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Gantry false work on heavy-duty MK shoring towers for the load-carrying structure

Sep 23, 2014
The two-lane, seventeen span and almost 950 meters long ES 5.5 overpass was built within the S-8 expressway in Poland, between the Walichnowy and the Wrocław junctions. Its load carrying structure consists of a prestressed box, divided into four segments with expansion joints.

The first segment included two spans – each 40 meters long – constructed over solid ground, while the other includes three spans – two adjacent to the current and a non-current one – over the Warta river. The last two segments consist of two 6-span structures. The height of the box section varies from 2.6 to 6.0 meters within the in-current spans. ULMA was involved in the project with innovate solutions and onsite technical support.

 Due to diversified ground conditions, the contractor for the structure (STRUKTURY Sp. z o.o., and DRAGADOS as subcontractor) decided to use diverse methods for constructing the individual load-carrying structure segments. Thus, the initial spans, located over the ground, are constructed traditionally, on stationary scaffoldings, the in-current span – with the use of cantilever carriers, while the two six span segments – with the use of self-launching trusses.

ULMA provides services for this construction regarding, among others, the design and supply of formworks for supporting the initial components in the cantilever method and for constructing the spans adjacent to the current one, constituting a counterweight to the overhang carriers. Due to the ground conditions, a portal solution was employed, based on heavy duty MK towers.

The MK Shoring system of ULMA is a very versatile modular system for different shoring configurations. With standards parts only, ULMA offers the best solution for high load requirements. In order to optimise the potential of the supplied equipment, the towers were designed with 12.0 meter spacing, except for the area around the initial component, with 8.0 meter spacing. The considerable spacing forced the anchoring of towers to temporary foundations constructed beforehand, which guaranteed the safe transfer of loads of around 320 kN. The MK shoring system allows designing components that transfer loads of up to 360 kN for a single tower leg. The design of the system allows safe horizontal assembly of the individual tower segments and subsequently setting them one on top of each other with use of a crane. The system also includes platforms enabling vertical communication inside the tower and top platforms for handling the adjustable heads used for setting the elevation of the structure or for dismantling the formwork.

The inside part of the box was constructed with two types of formwork by ULMA: ORMA modular formwork and VMK beam formwork. The external surface was boarded with standard ORMA boards, while the internal surface – due to the geometry and the necessity of fitting it to the external surface – with VMK beam formwork. The wall formworks were placed on steel profiles which transferred the loads to the towers via a system of beams.

In comparison with a traditional solution based on support towers, the gantry false work system on ULMA heavy-duty MK shoring towers is characterised by a significantly lower number of components to be installed, which, in turn, has a positive impact on the speed of carrying out the works and the cost of leased equipment.         

ULMA guarantees maximum performance with its innovative products and structures made from standard modular material.