Technical and editorial problems may be encountered during the implementation of Eurocodes into the systems of national standards. The main technical problems to be solved include specification of the target reliability levels of different types of construction works, definition of characteristic values, partial and combination factors and load combination rules for structures and geotechnical design. It is expected that in the next generation of Eurocodes further harmonisation and reduction of NDPs on the basis of technical assessment will be provided.
Present generation of Eurocodes encompass a suite of 58 Parts which represents a great achievement in European harmonization of structural codes. The key role in the design of new and existing structures represents the concept of reliability differentiation of construction works and the selection of target reliability level. Recommended target reliability level, expressed commonly by reliability index b = Φ-1(), where Φ denotes the standardized normal distribution function and the failure probability, are provided in several documents.
Load combination rules for verification of geotechnical design (ULS of type GEO) give three alternative approaches leading in some cases to considerably different results. For example, resulting dimensions of common footing may have differences about 20 to 40 %.
Other technical problems of implementation include lack of guidance for application of different design situations. For example a structure under fire should be verified according to the accidental design situation for which alternative combination factors are indicated in EN 1990. During subsequent repair the structure should comply with the requirements for the transient design situation, for which, up to now, there are no explicit rules for existing structures provided by Eurocodes.
Another problem is a unified definition of the characteristic values for variable actions, particularly for imposed and climatic actions, when 0.98 fractile for time dependent components should be supplemented by probabilistic specification of resulting action effect (for example, for imposed load and wind).
System of Eurocodes constitutes a great achievement in harmonization of European standards for structural design. In national implementation, it is strongly recommended to specify a unique (unambiguous) variant chosen from recommended options. Terminology and translation should be adapted to the sense of the original English version. Other manner of translations may be confusing or misleading.

The author provides an overview of the main urban planning trends in the present-day Bulgaria. The author also demonstrates principal approaches to area planning and provides examples of master plans of major cities of the country. The author emphasizes the need to resolve the environmental problems of urban territories, to develop their public transportation networks, resorts, landscape gardening, and a special role of historic and archeological monuments in the present-day cities.
Today, multiple hierarchically arranged plans of districts and towns are being developed in accordance with the Law on area arrangement of 2001. There are three levels of area planning in Bulgaria: strategic, tactical and operative/applied. The level of strategic planning covers the territory of the whole country (or its major parts, including regions and clusters of communities). The second level of area planning represents a tactical level. It is applied to smaller sections of the territory (communities, towns) and it converts into more detailed planning of the territory if compared to the top level of area planning. The general structure of the territory is developed at this level of planning. This level includes master plans of cities and towns. The third level, the level of operative/ applied planning, is applied to separate parts of populated areas, even particular sites. This level is characterized by detailed elaboration and it serves as a link to architectural planning. This level incorporates detailed area plans.

The present-day postindustrial or information-oriented society features an ever growing role of creative and intellectual abilities. This trend facilitates transformation of the workforce, as the portion of manual labor is reduced, while the one of intellectual labor goes up. As a result, architectural placemaking has to meet the new requirements driven by the specific nature of social and physiological constituents of the headwork. The aim of the article is the identification of new challenges that the high-quality architecture has to meet in its efforts to service the intellectual labour environment. For illustrative purposes, the author has chosen research and technology parks as the most typical postindustrial facilities.
According to the author, intellectual constituents of the architectural practice represent systematic and research components. This division is the result of the analysis of research and technology parks. The author has made an attempt to identify special conditions of effective creativity in architectural practice. They include comfort, availability, information system development, calm, sociality, significance and variability.
The list of conditions and general methods of their implementation presented by the author can be used in a wide range of project goals connected with the architectural design of research and technology parks and stimulation of creative potential of the people involved.

The indoor environment of residential buildings is a complex system. It consists of diverse though related elements. An optimal correlation of parameters of the indoor space converts into the appropriate equilibrium and harmonious human living free from any stimulating or irritating factors that interfere with any working and/or relaxation processes. The author has selected the following three principal factors of the indoor environment. They include heat, daylight and sound.
The research has revealed a strong linkn between these factors. Noise pollution of residential houses is taken into account through the introduction of the airborne insulation index and the impact sound index underneath the inserted floor. The findings of theoretical researches and experiments have proven a strong functional relationship between airborne and impact sound values.

Despite the ever improving living conditions and the quality of medical care, the percentage of disabled people in the society is now as high as it was in the past. Social adaptation and accessibility of the urban environment for people with disabilities remains the most important problem of contemporary architecture.
The solution is to establish public rehabilitation centres that perform recreational, educational, sports, cultural, social, technological and production functions. This solution is most needed for blind and visually impaired people, because they experience particular problems in travelling in the urban environment. Establishment of the barrier-free environment can solve the problem of socialization of disabled people, because it contemplates all functional processes that they need. Integration of various functional units within public rehabilitation centres helps improve the living conditions of disabled people, and at the same time it contributes to the profitability of these centres as a whole and provides the necessary impetus boosting the development of techniques and technologies required for low mobility groups of people.

