4 stroy steel structure on top 2 story existing concrete

huangyhg

4 stroy steel structure on top 2 story existing concrete.
an existing 2 story concrete hotel building was built with the intention of construction of further 2 stories on it in the future, but now the owner wants to build four more stories on it , the isolated footings are small to take load of a total of six stories of concrete structure. therefore will it be a good idea to construct further 4 stories of steel rigid frame structure on it, the estimated dead load will be almost 1/4 th of the concrete structure. an initial static analysis show that the footings will be just fine.
the existing concrete columns at some locations are weak ! they can be retrofited by jacketing.
please comment and if possible kindly tell me examples of such buidings.  
wind and possibly siesmic loading will also need to be assessed.