles

Edit: also, using Hammer. forgot to put that in EDIT 2: google is crap and did not help

Hello sandie, welcome to the forums!

The smashing is an animation for a particular glass model.
For Wheatley smashing the player into the ground: it is the model models/props_destruction/glass_break_40x116_g.mdl with the animation: hammer1.

If you are looking for no particular smashing glass animation: filter glass models and specifically look for models under 'props_destruction'.

As always, I encourage mappers to decompile maps to see how Valve does things.