Papers by Keyword: Beam

Abstract: Concrete, often conceptualized as an inert construction material, is fundamentally a dynamic composite that undergoes continuous physicochemical transformations throughout its service life, governed by natural degradation processes and mechanical aging. Despite its widespread utility, concrete’s quasi-brittle behavior, characterized by low tensile strength and susceptibility to abrupt failure under traction-dominated loading regimes, remains a critical limitation in structural engineering. To address these intrinsic vulnerabilities, the rehabilitation of concrete infrastructure has emerged as a pivotal research domain, with advanced retrofitting techniques focusing on enhancing tensile performance and transitioning failure modes from brittle to ductile. Among these, externally bonded reinforcement (EBR) using fiber-reinforced polymer (FRP) composites has gained prominence as a high-efficacy solution for augmenting load-bearing capacity and structural resilience. This study employs a parametric finite element analysis (FEA) framework in Abaqus/CAE to systematically evaluate the mechanical efficacy of two distinct carbon fiber-reinforced polymer (CFRP) retrofitting strategies: (1) externally bonded CFRP plates and (2) internally embedded CFRP reinforcement within the beam’s cross-section. The computational investigation quantifies the influence of reinforcement placement on critical performance metrics, including ultimate load capacity, deformation ductility, and failure mechanisms. Numerical results demonstrate that internally integrated CFRP reinforcement significantly enhances structural ductility and peak load resistance, while maintaining a marginal mass differential. These findings underscore the critical role of reinforcement topology in optimizing stress redistribution and crack mitigation, offering actionable insights for the design of next-generation retrofitting protocols that prioritize both strength and serviceability. The study advances the discourse on sustainable infrastructure rehabilitation by delineating a pathway for leveraging embedded composite systems to transcend the inherent limitations of conventional concrete matrices.

Abstract: The problem of bending of a beam of variable stiffness resting on a continuous homogeneous elastic Winkler-type foundation is considered. The exact solution of the corresponding bending differential equation is found for the case when the beam stiffness is an arbitrary continuous function. Based on the exact solution, an analytical method for beam calculation is developed. This method produces accurate results and is computationally efficient. It is implemented in a computer program and demonstrated by the calculation of a truncated wedge-shaped beam. The calculation results are provided in numerical and graphical formats.

Abstract: In the summer school of PSD2024, focusing on spin-polarized positron annihilation spectroscopy in materials science, I reported the historical background and its possibility concerning current spintronics field, the basic principles, and prospects. Here, as a memorandum, I mainly summarize the basic principles, which can be relatively well-formulated, with some remarks.

Abstract: Calculation formulas are given in the analytical form, which allow to study the bending of beams on a non-homogeneous solid Winkler elastic foundation. An example demonstrates the practical application of the developed method. The case is considered when the bed coefficient changes according to a parabolic law, and the variable distributed load acting on the beam is given by a linear law. The results of the calculation by the author's method are presented in numerical and graphical formats. For comparison, the calculation results obtained by the finite element method are also provided.

Abstract: Building industry is an important player that consumes a significant part of raw materials and energy. With regard to construction industry sustainable development and design requirements there is a space for innovative solutions, where one of the possibility include the use of high-strength concrete. The paper deals with the substantial description and detailed evaluation of the testing of reinforced high strength concrete beam which was exposed to three point loading test. Large scale experiment was complemented with material diagnosis of selected mechanical properties using destructive and non-destructive methods. Non-destructive methods were used to verify compressive strength and dynamic modulus of elasticity. Destructive compressive strength testing was applied on cylinder samples prepared with core drilling and determined values were compared with non- destructive testing. Measured data will be used for future advanced non-linear modelling.

Abstract: In this paper, a lengthwise fracture analysis of a viscoplastic inhomogeneous cantilever beam of circular cross-section acted upon by a torsion moment is presented. The beam is with an arbitrary number of concentric lengthwise cracks. The time-dependent mechanical behaviour of the beam is treated by a viscoplastic model representing a series of units which are combinations of springs, dashpots and frictional sliders. Due to the sliders, the model units start to deform one after another with increasing of the external load. Constitutive laws of the viscoplastic model are obtained and applied to treat the beam mechanical behaviour when deriving time-dependent strain energy release rates for the lengthwise cracks.

