1. Nonlinear semi-numeric and finite element analysis of three-point bending tests of notched polymer fiber-reinforced concrete prismsŽiga Unuk, Milan Kuhta, 2024, izvirni znanstveni članek Opis: A nonlinear semi-numeric and finite element analysis of three-point bending tests of notched polymer fiber-reinforced concrete prisms was performed. The computational and experimental results were compared in terms of the load-displacement behavior. The vertical midspan displacement and the crack mouth opening displacement results were considered. The nonlinear semi-numeric computational procedure involved the moment-curvature relation, calculated by considering the constitutive material law from the fib Model Code for Concrete Structures 2010, and considered a plastic hinge mechanism to simulate the cracked region behavior. Two sets of tensile mechanical properties were considered for the constitutive material law: back-calculated (by an inverse analysis) tensile strength properties from the experimental results, and tensile strength properties calculated by simplified expressions from the fib Model Code for Concrete Structures 2010. Other mechanical properties were determined by additional compressive tests and standard relations for the dependency of various mechanical properties on the concrete compressive strength. The nonlinear finite element analysis incorporated the Menetrey-Willam material model to simulate the fiber-reinforced concrete behavior. The nonlinear semi-numeric analysis load-displacement results based on the back-calculated tensile strength properties relatively accurately matched with the experimental results, whereas the nonlinear semi-numeric analysis load-displacement results based on tensile strength properties calculated by simplified expressions from the fib Model Code for Concrete Structures 2010 and the nonlinear finite element analysis load-displacement results showed certain shortcomings.
Ključne besede: polymer fiber-reinforced concrete, moment-curvature relation, nonlinear plastic hinge, load-displacement relation, crack width, nonlinear analysis, finite element analysis, Menetrey-Willam material model, three-point bending test, compressive test
Objavljeno v DKUM: 19.02.2024; Ogledov: 350; Prenosov: 26
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2. Evaluating the bending rigidity of flat textiles with the use of an Instron tensile testerMirosława Kocik, Witold Żurek, Izabella Krucinska, Jelka Geršak, Jan Jakubczyk, 2005, izvirni znanstveni članek Opis: The purpose of this work is to verify the possibility of using an Instron tensile tester for evaluating those mechanical properties of flat textile fabrics which are responsible for their handle properties. A method of evaluating the bending rigidity of woven fabrics was developed. The method consists in axially compressing samples fixed at both ends and placed in a vertical position, which leads to their buckling. The bending rigidity was determined on the basis of the critical maximum force occurring at buckling, and the curvature of the buckled sample which appears as result of the action of this force. The results obtained by this method were compared with those obtained with the use of the FAST system. The good compatibility of both these methods was proved by the correlation coefficients.
Ključne besede: flat textiles, mechanical properties, measurements, fabric handle, bending rigidity, bending moment, curvature, buckling, buckling length
Objavljeno v DKUM: 01.06.2012; Ogledov: 1852; Prenosov: 54
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3. Analysis of cracked slender-beams on Winkler's foundation using a simplified computational modelMatjaž Skrinar, Boris Lutar, 2011, izvirni znanstveni članek Opis: This paper discusses the coupling of Winkler's soil model with a simplified computational model that is widely used for the calculation of transverse displacements in transversely cracked slender beams. The bending problem of a cracked beam embedded in Winkler's soil is addressed by means of an analytical approach. The solving of the corresponding differential equation solutions is studied in order to obtain exact analytical expressions for the transverse displacements of the simplified computational model. After the solutions for the displacements of the beam are obtained, the inner bending moment and the shear force distributions within the beam can be calculated, either by using known, established relationships from the Euler-Bernoulli beam theory or by implementing two mechanical equilibrium conditions. Numerical examples covering several load situations are briefly presented in order to support the discussed approach. The results obtained with the presented approach are then further compared with the values from huge 2D finite-element models, where a detailed description of the crack was achieved using the discrete approach. It is evident that any drastic difference in the computational effort is not reflected in the significant differences in the results between the models.
Ključne besede: beams with transverse cracks, simplified computational model, elastic foundation, Winkler's soil, transverse displacements, bending moment, shear forces
Objavljeno v DKUM: 01.06.2012; Ogledov: 2262; Prenosov: 58
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