The answer to your query about smoke alarms and common property very much depends on the type of smoke alarms that were installed and how they were installed.
The extract below is from the Strataman site:
Repair & Maintenance
Under current legislation, the Owners Corporation is responsible for repairing AND maintaining smoke alarms IF the smoke alarms are hard-wired to the lot’s electricity supply with a backup battery or connected to a common fire board or panel. However, if the smoke detectors are stand alone and battery-operated, then the lot owner (or tenant) is responsible for checking and changing the battery. Ultimately, The Owners Corporation is responsible for replacing or repairing a faulty smoke alarm.