"Can the cargo hold be loaded with steel coils up to the weight calculated by multiplying the tank top area(m2) by the allowable tank top load(ton/m2)?"

This question has been asked many times. Standard steel coil loading conditions may be included in the loading manual are normally based on steel coils with the same weight and dimensions. When coils are different, due to the special futures of steel coil loads, the local structure strength of the inner bottom plating and longitudinals must be specially checked. 
Due to the stowage arrangements made, the point loads on some longitudinals caused them to bend downwards. This in turn affected the supporting transverse girders, and especially, caused buckling in the floors (the web plates in the transverse girder), and bending of some local stiffeners.
The vessel is scheduled for repairs to maintain Class. Most probably many plates and stiffeners in the transverse girders will need to be cut out and replaced, together with some of the affected longitudinals.

In case that you are interesting our office may be consulted for assistance in calculating tank top strength for steel coil loading, in order to avoid damage to the hull structure (see relevant brochure).