Dynamic fracture of concrete compact tension specimen: Experimental and numerical study

AbstractCompared to quasi-static loading concrete loaded by higher loading rates acts in a different way. There is an influence of strain-rate and inertia on resistance, failure mode and crack pattern. With increase of loading rate failure mode changes from mode-I to mixed mode. Moreover, theoretical and numerical investigations indicate that after the crack reaches critical velocity there is progressive increase of resistance and crack branching. These phenomena have recently been demonstrated and discussed by Ožbolt et al. (2011) on numerical study of compact tension specimen (CTS) loaded by different loading rates. The aim of the present paper is to experimentally verify the results obtained numerically. Therefore, the tests and additional numerical studies on CTS are carried out. The experiments fully confirm the results of numerical prediction discussed in Ožbolt et al. (2011). The same as in the numerical study it is shown that for strain rates lower than approximately 50/s the structural response is controlled by the rate dependent constitutive law, however, for higher strain rates crack branching and progressive increase of resistance is observed. This is attributed to structural inertia and not the rate dependent strength of concrete. Maximum crack velocity of approximately 800m/s is measured before initiation of crack branching. The comparison between numerical and experimental results shows that relatively simple modeling approach based on continuum mechanics, rate dependent microplane model and standard finite elements is capable to realistically predict complex phenomena related to dynamic fracture of concrete

Evaluation of Implementation of LIADO Program for Artistically Gifted Students of Elementary School

Ovim se radom nastojala evaluirati provedba LIADO programa za likovno darovite osnovnoškolce u gradu Rijeci s ciljem utvrđivanja stupnja uspješnosti ispunjavanja njegove svrhe, ciljeva i zadataka, kao i ispitati učeničku i nastavničku perspektivu njegova provođenja. Istraživanje je provedeno koristeći kvantitativnu i kvalitativnu metodologiju. Rezultati kvantitativnog djela istraživanja pokazuju kako su učenici u velikoj većini zadovoljni kvalitetom sadržaja koju nudi LIADO, dok su isto tako izrazili natprosječnu motivaciju za rad unutar istog. Pokazalo se kako učenici iskazuju visoki stupanj osvještenosti za očuvanje kulturne baštine na području Grada Rijeke te kako su zainteresirani za sudjelovanje u tom istom procesu. Rezultati kvalitativnog djela istraživanja pokazuju kako su sudionice istraživanja, mentorice u LIADO programu, detaljno upoznate sa sadržajem programa te kako je razgovor najčešća metoda rada koju koriste pri poučavanju. Utvrdilo se, kako program nudi dosta slobode prilikom provođenja radionica prilikom čega kompetentnost mentora dolazi do izražaja. Najveći izazov sudionice istraživanja vide u kvaliteti suradnje sa vanjskim dionicima koji pomažu u održavanju LIADO-a (Grad Rijeka, OŠ „San Nicolo“). Iz analize prikupljenih podataka proizlaze tri preporuke. Prve dvije preporuke odnose se na povećanje stupnja i kvalitete suradnje između Grada Rijeke te OŠ „San Nicolo“ sa dionicima LIADO-a kako bi se omogućio čim kvalitetniji razvoj njegovih polaznika. Treća preporuka predstavlja poziv stručnjacima u području darovitosti za provođenjem većeg broja evluacijskih istraživanja ove vrste s ciljem poboljšanja postojećih te efikasnijeg planiranja i osmišljavanja novih programa za ovu skupinu učenika.The aim of this paper was to evaluate the implementation of LIADO program for artstically gifted students of elementary school in Rijeka with the aim of identifying the degree of the realization of its purpose, aims and tasks, as well ass to explore student's and teacher's perspective of its implementation. The study was carried out using the mixed-method methodology. The results of the quantitative part of the study have shown that the students are in the vast majority satisfied with the quality of the LIADO's content while simulatenously showing above average motivation to work in it. The results have shown that the students have shown above average degree of awareness for the preservation of cultural heritage of city of Rijeka as well as intention to act in order to perserve its cultural value. The results of the qulatitative part of the study have shown that the research participants are entirely familiar with the program's content as well as claiming that dialouge is the teaching method that they use the most. Furthermore, the program offers a lot of freedom when it comes to class planning and organizing during which the competence of the teachers can be seen. Research participants claim that the biggest challenge of LIADO is the quality of cooperation between them and subjects that help in supporting of LIADO (the City of Rijeka, OŠ „San Nicolo“). Three reccommendations have emerged from the analysis of collected dana. The first two reccommendations refer to the improvment of the quality of cooperation between the City of Rijeka and OŠ „San Nicolo“ with the subjects of the LIADO program in order to ensure the best development of the students. Third reccommendation respresents an appeal to the experts in the field of giftedness to carry out more evaluation studies of this kind with the aim of improving the quality of existing programs as well ass more efficient planning and designing new ones for this particular group of students

