Oyposhsha B. Sabirova
Oyposhsha B. Sabirova

Сабирова Ойпошша Бахтияровна Oyposhsha B. Sabirova
engineer, Emperor Alexander I St. Petersburg state transport university, "Industrial and civil construction" department. Russian Federation, St. Petersburg


Publications

Pneumatic protection of water towers
Issue: #1-2023
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The paper discusses the effectiveness of using pneumatic protection to reduce seismic loads on a water tower. The tower carries a reservoir with a capacity of 30 m3. Air tanks, used as pneumatic protection, are placed along the reservoir perimeter in the zone of maximum hydrodynamic pressure. The volume of air was accepted according to the recommendations of O.A. Savinov and M.M. Peychev and is equal to 4 m3. The analysis of the hydrodynamic equations makes it possible to divide the liquid in the reservoir into two parts. One part is rigidly connected to the reservoir (attached mass of liquid), and the second part is connected with the tank by a spring simulating an air shock absorber. In the performed calculations, the added mass was 14 tons. The effect of the seismic load decrease was less than expected. This is due to the fact that the structure of the tower itself is quite heavy, and the load from its own weight is approximately equal to the load caused by the weight of the liquid. Therefore, doubling the liquid load reduces the total load by only 25%.

Purpose: To increase the seismic resistance of water towers by applying pneumatic protection. Traditionally, the seismic resistance of water towers is provided by a constructive solution of the tower shaft; in this case, increasing the seismic resistance of already operated towers is problematic. In this regard, the task was set to change the dynamic characteristics of the structure through the use of pneumatic protection directly in the reservoir of the structure.

Methods: The article discusses the constructive solution of internal pneumatic protection and the method of calculating water towers with its application to seismic loads, and evaluates the effectiveness of this type of seismic protection. A numerical calculation of the volumes of pneumatic protection and numerical values of the parameters of the calculation-dynamic model of the design of a water tower with internal pneumatic protection in relation to the A.A. Rozhnovsky. Calculations for seismic impact have been performed and forces in the structural elements of a water tower without pneumatic protection and with its installation have been determined.

Results: A comparative analysis of the oscillations of a water tower without pneumatic protection and with it was carried out. The results show that in the presence of pneumatic protection, the dynamic characteristics of the system change, which leads to a decrease in seismic loads and a significant decrease in the forces in the design of the water tower, including in the shaft.

Practical significance: The device of internal pneumatic protection will ensure seismic resistance, including operated water towers in those areas where the seismicity of the construction site has been increased due to the revision of general seismic zoning maps. Internal pneumoprotection makes it possible not to provide for additional insulation of pneumoprotective installations, since they are located inside the tank. In addition, this solution facilitates the operation of a water tower equipped with pneumatic protection, since the structural elements of the device are protected from external influences.

Estimating Combination Coefficients of Seismic and Ice Loads
Issue: №1 2019
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Abstract: Combination coefficients of ice and seismic loads for earthquakes of different frequencies have been considered. As the density function of the ice load distribution, the Weibull law, supplemented by a delta function at the origin was used, which allowed us to take into account the absence of ice in the warm season. The interval between earthquakes was taken according to the Poisson law. It has been shown that the magnitude of the design loads significantly depends on the frequency of earthquakes, and the combination coefficients are practically independent. Combination coefficients determine equally probable pairs of actions, which in their term determine the dependence of the combination coefficient to ice loads on the combination coefficient to seismic ones.
An example of calculations for the region respectively with situational seismicity of 9, 10 and 10, using maps A, B and C of general seismic zoning maps of the territory of Russia is given

The Combination Coefficients of Seismic and Wind Loads
Issue: №6 2018
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The combination coefficients of seismic and wind loads for multilevel designing buildings and structures in high seismic regions are considered. For design and maximum design earthquakes equiprobable pairs of seismic and wind loads are determined.  Correspondingly, these pairs are iven coupling coefficients for the loads under consideration, which determine the dependence of one combination coefficient on the other. In constructing the equiprobable pairs, the wind load is described by Weibull law and seismic load is described by Poisson’s law. It is shown that for the seventh wind zone with high seismic intensity in calculating structures under the action of the esign earthquake, the combination coefficients are close to 1, and in calculating structures under the action of the maximum design earthquake they are less than 1, and therefore it becomes necessary to choose the most dangerous pair of seismic and wind loads.

Multi-level designing structures in tsunami-prone areas
Issue:
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The paper proposes a two-level approach to the calculation of structures for the tsunami effect. The concept of the design tsunami and the maximum design tsunami and their corresponding limit states is introduced. The estimated loads on the bridge piers from the design and maximum design tsunami are estimated, depending on the territory danger and the bridge responsibility. At the same time, bridges, in accordance with the approach adopted in transport construction, are divided according to their degree of responsibility into four categories. A formula is obtained to estimate the design splash value for the design and maximum design tsunami, depending on the bridge category. In addition, graphs are provided showing the frequency of the tsunami and the calculated wave height corresponding to this frequency. To estimate the combination coefficient of wind and tsunami loads, their equally probable pairs are considered. At the same time, the Weibull distribution is used to set the wind load, and for the tsunami load, the distribution given in the Code of Rules for Ensuring Tsunami Safety is used. Taking into account such load pairs is relevant for bridges with high piers, when the height of the splash does not exceed the pier height and there is a high probability of a simultaneous combination of wind and tsunami loads. The paper presents the calculations of surges for two types of tsunamis: the design one with a repeatability of once in 50 years and the maximum design one with a repeatability of once in 500 years for the Kamchatka region and the Kuril Islands for bridges of the first and second categories. Studies show that for the design tsunami and the maximum design tsunami, the coefficients of combinations with wind load differ significantly.