Vol 17, No 3 (2021)

The economically effective method for determining the unknown parameters of the dependence of the durability of structural materials on the level of acting constant stresses in them and their absolute temperature for various structural materials is proposed, taking into account the data established by Academician of the USSR Academy of Sciences S.N. Zhurkov. It does not require long-term testing of materials, but is based on the use of the results of short-term standard machine failure of two groups of standard samples of materials at two significantly different temperatures. When using these parameters and the Bailey integral criterion for summing up the losses in the durability of materials, it is possible to calculate the endurance of elements of road bridge structures from any structural materials and to determine the residual durability resource of the structure under the predicted subsequent mode of loading it with real temporary vertical loads.

Over the past 20 years, rolled compacted concrete (RCC) dams have continued to be built in many countries because of their technical and economic advantages over conventional dams of vibrating concrete and embankment dams. The aim of this study is the development of new structural and technological solutions in RCC dams in order to reduce the consumption of cement and expand their use on non-rock foundations, which will allow them to successfully compete with concrete face rockfill dams. The numerical analyses of static and seismic stress-strain state (SST) of gravitational dams in roller compacted very lean concrete dams have been made, as well as their stability, strength and cost have been assessed. For rock and dense sandy-gravel foundations the most economical is the concrete face rockfill dam and symmetrical RCC dam of very lean concrete with bases (0.5-0.7) of both slopes and outer zones of conventional concrete and central zone of rockfill strengthened by cement-ash mortar. Taking into account that the cost of diversion and spillway tunnels for very lean RCC dam will be less and the construction period - shorter than for the concrete face rockfill dam, it can be concluded that variant of symmetrical RCC dam of very lean concrete is the technically and economically effective. Symmetrical RCC dams of very lean concrete with 1V/(0.5-0.7)H slopes have more seismic resistance and technical and economic efficiency as compared with conventional gravitational RCC dams and other types of dams. These dams up to 200 m high can be built on rock foundations and up to 100 m high - on dense sandy gravel foundations.

This paper content is structure subjected sudden story drift as a result from earthquakes, forming hinges and eventually collapsing. The aim of this paper is to develop building thirty story building for seismic in Khartoum using finite element method (FEM) and the equivalent lateral force (ELF) procedure of American code ASCE 7-16. In current work the thirty-story reinforced concrete building was considered is to analyze the seismic behavior of the reinforced concrete structure to find the drift between the story by finding the maximum displacement from the program that causes the building to collapse, by choosing the shear wall as the support system to resist the lateral load and by looking to model the building inclined to the horizontal plane. Calculations were also made on the drift between the story to compare with the allowable drift. It is implemented in the Robot structural program - an ingenious program for designing and analyzing lateral (seismic) loads.

Bearing units of lifting machines, products of construction, road, aviation, space and other branches of technology are very important structural elements, since the failure of even one bearing can cause the failure of the entire product. The results of experimental verification of the theoretical model of bearing operation under combined loading conditions are presented. The behavior under load of bearing units in the most general case can be represented by a sequence of five design schemes, expressed in the form of five statically indeterminate beams. The purpose of the experiments was to test this model under real loading conditions. The experiments were based on the analysis of the geometric shape of the curved elastic line, which the shaft of the bearing assembly acquires under load. The experimental results confirmed the validity of the model and showed that the previously generally accepted model of a two-support beam is not implemented. The conclusion is confirmed that in responsible lifting machines, as well as in responsible products of construction, road, aviation, space and other branches of technology, it is impractical to calculate bearings according to the traditional method, since an erroneous value of bearing durability can be obtained, overestimated from 28.37 to 26.663.9 times.

In concrete mixing plan, we usually encounter a combination of aggregates including sand, the amount of cement, which is actually the criterion of concrete grade, and the volume of water consumed. Changes in the quality and quantity of these components actually create the usual types of concrete. But the attitude that formed the basis of this research is based on the change in the nature of the components of the concrete mixing design. Removal of water and cement from the mixing plan and replacement of polymeric materials as well as the use of mixed LECA aggregates instead of aggregates is the basis of this research. In this paper, by examining and selecting LECA grain style and pre-treatment (hydrophobicity and coupling), in a constant ratio of resin, concrete samples were selected from three dimensional categories. After making the samples, flexural strength test was performed on them and the results were analyzed. Various compounds and processes have so far been proposed in the lightweight concrete mixing scheme. The distinctive point of this study is the use of lightweight expanded clay concrete with heat-treated acrylic polymer (crosslinking constituents) and related coupling agents. It is also important to select and apply the right amount of hydrophobic nanoparticles for hydrophilic surface hydrophobicity. Hydrophobicity was possible due to the non-polar nature of the acrylic polymer and the use of hydrophobic nanomaterials.