Construction of precast concrete shells in Georgia

Constriction of monolithic concrete shells requires the creation of costly, time-consuming formwork. The means of solving this problem is the construction of precast reinforced concrete shells. Since the second half of the 20th century construction of precast reinforced concrete shells started (over 30 m in span) in Georgia. Their number exceeds 40. These include: Bath building no. 8 dome cover (1956) in Tskhaltubo resort town (span of dome 2R = 40 m, rise f =3.2 m, effective thickness t = 0.15 m), the dome cover of the sports hall (1958) in Tbilisi (span of dome 2R = 76 m, rise f = 13.5 m, effective thickness t = 0.15 m), dome covers of reservoirs (1962-1972) in Tbilisi (for water), Gardabani (for fuel oil) (span of dome 2R = 40 m, rise f = 3.8 m, effective thickness t = 0.15 m) and others, square-in-plan precast-monolithic dual curvature cover (1982) in the city of Sukhumi (side of the square L = 40 m, rise f = 8.0 m, effective thickness t = 0.10 m), and others. Structure of these covers and uniqueness of their construction drew attention in Georgia. Despite this, due to the novelty of precast construction and specifically the precast shells, during the operation period some cracks appeared and significant deformation developed; there were even cases of collapse. The article presents and summarizes the experience of precast and precast monolithic concrete shells construction in Georgia. It describes typical defects of precast reinforced concrete shells that appeared during the operation. We survey the reasons for the collapse of the tank ceiling dome and demonstrate the enhancement of shell reliability by using the replacement of the roofing coverage.