Many problems of identification of the stress-strain state against the background of the heat and mass transfer are solved through the application of constant (averaged) values of mechanical properties (elastic modulus, Poisson's ratio) and derivation of differential equations with constant coefficients. Due to irregular distribution of temperature and other factors of impact, including the moisture content, mechanical properties of many materials change significantly; therefore, the problems in question are solved within the framework of mechanics of heterogeneous bodies.
In this paper, the authors solve the classical problem of the steady-state moisture-induced elasticity of a thick-walled cylinder by taking account of the changes in the value of the elastic modulus caused by the influence of moisture. In this case, the problem is reduced to a differential equation with variable coefficients, which makes the solution more complicated though more accurate. It is proven that due regard for the heterogeneity leads to a significant increase in stresses, if compared to the solution based on the mean values of the modulus of elasticity.

Operating conditions of uneven heating can cause changes in the physical and mechanical properties of materials. Awareness of the values and nature of thermal stresses are required for a comprehensive structural strength analysis. The authors propose their solution to the problem of identification of natural frequencies of vibrations of rectangular plates using a thermal factor.
The introductory part of the paper covers the derivation of equations of (a) the thermoelastic vibration of a plate, (b) initial and boundary conditions.
In the next part of the paper, the authors describe a method of frequency equation derivation for plates exposed to special boundary conditions, if the two opposite edges of the plate are simply supported, the temperature of the plate surface is equal to zero degrees Celsius, while the two other edges have an arbitrary type of fixation and an arbitrary thermal mode.
The authors have derived a general solution for the above boundary conditions, and by altering the method of fixation of the two edges of a plate, the authors obtain transcendental trigonometric equations reducible to algebraic frequency equations by using expanding in series. Thus, derivation of frequency equations different from the general solution is feasible for various types of boundary conditions.
The final part of the paper contains a derivation of the solution to the selected problem using the proposed method. The results demonstrate that the thermoelastic plate has four natural frequencies, two of them being equal to the frequencies of a plate free from the temperature influence, while the other two are close to the frequency of free vibrations of a plate.

The number of accidents at construction facilities has increased dramatically over the recent years. The engineering analysis of the reasons of accidents in the Russian Federation has revealed that the majority of accidents are caused by the loss of stability of specific structural elements, and a substantial reduction of the bearing capacity of structures. At the same time, no proper methodologies of processing and analyzing the results of inspections of structures, or methodologies of assessing the residual service life of structures are available, although advanced diagnostic tools are at hand. Therefore, advanced methods of accident risk analysis assume importance.
A quantitative assessment of the risk exposure of buildings and structures at any stage (design, construction and operation) can only be made through the employment of probabilistic calculations, especially if extreme loads are in the focus. Probabilistic methods are more robust as they evaluate the safety as the possibility of failure. Parameters are treated as stochastic variables.
Based on the research completed by the authors, a 3D computational model of a single-storey industrial building has been developed. The software programme developed by the authors is designated for the resolution of a wide range of problems of reliability, durability, stability and accident risk analysis in respect of buildings exposed to various internal and external loads.
The software may be used to resolve both direct and inverse problems. This feature is highly relevant in assessing structural behaviour. Their structures may constitute defects that affect their rigidity, strength and stability. The behaviour pattern of a loaded structure may be identified by means of an experiment, and thereafter, its rigidity may be identified by resolving the inverse problem in order to assess the life span of the structure.

The problem of wave loads on a relatively short wall is related to the issue of the general design of the structure at the stage of its construction, particularly, if the structure is build offshore. The physical nature of interaction between waves and vertical walls that have different lengths is the subject matter of this paper. It is assumed that the wall is absolutely rigid. The comparison of numerical test results and an analytical calculation based on a short wall model is made. As a result, wave forces identified through the employment of the above two models demonstrate their satisfactory convergence. The difference is substantial for longer walls, and it increases along with the increase of the wall length. The conclusion is that a short wall is exposed to the wave load that is not accompanied by any diffraction, therefore, a related method of design may be recommended. Numerical models may be considered as the universal ones.

The subject matter of this article encompasses a detailed study of spectral density through the employment of narrow-band filters. The article is composed of the two sections. The theoretical section contains a theoretical estimation of spectral density and its theoretical substantiation. Further, we assume that the spectrum is constant. We have also made an intermediate conclusion that the estimation of spectral density will be ergodic if the two conditions are simultaneously satisfied. The strength of this method is that any estimates made on its basis are ergodic.
In the second practical part the estimations are entered into the Matlab software and applied to the aerodynamic factor of front resistance. Before the entry of estimations, statistical checks have been made. No spectral analysis is possible absent of the above checks.

The problem of stability of a freely supported truncated circular conical shell, compressed by the upper base of a uniformly distributed load per unit length , referred to the median shell surface and directed along the generatrix of the cone, was solved by the Ritz-Timoshenko energy method. The orthogonal system of curvilinear coordinates of the points of the middle surface of the shell was adopted to solve the problem. Possible displacements were selected in the form of double series approximation functions. The physical principle of inextensible generatrix of the cone exposed to buckling at the moment of instability was employed. In addition, the fundamental principle of continuum mechanics, or the principle of minimal total potential energy of the system, was taken as the basis. According to the linear elasticity theory, energy methods make it possible to replace the solution of complex differential equations by the solution of simple linear algebraic equations. As a result, the problem is reduced to the problem of identifying the eigenvalues in the algebraic theory of matrices. The numerical value of the critical load was derived through the employment of the software.

