Title Analiza pouzdanosti geotehničkih konstrukcija Title (english) The reliability analysis of geotechnical structures Author Antonio Jaguljnjak Mentor Krešo Ivandić (mentor)Committee member Sanja Kovač (predsjednik povjerenstva)Committee member Krešo Ivandić (član povjerenstva)Committee member Stjepan Strelec (član povjerenstva)Committee member Jasmin Jug (član povjerenstva)Granter University of Zagreb Defense date and country 2022-07-14, Croatia Scientific / art field, TECHNICAL SCIENCES Abstract U radu je dan prikaz metoda pouzdanosti koje se u inženjerstvu koriste za procjenu
pouzdanosti konstrukcija, te njihova primjena na nekoliko geotehničkih problema. U
prvom dijelu rada dan je osvrt na varijabilnost tla, koja je jedan od glavnih uzroka
neizvjesnosti u geotehničkim analizama. U analizama pouzdanosti, geotehnički parametri
tretiraju se kao slučajne varijable, što zahtijeva poznavanje podataka o njihovim
statističkim značajkama. Na taj su način uzete u obzir neizvjesnosti koje proizlaze iz
različitih izvora, kao npr. prirodna varijabilnost tla, pogreške transformacijskih modela i
slično. Za većinu geotehničkih parametara u literaturi dostupni su podaci o njihovim
statističkim razdiobama, tipičnim srednjim vrijednostima i koeficijentima varijacije, što
omogućuje provedbu analiza pouzdanosti u slučaju nedovoljnog broja podataka iz
rezultata istražnih radova.
Pitanje varijabilnosti tla i njenog utjecaja na rezultate geotehničkih analiza prepoznato je
i u normi Eurokod, stoga je u radu dan osvrt na navedeno. Opisan je pojam indeksa
pouzdanosti, koji se koristi kao mjera pouzdanosti konstrukcija. Uz to, njegova primjena
moguća je i za kalibraciju parcijalnih faktora djelovanja, materijala i otpornosti
propisanih u normi Eurokod.
U radu su opisane i primijenjene dvije metode pouzdanosti, analitička metoda FORM i
simulacijska metoda Monte Carlo. Provedeno je niz analiza pouzdanosti s varijacijama
geometrijskih karakteristika i koeficijenata varijacije dominantnih geotehničkih
parametara. Za odabrane geotehničke probleme analizirana je konvergencija metode
Monte Carlo, pogreška metode FORM i utjecaj koeficijenta varijacije na veličinu indeksa
pouzdanosti. Sve analize u ovom diplomskom radu provedene su korištenjem
programskog jezika Python i knjižnice otvorenog koda Pystra. Pokazano je da u svim
razmatranim primjerima metoda FORM ima zadovoljavajuću točnost, te da koeficijent
varijacije ima značajan utjecaj na indeks pouzdanosti, radi čega je potrebno obratiti
posebnu pozornost prilikom utvrđivanja njegove vrijednosti.
Abstract (english) The master thesis presents reliability methods which are used in engineering to assess the
reliability of structures, and their application to several geotechnical problems. The first
part of the paper reviews soil variability, which is one of the main causes of uncertainty
in geotechnical analyses. In reliability analyses, geotechnical parameters are treated as
random variables, which requires knowledge of data on their statistical characteristics. In
this way, uncertainties arising from different sources are taken into account, such as
natural soil variability, errors of transformation models and the like. For most
geotechnical parameters in the literature, data on their statistical distributions, typical
means and coefficients of variation are available, which allows the implementation of
reliability analyses in case of insufficient data from the results of research.
The issue of soil variability and its impact on the results of geotechnical analyzes is also
recognized in the Eurocode standard, so the paper gives an overview of that.. The notion
of reliability index, which is used as a measure of structural reliability, is described. In
addition, its application is possible for the calibration of partial factors of action, materials
and resistance prescribed in the Eurocode standard.
Two reliability methods are described and applied in the paper, the FORM analytical
method and the Monte Carlo simulation method. A series of reliability analyses with
variations of geometric characteristics and coefficients of variation of dominant
geotechnical parameters were performed. For selected geotechnical problems, the
convergence of the Monte Carlo method, the error of the FORM method, and the
influence of the coefficient of variation on the magnitude of the reliability index were
analysed. All the analyses which are presented in the thesis were conducted by using the
Python programming language and the Pystra open source library. It can be concluded
that in all considered examples the FORM method had satisfactory accuracy, and that the
coefficient of variation had a significant impact on the reliability index, which is why it
is necessary to pay special attention when determining its value.
Keywords
analiza pouzdanosti
indeks pouzdanosti
vjerojatnost pojave sloma
Keywords (english)
reliability analysis
reliability index
probability of failure
Language croatian URN:NBN urn:nbn:hr:130:242922 Study programme Title: Geoenvironmental Engineering; specializations in: Geoenvironmental Engineering, Environmental Management, Water Management Type of resource Text File origin Born digital Access conditions Open access Terms of use Created on 2023-01-19 10:10:45
