Dome disasters
A Bini dome as discussed previously is a thin reinforced concrete shell structure which is inflated into place, a process of which needed complete accuracy to succeed. Bini's shells rely on: the even distribution of reinforcement and in turn concrete and the air pressure and temperature during inflation and curing. Errors in the above can lead to structural collapse.
Below are two case studies where structural collapse occurred and are of particular interest as Bini was the Architectural consultant on both projects. Hubben, C. (2010)
Below are two case studies where structural collapse occurred and are of particular interest as Bini was the Architectural consultant on both projects. Hubben, C. (2010)
Pittwater High school
It is said that during the curing process a blower was turned off inducing internal buckling within the concrete. This resulted in the semi cured concrete having a flatter crown then originally designed and a strength lower than that of the design strength. These factors resulted in the crown cracking. In order to try and rectify the problem additional concrete in the form of a cap was placed over the crown. Due to the absence of a bonding substance little strength was gained with the additional dead load. The presence of large loads aided the flattening of the structure making it the flattest crown of any large dome structure. Over a period of time the concrete begins to creep resulting in the formation due to the concrete yielding in compression. The stresses in the dome where then supported by the reinforcement. Loss of stiffness cause by cracking eventually lead to deformations within the shell and the shell began to sag. Eventually the deformations were too large and the concrete was overstressed leading to its collapse.
Fairvale High school
Reports have suggested the failure of this structure was due to a large temperature gradient within the concrete caused by the fluctuating weather between windy rainstorms and a hot summers day. The thermal gradient induces large bending moments throughout the dome resulting in the formation of cracks over a sagging crown. The concrete began to creep, weakening the structure resulting in the dome collapsing.
Thankfully there were no major casualties in either of these failure events. The Fairvale collapse showing early signs of fatigue to allow for the school to be evacuated before the collapse however the Pittwater collapse occurred whilst it was in use but was luckily enough to not endanger any pupils.
It is said that during the curing process a blower was turned off inducing internal buckling within the concrete. This resulted in the semi cured concrete having a flatter crown then originally designed and a strength lower than that of the design strength. These factors resulted in the crown cracking. In order to try and rectify the problem additional concrete in the form of a cap was placed over the crown. Due to the absence of a bonding substance little strength was gained with the additional dead load. The presence of large loads aided the flattening of the structure making it the flattest crown of any large dome structure. Over a period of time the concrete begins to creep resulting in the formation due to the concrete yielding in compression. The stresses in the dome where then supported by the reinforcement. Loss of stiffness cause by cracking eventually lead to deformations within the shell and the shell began to sag. Eventually the deformations were too large and the concrete was overstressed leading to its collapse.
Fairvale High school
Reports have suggested the failure of this structure was due to a large temperature gradient within the concrete caused by the fluctuating weather between windy rainstorms and a hot summers day. The thermal gradient induces large bending moments throughout the dome resulting in the formation of cracks over a sagging crown. The concrete began to creep, weakening the structure resulting in the dome collapsing.
Thankfully there were no major casualties in either of these failure events. The Fairvale collapse showing early signs of fatigue to allow for the school to be evacuated before the collapse however the Pittwater collapse occurred whilst it was in use but was luckily enough to not endanger any pupils.