doctoral thesis
Influence of openings on the seismic response of reinforced concrete frames with masonry infill

Davorin Penava (2012)
Josip Juraj Strossmayer University of Osijek
Faculty of Civil Engineering
Metadata
TitleUtjecaj otvora na seizmički odgovor armirano-betonskih okvira sa zidanim ispunom
AuthorDavorin Penava
Mentor(s)Vladimir Sigmund
Abstract
Okviri s ispunom su kompozitne konstrukcije koje se sastoje od okvira (armirano-betonski ili čelični) i ispune za koju se u Hrvatskoj uobičajeno rabe blok opeke ili čak betonski blokovi. Sličan konstruktivni sistem čine i zidovi s vertikalnim i horizontalnim serklažima uz razliku što se kod okvira s ispunom se prvo naprave okviri, a tek se onda zida ispun, a kod zidova s serklažima se prvo sazidaju zidovi, a onda se izvode serklaži (okviri). Ispuna bitno mijenja odgovor konstrukcije na potres i njen se utjecaj mora na odgovarajući način uzeti u proračun. Dosadašnji propisi ne sadrže pojašnjenja o tome kako se i na koji način to čini. Uz vrlo detaljan prikaz proračuna okvira i drugih uobičajenih armirano-betonskih konstrukcija i suvremene metode proračuna na raspolaganju projektantima, nedostatak pojašnjenja za okvire s ispunom se može pripisati nedovoljnom razumijevanju njihova utjecaja kao i velikom broju nejasnoća uključenih u modeliranje djelovanja ispune. Iskustva iz prijašnjih potresa su pokazala i povoljna i nepovoljna ponašanja konstrukcija okvira s ispunom. Međutim suvremeni propisi su uglavnom orijentirani na nepovoljna djelovanja odakle rezultiraju predimenzionirane i neekonomične konstrukcije. Interakcija između nearmirane ispune i okvira može dovesti do neuobičajenih ponašanja okvira bilo lokalno (efekt kratkog stupa, posmični slom čvora) ili globalno (nastanak meke etaže). Zbog svoje složenosti, pozitivna i negativna djelovanja ispune još uvijek predstavljaju kontroverznu temu na kojoj treba poraditi, a poseban su problem okviri s ispunom s otvorima. Disertacija detaljnije istražuje utjecaj otvora u zidanom ispunu pomoću ispitivanja modela i numeričkih istraživanja. Eksperimentalni dio disertacije se sastoji iz provedenih ispitivanja na modelima jedno-katnih i jedno-rasponskih okvira sa zidanim ispunom izloženih djelovanju konstantnog vertikalnog i promjenjivog horizontalnog opterećenja. Program ispitivanja uključivao je deset jednakih uzoraka modela armirano-betonskih okvira, sa i bez otvora u zidanom ispunu. Okviri su bili dimenzionirani prema europskim normama bez uzimanja u obzir efekta ispuna. Nakon njihova betoniranja, oni su bili ispunjeni sa zidanim ispunom jednakih materijalnih svojstava, ali različitog smještaja, vrste i izmjera otvora te sa ili bez izvedbe vertikalnog serklaža oko otvora. Izvedba uzoraka, provedba ispitivanja i dobiveni rezultati povećali su razumijevanje ponašanja ovakvih konstrukcija. Obzirom na nužnu ograničenost eksperimentalnog ispitivanja te neophodnost generalizacije zaključaka, eksperimentalni rezultati su nadopunjeni s numeričkima primjenom nelinearne metode konačnih elemenata primjenjene u programu ATENA ver. 4.3. Radi pouzdanosti numeričkih rezultata, isti su prvo kalibrirana na izmjerenim vrijednostima, a zatim su takovi kalibrirani modeli iskorišteni za proširivanje opsega istraživanja. Numerička analiza je obuhvatila otvore drugih izmjera i smještaja, druge izmjere i vrste materijala ispuna te količine poprečne armature okvira. Na osnovi takove proširene slike ponašanja, dobiveni su parametri utjecaja zidanog ispuna s otvorima i bez njih na armirano-betonski okvir. Razumijevanje mehanizma i slijeda gubitka nosivosti, pomoći će u praktičnom uzimanju u obzir utjecaja zidanog ispuna s otvorima. To u konačnici omogućava primjenu okvira sa zidanom ispunom s i bez otvora, kao konstruktivnog elementa, što će rezultirati u većoj ekonomičnosti i pouzdanosti u procjeni ponašanja armirano-betonskih okvira s ispunom na djelovanje potresa.
