Uporaba metode načrtovanja nosilnosti za jeklene konstrukcije daljnovodnih stebrov : diplomska naloga

Azinović, Boris (author), Dolšek, Matjaž (mentor)

V diplomski nalogi obravnavamo problematiko porušitev jeklenih paličnih daljnovodnih stebrov. Porušitev enega ali več zaporednih stebrov, lahko povzroči prekinitev prenosa električne energije. Posledično se zmanjšajo dohodki iz naslova prenosa energije, poleg tega so precejšnji tudi neposredni stroški zaradi vzpostavitve prvotnega stanja. V teoretičnem delu so na kratko predstavljeni najpogostejši vzroki porušitev in možne zaščite pred porušitvami stebrov zaradi pojava prekomerne dodatne obtežbe na vodnikih. V praktičnem delu diplomske naloge obravnavamo nosilni daljnovodni steber NC74 daljnovoda 2 × 110 kV, pri čemer projektne vplive na konstrukcijo definiramo po predpisih SIST EN 50341-1 ter na podlagi linearno-elastične analize preprojektiramo kritične elemente obstoječe konstrukcije. Sledi nelinearna statična analiza za obtežne kombinacije z žledom, ki so se izkazale za najbolj kritične pri projektiranju. Izkaže se, da so za daljnovodni steber značilne razmeroma majhne dodatne nosilnosti zaradi vpliva prerazporejanja obremenitve na nosilne elemente konstrukcije. Dodatna varnost proti porušitvi je zato v veliki meri posledica stopnje izkoriščenosti elementov pri projektiranju. V zadnjem delu diplomske naloge projektiramo daljnovodni steber po načelih metode načrtovanja nosilnosti. Z namenom, da bi preprečili globalno porušitev konstrukcije, varujemo diagonalne in vertikalne elemente, medtem ko za šibek člen, kjer dopustimo poškodbe, izberemo konzole stebra, na katere so obešeni vodniki daljnovoda. Oslabitev konzole smo dosegli z zmanjšanjem profila najbolj izkoriščenega elementa na konzoli, utrditev trupa stebra pa s povečanjem profilov za diagonalne in vertikalne elemente. Na ta način smo preprečili globalno porušitev konstrukcije, pri čemer se je masa konstrukcije povečala za približno 14%. Za aplikacijo metode v praksi bi bilo potrebno predhodno izvesti verjetnostno analizo pojava izrednih obtežb in stroškovno analizo, s katero bi ugotovili, ali je predlagan način projektiranja ekonomsko upravičen.

• Language: Slovenian
• Keywords: gradbeništvo, UNI, konstrukcijska smer, KS, daljnovodni stebri, porušitve, projektiranje, SIST EN 50341-1, potisna analiza, načrtovanje nosilnosti
• Work type: Undergraduate thesis
• Typology: 2.11 - Undergraduate Thesis
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: [B. Azinović]
• Year: 2012
• Number of pages: X, 72 str.
• PID: 20.500.12556/RUL-32639
• UDC: 006:621.315.1:624.07(043.2)
• COBISS.SI-ID: 5957217
• Publication date in RUL: 10.07.2015

Secondary language

• Language: English
• Title: Application of capacity design procedure for transmission towers

Abstract

The issues of collapse of steel-truss transmission towers are addressed in the thesis. The collapse of one or several consecutive towers causes loss of electricity supply. Consequently, a part of income from energy supply may be lost. In addition, collapse of tower cause high direct costs of restoration of transmission line. In the theoretical part of the thesis, the most frequent collapse patterns due to extreme action on conductors, as well as possible solutions for protection of the towers against collapse are presented. The practical part of the thesis, which addresses electric transmission tower NC74 of the 2 × 110 kV transmission line, involves definition of the design action according to standard EN 50341-1 and redesign of critical elements of the existing tower on the basis of linearelastic analysis. Follow nonlinear static analysis for sleet-based load cases, which represented the most critical action for design of the tower. The results of nonlinear static analysis indicated that overstrength due to redundancy of such towers is minor. The estimated overstrength of the tower is thus primarily consequence of the utilization rate of the structural elements in the design. In the last part of the thesis, capacity design procedure is applied to the transmission tower in order to prevent global collapse of structure. The diagonals and the vertical elements of the tower were protected against failure, whereas cantilevers of the tower were selected as week parts of the structure. In order to meet this requirement, the diagonals and vertical elements of the tower were strengthened, and the element of the cantilever, which had the largest utilization rate, was weakened by selecting smaller cross-section of the structural element of the cantilever. This design procedure prevents global collapse of structure for the price of increased mass of the structure, which was in this case approximately 14% larger than that in the case of conventional design. For the application of the proposed design approach in practice, a probabilistic analysis of the occurrence of the extreme actions and the cost-benefit analysis should be performed in order to prove or disprove the economic feasibility of the proposed design approach.