This is the 14325th most frequent Turkish word.
olanca
"Olanca" means "all, entire, utmost, or as much as possible."
"Olanca" is used here to emphasize the totality or completeness of the strength applied to the action of banging on the door.
Olanca gücüyle kapıya vurdu.
He banged on the door with all his strength.
In this sentence, "olanca" enhances the noun "neşeleri" (cheerfulness) to indicate its full extent or intensity.
Çocuklar olanca neşeleriyle bahçede oynuyordu.
The children were playing in the garden with all their cheerfulness.
Here, "olanca" modifies "ciddiyetiyle" (with seriousness) to convey the thorough or complete manner of her attitude during the meeting.