Condition assessment and strengthening of residential units

• Rehabilitation of existing structure.
• Condition assessment using NDT.
• Strengthening design using FRP, WWF and PPFRM.

About 40, ground plus one (G+1) residential units were designed using a hybrid structural framing system (RC frame and load bearing walls). A few months after the completion of the ground floor of the residential units, cracks appeared at several locations in the structure. Field and Laboratory testing was conducted to ascertain the in situ strength of concrete and steel reinforcement. The results of the experimental work were used in the analytical ETABS model for the structural stability calculations. The results indicated that residential units were marginally safe in the existing condition (completed ground floor), but the anticipated construction of the floor above the ground floor (G+1) could not be carried out as the strength of the structural system was inadequate. To increase the safety of existing ground floor and to provide the option of the construction of one floor above, rehabilitation and strengthening design was performed. The proposed strengthening design made use of welded wire fabric (WWF) and carbon fibre reinforced polymer (CFRP) laminates/sheets for the strengthening of walls, columns and slabs. The residential units will be strengthened in the near future.