The Swiss agricultural company, Syngenta, is completely transforming its headquarters in the centre of Basel. For this, a 54 m high tower block had to be removed. Due to the position of the building which is directly adjacent to the corporate campus as well as in close proximity to the highly frequented Schwarzwaldallee and the Badischer Bahnhof, demolition using large demolition excavators was out of the question. PERI engineers in collaboration with contractor ERNE AG developed a concept on the basis of the RCS Rail Climbing System which allowed a safe and efficient dismantling of the structure within an all-round enclosure.
Urbanization is creating an ever-increasing demand for space in towns and cities. If, however, available space becomes very scarce, often the only option is to build upwards. The high-rise structures are sometimes positioned very close to one another being just a few metres apart. This leads in part to the creation of world-famous skylines but any subsequent demolition is far more complicated to carry out than for buildings that are individually positioned. The structures must be taken apart piece by piece with each floor being removed separately.
In order to minimize the emissions generated during the demolition of the Syngenta high-rise building and to avoid any damage to the surrounding buildings, ERNE AG relied on the PERI enclosure variant along with the help of the RCS Climbing Protection Panel. Thanks to this, the high-rise structure in the Basel city centre has disappeared very unspectacularly: in spite of continuous demolition work and a weekly climb down from floor to floor, activities have been hardly noticed in the immediate vicinity.
In the tender submissions phase, the project managers together with a team of PERI engineers from Switzerland and Germany were already working on a detailed variant that protected the environment as well as the construction crew from demolition emissions in the best way possible. In the process, particular emphasis was placed on ensuring the safe execution of all work steps. The solution developed avoided workers being put at risk in any way as well as preventing construction materials and tools falling to the ground at no point during the demolition process. Consequently, the high safety requirements of the client have been consistently fulfilled which is something that has always stood out during regular site inspections. This was realized through the use of the RCS Climbing Protection Panel. In sync with the progress of the demolition work, this has been climbed downwards from floor to floor on a weekly basis providing the jobsite with an all-round gap-free enclosure. In addition, all work on the outer facade could be safely carried out from the integrated working platforms.
The RCS Protection Panel Units could be precisely adapted to match the building floor plan and the planned demolition process. At the start of the demolition work, RCS Climbing Platforms were pre-assembled and delivered to the jobsite as frameworks and then put together in accordance with the PERI assembly plans to form protection panel units – competent support was provided by an experienced PERI supervisor.
The enclosure system – covering three storeys of the building – was closed on the outside using trapezoidal metal sheeting and prevented dirt, dust and noise from escaping outwards. Apart from the fact that the demolition measures have hardly been noticed in the immediate surrounding area, the enclosure could also be used as highly visible advertising space.
Anchoring the RCS units to the existing structure presented a challenge as, compared to a new building, it was not possible to embed the climbing cones for the next climbing step. Together with demolition specialists from ERNE AG, a project-specific solution was developed for this purpose. As a result, both the horizontal and vertical loads could be reliably transferred into the structure. The top anchorage for the initial assembly was realized using the roof of the building and the top storey, and secured externally by means of a lifting platform. Subsequent anchorage for the downward climbing procedure could be realized in the planned weekly demolition cycle using the lowest level of the RCS Climbing Protection Panel. Mounting the climbing units was carried out with the help of climbing shoes from the RCS Modular Construction System as well as project-specific supporting elements that were specially adapted to suit the exisiting structure.
Within the RCS protection panel enclosure, a controlled and safe dismantling of the building took place over the height of three floors. Each level has had its own designated dismantling procedure which meant that a range of work steps could be carried out almost simultaneously. On the lower level, the facade was removed and RCS Climbing Shoes – used for anchoring the RCS Climbing Rails – were mounted in readiness for the next lowering procedure. At the same time, removal of the windows and insulation took place on the middle level. At the top, small demolition excavators took on the task of the dismantling of the reinforced concrete structure of the building.
After the complete removal of an entire storey, the climbing protection elements were then quickly lowered downwards one level by crane – rail-guided and always securely connected to the structure. As a result, climbing could still take place even in strong winds. This method of working, together with the preparatory planning, ensured that the high-rise structure could constantly shrink by one floor in weekly cycles.
An important advantage of the demolition carried out by ERNE AG compared to a conventional building demolition with large equipment is the possibility of controlled separation of material and contaminants. In this way, building materials can be specifically removed, disposed of or recycled. In addition, contaminated areas on site could be decontaminated within the affected floor of the building while demolition work was carried out on the upper storeys.