The research project covered by this article consists in the assessment of the accuracy of the findings of the analysis of the stress-strain state of earth dams that have thin rigid seepage control elements, if performed using the finite elements method. The testing procedure has demonstrated that the modeling of the stress-strain state of the earth dams that have a reinforced concrete face require high-order finite elements; otherwise, the results are distorted. The employment of finite elements with a quadratic approximation of displacements provides a sufficient accuracy in terms of the final solution. In order to simplify the problem-solving procedure that involves high-order elements, the author suggests using these elements only in the modeling of the thin rigid seepage control element. The testing procedure has demonstrated that high-quality results need non-linear finite elements applicable to both a thin rigid structure and the adjacent areas.

Accurate and adequate description of external influences and of the bearing capacity of the structural material requires the employment of the probability theory methods. In this regard, the characteristic that describes the probability of failure-free operation is required. The characteristic of reliability means that the maximum stress caused by the action of the load will not exceed the bearing capacity.
In this paper, the author presents a solution to the problem of calculation of structures, namely, the identification of reliability of pre-set design parameters, in particular, cross-sectional dimensions. If the load distribution pattern is available, employment of the regularities of distributed functions make it possible to find the pattern of distribution of maximum stresses over the structure.
Similarly, we can proceed to the design of structures of pre-set rigidity, reliability and stability in the case of regular load distribution. We consider the element of design (a monolithic concrete slab), maximum stress which depends linearly on load . Within a pre-set period of time, the probability will not exceed the values according to the Poisson law.
The analysis demonstrates that the variability of the bearing capacity produces a stronger effect on relative sizes of cross sections of a slab than the variability of loads. It is therefore particularly important to reduce the coefficient of variation of the load capacity. One of the methods contemplates the truncation of the bearing capacity distribution by pre-culling the construction material.

The cyclic nature of effects of ice loading contributes to the formation of non-reversible deformations and defects of structural elements that may cause loss of the bearing capacity of the structure due to the accumulation of fatigue damages in dangerous sections. The damages in question are caused by moderate loads of multiple repeatability. In order to assess the number of cycles of ice loading that the structure may be exposed to without any substantial damages, the authors have developed a simulation model of ice load formation that serves as the basis for the analysis of the loading pattern that the structure is exposed to. This loading pattern is the initial one for the purposes of calculation of the fatigue resistance of structural elements to ice load effects. In the research, the authors provide for the joint application of the simulation model of ice load formation and the model of accumulation of fatigue damages to assess the ice resistance of a platform and its reliability from the viewpoint of its failure.

The authors argue that the availability of substantial hydrocarbon reserves in the waters of oceans and growing needs for this type of resources boosts the development of mining operations in the shelves of seas and oceans. The majority of continental shelves of the Russian Federation are located in the areas of freezing seas; therefore, the calculation of ice loads is an important issue. Analysis of ice loads that the offshore structures are exposed to represents a major problem. A significant reduction in the construction costs is attainable through rational design that contemplates a pressing need for simple and reliable methods of calculation. The paper represents an attempt to consolidate and analyze the main normative procedures that govern the calculation of ice loads, and to present them in the form that may be easily processed by the software.

The principal mission of structural design consists in the development of economical though reliable structures. Any safety-related improvements boost the cost of a structure, while any reduction of costs involves higher risks. The objective of any structural designer is to pinpoint the optimal structural parameters among the whole variety of solutions that fall within the range of the pre-set design requirements and minimal risks. Selection of the optimality criteria applicable to reinforced concrete structures is to be based on a set of requirements, including low costs, technological efficiency, safety and observance of limits imposed onto the expenditure of material resources and the workforce.
The author suggests splitting the aforementioned parameters into the two groups, namely, natural parameters and value-related parameters that are introduced to assess the costs of development, transportation, construction and operation of a structure, as well as the costs of its potential failure. The author proposes a new improved methodology for the identification of the above parameters that ensures optimal solutions to non-linear objective functions accompanied by non-linear restrictions that are critical to the design of reinforced concrete structures. Any structural failure may be interpreted as the bounce of a random process associated with the surplus bearing capacity into the negative domain. Monte Carlo numerical methods make it possible to assess these bounces into the unacc eptable domain.

