Mount Saint Vincent University – Halifax, Nova Scotia
Structural steel towers were installed to shore the defective reinforced concrete ring beam supporting the auditorium roof framing.
J.W. Cowie Engineering Limited was retained by Mount Saint Vincent University to investigate the excessive downward deflection of the reinforced concrete ring beam supporting the auditorium roof of Seton Academic Centre.
The flat roof area over the auditorium was ponding water and the moveable wooden curtains used to divide the auditorium into four lecture theatres were jambing. The area of the water ponding was over the concrete ring beam in question and the movable wooden curtains were suspended from the concrete ring beam.
Cowie's investigation revealed the ring beam had inadequate strength and stiffness. Temporary structural support was required. Cowie prepared structural design drawings and specifications for two structural steel towers for support of the ring beam. The structural steel towers extend from the underside of the ring beam, through the auditorium floor with bearing on a structural steel grillage mat placed on top of the basement concrete floor slab. The underside of the basement concrete floor slab was grouted to prevent settlement.
After the structural steel towers were installed, the concrete ring beam was jacked up by the use of hydraulic jacks with steel shims installed between the underside of the concrete ring beam and the top of the structural steel towers. The concrete ring beam was jacked up sufficient height to prevent jambing of the moveable wooden curtains. The steel support towers interfere with the view of the stage when the curtains are withdrawn providing a theatre in the round as per the original design.
Cowie developed permanent structural restoration design alternatives to provide support and/or strengthening of the defective ring beam without the use of internal supporting towers thereby avoiding disruption of the view of the stage when the moveable wooden curtains are retracted permitting the auditorium to be used as a theatre in the round.
Photos
01. Temporary structural steel support tower with working platform. Workmen jacking up the deflected reinforced concrete ring beam using hydraulic jacks and installing steel shims to shore the defective reinforced concrete ring beam supporting the roof framing over the auditorium of the Seton Academic Centre. (See photograph no. 2)
02. Hydraulic jacks placed between the underside of the reinforced concrete ring beam and the top of the structural steel support tower. Steel shims installed as the ring beam is jacked up.
03. Vertical HSS members of the support tower passing through cored holes within the reinforced concrete slab of the auditorium floor.
04. Vertical HSS members of the support tower passing through the auditorium floor and bearing on top of the structural steel grillage mat located on top of the basement concrete floor slab.
05. Base of the structural steel support tower bearing on top of the structural steel grillage mat. The mat is bearing on top of the basement floor slab. Grout was injected below the basement floor slab to prevent settlement.
06. Concealed structural steel grillage mat shown in photograph no. 5.
07. Completed installation of the two structural steel support towers with the moveable wooden curtains retracted. The moveable wooden curtains allow the auditorium to be divided into four lecture theatres.
