Macro-strain based deflection and neutral axis position monitoring of reinforced concrete beams during corrosion

This article proposes a new technique of monitoring neutral axis positions and deflection of Reinforced Concrete (RC) beam during corrosion of steel reinforcement using macro-strain measurements of distributed long-gauge sensors. A different group of distributed long-gauge Packaged Carbon Fiber Line (PCFL) sensors with self-compensation and effective packaging system is installed on the compression and tension fibers of the concrete surface and steel reinforcements of RC beam to verify the proposed method experimentally. An accelerated corrosion method utilizing a salt solution and the constant current was used to achieve the required corrosion levels. The estimated deflection measured by the developed method is compared with the results using Linear Variable Displacement Transducer (LVDTs). It has been demonstrated that long-gauge PCFL sensors could provide the same accuracy. The distributed measured strains were utilized to evaluate the deterioration of the structure’s health with the advance of corrosion. Based on corrosion monitoring experimental results, it can be confirmed that using distributed PCFL sensors mounted on steel reinforcements or concrete surface, the locations and progress of the damage with corrosion time can be detected effectively. The maximum error in the estimated deflection from PCFL sensors mounted on the concrete surface compared to the LVDTs before the onset and after 24 h of accelerated corrosion was 0.5% and 2.5%, respectively.

Structural and physical evaluation of a reinforced beam using strain gauges

In this research project,the deformations in the longitudinal and transverse reinforcing steel of a reinforced concrete beam with 2ϕ½” were estimated.Additionally,the displacements in thecenter of thespanweremeasuredtogether with theloads, which generatedthecrackingof the beam of dimensions180 mm×240 mm×3100 mm.Displacement were performed using a linear variable displacement transducer, and strain gauges were used to measure deformations. Finally, the applied load’s measurements were obtained with a load cell Pinzuar/Model-100/20T equipment.The physical-mechanical properties of the concreteused were determined through compressive strength tests at 28 days and modulus of elasticity.For this purpose, a load-bearing frame was used to support the beam at three points for load application.The data was collected directly on the Quantum/X2 equipment and analyzed with the help of the Catman/AP software.The maximum deformations found in the bending test at three point since there inforced concrete beam we are not greater than 8483µm/mm,presenting a failure in the center of the beam due to the creep of the tensile steel for a maximum load of 3115 Kg.Finally,the physical behavior of there inforced concrete beam with applying aload allows evaluating and optimizing this kind of systems.

Electro-Hydraulic Proportional System Real Time Tracking Control Development Based on Pulse width Modulation Method

The presented work was directed to develop the dynamic performance of an electro-hydraulic proportional system (EHPS). A mathematical model of the EHPS is presented using electro- hydraulic proportional valve (EHPV) by Matlab-Simulink, which facilitates the simulation of the hydraulic behavior inside the main control unit. Experimental work is done and the closed loop system is designed using the linear variable displacement transducer sensor (LVDT). The controller of the system is an Arduino uno, which is considered as a processor of the system. The model is validated by the experimental system. The study also presents a real time tracking control method, based on pulse width modulation, by controlling the speed of the actuator to achieve the position tracking with minimum error and low transient time, by applying the constant input signal 50mm the transient time was 0.9 seconds and the error 1.8%.

Electro-Hydraulic Proportional System Real Time Tracking Control Development Based on Pulse Width Modulation Method

The present work is directed to develop the dynamic performance of an electro-hydraulic proportional system (EHPS). a mathematical model of (EHPS) is presented using electrohydraulic proportional valve (EHPV) by the aim of Matlab-simulink which facilitate the simulation of the hydraulic behavior inside the main control unit. Experimental work is done and closed loop system is designed using linear variable displacement transducer sensor (LVDT). The controller of the system is an Arduino uno which is considered as the processor of the system. The model is validated by the experimental system. The study also presents a real time tracking control method based on pulse width modulation by controlling the speed of the actuator to achieve position tracking with minimum error.