Design of a Load Carrying Structure of a Dwelling-House

The following work presents static calculation of a dwelling-house in accordance with the applicable standards from the Eurocode family. The structure has the following plan view dimensions: 14 x 14m, and it comprises basement, ground floor, and attic. It has reinforced- concrete strip foundations, the walls are made out of bricks, and together with vertical beams represent confined masonry. The floor structure between the basement and the ground floor is a reinforced-concrete plate, and one way concrete hollow-clay-tile floor system is located between the ground floor and the attic. Roof construction consists of two inferior and two middle purlins, and two inferior purlins and a ridge beam on the part, which is perpendicular to the main axsis of the roof. Rafters are inter-connected with collar ties, ridge ends are concluded with “čopi”, and the roof angle is 38°. The house is located in the Notranjska region, 300 meters above the sea-level. The majority of the thesis studies the course of forces along the construction and the selection of calculation models of individual sets.

Educational Guidance of Gifted Children

Cilj rada bio je dati doprinos postojećim radovima na temu darovitosti kroz kratki pregled povijesti fenomena, stanja u obrazovanju darovitih u svijetu i u Hrvatskoj te način programiranja sadržaja za tu skupinu učenika. Pružanje podrške darovitima već je drugo predmet rasprava stručnjaka na području odgoja i obrazovanja. Mediji često donose priče o djeci izuzetnih sposobnosti, međutim stvarnost je da su njihove potrebe još uvijek u velikoj većini zanemarene te je potrebno posvetiti veću pozornost osiguravanju istih. U radu su navedene sve bitnije karakteristike darovite djece te uloga školske kulture kao i samih nastavnika u njihovom obrazovanju. U skladu s time, ukratko je analizirano stanje u kojem se obrazovanje darovitih danas u Hrvatskoj, ali i u drugim zemljama svijeta. U sklopu navedene tematike, opisani su i poznati teorijski modeli koji još uvijek potiču njezin daljnji razvoj. Posljednje poglavlje posvećeno je analizi stanja u praksi na području darovitosti, sa posebnim naglaskom na programiranje nastavnog sadržaja. Uz to, predloženo je i nekoliko nastavnih metoda te načina rada koji bi mogli pomoći nastavnicima i stručnim suradnicima pri identifikaciji, ali i svakodnevnom radu sa darovitim učenicima.The aim of this paper was to contribute to the existing works on the topic of giftedness through a brief overview of the term, the state of the gifted education around the world and in Croatia as well as how to program curriculum contet for this group of students. Enabling proper support for the gifted has been a long-time topic for discussion among experets on the field of eductaion. The media often make stories about exceptionally talented children, but in reality, their needs are still mostly neglected thus it is important to put more work in order to satisfy aforementioned needs. Furthermore, the paper lists most notable characteristics of the gifted children, as well as the role of school culture and teachers in their education. Accordingly, the paper briefly analyses current state of education for the gifted in Croatia in comparison with other countires in the world. Moreover, the paper brings about short descriptions of influental theoretical models which still play major role in the further development of the concept. The last chapter analyses the current state in practice on the field of gifted education, with emphasis on programming curriculum contet. Lastly, it suggests couple of methods and techniques which would help teachers and school counselars during the process of identification of the gifted, but also in their daily work

Whole Building Design as Integrated Project Work

This thesis presents an integrated project design as a way how to realize whole building design. The description of the whole building design is given. The goals of the whole building design are described with special focus on the sustainability as a crucial leading factor in design of buildings in the future. An analysis of the designers and their work is done with focus on those, who should form a core of the project team. The second part focuses on the integrated project design as the best way to apply whole building design in practice. A comparison with the traditional project delivery is given. Tteam of specialist plays a crucial role in an integrated project delivery. Integrated team works together from the beginning of the project. Principles, how to form an integrated team, how to cooperate with other designers and interdisciplinary work are given. The phases of the whole building design are described in detail and the goals for each phase are set. PBL class Stanford is an example of the integrated project design. The main vision of the class is to design building as a team and learn new things from other disciplines. The description of the process is given with focus on the created project of university building, which was created with the cooperation of the strudent from universities in USA, Germany and Slovenia

