Title The effect of some parameters on behaviour and bearing capacity of multi-drum stone columns under static load and earthquake : dissertation Title (croatian) Utjecaj nekih parametara na ponašanje i graničnu nosivost višedijelnih kamenih stupova pri statičkom opterećenju i potresu : disertacija Author Ante Buzov Mentor Jure Radnić (mentor)Mentor Nikola Grgić (komentor)Committee member Alen Harapin (predsjednik povjerenstva)Committee member Mladen Glibić (član povjerenstva)305482260 Committee member Goran Baloević (član povjerenstva)Granter University of Split Defense date and country 2019-03-15, Croatia Scientific / art field, TECHNICAL SCIENCES Universal decimal classificationUDC ) 624/625 - Civil and structural engineering. Civil engineering of land transport. Railway engineering. Highway engineering Abstract In this thesis, the effect of several important parameters on the behaviour and bearing capacity of multi-drum stone columns loaded by short-term static loads and earthquakes was investigated. These parameters have not been investigated to date or have been investigated only sporadically. All of the experiments were conducted on smallscale column models using modern equipment for testing and measuring. Dynamic testing of the models was performed using an established earthquake platform. The
... More effects of the column block number and joint type were investigated, as well as several parameters for the bolts used in the column joints (material, length, bolt diameter and the diameter of the bolt hole). Static tests were conducted separately for centric compressive loads and for bending loads with longitudinal compression. During the dynamic tests, the samples were exposed to the acceleration of three different earthquake types with a successive increase in acceleration to failure. During the action of all loads, the characteristic displacements, accelerations and strains of the model were recorded. The motion of the model was recorded with a precision camera. The aim of this research was to contribute to the development of science in the subject area, which has been accomplished through the publication of five scientific papers in relevant worldwide journals. The purpose of this research is to provide conclusions regarding the investigated effects of important multi-drum stone column parameters, and the results should find practical application in the restoration/strengthening of existing multi-drum stone columns and the creation of new multi-drum stone columns. The most important conclusions of the research are listed below. Increasing the number of blocks (joints) in the multi-drum column reduces the column’s stiffness and increases its deformability. The consequence of this is a significant reduction in the column’s bearing capacity for static loads, as well as for longer duration earthquakes, which entered great energy in the construction. For impact-type earthquakes, increasing the number of blocks in a column can result in a greater bearing capacity because the column stiffness is reduced, and smaller earthquake forces are generated in the column. Soft joints (dry, joints made from stone powder and weaker mortar), compared to rigid joints and single-block column, result in a softer column with a lower bearing capacity for static loads and long lasting earthquakes with greater generated energy. However, for impact-type earthquakes, column with soft joints can have a greater bearing capacity than columns with rigid joints or single-block columns. Bolts in multi-drum stone columns significantly contribute to their bearing capacity during earthquakes. The bolt material has no major impact on the column bearing capacity during earthquakes if the column collapse is predominantly followed by bending and less by shear, i.e., if the failure is caused by the bolts pulling out and not by shear failure. The diameter of the bolt has no major effect on the column bearing capacity when it is loaded with smaller transverse forces. In that case, a thick bolt can be unfavourable for some earthquakes, as a thick bolt increases the stiffness of the column, and pull on it larger earthquake forces. In this case, the column failure is followed by the bolt pulling out but not by its failure. When the column is subjected to large shear with respect to bending, increasing the bolt diameter increases the column capacity. The bolt length does not have a greater effect on the column bearing capacity when the bolt has no adhesion with the block, i.e., when the bolt cannot withstand tensile forces. Increasing the bolt hole diameter in relation to the bolt diameter and having a bolt that cannot withstand tensile forces decreases the column bearing