A critical parameter in the evaluation of the liquefaction of soils is the residual or liquefi ed
shear strength. Liquefaction of granular soils can have extremely detrimental effects on the stability
of soil slopes and deposits, and on structures founded on them. This liquefi ed shear strength determines
the magnitude of the deformation that the soil will undergo once it has liquefi ed. Current procedures
for estimating the liquefi ed shear strength are based on laboratory testing programs or from
the back-analysis of case histories of liquefaction failures where in-situ test data were available. The
case-histories approach is the procedure that is preferred in practice. However, it has several limitations
including the very limited amount of data available, the signifi cant uncertainties involved in the
back-calculation of the liquefi ed shear strengths, and the lack of consistent and rational methods in
the use of the available data. To address these current limitations, this paper proposes new probabilistic
liquefi ed shear strength criteria for liquefi able soils from case histories.
The paper presents probabilistic undrained residual or liquefi ed shear strength values of liquefi
able soils as function of SPT blow count. The liquefi ed shear strengths were back-calculated
using slope stability analysis of previous case histories of fl ow liquefaction failures. Probabilistic procedures,
including the First-Order Reliability Method (FORM) and Monte Carlo Simulations (MCS)
were used in combination with limit equilibrium methods to analyze case histories of fl ow failure presented
in the deterministic companion paper. Depending on the post-failure geometry of the case
history, either the simplifi ed infi nite slope stability analysis or the more general Spencer method of
slices analysis was used in the back analysis. The Beta Probability Density Function was used to
model the statistical distributions and uncertainties in the geotechnical parameters involved in the
probabilistic analyses. For FORM, a Bayesian Mapping procedure is used where values of PF are
computed from the probability density function of the reliability indices of fl ow failure. The logistic
mapping function is obtained by relating the deterministic factor of safety to for the liquefi ed
shear strength relationships. A parameter 1 was introduced to account for model uncertainty in the
reliability calculations.
Probabilistic versus minimum (1)60 criteria were presented for contours corresponding
to 2 %, 16 %, and 50 %. It was shown that the = 50 % relationship is very close to the
best fi t relations obtained from the deterministic analysis of the case histories. The probabilistic
versus minimum (1)60 criteria provide a more rational procedure for estimating the postliquefaction
stability of cohesionless soils deposits by providing estimates of the probability of failure
in addition to traditional values of factor of safety. The probability of failure can account for the different
uncertainties in the back calculation of the liquefi ed shear strength values from case histories,
and the natural variability and uncertainties and properties of soil deposits.

In the article, the authors consider heat and mass transfer inside reinforced concrete structures, and their impact on the mechanical properties of the latter.
The authors argue that humidity is an important factor of concrete hardening. As a rule, concrete-to-environment mass transfer, as well as the mass transfer inside concrete products, cause fast dehydration in the course of hardening, thus, leading to the insufficiency of strength. This phenomenon may be exemplified by prefab concrete products hardened in the hot and dry climate. The findings of the authors constitute a simple though efficient solution that consists in the employment of solar chambers equipped with an intermediate, or supplementary, heat carrier. Solar chambers are to be installed inside production premises.
Reinforced concrete products manufactured in accordance with the technology proposed by the authors feature high strength and durability. The concrete structure and properties (namely, compressive strength, tensile strength, modulus of elasticity and cold resistance) even exceed those of the concrete products hardened within 28 days in the regular temperature and humidity environment.
Theoretical principles and experimental research findings of the authors have been invested into the year-round technology of manufacturing of reinforced concrete products inside production premises, where products are treated by the solar energy and a supplementary source of energy. The concrete mix is poured into the form and compacted there; thereafter, the product surface is smoothed. Immediately after that a cover is fixed onto the form and tightly attached to the form walls. The process is to be initiated at 8 a.m. to maximize the period of solar energy consumption and to accelerate the process of concrete hardening.

Polymeric materials are widely used in construction. The properties of polymeric construction materials vary to a substantial extent; their durability, thermal stability, frost resistance, waterproof and dielectric properties are particularly pronounced. Their properties serve as the drivers of the high market demand for these products. These materials are applied as finishing materials, molded sanitary engineering products and effective thermal insulation and water proofing materials.
The authors analyze the influence of the chemical structure and structural features of polymers on their properties. The authors consider flow and vitrification temperatures of polymers. These temperatures determine the parameters of polymeric products, including those important for the construction process.
The analysis of influence of concentration of the plasticizer on the vitrification temperature is based on the two basic theories. In accordance with the first one, reduction of the vitrification temperature is proportionate to the molar fraction of the injected plasticizer. According to the second concept, reduction of the vitrification temperature is proportionate to the volume fraction of the injected solvent. Dependencies of the flow temperature on the molecular weight and the molar fraction of the plasticizer are derived for PVC. As an example, two plasticizers were considered, including dibutyl sebacate and dioctylftalatalate. The basic parameters of all mixtures were calculated through the employment of "Cascade" software programme (A.N. Nesmeyanov Institute of Organoelemental Connections, Russian Academy of Sciences).

Non-autoclaved foam concrete is an advanced thermal insulation material. Until recently, foam concrete production has been based on separate preparation of foam and solution, followed by their blending in a mixer. The situation changed when high-quality synthetic foaming agents and turbulence cavitation technology appeared on the market. Every model provides a dependence between the foam concrete strength and the water-to-cement ratio. According to the water-cement ratio we can distinguish strong concrete mixtures (with the water-to-cement ratio equal to 0.3…0.4) and ductile ones (with the water-to-cement ratio equal to 0.5…0.7). Strong concrete mixtures are more durable. The lower the water-to-cement ratio, the higher the foam concrete strength.
However super-plastic substances cannot be mixed by ordinary turbulent mixers. Foam concrete produced using the turbulence cavitation technology needs air-entraining, its intensity being dependent on several factors. One of the main factors is the amount of free water, if it is insufficient, the mixture will not be porous enough. A researcher needs to identify the optimal water-to-cement ratio based on the water consumption rate. Practical production of prefabricated concrete products and structures has proven that the reduction of the water-to-cement ratio improves the strength of the product. The task is to find the water-to-cement ratio for the foam concrete mixture to be plastic enough for air entraining. An increase in the ratio causes loss in the strength. The ratio shall vary within one hundredth points. Super-plasticizers are an alternative solution.