Keywordsinfilled reinforced-concrete frame masonry infill opening seismic response
Parallel title (English)Influence of openings on the seismic response of reinforced concrete frames with masonry infill
Committee MembersIvica Guljaš (committee chairperson)
Ivica Kožar (committee member)
Vladimir Sigmund (committee member)
GranterJosip Juraj Strossmayer University of Osijek
Faculty of Civil Engineering
PlaceOsijek
StateCroatia
Scientific field, discipline, subdisciplineTECHNICAL SCIENCES
Civil Engineering
Supporting Structures
UDK624/625
APPLIED SCIENCES. MEDICINE. TECHNOLOGY
Civil and structural engineering. Civil engineering of land transport. Railway engineering. Highway engineering
Study programme typeuniversity
Study levelpostgraduate
Study programmePostgraduate university study program in civil engineering
Academic title abbreviationdr. sc.
Genredoctoral thesis
Language Croatian
Defense date2012-08-29
Parallel abstract (English)
Infilled frames are composite structures that consist of a frame (reinforced concrete or steel) and infill for which is the clay or even concrete block commonly used in Croatia. A similar structural system called confined masonry consists of the masonry walls with vertical and horizontal confining elements. In infilled frame systems the infill is built after frame is hardened. As opposed to the infilled frame system, in the case of confined masonry, the masonry walls are built first and then confining elements around them. Infill significantly alters the structural response under earthquake load and its influence must be taken into account. Current regulations do not provide explanations about it and how it should be calculated. With a very detailed explanation of frames and other common reinforced concrete structures and modern regulations available to designers, the lack of explanation on the infilled frames can be attributed to insufficient understanding of their influence as well as to a number of uncertainties involved in infill modeling. The experiences from past earthquakes have shown the favorable and unfavorable behavior of infilled frame structures. However, modern regulations are mainly oriented to the adverse effects, which results with oversized and uneconomical design. The interaction between unreinforced infill and the frame can lead to unusual behavior of the latter whether locally (the effect of short columns, node shear failure) or globally (the occurrence of soft floors). Because of its complexity, the positive and negative effects of the infill are still the controversial topic that requires serious attention. Special problem are infilled frames with openings. The dissertation further investigates the influence of openings in the masonry infill using experiments tests and numerical studies. The experimental part of the dissertation consists of tests performed on models of single-storey single-span frame with masonry infill when subjected to constant vertical and horizontal cyclic loads. The program tests involved ten equal specimens of reinforced concrete frame models, with or without openings in the masonry infill. The frames were designed according to European standards, without taking into account the effect of the infill. After their casting they were filled with masonry infill of equal material properties, but with different position, types and opening dimensions, with or without the performance of the vertical confinement around the opening. Performance of specimens, experiments and test results obtained have increased the understanding of the behavior of such structures. Given the necessary limitations of the experimental tests and the necessity of generalization of the conclusions, the experimental results are supplemented with numerical studies, through nonlinear finite element method applied in ATENA ver. 4.3. For the reliability of numerical results, they were first calibrated with the experiments, and then such calibrated models were used to expand the scope of research. Numerical analysis included the openings of other dimensions and position, other dimensions and types of infill material and the amount of transverse reinforcement of the frame. Concluding the results of the overall picture of behavior, influence parameters were obtained for masonry infill with and without openings on the reinforced concrete frame. Understanding of the mechanism and the sequence of the failure will help to take into account the influence of masonry infill with openings in the practice. This eventually enables the use of frame with a masonry infill, with and without opening, as structural element, which will result in greater efficiency and reliability in assessing the its behavior in case of seismic action
Parallel keywords (Croatian)armirano-betonski okvir s ispunom zidani ispun otvor seizmički odgovor
ExtentXXXVI, 309 str. : graf. i tabelarni prikazi : ilustr. (djelomice u bojama) ; 30 cm
Versionaccepted version
Resource typetext
Access conditionOpen access
Terms of usehttp://rightsstatements.org/vocab/InC/1.0/
Noteaccepted version
URN:NBNhttps://urn.nsk.hr/urn:nbn:hr:133:214229
CommitterVesna Zobundžija