Experimental tests of some composite steel-concrete, wood-concrete and concrete-concrete elements

The paper presents the results of experimental tests of some composite steel-concrete, wood-concrete and concrete-concrete elements. Deflections at midspan under monotonically increasing static load were measured. The influence of different composite making means on the results was researched. The emphasis was given to efficiency of different composites with Omnia-slabs that are commonly used in practice

EXPERIMENTAL TESTING OF SCALED MODEL AND ARCH SEGMENTS OF THE OLD BRIDGE IN MOSTAR

Zidani lučni mostovi zbog svojega karakterističnog izgleda i kompleksnosti materijala od kojih su građeni i danas su predmet eksperimentalnih i numeričkih analiza. Jedan od istaknutih primjera ovog tipa konstrukcija jeste i Stari most u Mostaru, koji je, zajedno s lokalitetom mosta, pod zaštitom UNESCO od 2005. godine. Upravo je ovaj simbol grada na Neretvi odabran kao osnova za analizu ponašanja zidanih lučnih mostova i njihovih elemenata. Kroz rad će biti prikazani rezultati kvazistatičkih ispitivanja elemenata veze provedenih na modelima segmenata svoda Starog mosta u razmjeri 1:3 kao i rezultati ispitivanja ponašanja fizičkog modela Starog mosta skaliranog u razmjeri 1:9 ispitivanog na seizmičkoj platformi za različite nivoe seizmičke pobude. Modeli su izgrađeni s realnom aplikacijom veza između kamenih elemenata - klamfe, trnovi i tekuće olovo. Utvrđivanje kapaciteta nosivosti i načina popuštanja elemenata veza ispitivanih segmenata te određivanje mehanizma loma modela mosta osnovne su zadaće provedenih eksperimentalnih istraživanja.Due to their characteristic appearance and complexity of materials used for their construction, masonry arch bridges are still the subject of experimental and numerical analyses. One of the characteristic examples of this type of structures is the Old Bridge in Mostar that, along with the bridge location, has been under UNESCO protection since 2005. It is exactly this symbol of the town residing on the Neretva River that has been selected as the basis for analysis of behavior of masonry arch bridges and their structural elements. This paper will present the results of the quasi-static tests on connection elements carried out on models of arch segments of the Old Bridge at the scale of 1: 3 as well as the results of the shaking table tests of the behavior of the physical model of the Old Bridge scaled to 1:9 under different levels of seismic excitation. The models were built by application of real connection elements between stone elements – cramps, dowels and liquid lead. Definition of bearing capacity and mode of deterioration of the connection elements of the tested segments as well as definition of the failure mechanisms of the bridge model are the main tasks of the performed experimental investigations

EXPERIMENTAL TESTING OF SCALED MODEL AND ARCH SEGMENTS OF THE OLD BRIDGE IN MOSTAR

Zidani lučni mostovi zbog svojega karakterističnog izgleda i kompleksnosti materijala od kojih su građeni i danas su predmet eksperimentalnih i numeričkih analiza. Jedan od istaknutih primjera ovog tipa konstrukcija jeste i Stari most u Mostaru, koji je, zajedno s lokalitetom mosta, pod zaštitom UNESCO od 2005. godine. Upravo je ovaj simbol grada na Neretvi odabran kao osnova za analizu ponašanja zidanih lučnih mostova i njihovih elemenata. Kroz rad će biti prikazani rezultati kvazistatičkih ispitivanja elemenata veze provedenih na modelima segmenata svoda Starog mosta u razmjeri 1:3 kao i rezultati ispitivanja ponašanja fizičkog modela Starog mosta skaliranog u razmjeri 1:9 ispitivanog na seizmičkoj platformi za različite nivoe seizmičke pobude. Modeli su izgrađeni s realnom aplikacijom veza između kamenih elemenata - klamfe, trnovi i tekuće olovo. Utvrđivanje kapaciteta nosivosti i načina popuštanja elemenata veza ispitivanih segmenata te određivanje mehanizma loma modela mosta osnovne su zadaće provedenih eksperimentalnih istraživanja.Due to their characteristic appearance and complexity of materials used for their construction, masonry arch bridges are still the subject of experimental and numerical analyses. One of the characteristic examples of this type of structures is the Old Bridge in Mostar that, along with the bridge location, has been under UNESCO protection since 2005. It is exactly this symbol of the town residing on the Neretva River that has been selected as the basis for analysis of behavior of masonry arch bridges and their structural elements. This paper will present the results of the quasi-static tests on connection elements carried out on models of arch segments of the Old Bridge at the scale of 1: 3 as well as the results of the shaking table tests of the behavior of the physical model of the Old Bridge scaled to 1:9 under different levels of seismic excitation. The models were built by application of real connection elements between stone elements – cramps, dowels and liquid lead. Definition of bearing capacity and mode of deterioration of the connection elements of the tested segments as well as definition of the failure mechanisms of the bridge model are the main tasks of the performed experimental investigations