The authors present their methodology of synthesis of a nano-scale additive designated for the stabilization of synthetic foaming agents. The nano-scale admixture is composed of iron hydroxide (III) sol and aqueous sodium hydro silicates (water glass). Besides the above method, the topological structural model of the nano-scale additive is proposed. The additive stability was assessed upon its one-day storage (with the foaming agent added), and the assessment data are provided in the article. The authors have discovered that it is advisable to use an iron chloride solution in the concentration of 1 % to manufacture the iron hydroxide (III) sol.
The authors have also discovered that the rate of jellification goes up in the process of injecting the foaming agent into the foam that contains the nano-scale admixture developed by the authors. Dependence between the amount of sodium hydro silicate and the viscosity of the system composed of the water glass and the sol of iron hydroxide (III) is examined in detail. The authors have identified that the average water glass viscosity curve demonstrates an extreme nature. The additive is used for the stabilization of the foam generated by synthetic foaming agents. The injection of the proposed additive improves foam stability. It is noteworthy that this positive result is free from any negative side effects.

The subject of the research is the influence of the type of Portland cement, as well as the nature and concentration of additives that represent electrolytes and polymers, onto the foam stability. The project is implemented within the framework of the research of foamed ceramic. Detailed explanation of the influence pattern is provided.
The research performed by the authors has generated the following findings. Besides the rheological properties of the solution, chemical interaction between the mix components must be taken into account in the course of development of the best foamed ceramic mix composition, as chemical processes produce a substantial influence onto the foam stability. Polymer additives based on liquid carbamyde-formaldehyde and polyacrylamide substantially improve the quality of the foam mineralized by the particles of the cement binder. They also assure the foam stability rate sufficient for the formation of a high-quality foamed material.

Present-day methods of recovery of used wooden railway ties, including burial, chemical neutralization, gasification and subsequent burning, utilization in the capacity of composite materials, are expensive and unsafe for the environment. The authors propose a new method of their utilization. Ash generated in the course of their burning may replace a portion of cement in composite solutions and act as an additive to grouting mortars designated for the filling of the annulus space of manifold tunnels. The chemical composition of the ash was identified by the x-ray method applied to three samples taken during various periods of time from out of a dry-type dust collector.
The level of human health/environmental hazard of the ash is based on its chemical composition. Changes in the rheological properties of composite solutions that contained concrete fractions, various ratios of ash, and 5% of liquid glass were studied in the course of the research. The experiments have proven that in the event of replacement of 20% of cement by ash, the strength of the composite solution is approximately the same as the one of the benchmark sample; therefore, this ash content ratio is deemed acceptable. The finding demonstrate that the ash has no toxic effect, and the ecological safety of this solution is thus confirmed. The authors have proven that 20% of cement may be replaced by the ash generated in the course of burning of waste railway ties.

Use of a special injection aimed at the partial replacement of cement by ash generated in the course of combustion of waste wooden crossties may solve two problems: recycling of a toxic
by-product generated in the course of combustion of crossties, and reduction of the cement consumption rate. The authors have identified that ash added into the injection does not cause any deterioration of the mortar strength; rather, it assures its structural stability and prevents any leaching of heavy metals that it contains. The authors have identified that adding 20 to 26 % of flue ash into the injection reduces the mortar hardening time by 30 %, while the strength of the mortar that has 20 % of ash is almost equal to the one of the benchmark sample. However, any higher ash content causes deterioration of the hardening strength of the mortar. Therefore, the authors have discovered that 20 % of the cement may be replaced by the ash generated in the course of combustion of waste crossties. This replacement is to be performed in the course of preparation of mortars, and it is aimed at the strengthening of the soil. This operation is to be performed in the incinerator to preserve the solution properties. This technology reduces the amount of hazardous by-products through their recycling.

