The influence of nonlinear seismic response of structures on the floor acceleration spectra : doctoral dissertation

Vukobratović, Vladimir (author), Fajfar, Peter (mentor)

V disertaciji so obravnavani etažni spektri pospeškov, ki so pomembni za potresno projektiranje in ocenjevanje opreme, občutljive na pospeške. Razvita je razmeroma enostavna za prakso uporabna metoda za določanje etažnih spektrov pospeškov iz spektrov tal. Upoštevano je bilo elastično in neelastično obnašanje konstrukcije. Obsežne parametrične študije so bile izvedene za modele konstrukcije z eno (SDOF) in več prostostnimi (MDOF) stopnjami. S časovno analizo odziva (RHA) je bilo izračunano veliko število etažnih spektrov pospeškov. V primeru SDOF konstrukcij sta bili uporabljeni dve neodvisni skupini akcelerogramov, v primeru MDOF konstrukcij pa je bila upoštevana le ena od teh skupin. Raziskovani so bili vplivi tipa, nihajnega časa, histereznega obnašanja in duktilnosti primarne konstrukcije, in vpliv dušenja opreme. Za SDOF konstrukcije je bil raziskan tudi vpliv karakteristik vhodnih akcelerogramov. Dobljeni rezultati so potrdili dejstvo, da neelastično obnašanje primarne konstrukcije lahko pomembno zmanjša etažne spektre pospeškov, zlasti njihove maksimalne vrednosti. Metoda za direktno določanje etažnih spektrov je bila najprej razvita za SDOF konstrukcije in potrjena s primerjavo njenih rezultatov z etažnimi spektri, dobljenimi z RHA. Opaženo je bilo dobro ujemanje rezultatov, dobljenih za elastično in neelastično obnašanje konstrukcije. Metoda je bila razširjena na MDOF konstrukcije in povezana z nelinearno N2 metodo, ki temelji na potisni analizi. V primeru elastičnih konstrukcij daje metoda etažne spektre pospeškov, ki se zelo dobro ujemajo z rezultati, dobljenimi z RHA. V primeru neelastičnih konstrukcij je v splošnem mogoče doseči zadovoljivo natančnost.

• Language: English
• Keywords: civil engineering, thesys, floor response spectra, direct method, parametric study, response-history analysis, primary structure, secondary structure, equipment, inelastic behaviour, ductility, peak floor acceleration
• Work type: Dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: [V. Vukobratović]
• Year: 2015
• Number of pages: XXVII, 208, XXXIV str.
• PID: 20.500.12556/RUL-71916
• UDC: 624.012.45:624.042.7(043)
• COBISS.SI-ID: 7080033
• Publication date in RUL: 10.08.2015

VUKOBRATOVIĆ, Vladimir, 2015, The influence of nonlinear seismic response of structures on the floor acceleration spectra : doctoral dissertation [online]. Doctoral dissertation. Ljubljana : V. Vukobratović. [Accessed 15 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=71916

Secondary language

• Language: Slovenian
• Title: Vpliv nelinearnega potresnega odziva konstrukcij na etažne spektre pospeškov

Abstract

Floor acceleration spectra, which are important for seismic design and assessment of accelerationsensitive equipment, were studied in the dissertation. A relatively simple practice-oriented method for the determination of floor acceleration spectra directly from the ground motion spectra was developed. Elastic and inelastic structural behaviour was taken into account. Extensive parametric studies were performed on single- (SDOF) and multi-degree-of-freedom (MDOF) structures and a large number of floor acceleration (response) spectra were calculated by using the response-history analysis (RHA). In the case of SDOF structures two different sets of ground records were used, whereas in the case of MDOF structures only one of these sets was considered. The influences of the type, natural period, hysteretic behaviour, and ductility of the primary structure, as well as the influence of the equipment damping, were studied. Additionally, in the case of SDOF structures, the influence of input ground motion characteristics was also investigated. The obtained results confirmed the fact that inelastic behaviour of the primary structure can significantly reduce floor acceleration spectra, especially their peak values. The method for direct determination of floor response spectra was firstly developed for SDOF structures and it was validated by comparing its results with the floor response spectra obtained from the RHA. A good agreement between the results obtained for both elastic and inelastic structural behaviour was observed. The method was extended to MDOF structures and it was coupled with the nonlinear pushover-based N2 method. In the case of elastic structures the method provides floor response spectra which are in very good agreement with the results obtained from the RHA. In the case of inelastic structures, in general, a satisfactory accuracy can be achieved.

• Keywords: gradbeništvo, disertacije, etažni spektri odziva, direktna metoda, parametrična študija, časovna analiza odziva, primarna konstrukcija, sekundarna konstrukcija, oprema, neelastično obnašanje, duktilnost, maksimalni etažni pospešek