Scope of works: Making safe access of blown concrete and removal of Brise Soleil using Rope Access Techniques.
Brief Description: The Dental Hospital is a six-storey building which consist of Insitu reinforced concrete structure believed to have been constructed circa 1970’s.
The main roof structure is a combination of In-situ reinforced concrete, or profiled metal sheeting deck supported on a series of reinforced concrete down beams.
External walls are constructed in concerned brick/block which judging by the bond and thickness are of a cavity type construction. The external walls project above the main roof level forming a parapet. These are finished with concrete coping. There are projecting cantilevered canopies at each floor level to the pinnacle elevation. Secured to concrete, down stand edge beam of the canopies is a timber Brise Soleil.
The window framing and casements are powder coated aluminium with inset glazing.
Observations and remedial action:
Concrete canopies/ring beams. Principle defects to the canopies noted are spalling/dislodged sections of concrete.
This predominantly at the abutment /junction section with the main structure. Where the concrete has become detached, corrosion of the embedded steel reinforcement is evident. The above issues are due to the corrosion of the embedded steel reinforcement.
As the steel corrodes, it expands and forces the masonry to break away. This This process is exacerbated once the concrete has been dislodged and the reinforcement is exposed, generally the corrosion to the other surface, with no significant loss or form.
Brise Soleil:
To the principal South facing elevation on both wings and single storey structures, timber Brie Soleil’s are fitted to the underside of the concrete canopies.
These are formed with 2 no 100mm vertical timber posts, bolted to the concrete edge down stand.
Horizontal timber panels are secured to the post.
Significant decay occurs to a number of timber panels posing a structural risk of debris falling from height.
Conclusion: Brise Soleil’s required to be removed urgently.
We deployed portable anchorage equipment in the form of portable dead weight trolleys and portable ‘A’ frame trolley for the work positioning and Rope Access. Due to the potential/increased risk of debris falling from height because of the condition of the external facades we were able to deploy Rope Access Technicians who were able to successfully access all elevations of the building and over a period of 10 days removed, made safe and prepared for repair areas of ‘Blown’ concrete.
During this time, we were able to plan and prepare a safe system of work to access and remove all Brie Soliel via Industrial Rope Access, Rope Access, Abseiling and work positioning techniques. The removal of the Brie Soleil was a rather primitive but effective, safe and effective method using bow saws and basic hauling and lowering techniques.