The authors provide their research findings concerning lightweight masonry mortars with hollow glass microspheres and antifreeze admixtures. These mortars are used in the construction of filler structures at negative temperatures. The application of multilayer filler structures causes reduction of their thermal homogeneity factor. Therefore, single-layer filler structures have the strongest potential. There is a need to employ lightweight masonry mortars to ensure the thermal homogeneity of structures made of lightweight concrete blocks. The masonry mortar that has traditional weight
reduction fillers (such as inflated pearlite, vermiculite etc.) demonstrate low strength properties, as such fillers have a high water content. Hollow glass (or ceramic) microspheres are known as efficient fillers for lightweight mortars. Multiple research undertakings contain information on the masonry mortar that has the following properties: average density of dry mortar - 450 kg/m3, thermal conductivity factor - 0.17 W/(m·°C), compressive strength at the age of 28 days - 3.2 MPa, water retention rate - over 90 %.
The climatic conditions of Russia determine the need to perform masonry works at negative temperatures. Adding antifreeze admixtures is an easy and cheap method that guarantees hydration of the Portland-cement at negative temperatures. The subject of this research covers masonry mortars that have a 15 % hollow glass microsphere content and antifreeze admixtures. Contemporary antifreeze admixtures are multifunctional. Therefore, traditional antifreeze admixtures such as sodium chloride, calcium chloride, sodium nitrite, sodium nitrate, sodium formate, potash were used in the research. The per-cent content of antifreeze admixtures was calculated. The following properties of masonry mortars with a 15 % content of hollow glass microspheres and antifreeze admixtures were identified: average mortar and mortar mixture density, setting time, water retention, compressive and bending strength, and water absorption. Standard research methods were employed.
Every mortar has an 8 cm mobility. The benchmark mixture has an average density of 1.085 kg/ m3, average cement stone density of 980 kg/m3, compressive strength at the age of 28 days - 19.8 MPa, water retention rate - 97 %, setting time - 4.5 hours.
The attention was driven to the strength analysis of mortars with hollow glass microspheres and antifreeze admixtures at positive and negative temperatures. The authors proved that antifreeze admixtures demonstrated a negative influence on the strength and setting time of the mortar if hardened at 20 °C. The strength of mortars with antifreeze admixtures was below that of the benchmark mortar. Mortars that had sodium nitrite and sodium chloride demonstrated better results, while the mortar with calcium chloride showed the lowest strength.
Sodium nitrite, sodium formate and potash were mostly efficient at negative temperatures. The mortar with sodium nitrite demonstrated the highest strength, as it had hardened at the positive temperature. Optimal mixtures for the temperature of -10 °C were developed by the math planning method.
The results of the microstructure analysis for optimized mixtures are provided in the article. The finding of the authors are that at the temperature of -10 °С the following mixtures have the best properties: lightweight masonry mortars with hollow glass microspheres and sodium nitrite (7 %), or sodium formate (5 %), or potash (7 %) with a setting retarder added.

The status of nanotechnologies in material science predetermines development of nanotechnology-intensive products that demonstrate pre-set properties of modified materials. The presence of nano-size particles of substances makes it possible to benefit from their physical and chemical potential and to overcome some negative developments that accompany the structure formation process (at interphase boundaries). The barrier properties are variable, which is quite important in terms of the increase of the asphalt concrete durability. Production of a modifier (that has nano-particles of the pre-set chemical composition) to be added into asphalt concrete mixes is also of interest.
The authors present their findings concerning the nano-scale modifier that has a chemically inert component and a hydraulically active substance. The method of de-aggregation is used to produce the nano-scale modifier. By-products are often welcomed as mineral components of the asphalt concrete, as they reduce its cost.
The findings of the authors concerning the influence of the grinding mode on the integrated characteristics of the powder are presented in the paper. It is proven than dependence of integrated dispersion indicators is nonlinear due to processes leading to aggregation of mineral powder particles.
The analysis of the experimental data collected in the course of "wet" grinding proves that surface-active substances stimulate the process of grinding. The type and concentration of an additive that improves the grinding efficiency is also identified.

The article has the author's analysis of the status of the sector of wastewater treatment and the condition of waste water treatment plants (WWTPs). It is pointed out that a big number of
WWTPs fail to perform proper treatment due to their being worn-out and obsolete. However a tougher legislation accelerates their reconstruction. Approaches to the WWTP reconstruction should demonstrate a strong economic and technological base. The author proposes a new algorithm for their reconstruction.
A sensible combination of the principles of WWTP restructuring, development of new fine wastewater cleaning methods, and assimilation of new materials and chemical agents will help resolve the vital problem of waste water discharge into Russia's water bodies. This is the first methodology of reconstruction of WWTPs developed on the basis of the above concept and supported by practical implementation.

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.

Loessial pseudokarst is the result of hydrodynamic, gravitational, physicochemical, and biogenic failure of loess or loess-like soils due to their watering. This dangerous geological phenomenon is mainly caused by anthropogenic reasons, and it manifests itself as cavities, swallow holes, collapse sinks, gullies, etc. Their sudden formation is no less serious problem for a civil engineer than a well-known collapse of loessial and loess-like soils; therefore, there is a need to mitigate the consequences of the above phenomena to protect buildings, structures, roads, railways, and agricultural lands from the consequences of the loessial pseudokarst. Many protective actions are identical to those aimed at protection from karst, and they can be attributed to the passive or active type. The first one does not influence the formation of the loess pseudokarst, but the second does.
Passive actions include planning and designing of subsidence-resistant structures, as well as monitoring of their condition. Dewatering of loess or loess-like soil, control over irrigation, organization of the surface water runoff, erection of waterproof screens and hydraulic curtains, filling of pseudokarst cavities and holes, and improving loess or loess-like soil by injecting the grout represent active mitigation actions. Some of them can only be implemented before the construction is initiated, others can be implemented as operative actions in the course of or in the aftermath of the construction, but most of them can have a double nature.