Case study examples for Raspberry Pi

Wide range of ARM development boards is currently available on the market. Their complexity spans from the simple 8-bit boards to more powerful ones that are also suitable to use as general purpose computers. The most popular ARM board currently available is without any doubt Raspberry Pi. Several study examples that demonstrate its usage are available on the internet. While the input/output devices available in the basic set are very fundamental, these examples are hard to use in the educational purposes directly. We have developed our own input/output extension board with the basic components. We additionally implemented HTML and javascript based development environment for Raspberry Pi programming. 9 educational case study examples, which demonstrate the basic tasks, such as buttons and LED module control, and also more complex tasks, such as PWM (Pulse Width Modulation) output control and I2C communication, were written

Determination of the displacements of the barrier at Prigorica

In the graduation thesis we have presented the determining of the displacements of the barrier at Prigorica. Our calculations were made in five term measurements. The thesis constist of the calculation of all combinations between term measurements. The measurements have been made with instruments Leica TC 1700 for angular and linear measurements and nivelir Leica- NAK 2 with a planparalel plate for vertical movements. Before we began analysing the displacements, individual term measurements have been adjustment by least – squares principle. The final adjustment has given us the answer whether there are any gross errors among the measures or observations, the adjusted coordinates and the accuracy analysis. To begin with the analysis of the displacement, we must first ensure, along with the prior adjustment, that the number of points is identical in all term measurements. The choice of method for determination and analysis of the displacement depends on the assignment. For analysing point displacements we have decided for a simple procedure with program Premik and the method of Hannover for a detailed deformation analysis. The method of Hannover is a procedure that reveals and determins the caused displacements with methods of statistical analysis. We test homogenity of accuracy of term measurements, we make a global test of reference points stability and determine and test possible displacements on an observed object. Both procedures are presented in detail in the graduation thesis. For conclusion we have presented the results of analysis and compared them with each other

Evaluation of Implementation of LIADO Program for Artistically Gifted Students of Elementary School

Ovim se radom nastojala evaluirati provedba LIADO programa za likovno darovite osnovnoškolce u gradu Rijeci s ciljem utvrđivanja stupnja uspješnosti ispunjavanja njegove svrhe, ciljeva i zadataka, kao i ispitati učeničku i nastavničku perspektivu njegova provođenja. Istraživanje je provedeno koristeći kvantitativnu i kvalitativnu metodologiju. Rezultati kvantitativnog djela istraživanja pokazuju kako su učenici u velikoj većini zadovoljni kvalitetom sadržaja koju nudi LIADO, dok su isto tako izrazili natprosječnu motivaciju za rad unutar istog. Pokazalo se kako učenici iskazuju visoki stupanj osvještenosti za očuvanje kulturne baštine na području Grada Rijeke te kako su zainteresirani za sudjelovanje u tom istom procesu. Rezultati kvalitativnog djela istraživanja pokazuju kako su sudionice istraživanja, mentorice u LIADO programu, detaljno upoznate sa sadržajem programa te kako je razgovor najčešća metoda rada koju koriste pri poučavanju. Utvrdilo se, kako program nudi dosta slobode prilikom provođenja radionica prilikom čega kompetentnost mentora dolazi do izražaja. Najveći izazov sudionice istraživanja vide u kvaliteti suradnje sa vanjskim dionicima koji pomažu u održavanju LIADO-a (Grad Rijeka, OŠ „San Nicolo“). Iz analize prikupljenih podataka proizlaze tri preporuke. Prve dvije preporuke odnose se na povećanje stupnja i kvalitete suradnje između Grada Rijeke te OŠ „San Nicolo“ sa dionicima LIADO-a kako bi se omogućio čim kvalitetniji razvoj njegovih polaznika. Treća preporuka predstavlja poziv stručnjacima u području darovitosti za provođenjem većeg broja evluacijskih istraživanja ove vrste s ciljem poboljšanja postojećih te efikasnijeg planiranja i osmišljavanja novih programa za ovu skupinu učenika.The aim of this paper was to evaluate the implementation of LIADO program for artstically gifted students of elementary school in Rijeka with the aim of identifying the degree of the realization of its purpose, aims and tasks, as well ass to explore student's and teacher's perspective of its implementation. The study was carried out using the mixed-method methodology. The results of the quantitative part of the study have shown that the students are in the vast majority satisfied with the quality of the LIADO's content while simulatenously showing above average motivation to work in it. The results have shown that the students have shown above average degree of awareness for the preservation of cultural heritage of city of Rijeka as well as intention to act in order to perserve its cultural value. The results of the qulatitative part of the study have shown that the research participants are entirely familiar with the program's content as well as claiming that dialouge is the teaching method that they use the most. Furthermore, the program offers a lot of freedom when it comes to class planning and organizing during which the competence of the teachers can be seen. Research participants claim that the biggest challenge of LIADO is the quality of cooperation between them and subjects that help in supporting of LIADO (the City of Rijeka, OŠ „San Nicolo“). Three reccommendations have emerged from the analysis of collected dana. The first two reccommendations refer to the improvment of the quality of cooperation between the City of Rijeka and OŠ „San Nicolo“ with the subjects of the LIADO program in order to ensure the best development of the students. Third reccommendation respresents an appeal to the experts in the field of giftedness to carry out more evaluation studies of this kind with the aim of improving the quality of existing programs as well ass more efficient planning and designing new ones for this particular group of students

