The article is devoted to the design methods for strenthened foundation based on the actual stress-strain state of bases and foundations. In the normative documents there are no recommendations on the calculation for strengthened slab foundations with piles and methods of strengthening of the Foundation with piles proposed in the scientific literature do not take into account the loads that were passed before the foundation was strengthened. It is shown that as a result of such calculations the piles are or strongly overloaded, or underloaded. Numerical study of the raft foundation and grouting strengthening piles interaction considering loading history were done. The factors were identified that determine the load on the pile in the local position. There are some regularities recommended for strenthened foundation design. The design method of the loads on the soil-cement piles at strengthening slab foundation, taking into account the loads that were passed before, and recommendations for pile field parameters determination were offered.

The influence of deformation rate of the timber on the value of the initial modulus of elasticity and tensile strength can significantly affect the result of the construction calculation under the influence of the low-speed load. The experimental results of the pinewood samples of uniaxial compressive load speed range from 4 mm/min. to 1000 mm/min. are given below. The regularities of changing of initial modulus of elasticity and tensile strength along the wood fibres in the radial and tangential directions are found. The dependences of modulus of elasticity and tensile strength of wood from the load speed are revealed. The experiments have shown that depending diagrams of elasticity modulus with increasing load speed are nonlinear with the largest gradient in the initial stage of deformation. Specific forms of experimental specimens destruction under along fibres compression in the radial and tangential directions are found. The exposed to compression in the tangential direction specimens are most sensitive to increasing of the load speed.

The analytic dependence of deflection of statically determinate trusses with parallel belts and console sections, depending on its size and number of panels is obtained. Analyzes of asymptotic properties of the solutions taking in to account different stiffness rods of the belts, and lattice. The forces in the rods are determined by cutting out the nodes by the author's program written for the computer algebra system Maple. Generalization of the solutions obtained for trusses with different number of panels produced by the method of induction. The similarity of the formulas for deflection allows to write the sequence of coefficients of the respective parameters of the truss. Using a system Maple displays the recurrence equation which satisfy the members of the sequence and its solution. The solution also allows to optimize the farm due to the choice of the most rational distribution of element cross-sections.

The results of experimental studies of deformation and fracture five series of reinforced concrete beams usual and composite cross-sections, including samples with the modeling of corrosion damage, are analyzed in article. The methodology and program of tests of reinforced concrete structures is given with a brief description. It is prepared the analysis of the influence and main variable parameters (shear span values, the presence of the contact seam structure section rust samples) in the form of the destruction and the bearing capacity of the inclined cross-section solid and composite structures. Attention is paid to the occasion and the destruction of a composite reinforced concrete beam seam contact between two concretes. It has done the analysis of the main types characteristics of stress-strain state in the area with inclined cracks that need to be taken into account in justifying appropriate durability criteria.

This article examines the question about the similarity of graphs "the maximum deflection of elastic plates - with respect to their conformal radii" and "the main oscillation frequency - the ratio of the conformal radius". Examines the records in the form of a polygon, circumscribed around the circle (triangles, rhombuses, correct n-squares). Introduces the concept of coefficient of similarity, which can be used according to the known values of the maximum deflection of plates with hinged support conditions on the contour to evaluate approximately the value for plates with rigid edges fixed and Vice versa. Likewise assessed and the main frequency of the considered records. Numerical examples of calculations are given. Use of the offered method of determination of the maximum sag and basic frequency of oscillations by means of coefficient of similarity can be recommended for obtaining evaluation results on initial stage of design of constructions in the form of plates.

The technical condition and failure mechanisms of exploited cylindrical masonry vaults are discussed. Known techniques for their strengthening are given. The advantages and disadvantages of strengthening techniques by installation of solid reinforced plaster layer and stiff edges(beams) are described. The strengthening of vault by composite mesh (FRP) reinforcement is offered as more modern and preferred method. Installation technology and advantages of strengthening system by using composite materials which is called Fibre Reinforced Cementitious Matrix (FRCM) are presented, within which, instead of an epoxy adhesive, used special plasters. The results of experimental investigations of reinforced and unreinforced masonry compression bending specimens are analyzed. It is concluded that the greatest effect of composite mesh (FRP) reinforcement can be obtained for semicircular vaults, and the least effect for shallow (low angle) vaults.

