Optimalno dimenzioniranje osno-upogibno obremenjenega armirano betonskega nosilca : diplomska naloga

Bulić, Nenad (author), Saje, Drago (mentor)

V diplomski nalogi sem predstavil postopek dimenzioniranja armirano betonskega nosilca. Odpornost betonskega prereza je odvisna od geometrije prereza, vrste betona in količine armature. V praksi pogosto določene parametre vnaprej izberemo in na njihovi osnovi določimo ostale karakteristike. Ta način projektiranja omogoča hitro reševanje problema, ne zagotavlja pa optimalne cene. Če bi želeli poiskati najcenejšo možnost, bi morali za vsak trdnostni razred betona, pri različnih geometrijskih karakteristikah, izračunati potrebno količino armature in med dobljenimi rezultati poiskati najcenejšo možnost. Postopek računanja je obsežen, ker je potrebno narediti veliko ponovitev. V sklopu svoje diplomske naloge sem izdelal aplikacijo v programskem okolju Excel, ki vsebuje modul Solver – Reševalec, s katerim lahko v množici armiranobetonskih prečnih prerezov poiščemo najcenejši element. Uporabnik poda trdnostne razrede betona in cene materialov ter omeji geometrijske lastnosti. Na podlagi izbranih parametrov program poišče najcenejšo rešitev. Rezultati programa so trdnostni razred betona in geometrijske lastnosti prereza: višina, širina, količina armature. V diplomski nalogi nisem upošteval cene opaža pri optimalnem dimenzioniranju elementa. Omejil sem se na osno-upogibno obremenjen element. Statični model je prostoležeči nosilec. Program je možno nadgraditi za druge modele konstrukcij. Upoštevati moramo predpostavko, da upogibni moment prevladuje in imamo veliko ekscentričnost. Na podlagi obremenitev določimo le vzdolžno armaturo, ne pa tudi strižne. Prerez dimenzioniramo po standardu Evrokod 2. Upoštevajoč navedeni standard, dokazujemo nosilnost prereza v mejnem stanju nosilnosti in mejnem stanju uporabnosti. Na podlagi izvedenih primerov sem ugotovil, da je za prostoležeče nosilce, katerih prečni prerezi so obremenjeni z velikimi upogibnimi momenti, najboljša rešitev uporaba betonov trdnostnih razredov med C40 in C50.

• Language: Slovenian
• Keywords: diplomska naloga, gradbeništvo, betonski nosilec, pravokotni prerez, dimenzioniranje, mejno stanje nosilnosti, mejno stanje uporabnosti
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: [B. Nenad]
• Year: 2015
• Number of pages: VII, 34 str., [3] str. pril.
• PID: 20.500.12556/RUL-72799
• COBISS.SI-ID: 7209569
• Publication date in RUL: 01.10.2015

BULIĆ, Nenad, 2015, Optimalno dimenzioniranje osno-upogibno obremenjenega armirano betonskega nosilca : diplomska naloga [online]. Bachelor’s thesis. Ljubljana : B. Nenad. [Accessed 22 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=72799

Secondary language

• Language: English
• Title: Optimal Design of Reinforced Concrete Beam with respect to bending moment and axial force

Abstract

The thesis paper describes the procedure of designing reinforced concrete sections. Cross section resistance depends on the number of reinforced bars, section dimensions and concrete strength. Usually we choose the type of concrete, the geometry of the section and then determine the number of reinforced bars. This is the fastest way of designing, but not the cheapest. In order to look for the most economical solution, it is necessary to calculate all the parameters for all types of concretes. This way is more complicated and requires more time. Part of my graduation thesis is in Excel, which has an integrated solver application. With this add-in we can find the best solution with less difficulty. Users enter the types of concrete and their prices, limit values of the geometry parameters and loads. Using nonlinear functions to solve equations, solver gives results for every type of concrete, and the number of reinforced bars and section dimensions. The static model is a simply supported beam. It is possible to modify the program for different types of constructions. The beam is loaded with an axial force and bending moment. The assumption is: the bending moment is significantly larger than the axial force. This state of stress causes large eccentricity. The computer program calculates only longitudinal reinforcement, but not the shear reinforcement. The design procedure is explained in the standard Eurocode 2. It is required to check the ultimate and serviceability limit state. Based on the obtained results, the conclusion is that for construction loaded with a large bending moment and a small axial force, the most economical concrete is between C40 and C50.

• Keywords: graduation thesis, civil engineering, concrete beam, rectangual cross-section, desin, ultimate limit state, serviceability limit state