The authors have analyzed the energy potential of the Russian regions based on the planning of territories through the employment of renewable sources of energy, their incorporation into architectural solutions applicable to buildings and structures. The authors also provide their comparative analysis of different sources of renewable energy, of which windmills are covered in more detail.
Urban development of Russia is accompanied by environmental changes and substantial growth of power consumption caused by the expansion of urban clusters that feature high concentration of population and housing density. Against this background, optimization of energy consumption through the incorporation of energy efficient technologies and renewable sources of energy into the process of construction and operation of buildings is of particular importance. The principal
renewable sources of energy include water, sun, and wind. Wind power engineering best fits the conditions of the Russian territories. However, experts believe that the wind power is to be backed by other sources due to the irregularity of its generation. This approach to the power generation and planning of territories coupled with the integration of renewable energy technologies into architectural designs of buildings and structures will make it possible to identify the prerequisites for the energy generation specialization of the subjects of the Russian Federation on the basis of their climatic conditions and urban development patterns. Private investments into renewable sources of energy will assure sustainable population settlement patterns and optimal energy generation and consumption.

The authors consider several aspects of applicability of the new approach to formation of effective stresses in soils in relation to sands, as it was set out in the theory developed by academician
V.I. Osipov. The analysis of several genetic types of quaternary sands, performed by the authors, makes it possible to use the number of contacts to identify the morphology of sand grains within the framework of the analysis of soils.
The authors demonstrate that the employment of the formulas developed by academician V.I. Osipov in the calculation of the number of contacts between particles in natural sandy soils is virtually impossible due to the fact that no natural sand particles can boast an ideal spherical shape. The number of contacts between the sand particles may increase due to the defects of their shape and the nature of the particle surface.
In this study, the shape and nature of the surface of sand grains represent those of the sands of various origins. The authors have employed a composite index of morphology that takes account of the shape and nature of the surface throughout the amount of sand under research. Similar calculations that take account of the morphology of grains were performed for selected fractions of sands to eliminate the influence of grain size on the packing of sands.
The analysis of provisions of the physical and chemical theory of effective stresses of soils and the study of multiple types of natural sands demonstrate that further research of formation and phases of coagulation contacts between particles of soil requires a detailed study of structural features of sands. These structural features include the grain size, homogeneity, the shape and nature of the surface of sand grains.
Both individual particles of sand and sandy soil are to be subjected to morphological assessments. The parameters to be assessed will include density and composition of sandy soils, as the soil porosity affects the formation of true contacts between particles of sand and determines their number. Mineral composition is an important factor affecting the shape and nature of the surface of sand grains. The research performed by the authors contemplates the study of the morphology of monogene, polymineral, oligomictic and polymictic sands. However quartz is the principal mineral in the structure of sand under research. Further research will cover other minerals to obtain more information about the formation of contacts between sand grains.

The problem of waste collection and disposal is one of the oldest in the history of mankind. Currently, the main purpose of waste management consists in the prevention of the harmful effect on the human health and the environment.
The author discusses the current situation in the area of use and disposal of waste in Russia. The author proposes a new methodological approach to the calculation and introduction of waste disposal fees to consolidate the ecological and economic constituents of the problem. This approach requires modification of the local legislation and introduction of the local geo-ecological stress factor to take account of the environmental status of regions, as well as the social and economic situation of regions. The geo-ecological stress factor is based on the local terrain and the population figures.

The article is focused on the main problems of competitive stability of construction organizations in connection with the accession of Russia to the WTO. Now Russian construction organizations should work on an equal footing with more developed foreign competitors.
A construction organization should be competitive to ensure its successful operation in the global market. Competitive stability is the ability of a organization to implement its economic development strategy and to strengthen its competitive positions in the market environment. Competitive stability improvement requires improvement of the innovative capacity.
The author develops an Innovative Audit method to improve the innovative capacity of a construction organization. An innovative audit incorporates 5 stages:
1. Choice of innovations and formation of the bank of innovations.
2. Choice of innovations corresponding to the innovative capacity level of a specific construction organization.
3. Definition of the innovative capacity level of a construction organization.
4. Reconciliation of the innovative capacity against the bank of innovations.
5. Approval of the final decision concerning the implementation of a specific strategy of innovations.

Formation of the pricing system and underlying investment and construction activities were analyzed by the authors in their research. It is noteworthy that the pricing system has a common basis with other human systems, as it incorporates such constituents as process, people, software, etc. Correct interaction between these elements ensures conformity between the anticipated and the practical performance of the system. The basis for the effective operation of the existing system and reduction of potential risks consists in early identification and analysis of requirements set by the user. Absent of implementation of an effective requirement management process, the pattern of the system development will look chaotic and unpredictable. In the process of the data analysis, the data set is converted into a set of the user requirements describing the anticipated behavior of the system in the course of its interaction with the operating environment.
The requirements of users comprise an important constituent of the system design. They affect the entire development process from the beginning to the very end. In accordance with the principles of the system engineering, the authors have identified the key pricing system parameters; their implementation assures the appropriate functionality with a view to the formation of the contract price at various stages of the life-cycle of the investment project. Analysis of the above requirements makes it possible to convert them into a technical vision of the desired product that can demonstrate the required functionality.
The methodology proposed by the authors contemplates decomposition of the levels of requirements; therefore, the authors employ a three-level model that describes the expected functionality of the system. The model includes an organizational level (basic processes, participants, information flows), a methodological level (method of calculating the cost of design, construction and operation, regulatory and methodological documents) and a technology level (information systems and technologies). A three-level functional decomposition of the system is used to simplify the comparison of the elements of the system architecture and the user acceptance.

