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This paper discusses the fracture-plastic material models for reinforced concrete and use of this model for modelling of reinforced concrete beams. Load-displacement relations and bearing capacity of reinforced concrete beams will be evaluated. A series of original (own) experiments - the beam and data from completed experiments - have been chosen for the numerical modelling. In case of the original experiments - reinforced concrete beams, stochastic modelling based on LHS (Latin Hypercube Sampling) will be carried out in order to estimate the total bearing capacity. The software used for the fracture-plastic model for reinforced concrete is ATENA.

Rebound hammer is the most frequently used non-destructive method for estimation of concrete strength. Measurement results are influenced by various factors (components and composition of concrete, humidity or age), which are well known for normalweight concrete. High-strength concrete (HSC) differs in quality and the question is to which extent these factors influence the test results. Knowledge about influence of aggregate and results of measurements with Schmidt rebound hammer is stated. Test results and evaluation of compressive strength are considerably influenced by the strength of parent material from which the coarse aggregate is made. Influence of granulometric curve is less important and for aggregate with strength over 90 MPa, it is negligible. To determine compressive strength of HSC with Schmidt rebound hammer, it is necessary to elaborate special calibration relationships for aggregate with various strength of parent rock. Use of calibration relationships elaborated for normal-weight concrete for determination of strength of HSC is problematic (different properties of aggregate and upper limit of calibration relationships is 70 MPa). Shifting the upper limit of calibration relations for normal-weight concrete up to the maximal rebound number measured at testing HSC is not recommendable; values of compressive strength calculated in accordance with adjusted formulas are smaller than real strength of HSC.

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Flow characteristics contraction of rectangular cross-section are investigated numerically and experimentally so as to gain an additional insight into the contraction design. They observed velocity field and turbulent intensity in the area of contraction and downstream of it. Individual numerical models sofware Ansys Fluent are evaluated and compared with measurements in a wind tunnel.

The paper is focused on research of physico-mechanical properties of concretes with Portland-limestone cement, Blastfurnace cement and Portland-composite cement in comparisom with concrete with Portland Cement CEM I. Following physico-mechanical properties of concretes exposed to extreme conditions were tested: compressive strength, flexural strength, tensille splitting strength, velocity of propagation of ultrasonic pulse, dynamic elasticity modulus and density of hardened concrete. Following environments were used in tests: sulphates, magnesic ions, nitrates, gaseous CO2, high temperatures.