The Owners Corporation is the entity that can be sued and is responsible for maintaining the common property in a safe condition. I am not sure what you mean by ‘the strata’. Colloquially, that is the owners corporation. The owners corporation is the ‘club’ all owners become a member of, whether they like it or not, when they buy a unit.
Now, it might get more complicated in that the OC in turn might have a claim against some other entity if, perhaps, the executive of the owners corporation could show that they had directed the managing agent to arrange the repair of the doors and provided the funding but it was not done. I think that would be a problem for the executive committee to sort out with the managing agent and not your problem.