I stay in a Semi-D,my management doesn't allow grills for windows and doors. So any ideas?

Nowadays, a lot of landed G&G are strata title property which need to follow house rule or management rule under DMC.

In a strata title property, you need to follow the house rule or DMC agreed.

So if want to install whatever like design one, then look for non-strata property. 

Actually the purpose of such rule on renovation issue is to make the housing area look neat and nice. Every house with same gill design matching the theme of the building, look nice and neat as compared every unit design totally different, rojak across, may not look so "high class".

Management only can govern the exterior look on renovation, interiorly, there is no restriction, so if the grill install inside, generally management won't care.

The mindset live in a strata property is different with non-strata property. 

Of course a grille over a door can be opened. I thought you meant the grilles over the windows can be opened in an emergency. That was what I said was my safety concern with grilles over windows. Even if there are such grilles I would be a bit uncomfortable with the idea as I wouldn't carry the grille key with me all the time. To each their own though.