doktorska disertacija
Blaž Zoubek (Author), Tatjana Isaković (Mentor), Boštjan Brank (Commission member), Mehmed Čaušević (Thesis defence commission member), Matjaž Mikoš (Thesis defence commission member), Matej Fischinger (Thesis defence commission member), Peter Fajfar (Thesis defence commission member)

Abstract

V disertaciji je predstavljena obsežna eksperimentalna in analitična študija vpliva stikov na potresni odziv armiranobetonskih montažnih konstrukcij. Raziskave so bile izvedene v okviru dveh evropskih projektov: SAFECAST in SAFECLADDING. Disertacija obravnavana dve pomembni skupini stikov, in sicer stike med stebri in gredami ter stike med armiranobetonskimi fasadnimi deli in konstrukcijo. Za obe skupini stikov so bili najprej opravljeni ciklični preizkusi. Ob podpori eksperimentalnih rezultatov ter podrobnih 3D-numeričnih analiz so bili nato pojasnjeni porušni mehanizmi stikov. Na podlagi novega znanja so bili določeni računsko manj zahtevni in robustni inženirski modeli. Ti upoštevajo nekatere ključne karakteristike cikličnega odziva obravnavanih vrst stikov, ki jim v okviru preteklih raziskav ni bilo posvečeno dovolj pozornosti. V modelih mozničnih stikov med stebri in gredami sta tako zajeta vpliva stremen ter velikih relativnih rotacij med stebrom in gredo na nosilnost stika, kar je tudi eden izmed bistvenih prispevkov disertacije. Da bi ovrednotili vpliv stikov na potresni odziv celotnih konstrukcij, je bila izvedena tudi obširna parametrična študija ranljivosti in potresnega tveganja enoetažnih in trietažnih armiranobetonskih montažnih stavb, situiranih v Ljubljani, pri čimer so bili uporabljeni na novo definirani inženirski modeli stikov. Ugotovljeno je bilo, da lahko napačno ocenjena nosilnost mozničnih stikov med stebri in gredami močno ogrozi varnost obravnavanih konstrukcij, saj je njihova zmožnost sipanja potresne energije s plastičnim deformiranjem relativno majhna. Pri stikih med fasadnimi paneli in konstrukcijo se je izkazalo, da je verjetnost porušitve obstoječih objektov v primeru uporabe vertikalnih panelov relativno visoka (2–30 % v petdesetih letih), v primeru horizontalnih panelov pa občutno nižja (1,0–5,5 % oziroma 0,1–1,3 %, odvisno od tipa uporabljenih stikov). V zadnjem delu disertacije so na podlagi novih ugotovitev oblikovani ustrezni napotki za pravilno načrtovanje mozničnih stikov med stebri in gredami ter stikov med fasadnimi paneli in konstrukcijo. Moznični stiki bi morali biti načrtovani po metodi načrtovanja nosilnosti, za to pa je nujna dovolj natančna ocena nosilnosti, kar omogočajo zaključeni izrazi, predlagani v tem delu disertacije. Podane so tudi potrebne kontrole, s katerimi preverimo ustreznost stikov med fasadnimi paneli in konstrukcijo. Če te ne moremo dokazati, lahko panele varujemo s pomočjo pridrževalcev. Zasnova, preizkušanje in ocena potrebne nosilnosti tovrstnega sistema so predstavljeni v zadnjem poglavju disertacije.

Keywords

Grajeno okolje;gradbeništvo;disertacije;montažne armiranobetonske stavbe;stiki med stebri in nosilci;moznični mehanizem;model nadomestnega paličja;fasadni paneli;pridrževalci;potresni odziv;

Data

Language: Slovenian
Year of publishing:
Typology: 2.08 - Doctoral Dissertation
Organization: UL FGG - Faculty of Civil and Geodetic Engineering
Publisher: [B. Zoubek]
UDC: 62-112.6:624.012.45:624.04.550.34(043)
COBISS: 7295329 Link will open in a new window
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Other data

Secondary language: English
Secondary title: Influence of connections on the seismic response of precast reinforced concrete structures
Secondary abstract: The dissertation describes the results of an extensive experimental and analytical investigation into the effect of connections on the seismic response of precast concrete buildings, which was performed within the framework of the two European projects: SAFECAST and SAFECLADDING. The investigation was concerned with two important groups of connections, i.e. those between columns and beams, and those between the cladding panels and the main structure. Cyclic tests were first performed on specimens from both groups of connections, after which the failure mechanisms, based on the obtained experimental results, and making use of detailed 3D numerical analyses, were explained. A number of robust engineering models were developed, which take into account some of the key characteristics of the cyclic response of connections of the investigated types. In the case of dowel connections, the effect, on the load-carrying capacity of the connection, of stirrups, as well as of the large relative rotations between columns and beams, was investigated. This represents one of the main contributions of the dissertation. In order to evaluate the effect of connections on the seismic response of whole buildings, an extensive parametric study was then performed, which examined the fragility and seismic risk of typical singlestorey and three-storey precast buildings located in Ljubljana. It was found that if the load-carrying capacity of the dowel connections was inaccurately assessed, then the safety of such structures could be seriously affected, since the ability of connections of this type to dissipate seismic energy by means of plastic deformation is relatively low. In the case of the connections between the cladding panels and the main structure, it was shown that the probability of failure was, in the case when vertical panels are used, relatively high (between 2.0 and 30% over a period of 50 years), whereas in the case of horizontal panels it was significantly less (between 1.0 and 5.5%, or between 0.1 and 1.3%, depending on the type of connections used). Based on the new findings, guidelines were prepared for the design of beam-column dowel connections, and connections between cladding panels and the main structure. Dowel connections have to be designed according to the capacity design method, for which their load-carrying capacity needs to be accurately estimated. In this part of the dissertation some expressions for the calculation of this capacity are proposed. Methods which can be used to verify the adequacy of connections between facade panels and the main structure are also given. If the performance of such verification methods is infeasible, then second-line back-up devices, i.e. restrainers, need to be installed. The design, testing, and evaluation of the necessary load-carrying capacity of such systems are presented in the final chapter.
Secondary keywords: Built Environment;civil engineering;doctoral thesis;precast reinforced concrete structures;beam-column connections;dowel mechanism;strut and tie model;cladding panels;restrainers;seismic response;
URN: URN:NBN:SI
File type: application/pdf
Type (COBISS): Doctoral dissertation
Thesis comment: Univ. v Ljubljani, Fak. za gradbeništvo in geodezijo
Pages: XXX, 231 str., [62] str. pril.
ID: 9077179