"Вестник МГСУ"

Technological peculiarities of high-rise buildings and structures are considered on the basis of the multifunctional 70-storeyed building («Moscow City»).
The application of advanced design techniques has proven their efficiency. Advanced methodology of design has reduced the time and cost of design due to repetitive use of the information accumulated in the course of design development, timely information support throughout the whole project development period, and the quality and timeliness of decision-making in terms of technology-related issues. The new design methodology was, to some extent, implemented by means of assurance of the standard functionality of construction-related systems and organizational actions, and through the customization of the system to assure the implementation of both the new functions and the methodology-related solutions.

Peculiarities of operating processes and mechanization of construction of modern multi-storied buildings and structures are considered by the authors. Principles of the robotized construction technology with the due account for multi-storied buildings are proposed in the article.
Advanced machinery and tooling employed in hi-rise construction operations (including cranes, building structures, installation and mounting devices) fail to be mutually adjustable. Therefore, cranes are capable of performing only one of 16 - 20 operations; the remaining operations are performed manually by the workers. The labour expenditures of workers exceed the time period of cranes in operation 4- to 5-fold.
The position of a building structure inside the building is based on the Cartesian coordinate system; any installation device must have a locating tool equipped capable of moving structural units alongside , and axes and of rotating them about the above axes. Thus, the machinery must be able to move building structures pursuant to six motion patterns.
High positioning accuracy requires a double-staged installation procedure. At Stage 1, a structural unit is relocated by crane mechanisms from the hard grip zone at maximal speed to assure maximal accuracy. At Stage 2, the new locating tool must move the structural unit at the minimal speed to accommodate it into its design position.
Erection performance rate may be improved by reducing the time period when the crane is in operation both in the automated and manual modes by converting the cyclical construction process into a continuous conveyor-type process (the crane construction is to be modified), and by introducing new joints into building structures to assure the self-locking and hard grip with a view to efficient manipulations and high-accuracy positioning.
Besides, an important constituent of the problem of improvement of the erection process represents the factors that may boost the labour productivity. These factors include the accounting of the machine time and the manual working time, as well as the time period of the whole erection process.

The authors provide an overview of multiple cases of application of piles, made through the use of electric discharges, as the foundations of high-rise buildings. The values of the bearing capacity of RIT piles identified on the basis of static field tests of specific construction facilities are provided. Nine RIT pile buildings, the height of which varied from 90 to 140 meters, were built before 2012.
The total number of high-rise buildings that rest on RIT piles is equal to nine. They are made of fine concrete prepared according to State Standard 26633-91*, B30 class of compression strength, and W10 grade of water permeability. The reinforcement of RIT piles was performed through the application of the reinforcing cage composed of two sections. A500C steel was used for longitudinal (bearing) rods, the design compressive strength was equal to 435 MPa; dimensions of the bearing steel were based on the principle of perception of the whole design load. The concrete transmitted the load into the soil and protected the steel from corrosion.
On the basis of the analysis of the monitoring results, the technology and tests of PIT piles, a conclusion can be made that PIT piles, that have a diameter of 320 mm, assure the pre-set reliability of high-rise buildings in complex engineering and geological environments.

Some results of high-rise buildings monitoring program are presented in this paper. The monitoring system is currently operating at the high-rise apartment building in Moscow. The vibrating wire strain gauges were embedded in the foundation slab and groundlevel walls during the construction. Measurements are carried out automatically at 6-hour intervals, and received in real time by the monitoring station. In this paper the result of measuring the strain in the concrete walls during 4 years is reported.The computer model of the building was made in order to compare the experimental and predicted data. Mathematical models of a high-rise building are simplified, but we are taking into account the main factors, that influence the stress-strain state of reinforced concrete structures. These factors are: influence of soil base, phases of construction and change of concrete deformation characteristics. The total strain in constructions was calculated as a sum of a strain under load, thermal strain, plastic shrinkage and creep. This data was compared with the total strain in structures measured by the gauges.The analysis of quantitative and qualitative correspondence between the model and actual data was performed. The comparison shows that the theoretical results obtained by the performed procedure are similar to the experimental data. It demonstrates that the model reflects the actual behavior of constructions. The differences found during the comparison are due to the redistribution of stresses from one part of a construction to the other that can occur even if the load is constant. This phenomenon is clearly seen during the suspension of construction. Some differences due to unaccounted factors were found, which should be investigated later.

The authors argue that no collapse of structures is likely in the event of a fire emergency in multistoried buildings, rather, other fire-related factors may endanger the lives of people inside high-rise buildings exposed to the fire emergency, including open fire, sparks, high ambient temperature, smoke and toxic combustion products, reduced concentration of oxygen, and combined influence of various factors.
In case of fire, the temperature inside buildings reaches 1100 °С. It exceeds the temperature of the ambient air acceptable for humans by far (70 °С).
The experiments demonstrate that combustion products contain hundreds of toxic chemical compounds. The most hazardous of them include carbon oxide, carbon dioxide, chloride and cyanic hydrogen, aldehydes and acrolein. The author provides the pattern of their influence on the human body.
The smoke consists of unburned particles of carbon and aerosols. The size of particles fluctuates within 0.05-50 MMK. Smoke produces a physiological and psychological impact on human beings.
It has been proven that dangerous fire factors emerge within the first five to ten minutes of the emergency situation. Evacuation is the principal method of safety assurance. However, the velocity of propagation of smoke and heat is so high that even if the fire prevention system is in operation, people may be blocked both on the floors that are exposed to the fire and those that escape its propagation.
New evacuation and rescue methods are recommended by the author. Various ways and methods of use of life-saving facilities are also provided.
Safe evacuation is feasible from buildings where the number of stories does not exceed 10- 12. During evacuation, high density human streams are formed inside buildings, therefore, the period of stay in a burning building is increased. The calculations have proven that a two-minute delay of evacuation converts into a safe evacuation of only 13-15% of people. Low reliability of smoke detectors can make the evacuation of people from high-rise buildings impossible. Special design of smoke detectors is needed for high-rise buildings.