UK: Обгрунтувано розрахункові параметри у формулі прямого методу підбору площі центрово–стиснутих стальних стрижнів. Із використанням цього методу на прикладі розрахунку панелі верхнього поясу крокв’яних ферм при розрахунковій довжині = 3 м і повздовжніх зусиллях N = 200…2000 кН показано переваги квадратних труб порівняно з парними кутиками, ефективність сталей підвищеної міцності, доцільність використання кутиків із великою тонкостінністю.
EN: Relevance. Weight (or area) of the steel elements of constructs is the main criterion for substantiation of the design decision.
Essence of the problem and substantiation of the design decision. Analysis of constrictive solutions of centrally–compressed elements fulfilled by using the method of direct selection of cross–sectional area with correction of the known formula for longitudinal bending coefficient calculation. Approved that for flexibility λ = 10…115 and steel C245…C375 the corrected formula of longitudinal bending coefficient is sufficient accuracy within the limits from λ = 25 to λ = 85…105 for steel C245…C375. Bu using the analysis of assortment of stiffeners and square tubes fulfilled approximate formulas for the specific radius of gyration calculation.
Research objective. By using the formula of the direct method for selecting the area of the centrally–compressed steel rods fulfilled the analysis of the advantages of square tubes in comparison to coupled stiffeners, the steels of additional strength have been provided efficient as well as the usage of the stiffeners with the high degree of wall thinness. Calculation were made for the centrally–compressed steel rods under computation length = 3 m and elongated efforts N = 200…2000 kN, appropriate diagrams were shown.
Conclusion. By using the practice of the direct method for selecting the area the fulfilled calculation gave an opportunity to make such point as:
- The advantages of square tubes in comparison to coupled stiffeners depend on elongated efforts N and increasing by amount of efforts decreasing, for example, under the efforts 200 kN the cross–sectional area of coupled stiffeners increases by 60…80 %;
- The steels of additional strength have to be used under elongated efforts N more than 1000 kN;
- The influence of the wall thinness parameter on the stiffeners can be significant under the elongated efforts less than 1000 kN.
