George Street, DunedinA 3 storey brick (URM) 1930’s Dunedin high value retail building was assessed as having a ‘low’ earthquake %NBS capacity rating (essentially no lateral bracing system ‘across’ at ground floor level) and the existing tenant had chosen to break the lease early because of this.
The building owner was after a cost effective and rapid strengthening ‘design / construction’ process that would bring the building up to 100%NBS capacity. The building façade had an ‘historic listing’ and in general the existing 3 storey brick front section and the single storey rear section were showing signs of decay.
BMC developed a pair of linked eccentrically braced frames (EBF’s) on the ground floor level to provide lateral stability while introducing a series of horizontal and vertical steel cross brace elements at upper floor levels to drag earthquake loads into the ground floor EBF’s.
The EBF frames provide a ductile mechanism for the overall structure allowing the lateral displacement / movement where it can be tolerated in the brick ‘out of plane’ actions while the inherently ‘stiff’ upper floor levels (with brick cross walls) are braced more rigidly by the cross brace system that has been added. BMC provided a full design / detail / construction monitoring service for the project.