Izbira akcelerogramov za projektiranje stavb

doktorska disertacija

Marko Brozovič (Author), Matjaž Dolšek (Mentor), Matjaž Mikoš (Thesis defence commission member), Peter Fajfar (Thesis defence commission member), Iztok Peruš (Thesis defence commission member), Vojko Kilar (Thesis defence commission member)

Abstract

Keywords

Grajeno okolje;gradbeništvo;disertacije;potresno inženirstvo;gradbene konstrukcije;

Data

Language:	Slovenian
Year of publishing:	2013
Source:	Ljubljana
Typology:	2.08 - Doctoral Dissertation
Organization:	UL FGG - Faculty of Civil and Geodetic Engineering
Publisher:	[M. Brozovič]
UDC:	624.042.7:624.072.23:699.841(043.3)
COBISS:	6452833
Views:	2253
Downloads:	551
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	Earthquake ground motion selection for the design of buildings
Secondary abstract:	The selection of ground motions has an influence on the parameters of seismic demand as well as on the computational time of nonlinear dynamic analysis. A two-stage procedure for the selection of ground motions is therefore proposed. In the first step, a larger set of ground motions is selected which is consistent with the seismic hazard at a given location. In the case if ground motions are selected to match a target spectrum, the conditional spectrum approach is used, which requires some additional work, but provides a less conservative seismic demand in comparison to that based on the more frequently used uniform hazard spectrum. The second step of the ground motion selection procedure is intended for the reduction of the computational time for analysis, while ensuring sufficient accuracy of the results, and for decision-making about the sufficient seismic safety of buildings against collapse. In this second step the suitability of the ground motion selection procedure depends on the accuracy of the used simplified nonlinear procedure, which is not computationally demanding. It is shown that the existing simplified procedures of seismic response analysis are not sufficiently accurate for the definition of seismic demand in the case of some buildings and ground motions. For this reason a new simplified procedure, called the envelope-based pushover analysis procedure, has been developed. The advantage of this procedure is that it can take into consideration the different system failure modes which can occur in buildings due to different ground motions. In addition to some other procedures, the use of the envelope-based pushover analysis procedure to establish a precedence list of ground motions in progressive incremental dynamic analysis is proposed. In this way, progressive incremental dynamic analysis, which makes possible the calculation of fractile curves of response parameterized versus intensity level by utilizing smaller subsets of records from the beginning of the precedence list, is extended to cases of buildings where consideration of only the fundamental mode shape or associated system failure mode does not provide sufficiently accurate results. Furthermore, a procedure is proposed which makes possible a rapid estimation of the safety against seismic collapse by using a small number of ground motions. This procedure significantly reduces the computational time, and provides an adequate level of accuracy of seismic risk estimation, which is needed in the case of an iterative design process of buildings towards the target risk by means of nonlinear dynamic analysis.
Secondary keywords:	Built Environment;civil engineering;doctoral thesis;earthquake engineering;structural engineering;
URN:	URN:NBN:SI
File type:	application/pdf
Type (COBISS):	Doctoral dissertation
Thesis comment:	Univ. v Ljubljani, Fak. za gradbeništvo in geodezijo
Pages:	XXVI, 154 str., [76 str.] pril.
Type (ePrints):	thesis
Title (ePrints):	Earthquake ground motion selection for the design of buildings
Keywords (ePrints):	Izbira akcelerogramov;analiza potresne nevarnosti;pogojni spekter;potisna analiza;EPA;progresivna inkrementalna dinamična analiza;potresno tveganje;okvirne AB stavbe
Keywords (ePrints, secondary language):	Ground motion record selection;seismic hazard analysis;conditional spectrum;pushover analysis;EPA;progressive incremental dynamic analysis;seismic risk;RC frame buildings