Discusses the features of the solution of some problems of calculating the strength of normal section of bendable reinforced concrete elements of rectangular section with single and double non-stressed reinforcement using the relative areas of resistance. Shows the impact on the reinforcement elements of concrete strength and geometric dimensions of the cross section. The proposed relations for determination of the min-imum concrete strength, minimum cross-section dimensions, the minimum single or double bending rein-forcement concrete elements depending on the external influence and position of the reinforcement along the height of the section. We consider the calculation of reinforced concrete elements with mixed reinforcement of stretched zone reinforcement of different classes, which are often found in the strengthening of reinforced concrete structures. The obtained dependences allow to solve problems of direct and inverse design of the normal section of bendable reinforced concrete elements with single and double reinforcement, getting economical solutions.

He article deals with the free vibration problem of elastic orthotropic parallelogram plates, boundary conditions of which are simple supporting or clamping along the sides. It is used approximate analytical technique - form factor interpolation method. This method based on the relation between integral geometrical parametr, which is known as form factor of midplane, and mechanical parameters (for example, frequency of free vibrations). Rectangular plate’s shape can be obtained from rhombic or rectangular plates, using affine geometrical transformation of its midplane. Rhombic and rectangular plate's frequency values are the referense solutions to the all plates with convex contour. Polynomial function is used as interpolation function. In the article we obtained functions for values of free vibration frequencies for orthotropic rhombic plates, when one of the orthotropy axes is directed along the side of a plate. Form factor and flexural rigidity ratios are parameters of these functions. The results of this investigation are compared with the FEM (SCAD and LIRA-SAPR programs).

The questions and the results of simulation of the dynamic hysteresis effect of pavement when exposed to the surface of the moving load of the design of the vehicle. Mechanical road structure layers during the simulation of dynamic effects of the design of the vehicle, complemented values damping rates, the determination of which is possible in field conditions. The relationship between the values of the elastic moduli of structural pavement layers and dynamic area of the hysteresis loop that characterizes the energy density transmitted to the surface of the pavement when driving wheels of the vehicle. The possibility of linking the energy dissipation area to the total number of rated load applications on the pavement surface. The prospects of research in the framework of this subject.

The pilot study of the system of cross beams on the square plan with a size of cells of 0,4х0,4 m with a covering is considered, in case of change of the scheme of an covering during the experiment statistical and dynamic tests as a result of which, there are the maximum sag and frequency of natural oscillations of system are carried out. It is revealed that with reduction quantity of support on one side, sags increase, and frequencies decrease. It is also set that in case of reduction of rigidness of nodal connection the maximum sag increases, and frequencies of natural oscillations of system decrease. Comparison of theoretical and experimental data is made. The analysis whom shows irrespective of a pliability of nodal connections and the scheme of an covering the experimental sags and frequencies is more received by a numerical method. For SPB depending on the scheme of an covering, the difference between the experimental and numerical values of sags makes from 1,70% to 6,84%, and the difference frequencies makes a boundary from 1,33% to 4,68%. A basic reason of a discrepancy of the experimental and numerical values of sags and frequencies of cross oscillations are that circumstance that at the expense of a high level of a pliability of nodes of system of its deformation in case of the high levels of loading take place in non-linear area. For coefficient To a difference between theoretical and experimental data reaches 15,62%. Based on a research it is possible to draw a conclusion on rather good convergence of results of numerical and experimental sags and frequencies of own oscillations, and also compliance of the experimental coefficient To and its applicability for systems of cross beams, to the analytical values removed by V. I. Korobko for the isotropic plates.

The application of the Dynamic Finite Element (DFE) to the analysis of building frame structures at impact load is considered. The DFE stiffness and inertia matrices are constructed on the base of analytical (exact) solutions of vibration equations of a bar. At impact load research the hypothesis that local deformations near contact zone of colliding bodies are related with the contact force by static dependencies, and also the general deformations of a building structure, which are determined by vibration theory methods, are taken into account. The influence of impact load parameters on frame system response is studied on the example of a single beam, subjected to tension (compression) and bending loads. The impact load was modelled as a sine curve with various frequency, and also in the form of equivalent impulse. It is shown, that at the increase of the impact load frequency the response character remains unchanged, however, its amplitude decreases. The efficiency of DFE application in impact problems is shown by comparison with existing analytical solutions, as well as with the analysis results, obtained with usage of classical finite element with polynomial shape functions.

The article deals with the technical condition of glued wood building structures with steel elements, which are subjected aggressive impact. It is presented results of long-term observations over the technical condition and development dynamics of corrosion processes of building materials and structures. It is described the processes of chemical and electrochemical corrosion of the porous and solid materials, the effect of salt content on strength and durability of wood, the dynamics of the corrosion processes in steel structures. We present the forecast for the development of corrosion in steel elements of existing warehouses arched shape according to the results of observation of samples. Conclusions are made about the operational reliability of building structures and details of their pairing. The prospects are estimated for replacement of steel structures with composite materials, with comparable in the aggregate properties strength characteristics.