Abstract: The paper presents the results of exposure of normal concrete to elevated temperatures (400 and 700) °C covered by layers (gypsum and plaster) with different thicknesses (10 and 20) mm. Through the figures shown in the paper, which were obtained from the experimental side of the research, the load-strain curves improved when the gypsum thickness increased during the specimens' exposure to fire. Where the relationship between them at a temperature of 400°C in a thickness of 20 mm was better than 10 mm when exposed to fire, so by increasing the thickness of the gypsum, the occurrence of strain is less because it protects the surface of the concrete from direct exposure to heat and thus prevents the occurrence of cracks in the outer surface of the concrete.

Abstract: This paper presents an analytical method for calculating the cracking moment of concrete beams reinforced with fiber reinforced polymer (FRP) bars, which considers the non-linear behavior of concrete in the tension zone and the contribution of FRP reinforcement. Theoretical cracking moments obtained by the proposed method were verified with the experimental results and the theoretical results calculated according to ACI 440.1R-15. The comparison results show good agreement between theoretical and experimental data. A parametric study on the effect of longitudinal FRP reinforcement ratio and elastic modulus of FRP on the cracking moment of FRP reinforced concrete beams also were done by using the proposed method. The parametric study results show that both longitudinal reinforcement and modulus of elasticity of FRP significantly affect the cracking moment of FRP reinforced concrete beams. Moreover, parametric study results also clarify the weakness of ACI 440.1R-15 in determining the cracking moment of concrete beams reinforced with a large amount of FRP reinforcement ratio and with high modulus of elasticity of FRP.

Abstract: The Boundary Element Method (BEM) is one among the most popular simulation techniques employed to simulate mechanical behaviour of materials, including smart engineering materials. Although BEM is a quite well-established numerical technique, literature tells that the method may not be well suited to simulate structures where one or two of the dimensions is much smaller than the remaining dimension/s (for a 3D problem). Hence in this work, deflection of a cantilever beam is simulated using constant boundary elements to get a feel of the accuracy of the BEM when used to simulate such type of structures. Although the concept is not new, the study assumes significance because studies which list the results in detail are not readily found in the literature. In this study, the results are obtained for different mesh resolutions also. The results indicate that - as expected - constant boundary elements are not a good choice for simulating the mechanical behaviour of smart materials when the structural member to be simulated is thin. Although it is a known fact that constant boundary elements converge very slowly, the present study helps to get a clearer picture on the accuracy and the convergence rate that one can expect from constant boundary elements. This paper heavily borrows content from this author’s PhD thesis [1]. The geometry considered in this paper is a beam. One may also note that the author is publishing another paper [2] (“Simulation of Mechanical Behaviour of Materials using Constant Boundary Elements - A Discussion on the Accuracy of Results for Bars”) that is very similar to this paper except that the geometry considered in that paper is a bar.

Abstract: The sustainable development of industry and society requires new approaches to the building structures design. The article presents the indices of strength, crack resistance and width of crack opening obtained as a result of experimental testing of beams with hybrid reinforcement with basalt plastic and metal armature. The following beams were examined for comparison purposes: the ferroconcrete beams of the control-series, and the twin beams reinforced only with basalt-plastic reinforcement. It was found that the replacement of the metal armature with basalt plastics led to an increase in strength, on average, by 40%. Similar strength indices were obtained for hybrid reinforcement beams. Crack resistance indices of hybrid reinforcement beams were found to be close to ferroconcrete beams of the control series. Crack resistance indices for these beams were also by 84... 89% higher in comparison with beams reinforced with basalt-plastics. The width of crack openings in hybrid reinforced beams did not exceed the maximum permissible norms at the operational level of loads (70% of destructive) and were smaller than in beams reinforced with basalt plastic reinforcement. Hybrid reinforcement efficiency has been established to improve the performance criteria of beams reinforced with composite armature.