CONTRACTORS WORKING on the fire ravaged Torre Windsor in Madrid are to create additional load paths between the eighth and tenth fl oors of the building to prevent a secondary collapse.
The 32 storey building was damaged beyond repair and has remained in danger of collapse since the blaze in February that took 19 hours to extinguish (NCEI April).
The building was undergoing refurbishment at the time of the blaze, with fire protection being added to structural steel.
The ninth floor level columns are the most heavily loaded without protection.
Demolition contractors were concerned that stresses placed on the ninth floor during the deconstruction could cause these members to fail completely.
'Fire protection had been applied as far as the eighth floor, so the ninth floor columns were the most heavily loaded members without protection, therefore they had begun to buckle, ' said Madrid city hall's head of building control, Emilio Garcia de Burgos.
To prevent failure, 5.3m long columns are being welded to the outside of the 8th and 10th floor columns, directly taking up the vertical loading from the buckling struts.
'We cannot install temporary supports inside the building as it is too unstable, ' said Burgos.
Demolition is expected to be complete by the end of August.