This paper presents the methodology for predicting the mechanical performance of structural elements made of polymer concrete (PC). A vinyl ester polymer concrete composition and the results of experimental studies to determine the basic mechanical properties of the material are presented. Following the strategy for sustainable development in the building industry, the material cost of polymer concrete was lowered by reducing the consumption of raw materials and the partial replacing of the microfiller fraction with recycled waste products—calcium fly ash. An accurate computational model enabling stress analysis is a convenient way to verify the suitability of PC as a construction material in structural applications. Due to difficulty in deriving an accurate analytical formula, numerical approximation (finite element method) was used as a method for solving the problem. Constitutive modeling of PC is a very important aspect of the strength calculations and here it was done within the framework of elasto-plasticity. Numerical evaluation of the static bearing capacity of PC manhole covers is shown as an example of the proposed FEM methodology. The results of computer simulations were compared with laboratory tests. Finally, the adequacy of the numerical modeling for testing new construction and material improvements is discussed. The study showed that the concrete damaged plasticity material model can be effectively used for the description of PC mechanical behavior.

This paper presents a new approach to characterisation of asphalt mixtures constitutive models, with application to pavement structures. It is well-known fact that temperature, frequency and time of loading have a great influence on the mechanical properties of bituminous mixtures. For this reason, the properties are usually presented in the frequency domain as complex numbers having real and imaginary parts. This convenient representation in terms of complex modulus and phase angle leads to the dynamic modulus master curve. The effective use of the theory of linear viscoelasticity to characterise constitutive model of asphaltic material is shown in this paper. Viscoelastic constitutive model is represented by a combination of rheological schemes, and its identification is based on both laboratory tests results and mixture composition. The temperature–frequency or temperature–time superposition principle being applied in order to produce master curves of mechanical properties is illustrated with real experimental data. Further, the process of identification of Huet–Sayegh parameters is carried out using best-fitting methods implemented in MATLAB. Fractional rheological model is used as it needs only a small number of elements to fully characterise the response of asphalt materials.

Constitutive properties of asphalt-aggregate mixtures are modelled very often applying viscoelastic models represented by rheological schemes. The parameters of these schemes are identified using cyclic test at various temperatures. The procedure leads to the dynamic modulus master-curve. The sigmoidal model is applied in order to represent the master-curve usually, but such a model does not have real physical meaning. The objective of the paper is to demonstrate the method of characterization of the complex moduli for bituminous mixtures using classical and fractional rheological models. Fractional models give the possibility to characterize the response of asphalt materials with a small number of elements. In order to find the parameters of rheological schemes, the optimization problem is formulated. The solution is obtained using least-squares methods implemented in MATLAB software

The design of flexible and semi-rigid pavements by applying mechanistic-empirical methods involves the determination of the stress and strain states in accordance with the assumptions of continuum mechanics. Advanced computational models should take into account the rheological properties of asphalt layers. Precise identification of visco-elastic parameters of asphalt aggregate mixtures requires a lot of expensive laboratory experiments. The objective of this paper is to propose a new method allowing the identification of visco-elastic constitutive parameters based only on the mixture composition. The effectiveness of the proposed approach is exemplified in the paper by numerical calcu­lations. Two linear rheological models were analyzed: the classical Burgers model and the Huet-Sayegh model described by fractional derivatives. Constitutive parameters of both models were obtained from the appropriate optimization algo­rithms and numerical techniques for determining inverse Laplace transforms.

The paper presents chosen elements of a dynamic analysis of a rail bridge located on the CMK trunk railway line in Poland. The calculations cover solving an eigenvalue problem for the structure (theoretical modal analysis) using several computational models created with different discretization methods (different accuracy levels) and determination of the dynamic response of the bridge span (time-history analysis - integration of equations of motion) to loading with HSLM train models as per PN-EN 1991-2. The results were compared to the current code and regulations relating to high-speed rail systems.