Damage Assessment and Strengthening of R/C Building Constructed on Expansive Soils

This paper presents an experience in assessment and strengthening of a R/C building carried out in Sudan during the last year. A four-story R/C framed hospital building was constructed five years ago in the middle of Sudan, by the White Nile River. Due to differential upheaval movement of the underneath expansive clay soils (15-25cm), the building had experienced serious instability problems and severe structural cracks. A comprehensive assessment of the building skeleton including geotechnical investigation, DT and NDT methods revealed the need of five different strengthening and retrofitting techniques; there are, transformation of foundation system from isolated footings to strap foundation to increase the stiffness and rigidity of footings, concrete jacketing of basement floor columns, metal jacketing of the second floor columns, construction of shear walls to enhance the stability of the building and finally CFRP laminates for strengthening of basement floor cover slab. The building had been monitored during and after completion of strengthening and retrofitting works to measure any movements during the last year rainy season. Measurements revealed the efficiency of implemented strengthening and retrofitting techniques.