St James Centre, Edinburgh
Dem-Master were appointed for the Demolition of 2 Multi storey Car Parks, the complex of Multi storey former Government Offices, the lower multi-level Shopping Centre, Hotel and Leith Walk Pedestrian Bridge.
The site was located at the East end of Princes Street, Edinburgh’s main shopping thoroughfare and surrounded by residential, commercial & leisure properties on all sides. It also lay at one of the city’s busiest intersections, so detailed fluid and adaptable traffic management planning played a key role to minimize disruption to commuters and road users.
Dem-Master Demolition successfully completed these works to make way for the much anticipated 850,000 sq. ft. development at St James Square, Edinburgh city centre which has been described as one of the UK's largest private sector regeneration projects.
Working closely with our engineers, IKM Consulting we were required to design the temporary works for this project. This necessitated a unique combination of a system of push/pull props to the upper elevational PC envelope. This transferred loadings to the in-situ lower podium. A phased advanced system of strengthening steel work was thus design approve and installed to follow the sequence of the upper and lower machine Demolition along with the key deconstruct zones in proximity. Dem-Master carried out these works ensuring the attached retained buildings with the adjacent retail giant, John Lewis was still in full operation. A complex sequence of hand deconstruct was required whilst working around and below the John Lewis store. We needed to maintain the full integrity of both the buildings to be Demolished and buildings to be retained.
There was also the duty to reduce noise, vibration and dust impacting on the busy live store, city bus station, tram way and active commercial premises all round the site.
Our Demolition works were finalised in January 2018 with the integration of the new construction by our client at the North end of the site and the perimeter contiguous piling which was ongoing throughout the Demolition.
This project required a unique combination of hand divorce, deconstruct, machine and specialist Ultra High Reach machine work over a range of varying constructions. We had huge public interface and enhanced technical issues of design and installation of complex temporary works here which made this project different.
The engineers report which was compiled identified many instances where the structures buildings and services / utility runs may be subject to collapse. The Demolition methods had to be carefully considered here giving safe consideration to the large and congested nature of the interlinked main multi storey car parks and office blocks on the site. There was an assessment made pre-tender that there was a risk of collapse due to the removal of the stability systems – generally provided by upper floor plates acting as horizontal diaphragms to the RC core walls and shear walls. The external precast wall panels were also a factor in addition to the frame on which they were hung.
The design team were mainly concerned at the possibility of collapse due to the lack of floor diaphragm continuity at movement joints. This in conjunction with the external panels and a concern that during the Demolition process we could have overloading of the floors with plant and debris etc.
Engineering Solutions
Loading limitations on the existing structures and lateral restraint to the external PC panels were major constraints in that due to the type of existing structure temporary steel propping had to be designed, procured and installed and this had to be commenced immediately after mobilization in order for us to be able to obtain approval for a ‘permit to Demolish’ through the site for the sections of podium and the high rise offices blocks in the required sequence. This was where our specialist Structural Engineers came in.
Bulk Excavation
Out with the Demolition and associated works, Dem-Master carried out the bulk excavation for the site. We excavated circa 250,000m3 in prep for the follow on trades.
