On the rails for the clouds: how to wash the glass in a skyscraper

On the rails for the clouds: how to wash the glass in a skyscraper


Wash the window, replace the damaged glass of the facade - the tasks seem to be simple, but when it comes to buildings with a height of 400 m, the complexity level of even the simplest operations grows many times. < br/>
image
Mountaineer behind the front glass of the Lakhta Center tower, project archive

EVOLUTION OF SUPERKLINGING


The higher and larger the building, the more stringent the requirements for cleanliness of windows, and the more difficult it is to keep the facade in order. At the dawn of skyscraper construction, this problem was solved in the classical way, since the buildings themselves were close in design to ordinary houses, so that they opened the window and wiped it outside with a cloth moistened with soapy water.

image

True, a lot of windows. For example, in Empire State Building there are 6514. And higher. Therefore, there were eight washers, and they served the entire facade for two weeks, after which they left for the next round of cleaning. The safety of the pioneers of industrial mountaineering provided a leather belt, clinging to the special hooks on the outside of the frame.

image

The technology is safer than the previous photo. But with modern skyscrapers such a trick will not work. The facades are completely glass, opening windows most often do not. So climbers work either from the roof or from special technological hatches located at certain levels of the high-rises.

image

However, for really large buildings, this method is not suitable or is used only in certain points of the facade. The performance is low, the risks are high, and there is not enough manpower in a couple of human forces, for example, to replace a damaged facade element. Therefore, these supertolls are equipped with built-in SOF , or in the international version BMU . As a rule, such systems are mini-cranes that lift platforms or cradles, and move along the facades along rails installed on the roof or on special technological platforms.

image

Such a system is integrated into the construction of the 310-meter tower "Eurasia" in Moscow City.

image

An additional complication for SOF designers was the geometry of the building, sharply tapering at the level of the 51st floor. For work at once with two vertical planes, the lift is equipped with a telescopic boom with a reach of 19 m and a special system for fastening to the facade soft rope system. Cradle capacity 240 kg, lifting speed - 8 m/min.

image

The “Eye” tower is equipped with a similar mechanism - here the geometry of the facades is simpler, respectively SOF too.

image

image

There are also more exotic options, for example, monorail facade systems that move along a profile made of aluminum alloy. A small platform moves along the guide profiles, 1-2 meters in length, suspended from cables. But such systems do not install on buildings above 80 m.

image

In the tallest buildings, SOFs are whole multi-level complexes. For example, such as in Burj Khalifa in Dubai. The tallest building in the world is 828 m, 162 floors and 142 thousand m2 of glass facades.

image

At the heart of the SOF of this giant is a special rail system integrated into the construction of a skyscraper and located on three floors - the 40th, 73rd and 109th. On the rails move 12 cradles weighing 1.5 tons each. Starting from the 110th floor, the rail system becomes too heavy to use and the facades of the upper floors are cleaned from ordinary hanging cradles.

image

A similar system serves the facade of the 315-meter tower of the Bank of China, located in Hong Kong. At the level of the 70th floor, along the whole perimeter of the building, there are guide rails, along which the working platform with a cradle moves.

image

But, be that as it may, the principle of all these systems is the same - a crane and a cradle. And they are suitable only for direct facades. Not for people like the tower of Lakhta Center.

METRO ON WALL



image

You can't hang a cradle on a crane here, so for the Petersburg Supertoll we had to develop an absolutely new SOF. In fact, this is a real rail transport, but vertical. On the edges of the facade of the building from 3 to 89 floors are installed 15 rail tracks. Each path is made up of 87 rails exactly the length of one floor, that is 4.2 m.

image

image

The rail itself is a rather complicated structure in which a busline is integrated for supplying energy (approximately, as in a subway), a facade lighting system and a stainless steel chain.

image

image

It is for this chain that the asterisks of the lifting mechanisms, which are equipped with four engines, will cling to each other - two at the top and bottom.

image

Between the lifting mechanisms installed on the two edges of the tower with rails, fixed platform. A platform with a length of 23 m is intended for work on wide planes between corners - three cradles for transporting people or facade elements are installed here. On narrow planes, an 8-meter platform will be used to accommodate one cradle.

image

image

In total, there are eight platforms in Lakhta Center's “garages” - four large and two small for transporting people and one for each size for moving glasses. At the same time, seven platforms will be able to work simultaneously on the facades.
Due to the complexity of the geometry of the tower when moving, the distance between the rails and the angle of the platform will constantly change. Therefore, the control system of the SOF will have to constantly monitor the position of the platform and adjust it, speeding up or slowing down the movement of lifting mechanisms.
Obviously, despite the grandeur of the Lakhta Center tower, it will be convenient and quite simple to maintain its facades with the help of one of the most advanced SOF in the world. Another thing is to mount it.15 edges with 87 rails each - more than 1.3 thousand rail elements. And every industrial climbers are installed virtually by hand.