capacity during an earthquake. With the same maximum amplitude, the type of earthquake (duration and predominant period) has a considerable effect on all column parameters considered in this research. Therefore, in practice, it is crucial to know what type of earthquake can be expected at the considered location. Less Abstract (croatian) U okviru teme ove doktorske disertacije, istražen je utjecaj nekoliko važnih parametara na ponašanje i nosivost višedijelnih kamenih stupova opterećenih kratkotrajnim statičkim opterećenjima i potresom, a koja do sada nisu bila istraživana ili su istraživana samo sporadično. Sva istraživanja su provedena eksperimentalno na umanjenim modelima stupova, koristeći suvremenu opremu za ispitivanja i mjerenja. Dinamička ispitivanja modela su provedena pomoću provjerene potresne platforme. Između
... More ostalog, istražen je utjecaj broja blokova i tipa sljubnica u stupu, te više parametara trnova u sljubnicama stupa (materijal, dužina i promjer trna, te promjer rupe za trn). Statička ispitivanja su provedena zasebno za centrično tlačno opterećenje i zasebno za savijanje s uzdužnom tlačnom silom. Kod dinamičkih testova, uzorci su bili izloženi ubrzanju triju različitih tipova potresa, sa sukcesivnim povećanjem ubrzanja do njihova sloma. Pri djelovanju svih opterećenja, praćeni su karakteristični pomaci, ubrzanja i deformacije modela, te snimano gibanje modela preciznom kamerom. Cilj istraživanja je doprinos razvoju znanosti u predmetnom području, koji je ostvaren objavom pet znanstvenih radova u relevantnim svjetskim časopisima. Svrha istraživanja je donošenje zaključaka u pogledu istraženih utjecaja razmatranih važnih parametara višedijelnog kamenog stupa, koji bi trebali naći svoju primjenu u obnovi/ojačanju postojećih i izradi novih višedijelnih kamenih stupova u praksi. Najvažniji zaključci istraživanja su niže navedeni. S povećanjem broja blokova (sljubnica) u višedijelnom stupu, smanjuje se njegova krutost i povećava njegova deformabilnost. Posljedica toga je značajno smanjenje njegove nosivosti za statička opterećenja, kao i za potrese dužeg trajanja koji unose veliku energiju u konstrukciju. Za potrese kratkog udarnog djelovanja, povećanje broja blokova u stupu može rezultirati njegovom većom nosivosti jer se smanjenjem krutosti stupa u njemu generiraju manje potresne sile. Meke sljubnice (suha, od kamenog brašna i slabijeg morta), u odnosu na krute sljubnice i stup iz jednog bloka, također rezultiraju mekšim stupom i njegovom značajno manjom nosivosti za statička opterećenja i potrese dugog trajanja s većom generiranom energijom. Međutim, za potrese kratkog udarnog djelovanja, stup s mekom sljubnicom može imati veću nosivost nego stup s krutim sljubnicama ili iz jednog bloka po visini. Trnovi u sljubnicama višedijelnog kamenog stupa značajno doprinose njegovoj nosivosti pri potresu. Vrsta materijala za trn nema većeg utjecaja na nosivost stupa pri potresu ako je slom praćen dominantno savijanjem i manje posmikom, tj. ukoliko dolazi do čupanja trnova a ne do njihovog posmičnog popuštanja. Promjer trna nema većeg utjecaja na nosivost stupa za slučajeve kada je opterećen manjim poprečnim silama. U tom slučaju debeli trn može biti nepovoljan za neke potrese jer se njime povećava krutost stupa i na njega navlače veće potresne sile, a pri tome je slom stupa praćen izvlačenjem trna a ne njegovim posmičnim otkazivanjem. Kada je stup opterećen velikim utjecajem posmika u odnosu na savijanje, povećanje promjera trna će rezultirati većom nosivosti stupa. Dužina trna nema većeg utjecaja na nosivost stupa u slučaju kada on nema prionjivost s blokom, tj. kada ne može nositi vlačne sile. S povećanjem promjera rupe za trn u odnosu na promjer trna i kada trn ne može nositi vlak, smanjuje se nosivost stupa pri potresu. Uz istu maksimalnu amplitudu, tip potresa (trajanje i predominantni period) ima vrlo veliki utjecaj na sve razmatrane parametre u ovom istraživanju. Zato je u praksi krucijalno znati kakvi se tipovi potresa mogu očekivati na razmatranoj lokaciji. Less Keywords
multi-drum stone columns
experiment
block height
joint type
bolt parameters
bearing capacity
static load
earthquake
Keywords (croatian)
višedijelni kameni stupovi
eksperiment
visina bloka
tip sljubnice
parametri trna
nosivost
statičko opterećenje
potres
Language english DOI https://doi.org/10.31534/DocT.048.BuzA URN:NBN urn:nbn:hr:123:957042 Study programme Title: Civil Engineering Catalog URL https://library.foi.hr/lib/knjiga.php?B=422&H=&E=&V=&lok=&zbi=&item=14234 Type of resource Text Extent 1 sv. (razl. pag.) : ilustr. u bojama, graf. prikazi ; 30 cm File origin Born digital Access conditions Open access Terms of use Created on 2019-03-26 10:45:21
