Climbing in reverse gear

European premiere: safe high-rise deconstruction using MGS-H rail-guided screen system

When buildings grow skywards, smooth progress (time is money!) and, above all, safety at work are of paramount importance. The same applies the other way around, of course, during top-down deconstruction. An increasing number of high-rises, after serving their purpose for decades, now need to be removed to free up space for modern and usually even bigger buildings.

The project

16 storeys and 54 m tall with a plain, rectangular footprint: the office high-rise of the Rhineland Landscape Association (LVR), inaugurated in 1966, was hardly an architectural jewel and in any case no longer met contemporary requirements. This prompted the decision to clear the site swiftly for redevelopment with a new office block housing some 1,200 workplaces. The sensitive central location automatically ruled out any possibility of straightforward demolition by longfront and chain excavators or even controlled blasting. Any disturbance to the neighbourhood – by vibration, dust, falling debris or noise – had to be prevented. The adjoining area is densely developed, with heavily trafficked roads, while the busy Messe-Deutz station lies in the immediate vicinity.

Moreover, the facades were found to be heavily contaminated with harmful asbestos insulation. This required painstaking removal and disposal together with precautions to prevent its escape into the surrounding environment. This then ruled out unshielded deconstruction as an option: only a fully enclosed solution with isolated zones was permissible. In tackling the deconstruction contract, Linkamp GmbH’s demolition and remediation experts had to exercise the utmost caution and adopt a flexible, easily manageable solution. Hence the selection of MEVA’s MGS-H rail-guided screen system.

Continuous, all-round protection at any height

The rail-guided screen system provides a full-perimeter protective housing at the slab edges on upper building levels. Lifted into place hydraulically or by crane, it reliably guards against falling objects and weather action. MGS-H meets tough international standards for high-rise construction and is used worldwide – frequently in conjunction with MEVA’s MAC und MGC-H climbing systems – to erect skyscrapers. The system also excels when used for “top-down” applications, i.e. when climbing downwards, as demonstrated on this contract – the first of its kind in Europe.

The system is adaptable to virtually any building geometry, including round, acute- and obtuse-angled shapes, with or without working platforms. The heights and widths of the MGS-H climbing units – which comprise platforms, guard railings and windshields with perforated or unperforated trapezoidal metal sheeting – are freely selectable. Each unit is connected to the building – also during the lifting and lowering operations – by two flexibly positionable vertical guiding rails. Use, attachment and lowering are possible at wind speeds of up to 20 m/s (72 km/h). This reduces the risk of costly downtimes, especially at great heights.

Site operations

The work cycles are tightly scheduled. The project in the Rhine city of Cologne was the first time the Linkamp team led by Project Managers Thorsten Blasse and Bernhard Gillig had ever encountered the MGS-H system. During the first few days of its use, MEVA master formworker Adam Szántó provided on-the-spot technical assistance. The procedures were planned by Stefan Kappler from MEVA’s Central Engineering department.

In spring 2022, 18 climbing units were assembled horizontally at two points on the ground. Each unit is between 4.60 and 5.10 m wide and comprises four platforms, guard railings and unperforated trapezoidal metal sheeting. Eight units were additionally equipped with side railings to guarantee safe circulation around the perimeter and maximum safety for the works carried out at the building corners. The units were lifted by crane from the assembly points and threaded from the top into the prepared suspension shoes with folding mechanism. After the guiding rails had been fitted in place and secured by safety locks, the next climbing unit was collected. In this way, the four top storeys of the over 30 m long and approx. 15 m wide building were soon completely enclosed.

The joints separating the working platforms of the units are only narrow. Yet all gaps, however small, including those at the junctions with the building wall and in the trapezoidal metal sheeting, were carefully sealed using stable, hard rubber lips. The gaps between the 5 cm thick planking and the guiding rails are covered by brush strips. Platform 1 at the top serves to protect the second level and to attach/detach the crane hooks. Platforms 2 and 3 are used for the remediation works to the asbestos-contaminated facades, subject to enhanced safe-working criteria.

After deconstruction of the top storey, the MGS unit is attached to the crane, lifted some 10 cm out of the fixing hooks and moved away from the wall. The top suspension shoe can then be released and refitted three storeys further down. The MGS unit – which is still connected to the building by the guiding rails – is lowered and re-anchored.

Drilling and casting

In contrast to new-build projects, where the climbing cones needed to fix the suspension shoes are simply cast in, deconstruction contracts require somewhat more elaborate measures: 350 mm holes are drilled in the external wall in order to move the suspension shoes, which are connected to a support rail, to the outside. The length-adjustable support rail bears fully on the slab, to which it is structurally connected so as to safely accommodate the loads from the screen system. The climbing cones (M24) and DW 15 tie rods are cast into a 100 mm hole through the slab with expanding grout and secured from below by a cross-stiffener (to guard against punching failure) with articulated flange nut.

A similar procedure is adopted at the stairwell locations: due to the slab openings near the wall, the climbing cones for two of the 18 MGS-H units could only be secured via the external wall. Here too, a 100 mm hole was drilled, an M30 climbing cone and DW 20 tie rod cast in, and secured by a cross-stiffener with articulated flange nut.

A real time-saver for the Linkamp team

Despite the unfamiliar procedure, the experienced Linkamp team already started to pick up speed after deconstruction of the top storey. Since then, work has proceeded more quickly and smoothly with each storey. Linkamp Project Manager Thorsten Blasse now knows that selecting the MEVA system was the right decision: 

Featured Products

• Climbing Formwork MGS-H

Contractor:
Linkamp GmbH, Anröchte, Germany

Project:
LVR high-rise deconstruction, Cologne, Germany

Engineering and support:
MEVA Schalungs-Systeme GmbH, Haiterbach, Germany