NUMERICAL MODEL FOR ANALYSIS OF STEEL FRAME STRUCTURES WITH INCLUDED GEOMETRIC IMPERFECTIONS

Prikazana je primjena numeričkog modela baziranog na metodi konačnih elemenata za analizu okvirnih konstrukcija izrađenih od čelika. Model je implementiran u računalni program [9] te podrazumijeva primjenu 1D štapnog konačnog elementa pri čemu se jednadžbe ravnoteže zadovoljavaju na deformiranom sustavu (teorija velikih pomaka). Na primjeru proračuna čeličnog okvira prikazana je mogućnost primjene numeričkog modela sa uzimanjem u obzir početnih geometrijskih imperfekcija. Pokazano je da se implementirani numerički model i računalni program [9] može uspješno koristiti za proračune čeličnih okvirnih konstrukcija prema EN 1993-1-1 [10]. Na kraju su dani komentari sa zaključcima.Numerical model based on finite element method for analysis of steel frame structures is presented. Model is implemented in computer program [9] and implies application of 1D (beam) finite element. Large displacement theory with incremental-iterative solution of equilibrium equations is applied. Application of numerical model is presented on an example of steel frame structure where initial geometric imperfections are also included. It is shown that presented numerical model and computer program [9] can be used for practical design of steel frame structures according to EN 1993-1-1 [10]. Main conclusions are given at the end

SIMULATING THE BEHAVIOR OF PRESTRESSED BEAMS WITH DIFFERENT DEGREES OF PRESTRESSING

U radu numerički se obrađuje eksperiment u kojem je napravljeno 5 „T“ nosača koji su opterećeni do loma pod presom. Nosači su projektirani tako da imaju istu graničnu nosivost uz različit odnos armiranja prednapetom i mekom armaturom. Daje se detaljan pregled eksperimenta sa točnim dimenzijama presjeka, kao i točnim položajem i odnosom prednapete i meke armature. Kao rezultat eksperimenta prikazane su i analizirane krivulje sila-pomak na pojedinim nosačima. Prikazan je i numerički model za nosače armirane prema eksperimentu. Korištena su dva modela materijala za analizu nosača; računski model materijala kako bi se provjerila računska lomna sila nosača i novi proizvoljni model materijala u kojem se određuje posebno ponašanje betona u vlaku kako bi se simuliralo stvarno ponašanje nosača. Svi nosači su postupno dovedeni do numeričkog loma inkrementalnim povećavanjem opterećenja koje simulira povećanje opterećenja na presi. Naposljetku, daje se analiza i usporedba rezultata numeričkog modela sa eksperimentom, kao i zaključak o valjanosti numeričkog modela.The paper covers numerical analysis of an experiment with five T-beams that are loaded to failure. The beams are designed to have the same ultimate bearing capacity with different ratios of prestressed to classic reinforcement. A detailed overview of the experiment is shown with exact section dimensions, as well as exact position and ratio of prestressed to classic steel. As a result of the experiment, force-displacement diagrams for each beam are presented and analyzed. Numerical model of the beams, reinforced in accordance with the experiment, is also shown. Two models for materials are used to analyze the beams: design model to check the design failure force and a new material model with concrete tension to simulate the actual behavior of the beams. All beams are gradually loaded to numerical failure by incrementally increasing the load that simulates press load. At the end, an analysis and comparison between experimental and numerical results is conducted to determine if the numerical model is a good representation of actual beam behavior