Luzhniki: when reconstruction is unique
Our colleagues has told in detail for Sport Build about how work has been done to dismantle obsolete elements - a very difficult task in the conditions of preserving the historical facade and the external enclosing structures of the Luzhniki stadium.
The Luzhniki Grand Sports Arena is a very interesting building: it has 3 structures that are independent. The coating, which stands on the columns and rests on pile grillages, an external brick wall, which rests on its foundation and is self-supporting, as well as a reinforced concrete frame of the stands. Partially, the coating holds onto the frame of the stands with vertical ties, only to prevent twisting. Thus, 3 epochs connected at the stadium: the outer wall of the 1950s, the roof and columns of the 1990s, and the reinforced concrete frame is a new story.
Alexei Kushchenko, head of the Metropolis design department, and Vladimir Muravsky, chief specialist of the design department, took part in the development of the dismantling project. Reconstruction work began in 2014 and included the dismantling of existing and the construction of new stands in accordance with FIFA requirements. It also required an increase in the area of translucent coating due to the installation of a visor along the inner contour of the roof of the stadium. Since the city decided to preserve the historical facades of the stadium and the cover, it was necessary to solve the unique problem of partially preserving the structure when dismantling all the supporting structures of the stands inside the arena.
Exterior facade walls with a height of 25 meters, which are of historical value, are an element of the spatial rigidity of the structural scheme for covering the stadium. The main problem to be solved was to ensure the stability of the facade walls, which at certain stages of the dismantling of the old stands could be left without horizontal fastening elements.
If we talk about the stages of dismantling, then at the initial stage it was necessary to disconnect the preserved roof structures from the main part of the stadium. It was not possible to dismantle the stands without detaching the cover, since they ensured the stability of the roof itself. At the same time, the roof was “fastened” to the structures of the stadium due to perimeter ties. To "unfasten" the roof from the stadium frame without loss of stability, temporary cross connections between the columns on which the coating rests were established. Later, the roof was “fastened” to the reinforced concrete frame of the new stands. Also, the facade wall has been mounted to the new frame using flexible horizontal ties.
The next and no less important task that was to be solved was to ensure the stability of the design of the retained front wall for the period of dismantling the supporting frame of the existing stands of the stadium. A variant of the spatial structure design outside the stadium was being worked out, which would ensure the inviolability of historical walls. However, for certain reasons, this option had to be abandoned. To ensure the stability of the outer walls, it was decided to use the structures of existing stands located inside the stadium. The supporting structures of the old stands were made of a metal frame with brick lining. Having exposed this metal, it became possible to create a system of additional temporary connections through which the wind load on the facade walls was transferred to the steel frame. Calculations were made of the required number of spans of stands adjacent to the outer wall, and it was concluded that only one span with the installation of temporary connections would be enough to ensure the strength and stability of the facade wall. Thus, along the front wall with an indent of 6 meters there were steel columns of the old frame, which, using the beams of the existing ceilings and temporary vertical cross connections, ensured the spatial work of the structures inside the stadium. At the next stage, the foundations, stands and structures of the under-tribune space were dismantled, with the exception of structures that hold the facade wall. Then a new reinforced concrete frame of the stands was erected.
With the help of metal beams and flexible horizontal ties, he began to hold the facade wall. There was an opportunity to dismantle the remaining steel columns and ties adjacent to the historical wall. Thus, there was a paradoxical situation when the possibility of dismantling was realized with the help of dismountable structures. And in this, an important role was played by the correct determination of the order of the stages of dismantling and the construction of new stadium structures.
Many decisions to rely on old structures on new ones had to be made already in the process of dismantling, because the available data was only enough to make conceptual decisions.
But for the development of nodes required accurate initial data on the actual position, dimensions of existing elements and their cross sections. In the process of dismantling structures, as well as disassembling individual elements, all the metal was exposed and new data were updated. As a result, the process of developing attachment points for temporary connections was constantly in motion. The appearance of new data led to the correction of already adopted and, it would seem, well-developed design decisions.