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Abstract: 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.
Keywords: 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
Published in DKUM: 19.02.2024; Views: 350; Downloads: 29
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Abstract: Practical example of signal processing from strain gauge, inductive transducer and total station measurements are used to illustrate the features of the bridge load testing measurements. FFT provides accurate representation of physical behavior for static and dynamic signals obtained when loading the bridge. As a reference measurement the signal from inductive transducer was taken. A static part of the load test was also geodetically measured and theoretically calculated. The results are comparable.
Keywords: bridges, measurements, strain gauge, load test, deformation, strain, signal processing
Published in DKUM: 12.07.2023; Views: 445; Downloads: 33
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Abstract: The unconfined compression strength is one of the most important engineering parameters in rock mechanics; it is used to characterize and study the behaviour of solid rocks. A good correlation between the unconfined compression strength test (UCS) and the point load strength (PLS) can be very useful, because it allows for faster and cheaper testing than other methods with the same security to calculate the structures and performances of solid rocks. A preliminary step to implement the correlation is to have a good method to determine the resistance to a point load. This determination is correct if we have a sufficient number of tests on specimens of the same nature, but usually this does not occur, and it is necessary to apply a size-correction factor, F = (De/50)α, with α = 0.45. This paper is based on limestone from Comunidad Valenciana, Spain, because it represents a very high percentage of the rocks. The implementation was conducted over 700 field and laboratory tests, of which 255 are PLT tests, 45 are UCS tests, and the rest are other parameters, like porosity and specific weight, Slake Durability, and ultrasonic velocity.
Keywords: resistance to point load, point load strength, Franklin test, size correction factor, unconfined compression
Published in DKUM: 14.06.2018; Views: 1246; Downloads: 80
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Abstract: By measuring the displacements and deformations at different structures we deal in the Faculty of Civil Engineering, transportation Engineering and Architecture in University of Maribor for about 20 years. At that time we measured over 600 structures. Most loading tests of bridges and Viaducts were made. The measurements of movements needed to be as precise and accurate as possible. To do that laboratory test of instruments were made to see which instrument gives us reliable results. Displacements can be determined by geodetic and physical methods, depends of the construction. The use of geodetic methods are still preferable. In the paper the measurements with the total station, the level and rotation level, photogrammetry and solutions on the field by physical methods with inductive transducers are presented. We need to measure displacements as quick as possible but efficiently because we can not repeat the measurements under the same conditions. Also the surveying on the bridge and in the lab with the comparison of methods is presented under the different hard terrain conditions - water beneath the construction, big height of the structure, unapproachability, large span structures.
Keywords: bridges, measurements, strain gauge, load test, deformation, strain, signal processing
Published in DKUM: 02.08.2017; Views: 1262; Downloads: 342
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