VERTICAL



image

In solving this unique problem, several more connected engineering puzzles had to be solved simultaneously. And the very first - how to deliver to the installation site the rails, weighing about 1.3 tons, when the cranes that worked on the construction of the tower were already dismantled? The way out was found in the experience of railroad workers who use road pavers building ahead of themselves the paths that they follow.

image

The rails to the installation site on the facade of the Lakhta Center skyscraper are delivered by a special conveyor-paver, also known as a freight elevator. It is driven by a winch installed on the 89th floor.

image

The elevator transporter moves on a 14-mm metal cable, which may well damage the glass of the facade, and already mounted rails. To prevent this from happening, rollers are installed every five floors, in which the cable is placed. Special guides had to be installed for climbing ropes, which due to this follow the bend of the building.

image

Actually, here begins the most difficult. After the special device on the conveyor feeds the rail to the facade, two climbers must get four fastening tabs into the hole of the lower rail - as in the designer. Only the designer element weighs more than a ton and hangs at a 300-meter height. And because of the bend of the building, it is necessary to fix it “for breaking”. So the climbers, who are also hanging not at a right angle and not having a reliable point of support, have to sweat even when performing the initial installation operation.
Then you need to connect the cables and wires of adjacent rails together, lower the mounted structure to the only point of its attachment to the skyscraper structures, combine the rail mounting axis with the bracket in four planes, which, due to the turn of the rail and the inclination of the facade, often do not coincide either. After that, the fastener is tightened with a rigidly fixed force with torque wrenches. To prevent the threaded joints from becoming “soured” over time, they are lubricated with graphite grease.

image

Installation of a single rail can take up to 10 hours, that is, the whole shift. Yes, even to get to the place of work can be difficult. Above the 30th level to the mounting point climbers descend from the very top of the tower. To do this, you need to go up to the 82nd floor by elevator. Then on foot from the 82nd to the 87th and back - down - this time already outside the tower along the cables. Up to level 20 is 30-40 minutes in summer and 1.5-2 hours in winter.

So up to level 20 is easier to rise from the bottom. Well, it's easier - just faster. But the physics for such an attraction should be extraordinary. Not every mountaineer is able to climb up to 80 meters on a rope along a vertical wall and then install a ton weighing rail for a few more hours.

Works on the facade go round the clock. Someone likes to work at night, although the entire installation - in the light of flashlights. Someone prefers a day when it is noisy, but the visibility is excellent.
With a wind strength of more than 10 m/s, work stops. In winter - taking into account the temperature and wind. With minus -15 down, up, with strong winds, maybe -25. Without wind, the temperature difference up/down is 1.5-2 degrees. Work climbers on the tower to -20.

SOF +


Climbers will remain regular "guests" of Lakhta Center even after SOF will be launched. After all, the rails of the system do not go above 89 level - they are decorative on the steeple. So all exterior elements located there will be serviced by industrial alpinists.

image

Their work is not the only addition to the main SOF. At the 89th level, a crane-crane, traditional for skyscrapers with straight facades, with a lifting capacity of 1 ton and moving along the rails is located.

image

image

The manipulator will service areas of the facade that are inaccessible to platforms; in emergency situations it will become a means of evacuating workers from SOF platforms.

image

Approximately on the same principle will serve the facades of the Multifunctional building. The SOF MFZ form two mobile cranes with a boom of 4.37 m, six cranes with a boom of more than 10 m and two cranes with a boom of 12.5 m for the atrium facades.

image

***

For assistance in preparing the material, we thank Alexander Luchina, Head of the Facades and SOF Building Directorate of the Tower of the Lakhta Center project office, Ildar Nasypov and Yegor Lapin, employees of the Tetrostroy contracting organization

Source text: On the rails for the clouds: how to wash the glass in a skyscraper