huangyhg

mthods of strengthing a rc column which has been cored
an existing some 30 years old 7 storey rc framed hotel has been suffering of spalling of concrete caused by corrosion of reinforcement due to sea sand was used as the fine aggregate and carbonation. previously an engineer was called to look at the case, he ordered several core tests to be done on structural members including slabs, beam and columns to check the concrete strength and found most of them just below 3,000 psi (20 n/mm2). one of the column on ground floor was cored which would poise a problem though it has been infilled back with some material. in order not to disturb this heavily loaded lowest internal column, it is suggest to carry out some strengthen work to it. can any expert suggest what are the good methods of strengthening this column and what are the important factors could affect the performance of the strengthened column? thank you.
if the core did not cut reinforcing, i would just fill it with nonshrink grout. from your description, it sounds like a hole in one column is the least of your worries.
i agree with hokie regarding the cores.
as for the reinforcing, i would think that a steel or frp jacket would be the most appropriate measure. design it to take the full load assuming that the reinforcing steel will corrode away.
there are a few references on this type of thing used for seismic retrofit.
if fiber is not an option (check your fire rating requirements) you can build a new column around the existing column. by adding say 6" on all sides you can probably have a reinforced member than can carry the load.

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