Analysis of Chloride Penetration in Concrete

Na armiranobetonskim konstrukcijama izloženim agresivnom okolišu često nastaju oštećenja uslijed korozije armature izazvane kloridnim ionima. Oštećenja nastaju u obliku pukotina i odlamanja zaštitnog sloja betona uslijed bubrenja produkata korozije, što nepovoljno utječe na nosivost i trajnost konstrukcije. Povrh toga, površina poprečnog presjeka armature smanjuje se istovremeno s procesom degradacije betona. No,  oštećenja se javljaju neposredno nakon depasivacije čelika uslijed kritične koncentracije kloridnih iona u blizini armature. Vrijeme koje je potrebno da kritična koncentracija kloridnih iona prodre do armature naziva se faza inicijacije, a osnovni cilj ovog rada je procjena njezinog trajanja. Trajanje faze inicijacije moguće je predvidjeti ukoliko se u obzir uzmu transportni procesi koji se odvijaju kroz zaštitni sloj betona. Najvažniji fizikalni procesi vezani uz fazu inicijacije su transport kapilarne vode, kloridnih iona te topline. Stoga je u okviru ovog rada razvijen 2D numerički model pomoću metode konačnih razlika, koji simulira navedene transportne procese. Primjena modela pokazana je na numeričkom primjeru u kojem je kvadratni poprečni presjek armiranobetonskog stupa izložen agresivnim morskim uvjetima. Proračun je proveden kako bi se istražio utjecaj širine pukotina na trajanje faze inicijacije. Numerički rezultati pokazuju da raspucalost zaštitnog sloja betona značajno smanjuje trajanje faze inicijacije, a samim time i uporabni vijek konstrukcija.Reinforced concrete structures exposed to aggressive environmental conditions often exhibit damage caused by chloride-induced corrosion of reinforcement. The damage occurs in the form of cracking and spalling of the concrete cover due to the expansion of corrosion products, which adversely affects the bearing capacity and durability of structures. Moreover, the cross-sectional area of reinforcement decreases simultaneously with concrete deterioration. However, the damage occurs shortly after steel depassivation caused by critical chloride concentration in the vicinity of the reinforcement. The time necessary for critical chloride concentration to reach the reinforcement is called initiation phase and the main objective of this paper is to estimate its duration. The duration of the initiation phase is possible to predict if transport processes, which take place through the concrete cover, are accounted for. The most important physical processes related to steel depassivation are the transport of capillary water, chloride and heat. Therefore, the development of a 2D is presented in this paper. The model is based on the finite difference method and simulates aforementioned transport processes. The application of the model is shown on a numerical example in which a square cross-section of a reinforced concrete column is exposed to aggressive maritime conditions. The analysis is carried out to investigate the influence of crack width in concrete cover on the duration of the initiation phase. The numerical results show that the cracking of concrete cover significantly reduces the duration of the initiation phase, and, consequently, the service life of structures