Model Test about Reflection Coefficient for Perforated Wall Caisson according to Perforated Wall Shapes: Single Chamber Open Slit Caisson

In this study, the hydraulic model tests for the single chamber perforated wall caisson were performed to investigate the reflection coefficients according to the slit shapes. The perforated wall with vertical and horizontal slits was applied to the tests. The random waves were used for the test by using Bretschneider-Mitsuyasu frequency spectrum. The similar reflection coefficients were measured in the vertical and horizontal slit caisson within a similar perforation ratio and area. The reflection coefficient according to relative slit length(S/Hs) was analyzed and the minimum reflection coefficients were measured in relatively small S/Hs (=2.7). The results from horizontal slits showed similar trends with those from the vertical slit perforated wall.

Calculation of the improved steel beams of buildings and structures of the mining and metallurgical complex

Load-bearing elements of buildings and structures of the mining and metallurgical complex in recent decades need to develop new more effective design solutions due to the intensification of technological processes, an increase in temperature loads and aggressiveness of the environment. The main direction of increasing the efficiency of such elements is their design from economically alloyed steel, which allows to increase the resource of structures and prevent accidents with a significant increase in temperature. Due to the fact that alloyed steels have higher mechanical characteristics at elevated temperatures, the question arises of creating lightweight beam structures from such steels, reducing their material consumption while maintaining the stability and fatigue strength of beams, the most promising is the use of welded beams with a perforated wall and composite beams. The creation of the most effective cross-sectional shape of metal beams with a perforated wall and welded beams, as well as crane beams in transverse bending, considering strength, local stability, flat bending stability and fatigue strength is considered. It is shown that an effective shape of beams with a perforated wall is a box-shaped structure made of perforated channels. A calculation was carried out to select a rational design made of an assortment of hot-rolled channel profiles. It is shown that due to the use of the proposed sectional shape, significant savings in the weight of the structure can be achieved. Considering the three-dimensional stress-strain state, the fatigue strength of welded metal crane girders operating in severe conditions is estimated. The efficiency of using a hot-rolled I-beam as the upper chord of such welded beams is shown. The necessity of using a hot-rolled I-beam and to ensure the fatigue strength of the lower chord is demonstrated. The use of the previously proposed combined method for calculating the structures of industrial buildings and structures and the use of economically alloyed steels allows us to create new designs of critical elements that reduce their material consumption and increase their resource. Further research can be carried out for real object designs in order to reduce their cost and increase reliability during operation in the conditions of mining and metallurgical production.

Beams with a perforated wall in large-span coatings of buildings

Описываются несущие стропильные конструкции покрытий и перекрытий стальных балок с перфорированной стенкой. Одним из основных способов повышения эффективности балочных конструкций является «роспуск» прокатных двутавров по различным траекториям реза стенки двутавра. По результатам «роспуска» двутавра образуются две гребёнки с формой таврового сечения, затем формируется двутавровое сечение большей высоты и последующая сварка гребёнок в единую конструкцию – двутавр с перфорированной стенкой. Высота сечения сквозного двутавра с перфорированной стенкой становится выше исходного двутавра в 1,2 – 1,6 раза, что позволяет существенно увеличить момент инерции и момент сопротивления относительно исходного профиля.