The Charleson is 44-story residential building with an irregular plan. Due to vortex shedding and open wind exposure of the building, the building was assessed to have relatively high acceleration. To mitigate the building vibration, a single large Tuned Liquid Sloshing Damper (TLSD) was designed. However, due to the fact that the excess of acceleration is not high and usually as-built building frequency is expected to be better than the theoretical value, supplemental damper design was postponed until building structure was nearly completion. This new procedure allowed very efficient damper design based on actual building frequencies and corresponding real building responses.