ALFIX Façade Scaffolding and ALFIX MODUL MULTI Combined
Bridges connect countless regions and form the basis for smooth traffic flow and for the development of efficient infrastructure. The federal highways in Germany alone currently include 39,500 bridges (source: German Federal Ministry for Digital and Transport, 2019). In order for bridges to provide smooth crossings in the long term, they must be maintained and renovated from time to time.
The Schkopau Saalebrücke bridge is part of the B 91 highway crossing the Saale river in the municipality of Schkopau. The bridge connects the cities of Merseburg and Halle, and is an important arterial road. As part of the repair work on the Saalebrücke bridge in Schkopau, the road must be replaced and the sidewalk rebuilt. In addition, repair work must be done to the underside of the bridge in order to integrate a new, separate guide bearing. The Saalebrücke bridge, constructed in 1950-1951 is a tied arch bridge with stiffening girders and a superstructure of approximately 80.0 m in length between the end points. In order for restoration and corrosion protection work to be possible on the arches and the hangers, it was necessary to use a combination of frame scaffolding and suspended scaffolding for the work scaffolding.
To complete the bridge repair work above the road surface, a frame scaffold using 70 ALFIX façade scaffolds was erected lengthwise, as the bowstring arches act much like a façade and enable the use of a work scaffold along the side of the object. The ALFIX façade scaffolding systems comprise prefabricated construction components and are able to be used as work scaffolding as well as roof fall arrest and brickguard scaffold. Along both the inner and outer side of each bridge arch, the ALFIX Technical Team planned the use of ALFIX façade scaffolding, width class W06 with a frame width of 0.73 m, along with ALFIX inner brackets measuring 0.36 m, load class 3 (200 kg/m2). This design was then erected by Gerüstbauunion GmbH. Following this design, all points of the arch were able to be reached from both inner and outer sides. The scaffold was mounted onto the bridge using pressure-proof anchors and tension members made using scaffolding tubes and normal couplers. The tension members connected the inner and outer scaffolding and the pressure-proof anchors stabilised and secured the scaffolding construction to the bridge arch. To ensure effective load distribution in the event of high winds, lattice girders were arranged diagonally at every axis and horizontally along the walking surface. To accommodate the shape of the arch, the scaffolding ranged in height from 2.00 m to 10.00 m at the highest point of the arch.
2.00 m – 10.00 m height: ALFIX façade scaffolding on the Saalebrücke bridge
Due to the nature of the restoration work, the entirety of the scaffolding was required to be completely enclosed using tarpaulins. The construction was covered with protective tarpaulins in two stages so as to avoid excessively straining the bridge due to a high wind load.
Tarpaulin coverage carried out in two parts to reduce wind load
Each work scaffold erected along the bridge’s arch was designed to have a 5-storey scaffold stair tower, in compliance with the corresponding technical rules for operational safety TRBS 2121-1 Part 1 when reaching even the highest points of the scaffolding construction.
Upon completion of the restoration work to the arches and the road side of the bridge, a work scaffold was securely affixed to the cross beams of the construction as surface-oriented suspended scaffolds. During this process, it was important to note that a certain distance from the surface of the water had to be maintained in order to serve both as protection against potential high water levels as well as ensure a continually smooth water traffic flow. In order to obtain the most flexibility and adaptability possible, the manufacturer planned a design using the ALFIX MODUL MULTI modular scaffolding system in combination with system-independent lattice girders. To not surpass the maximum weight allowance of the bridge, the ALFIX façade scaffolding on the surface side of the bridge had to be disassembled before beginning work on the underside of the bridge. Using 0.50 m spindled MODUL standards, a girder grid was constructed using criss-crossing steel lattice girders on the cross beams of the construction and covered with system lengths of ALFIX steel decks. A total of approximately 1200 m of non-system girder beams was installed. The suspended scaffolding was also erected in two stages so as not to pose a threat to the overall load capacity of the bridge, in accordance with the examination reports.
Special suspension points
Special suspension points were calculated and constructed for this specific construction project. Made using scaffold tubes and standard couplers in combination with wedge head couplers and distance couplers, suspension points with a load-bearing capacity of up to 3.0 tonnes were installed, making each point of the bridge’s profile accessible. This also allowed for a transverse working surface approximately 20.0 m wide and a lateral working surface approximately 34.0 m high for each construction section when working on the underside of the bridge.
Suspended scaffolding using ALFIX MODUL MULTI
Right from the beginning of the construction on the underside of the bridge, a complete enclosure using tarpaulins was required to cover the base surface area and the lateral scaffolding. The goal was to avoid contaminating the body of water under the bridge (the Saale River) with blasting materials. To remain under the planned live load of 200 kg/m2, the area required regular removal of blasting materials.
Thanks to comprehensive pre-planning, ALFIX GmbH was able to provide smooth and complete first-hand service to see the project from conception to completion: beginning with detailed project documents and visualisation using a 3D CAD program, through the development of parts lists and the elaboration of verifiable statics, all the way to the delivery of all project components directly to the construction site.
Due to the optimised connected values of the improved MODUL MULTI 4.0 modular scaffolding system which enable greater forces to be exerted on the modular discs, it was possible to select a larger field grid measuring 2.57 m x 3.07 m. This in turn decreased the amount of lattice girders required for the project, thereby also reducing the necessary assembly time for the user.
Since the middle of last year, the German scaffolding manufacturer ALFIX GmbH’s ALFIX MODUL MULTI 4.0 and ALFIX MODUL METRIC 4.0 modular scaffolding systems now feature higher connected values and target higher static values than nearly all market-standard scaffolding systems. The further developed modular scaffolding systems are also compatible with prior models and able to be combined with standard market systems. This information is outlined in the approval documents available in the Download section of our website, which can be accessed using the following https://www.alfix-systems.com/en/downloads/