Abstract (ePrints):	Z izborom akcelerogramov, ki v primeru nelinearne dinamične analize določajo potresno obtežbo, vplivamo na zanesljivost parametrov potresnih zahtev in tudi na računski čas analize. Zaradi tega v disertaciji predlagamo razdelitev postopka izbiranja akcelerogramov na dva koraka. V prvem koraku zagotovimo zanesljivost rezultatov, saj izberemo večjo skupino akcelerogramov v skladu s potresno nevarnostjo, na kateri je lociran objekt. Če izbiramo akcelerograme na osnovi ciljnega spektra, uporabimo metodologijo pogojnega spektra pospeškov, ki sicer zahteva nekoliko več dela, vendar določa manj konservativne potresne zahteve, kot tiste na osnovi spektra enotne potresne nevarnosti. Drugi korak dvostopenjskega postopka izbora akcelerogramov je namenjen zmanjšanju računskega časa analize ob zagotavljanju zadovoljive natančnosti in oceni ustreznosti potresne varnosti stavb. Primernost izbora akcelerogramov je v drugem koraku odvisna od natančnosti poenostavljenih in računsko nezahtevnih postopkov analize potresnega odziva. Manjšo podskupino akcelerogramov namreč izberemo glede na približne potresne zahteve, ki jih določajo posamezni akcelerogrami. Pokazali smo, da z obravnavanimi obstoječimi poenostavljenimi postopki analize ni mogoče dovolj natančno določiti parametrov potresnih zahtev v nekaterih primerih stavb in akcelerogramov. Zato smo razvili nov poenostavljen postopek analize potresnega odziva, ki omogoča upoštevanje vpliva tvorjenja različnih plastičnih mehanizmov zaradi potresne obtežbe. V nadaljevanju smo poleg drugih načinov predlagali uporabo novega poenostavljenega postopka analize potresnega odziva za določitev prednostne liste akcelerogramov v progresivni inkrementalni dinamični analizi. Ta omogoča izračun kvantilnih krivulj, ki določajo odvisnost potresnih zahtev od intenzitete, z upoštevanjem manjše podskupine akcelerogramov z začetka prednostne liste. S tem smo progresivno inkrementalno dinamično analizo razširili na primere, kjer upoštevanje zgolj osnovne nihajne oblike oz. pripadajočega plastičnega mehanizma ne zagotavlja dovolj natančnih rezultatov. Poleg tega smo predlagali postopek, s katerim dobimo majhno število akcelerogramov, ki jih lahko uporabimo za hitro oceno varnosti stavb pred porušitvijo. S tem postopkom bistveno zmanjšamo računski čas in zagotovimo primerno stopnjo natančnosti ocene potresnega tveganja, kar je pogoj za iterativni postopek projektiranja stavb na ciljno tveganje z uporabo nelinearne dinamične analize.
Abstract (ePrints, secondary language):	The selection of ground motions has an influence on the parameters of seismic demand as well as on the computational time of nonlinear dynamic analysis. A two-stage procedure for the selection of ground motions is therefore proposed. In the first step, a larger set of ground motions is selected which is consistent with the seismic hazard at a given location. In the case if ground motions are selected to match a target spectrum, the conditional spectrum approach is used, which requires some additional work, but provides a less conservative seismic demand in comparison to that based on the more frequently used uniform hazard spectrum. The second step of the ground motion selection procedure is intended for the reduction of the computational time for analysis, while ensuring sufficient accuracy of the results, and for decision-making about the sufficient seismic safety of buildings against collapse. In this second step the suitability of the ground motion selection procedure depends on the accuracy of the used simplified nonlinear procedure, which is not computationally demanding. It is shown that the existing simplified procedures of seismic response analysis are not sufficiently accurate for the definition of seismic demand in the case of some buildings and ground motions. For this reason a new simplified procedure, called the envelope-based pushover analysis procedure, has been developed. The advantage of this procedure is that it can take into consideration the different system failure modes which can occur in buildings due to different ground motions. In addition to some other procedures, the use of the envelope-based pushover analysis procedure to establish a precedence list of ground motions in progressive incremental dynamic analysis is proposed. In this way, progressive incremental dynamic analysis, which makes possible the calculation of fractile curves of response parameterized versus intensity level by utilizing smaller subsets of records from the beginning of the precedence list, is extended to cases of buildings where consideration of only the fundamental mode shape or associated system failure mode does not provide sufficiently accurate results. Furthermore, a procedure is proposed which makes possible a rapid estimation of the safety against seismic collapse by using a small number of ground motions. This procedure significantly reduces the computational time, and provides an adequate level of accuracy of seismic risk estimation, which is needed in the case of an iterative design process of buildings towards the target risk by means of nonlinear dynamic analysis.
Keywords (ePrints, secondary language):	Ground motion record selection;seismic hazard analysis;conditional spectrum;pushover analysis;EPA;progressive incremental dynamic analysis;seismic risk;RC frame buildings
ID:	8313086