Timber-concrete Composite Beams: Structural Analyses and Evaluation of the Results for Notched and Doweled Composites

U uvodnom dijelu rada ukratko je izložen pregled tipoloških skupina kompozita drvo – beton i područja njihove primjene, opisane su konstrukcijske značajke karakteristične za navedene tipologije te posljedične razlike učinaka sprezanja. Na temelju provedenog uvida u stanje područja (normizacija i dosadašnja istraživanja, dostupna iz bibliografskih izvora) dan je i pregled raspoloživih metoda proračuna (analitičkih i numeričkih), opisane su i diskutirane prednosti i ograničenja njihove primjene. Fokus ovoga rada jest konstrukcijska analiza dviju tipoloških grupa – u prvoj se sprezanje ostvaruje isključivo primjenom trnova (štapna spajala), a u drugoj primjenom zasijecanja (preoblikovanje kontaktnih rubova dijelova kompozita) s ili bez dodatnog štapnog spajala u zasjeku. Ove su dvije tipološke grupe izdvojene zbog različitosti s obzirom na mogućnost primjene analitičke procedure zasnovane na γ – metodi. Za obje tipološke grupe su izrađeni ravninski numerički modeli (sa štapnim konačnim elementima) prikladni za primjenu u praksi – tzv. tlačno – vlačni model (engl. Strut and tie, frame model, truss / lattice models). Djelotvornost numeričkih modela evaluirana je za dva karakteristična slučaja – uzimajući u obzir i zanemarujući krutost spoja. Proračunske analize (analitičke i numeričke) su provedene samo za početnu fazu sprezanja (izostavljeni su učinci dugotrajnih opterećenja i reološkog ponašanja konstitutivnih materijala). U provedbi analiza su korišteni rezultati istraživanja dobiveni eksperimentalno i numerički, dostupni iz literature. Rezultati analiza provedenih u ovom diplomskom radu su uspoređeni s bibliografskim podacima, izvedeni su zaključci i dane smjernice za praktičnu primjenu.In the introduction of this master thesis, an overview of the typological groups of timber – concrete composites and areas of their application were briefly presented and described. As well as their structural features and differences related to composite actions. Based on the insight into the state of the art (standardization and conducted research available from bibliographic sources) an overview of calculation methods (analytical and numerical) was given and the advantages and/or limitations of their application were described and discussed. The focus of this thesis is on the structural analysis of two typological groups - in one group the composite action is achieved exclusively by dowels, and in the other, using notches (or grooves, which implies that the contact edges of constituent parts of the T-section are reshaped) – the second group can but does not necessarily have an additional dowled fastener. These two typological groups were selected due to their differences, considering the possibility of applying the analytical procedure based on the γ – method. Planar numerical models, suitable for any practical application have been made for both groups - so-called strut and tie models. The effectiveness of created numerical models was evaluated in two different instances, in one instance the stiffness of the joint is considered, and in the other, it is completely disregarded. Design analyses (analytical and numerical) were performed only for the short-term composite actions (the effects of long-term loads and rheological behavior of the constituent materials of the composite were left out). The results of experimental and numerical research, available in the literature, were used as a basis for the analysis. The results of the analyses carried out in this thesis were compared with bibliographic data, conclusions were derived and guidelines for practical application were given