Numerical model for static and dynamic analysis of masonry structures

Ukratko je opisana problematika proračuna zidanih konstrukcija. Razrađen je model za statički i dinamički proračun raznih tipova zidanih konstrukcija. Modelirani su najvažniji nelinearni efekti ponašanja takvih konstrukcija, pri čemu su uključeni različiti aspekti materijalne nelinearnosti, kontaktni problemi i geometrijska nelinearnost. Prikazana je mogućnost simulacije interakcije tlo-konstrukcija. Na tri riješena primjera pokazane su neke mogućnosti primjene opisanog modela.Problems encountered during analysis of masonry structures are briefly presented. A model for the static and dynamic analysis of various types of masonry structures is presented. Most significant nonlinear effects of behaviour exhibited by such structures are modelled, which includes various aspects of material nonlinearity, contact problems, and geometrical nonlinearity. The possibility of simulating the soil-structure interaction is presented. Some possible applications of the described model are shown on three solved examples

Experimental Testing and Numerical Modeling of Masonry-Infilled Concrete and Steel Frames under Static and Dynamic Loads : Doctoral Thesis

U ovom su radu prikazani rezultati eksperimentalnih ispitivanja čeličnih i armirano-betonskih okvira sa zidanom ispunom. Eksperimentalni rad obuhvaća statička ispitivanja čeličnih okvira te dinamička ispitivanja čeličnih i betonskih okvira na potresnoj platformi. Aplicirana su dva umjetna akcelerograma i akcelerogram realnog potresa. Pobude su nanošene sukcesivno, s postepenim povećanjem amplituda akcelerograma za 0.1 g. Nadalje, u radu je prikazan razvijeni 2D numerički model za statičku i dinamičku analizu armirano-betonskih i čeličnih okvira sa zidanom ispunom koji može simulirati njihove najvažnije nelinearne efekte. U ovom je radu numerički model poboljšan s adekvatnom simulacijom faznog nastajanja okvira s ispunom te simulacijom nearmirane i armirane žbuke na vanjskim plohama ziđa. Razvijeni numerički model verificiran je pomoću rezultata prethodno provedenih eksperimenata. Primjenom ovog numeričkog modela, istražen je utjecaj više parametara na ponašanje okvira s ispunom. Na kraju su prikazani najvažniji zaključci o ponašanju ovakvih konstrukcija pod statičkim i potresnim opterećenjem te dani praktični savjeti i preporuke za njihov pouzdani proračun.This Thesis presents the results of experimental tests of masonry-infilled concrete and steel frames. The experimental work concerns static tests of masonry-infilled steel frames and dynamic tests of masonry-infilled steel and concrete frames on a shake table. Two artificial accelerograms and one real accelerogram were applied. The accelerograms were applied successively, by gradually increasing acceleration amplitudes for 0.1 g. Further, the Thesis presents a developed 2D numerical model for static and dynamic analysis of masonry-infilled concrete and steel frames that can simulate their main nonlinear effects. In this paper, the numerical model was improved with adequate simulation of structural formation and with simulation of reinforced and unreinforced plaster on exterior sides of a wall. The developed numerical model was verified using the results of the previous performed tests. The influence of several parameters on the behavior of masonry-infilled frames was investigated with the numerical model. Finally, main conclusions regarding behavior of these structures under static and dynamic loads are stated, followed by practical advises and recommendations for their reliable design

Experimental Testing of the Effects of Fine Particles on the Properties of the Self-Compacting Lightweight Concrete

The self-compacting lightweight concrete (SCLC) is a combination of the Self compacting concrete (SCC) and the Lightweight concrete. It combines all the good properties of those two materials and is extremely convenient for the construction of buildings that require low mass and do not require high compressive strength, for example restoration works in old structures (e.g., replacement of wooden floors), prefabricated elements that require transportation, and for structures and elements where the concrete surface should be visible. In this paper the effect of the amount of fine particles on the properties of the self-compacting lightweight concrete (SCLC) in the fresh and hardened state was explored. For this purpose, sets of specimens with different combinations of admixtures of silica fume, fly ash, and filler were prepared and tested. Slump flow and flow time of fresh concrete, as well as the dynamic elastic modulus and compressive strength of hardened concrete, were measured at different ages of concrete. The processes of manufacturing and methods of testing are described, as well as the obtained results

Effect of the Drum Height on the Seismic Behaviour of a Free-Standing Multidrum Column

The results of a shake-table study on the effect of the drum height on the seismic behaviour and bearing capacity of small-scale free-standing multidrum columns are presented. Columns of equal height with one, three, and six drums through their height were considered for the case of their self-weight only and for the case with an additional weight on the top of the column. The columns were exposed to a horizontal base acceleration of three accelerograms by successively increasing the maximum acceleration to their failure. The characteristic displacements and accelerations of the column were measured. It was concluded that an increase in the number of blocks in the column can significantly increase or decrease its ultimate bearing capacity, depending on the type of the applied accelerogram. It is expected that the experimental database can be useful in the validation of nonlinear numerical models for the dynamic analysis of multidrum columns

Mw 6.4 Petrinja earthquake in Croatia: Main earthquake parameters, impact on buildings and recommendation for their structural strengthening

Razorni potres Petrinja (opći pojam za potrese na Banovini) od 29.12.2020. magnitude Mw 6.4 oduzeo je 7 ljudskih života i prouzročio katastrofalne štete na području Banovine. U radu su prikazani i analizirani najvažniji parametri potresa te naglašena njihova važnost u razumijevanju nastalih oštećenja i rušenja građevina te oblikovanju optimalne konstrukcije za njihovu obnovu. Dan je doprinos u razumijevanju složenog mehanizma nastanka potresa preko analize naponsko-deformacijskog stanja u stijenskom masivu tijekom međudjelovanja tektonskih ploča. Uzroci rušenja i oštećenja zgrada objašnjeni su kombiniranim utjecajem svojstava njihove konstrukcije, tla i samog potresa. Predložena su rješenja optimalne konstrukcije novih zgrada, kao i rješenja konstrukcijskog ojačanja oštećenih zgrada.Strong Mw 6.4 Petrinja earthquake from 29.12.2020. took 7 lives and caused catastrophic damage in the Banovina area. The paper presents and analyses the most important earthquake parameters and highlights their importance in understanding the damage and demolition of buildings, as well as creating an optimal structure for their reconstruction. A contribution is made to the understanding of the complex mechanism of earthquake formation through the analysis of the stress-strain state in a rock mass during tectonic plate conflict. The causes of demolition and damage to buildings are explained by the combination of the properties of their structure, soil and the earthquake itself. Solutions for optimal structure of new buildings, as well as solutions for structural renovation of damaged buildings are proposed and described