Potresno tveganje izbranih konstrukcijskih sistemov z upoštevanjem nezanesljivosti : doktorska disertacija

Celarec, Daniel (author), Dolšek, Matjaž (mentor)

V doktorski disertaciji smo razvili poenostavljeno verjetnostno metodo za oceno potresnega tveganja stavb z upoštevanjem vplivov fizikalnih in modelnih negotovosti ter staranja materiala. Predlagana metoda temelji na splošni analitični metodi za oceno potresnega tveganja, pri čemer se parametri potresnega odziva izračunajo z metodo N2, ki jo uporabimo na stohastičnem modelu. Pri primerih uporabe predlagane metode smo se omejili na armiranobetonske (AB) okvire in okvire s polnili, pri čemer smo raziskovali nezanesljivost določitve potresnega odziva konstrukcije. Prvi sklop ugotovitev se nanaša na rezultate občutljivostne analize. Rezultati kažejo, da imajo negotovosti modela za določitev rotacijske kapacitete stebrov in gred največji vpliv na potresni odziv AB okvirov, medtem ko imajo v primeru okvirov s polnili največji vpliv na potresni odziv mehanske lastnosti opečnih polnil. Drugi sklop ugotovitev se nanaša na rezultate študije vpliva fizikalnih in modelnih negotovosti na parametre potresnega odziva treh AB okvirov. Rezultati te študije kažejo, da fizikalne in modelne negotovosti ne vplivajo le na oceno razpršenosti temveč tudi na oceno mediane parametrov potresnega odziva. Skoraj v vseh primerih se je zaradi upoštevanja fizikalnih in modelnih negotovosti izkazalo, da je ocena mediane pomikov in pospeškov v mejnem stanju blizu porušitve nezanemarljivo manjša v primerjavi s tistimi vrednostmi, ki smo jih določili z običajno deterministično analizo. Dodatno negotovost predstavlja vpliv korozije. Na primeru izbranega AB okvira ter ob upoštevanju poenostavljenega modela korozije smo ugotovili, da korozija povzroči lokalno strižno porušitev izpostavljenih elementov, kar lahko znatno poveča potresno tveganje. Poseben primer negotovosti predstavljajo pomanjkljivosti poenostavljenih nelinearnih modelov. Te vplive smo preučevali na primeru okvira s polnili. Z uporabo predlaganega iterativnega postopka nelinearne statične analize smo pokazali, da potresno tveganje preveč podcenimo, če v nelinearni analizi ne simuliramo strižne porušitve stebrov in vpliva polnila na povečanje prečne sile v stebru.

• Language: Slovenian
• Keywords: gradbeništvo, disertacije, potresno tveganje, metodaN2, nelinearna statična analiza, parametri potresnega odziva, fizikalne negotovosti, modelne negotovosti, staranje materiala, korozija, kapaciteta konstrukcije, verjetnost prekoračitve mejnega stanje, armiranobetonske okvirne konstrukcije, armiranobetonske okvirne konstrukcije z opečnimi polnili
• Work type: Dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: [D. Celarec]
• Year: 2012
• Number of pages: XVI, 158 str., [69] str. pril.
• PID: 20.500.12556/RUL-32568
• UDC: 624.042.7:624.072.2:699.841(043.3)
• COBISS.SI-ID: 5802081
• Publication date in RUL: 10.07.2015

Secondary language

• Language: English
• Title: Seismic risk assessment of the selected structural systems with consideration of uncertainties

Abstract

A simplified method for the probabilistic seismic performance assessment of buildings with consideration of the effects of physical and modelling uncertainties, taking into account the ageing processes of structural materials, was developed. The proposed method utilizes a general analytical method for estimating the seismic risk, whereas the seismic response parameters are determined by using the N2 method, which is applied to the stochastic structural model. This method was used to study the effects of uncertainties on the seismic performance of reinforced concrete (RC) frames and frames with infills. The first part of the results relates to the sensitivity of the seismic response parameters. The results show that the seismic response of RC frames is most sensitive to the uncertainty associated with the model of the rotation capacities of the plastic hinges in the columns and beams, whereas in the case of the infilled frames, the mechanical characteristics of the infills are the parameters which have the greatest impact on the seismic response of such buildings. The second part of the results refers to the study of the effects of physical and modelling uncertainties on the seismic response parameters, as applied to three RC frames. The results of the study show that these uncertainties affect not only the dispersion, but also the median estimates of the response parameters. In almost all cases their influence contributed to a considerable reduction of the median displacement and the acceleration capacity if the latter are compared to those determined by conventional deterministic analysis. Additional uncertainty arises due to the effects of corrosion. In the case of the selected RC frame, where corrosion has been modelled with simplified models, it has been shown that such corrosion can lead to the shear failure of the exposed columns, which may considerably increase the seismic risk. A particular source of uncertainty is represented by simplified nonlinear models. By using the proposed iterative pushover-based procedure it has been shown that the seismic risk may be significantly underestimated if possible shear failures of the columns and the contribution of the masonry infill to the shear forces in the columns are not properly simulated in a nonlinear analysis.

• Keywords: doctoral thesis, seismic risk, N2 method, nonlinear static analysis, seimic response parameters, physical uncertainties, modelling uncertainties, ageing of material, corrosion, structural capacity, probability of exceeding limit state, reinforced concrete frame structures, reinforced concrete frame structures with masonry infills