The paper presents some important aspects concerning material constants of concrete and stages of modeling

No abstract

A b s t r a c tThe article presents comparison of the results obtained from reinforced concrete beams experimental studies with the use of ARAMIS system (digital image correlation) with the results gained from numerical modeling. During studies, deviation from the plane of reinforced concrete beams was observed. Inventory of rebars positions in cross-section of this beams showed significant deviations. Analysis carried out in the work [1] revealed the impact of improperly embedded longitudinal reinforcement on the occurrence of horizontal displacements. Based on the collected data, numerical models of two selected reinforced concrete beams with correct and incorrect positon of the reinforcing bars were made using the Concrete Damaged Plasticity model in Abaqus software. It has been shown that premature interruption of the calculation appeared in models taking into account deviations in the position of reinforcing bars. However, the occurrence of horizontal displacements was still confirmed by numerical model for beams with incorrect positioning of rebars. S t r e s z c z e n i e W artykule przedstawiono porównanie wyników badań eksperymentalnych belek żelbetowych z wykorzystaniem systemu ARAMIS (korelacja obrazu cyfrowego) z wynikami uzyskanymi w wyniku modelowania numerycznego. W wykonanych badaniach zaobserwowane zostało odchylenie z płaszczyzny belek żelbetowych, spowodowane niezgodnym z projektem rozmieszczeniem prętów zbrojenia, co potwierdzono w pracy [1]. Inwentaryzacja położenia prętów zbrojeniowych w przekroju poprzecznym belek wykazała ich znaczne odchylenia. Na podstawie zebranych danych, w oprogramowaniu Abaqus, przy użyciu modelu Concrete Damaged Plasticity, wykonano numeryczne modele dwóch wybranych belek żelbetowych z prawidłowym oraz nieprawidłowym rozmieszczeniem prętów. Stwierdzono przedwczesne przerwanie obliczeń dla modeli uwzględniających odchylenie w położeniu prętów zbrojeniowych. Mimo to opracowany model numeryczny potwierdza występowanie przemieszczeń poziomych w belkach z niewłaściwym rozmieszczeniem prętów.

Laboratory research of wood–CFRP (carbon fiber reinforced polymer) structural elements, especially beams, is a scientific issue undertaken by many scientists. Research is often complemented with numerical analysis with the use of complex finite element method (FEM) models. Modern FEM software offers models that can reproduce such properties and phenomena as orthotropy and plasticity of wood and CFRP, delamination and mechanical behavior of adhesive layers, and damage of a strengthened element. The author of the paper reproduces numerical laboratory research of a four-point bending test of a glulam beam strengthened with CFRP tape. The main goal of the numerical research is an analysis of how the complexity of the FEM model influences the results of calculations, especially stress, deflection, and bearing capacity of the glulam beam. In some cases, a simpler model can be satisfactory, especially for a structural engineer, who takes into account serviceability limit states (permissible deflection of a structural member) and assumes that stress should not exceed the yield stress of timber.

This paper discusses a choice of the most rational reinforcement details for frame corners subjected to opening bending moment. Frame corners formed from elements of both the same and different cross section heights are considered. The case of corners formed of elements of different cross section is not considered in Eurocode 2 and is very rarely described in handbooks. Several reinforcement details with both the same and different cross section heights are presented. The authors introduce a new reinforcement detail for the different cross section heights. The considered details are comprised of the primary reinforcement in the form of straight bars and loops and the additional reinforcement in the form of diagonal bars or stirrups or a combination of both diagonal stirrups and bars. Two methods of static analysis, strut-and-tie method (S&T) and finite element method (FEM), are used in the research. FEM calculations are performed with Abaqus software using the Concrete Damaged Plasticity model (CDP) for concrete and the classical metal plasticity model for reinforcing steel. The crucial CDP parameters, relaxation time and dilatation angle, were calibrated in numerical tests in Abaqus. The analysis of results from the S&T and FE methods allowed for the determination of the most rational reinforcement details.