The author considers and analyzes different types of risks that an investment building project may be exposed to, as well as the influence of risks on the project life cycle; sustainability of organizations is studied in the context of risk as an attribute of uncertainty-related parameters of the external environment. The conceptual approach to managerial solutions based on (1) the criterion of flexibility, and (2) the rate of change of characteristics of external actions is proposed.
The proposed approach serves as the basis for the following conclusions:
the nature of project management as a system is based on the velocity of changes that affect the project sustainability environment;
the methodology of risk management applicable to investment building projects based on decision making under conditions of ambiguity fails to guarantee the viability of the project in the turbulent environment, namely, the environment that demonstrates intensively changing characteristics;
effective project implementation requires a reasonable combination of principles of optimal and extreme risk management;
minimization of risky situations requires reduction of the project implementation period;
development of domestic methodologies and standards of project risk management tailored to the conditions of our construction industry is a relevant assignment.

The authors argue that successful development and implementation of major infrastructural projects require special arrangements between the government authorities and the private sector. The authors have developed their proposals concerning models of interaction and strengths of the above arrangements that apply to the organizational structure of the management of infrastructural projects as a step towards the formation of an advanced and progressive model of interaction between public and private sectors. Public-Private Partnership (PPP) is the model in question.
Great Britain is the pioneer of the public private partnership model that was later picked up in the USA, Canada, Australia and the EU constituent states.
PPP and the construction industry have strong links in terms of the involvement of the private sector in the resolution of public problems of the urban infrastructure, namely, restructuring of airfields, railways, public healthcare facilities, kindergartens, schools, etc.

The authors argue that effective use of water resources requires accurate morphometric characteristics of water basins. Accurate parameters are needed to analyze their condition, and to assure their appropriate control and operation. Today multiple water basins need their morphometric characteristics to be adjusted and properly stored.
The procedure employed so far is based on plane geometric horizontals depicted onto topographic maps. It is described in the procedural guidelines issued in respect of the «Application of water resource regulations governing the operation of waterworks facilities of power plants». The technology described there is obsolete due to the availability of specialized software. The computer technique is based on a digital terrain model.
The authors provide an overview of the technique implemented at Rybinsk and Gorkiy water basins in this article. Thus, the digital terrain model generated on the basis of the field data is used at Gorkiy water basin, while the model based on maps and charts is applied at Rybinsk water basin.
The authors believe that the software technique can be applied to any other water basin on the basis of the analysis and comparison of morphometric characteristics of the two water basins.

Presently, effective regulations employed in the Russian Federation recommend the use of the methods developed by E.G. Kachuchin, G.S. Zolotarev, I.A. Pecherkin, etc. for the projection of patterns of reorganization of coastlines of water reservoirs. One of these methods, developed by E.G. Kachugin, belongs to the group of power methods based on the hypothesis that the amplitudes of destruction of the coast are proportionate to the total wave energy alongside the coastline. The Kachugin method was reworked into a computer-based two-dimensional engineering model of reorganization of the abrasion shore. The model generates alternative projections. It simulates the processes of washout and accumulation of soil in the coastal area and solves the problem of predicting the potential profile of the shore within a pre-set time period or until the abrasion is smoothed away in the course of formation of coastal shallows.
The model testing has proven its efficiency in solving the engineering problems of projecting the line of reservoir abrasion shores with a high degree of reliability.

A novel data structure for the topology of three-dimensional skeletons of buildings is presented. Each face of the skeleton is mapped to two half-faces in the topological model. The boundary of a half-face consists of a cycle of half-edges. Each edge is mapped to a bundle of half-edges containing one half-edge for each half-face at the edge. The bundle is decomposed into two dihedral cycles, one for each direction of the edge, containing the half-edges ordered according to dihedral angle. The topological model is constructed by partitioning three-dimensional space. Each partition subdivides a specified cell into two convex cells. Cells can be merged if the resulting cell is convex. The partition and merge operations are efficient because they are performed on a small subset of the elements of the model in the vicinity of the affected cell and are thus independent of the size of the model.

A novel integrated mathematical model for the devaluation of buildings with time and the restoration of their value through renovation is presented. The traditional approach of treating individual building components is extended to complete buildings and groups of buildings through the introduction of classified sets and renovation groups of building components. The time history of the accumulated renovation costs is determined. It is suitable for rational planning of the renovation strategy and of an economic balance between resources assigned to new construction and resources used for the renovation of buildings.