The article discusses the causes of discrepancies in the values of the pile load capacity based on the results of calculations made on the basis of existing regulations and the pile load capacity after static load test on the construction site. A brief overview of the causes of discrepancies in analytical and practical values of pile load capacity is provided in the article. The possible ways to solve this problem are suggested, namely, the development of the methods of analytical calculations of pile load capacity and the improvement of embedding technical processes. There is an example of such a discrepancy in the construction of a residential complex in Saint-Petersburg presented in the article. It was found that the variation in the results is not caused by the imperfections in the method of calculations, but by the infringements of construction technology. The article provides recommendations to minimize the discrepancies between the calculated and actual values of pile load capacity.
The structure of a mathematical algorithm and software for geometric and strength analyses, and the working diagram of multiple-pair meshing for GT are presented. Methods are considered for improving the reliability and quality of GT on the basis of multiple-pair meshing, which can be expanded to bevel GT with straight and spiral teeth, and cylindrical worm GT.Requirements are being raised for the strength and time-to-overhaul of gear trains (GT) in mechanical transmissions of chemical and oil-and-gas equipment. As a component part of power-generating sets, GT exert a major influence on their basic technico-economic indicators: mass, overall dimensions, time to overhaul, vibroacoustic activity, cost, etc. The cost of the GT may amount to 30% of the overall cost of the power-generating set. Enhancement of the reliability and quality of the GT, for example, their strength, is therefore a component part of the total problem of improving the reliability of the drive systems of any machine set.Basic causes of GT failures are: design errors, errors in fabrication and assembly, and violation of operating conditions. Traditional means of improving the reliability and quality of GT (an increase in dimensions, and improvement in fabrication precision, use of high-strength materials, surface hardening, etc.) have little effect in many cases, since they are associated with significant material outlays, and do not always lead to desirable results. A significant reduction in expenditures and, at the same time, improvement in quality indicators of the GT can be achieved by automating their design process. Computer technologies make it possible to shorten the time required for GT design, and essentially eliminate errors, as well as produce an optimal design in terms of strength conditions and time to overhaul, including designs based on new technical solutions.The following are basic attributes of the mathematical algorithm and software (MA and SW), which can be used, for example, for geometric and strength calculations of GT: a developed network of data bases; invariance with respect to parameters of the original profile; possibility of analyzing machined meshing and the fillet curve of the teeth, and also the stress-strain state of the teeth at all points of the profile; multicriterial optimization of transmission parameters; and communication between individual applied programs in a single processing network. Figure 1 shows the typical structure of the MA and SW employed for geometric and strength analyses of GT.It is expedient to execute the computer design of GT in both the package, and also dialogue modes. The package mode is used to determine parameters of the GT in first approximation. The dialogue mode makes it possible to optimize parameters of the GT in conformity with assigned reliability and quality criteria.Use of GT with multiple-pair meshing can be referred to as a new technical solution (Fig. 2). As a result of simultaneous contact between several pairs of gears (in contrast to standard GT with single-pair meshi...
The increase in the number of storeys is impossible without deviation from standard projects, where the structure of assemblies is not designed for buildings that have more than 12 storeys. That’s why it’s necessary to strengthen assemblies. For that purpose the testing of assemblies of the panel system, which is unique in modern textbooks on design, is performed. The paper presents the results of tests conducted at the plant ZHBI-Vostok of Chelyabinsk. The strength and stress-strain performance of an external horizontal assembly in two different versions (with slab-wall junction and without junction) is evaluated. As a result of experimental data processing, the effect of force eccentricity on the stress condition of assemblies is determined. This influence should be taken into consideration in case of hand calculations on assemblies. The axial and angular strain before the failure of assembly samples and the strength reserve of studied structures are specified.
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