| Abstract [eng] |
Newly made flexural combined steel fibre and ordinary reinforcement reinforced concrete composite members using conventional and ultra-high performance concrete were investigated in dissertation. Mechanical properties of different strength concretes and shear bond strength between layers of composite members were determined during experimental research under various curing conditions. Deflections, stresses of reinforcement and curvatures of intermediate size flexural reinforced concrete composite beams were measured and calculated. According to the results of carried out experiments, the method to describe the variation of residual tensile stresses in cracked section of ultra-high performance steel fibre reinforced concrete was created. Applying the created methodology, the calculations of curvatures can be done using analytical, layer (iterative) or other methods, taking into account the influence of elastoplastic behaviour of tensile concrete before cracking or not. When the curvatures of uncracked and cracked sections are determined, the average curvature can be calculated and the deflection of composite member founded. The calculation methodology for determination of optimal thickness of ultra-high performance concrete layer was also created in this work, taking into account the influence of different stiffness of composite member layers. Finite element analysis of flexural reinforced concrete composite members was done, when the influence of steel fibre in ultra-high performance concrete after cracking was evaluated through the fracture energy. |