A Study of Hybrid Composite Sandwich Beam

This study presents the testing and numerical modeling results of composite sandwich beams. The sandwich beams are constructed from balsa wood in the core and high strength steel wire and E-glass fiber reinforced polymer composite in the facings. The testing of these beams is performed using a monotonic static four-point loading to failure in accordance with ASTM C393-00. Local strain distribution in the mid-span of the beams is obtained using strain gauges. Mid-span deflections of the beams are real-time measured using linear variable displacement transducer (LVDT). From the experimental results, flexural properties of the beams are calculated, including bending stiffness, bending strength, core shear strength, and facing modulus, core modulus, etc. The experimental results have shown that the beams have all failed in the compression zone by local buckling of the top face and shear of the core. The bottom skin does not exhibit any type of premature failure or distress. No bond failure of the composite in the tension zone is observed in any of the tested beams. Finite element modeling of the beam has been conducted using ANSYS. The mechanical properties of the skin and core material used in finite element modeling have been determined by testing of coupons. The predicted results are compared to experimental results, with a reasonable agreement.

Synthesis and Characterization of Dental Nanocomposite Resins Filled with Different Clay Nanoparticles

Nanotechnology comprises a promising approach towards the update of dental materials.The present study focuses on the reinforcement ofdental nanocomposite resins with diverse organomodified montmorillonite (OMMT) nanofillers. The aim is to investigate whether the presence of functional groups in the chemical structure of the nanoclay organic modifier may virtually influence the physicochemical and/or the mechanical attitude of the dental resin nanocomposites. The structure and morphology of the prepared materials were investigated by means of wide angle X-ray diffraction and scanning electron microscopy analysis. Fourier transform infrared spectroscopy was used to determine the variation of the degree of conversion over time. Measurements of polymerization shrinkage and mechanical properties were conducted with a linear variable displacement transducer apparatus and a dynamometer, respectively. All the obtained nanocomposites revealed intercalated structures and most of them had an extensive filler distribution into the polymer matrix. Polymerization kinetics werefound to be influenced by the variance of the clay organomodifier, whilenanoclays with vinyl groups considerably increased the degree of conversion. Polymerization shrinkage was almost limited up to 50% by incorporating nanoclays. The absence of reactive groups in the OMMT structure may retain setting contraction atlow levels. An enhancement of the flexural modulus was observed, mainly by using clay nanoparticles decorated with methacrylated groups, along with a decrease in the flexural strength at a high filler loading. The overall best performance was found for the nanocomposites with OMMTs containing double bonds. The significance of the current work relies on providing novel information about chemical interactions phenomena between nanofillers and the organic matrix towards the improvement of dental restorative materials.

Analisis lendutan balok beton secara eksperimental dan perhitungan metode elemen hingga (MEH) dengan aplikasi SNI 2847 : 2013

Pada makalah ini disajikan analisis lendutan balok beton dari sebuah gedung. Analisa dilakukan menggunakan software berbasis finite element method (FEM) dan eksperimental dengan tujuan untuk mengetahui pengaruh jenis tumpuan dan tipe penampang balok terhadap lendutan.Dalam analisis menggunakan software FEM dilakukan perhitungan lendutan menggunakan persamaan lendutan balok pada dua tumpuan dengan asumsi sebagai penampang balok biasa dan penampang balok T. Selain itu, juga diperhitungkan kondisi tumpuan yaitu sebagai tumpuan sederhana dan tumpuan jepit-jepit. Dalam evaluasi secara eksperimental dilakukan uji beban terhadap balok beton yang bersangkutan sesuai SNI 2847 2013. Sebagai beban uji adalah air dan sebagai pengukur lendutan adalah linear variable displacement transducer (LVDT). Perhitungan lendutan di tengah bentang dengan software berbasis FEM dengan asumsi balok T dan tumpuan jepit-jepit menghasilkan lendutan untuk balok C 1-2 sebesar 1,652 mm dan untuk balok 2 A-B sebesar 1,987 mm. Lendutan netto di tengah bentang hasil uji beban untuk balok C 1-2 adalah sebesar 1,263 mm dan untuk balok 2 A-B adalah sebesar 1,625 mm. Dengan demikian pada eksperimen ini dapat disimpulkan bahwa lendutan balok beton hasil evaluasi menggunakan software FEM melalui perhitungan dengan asumsi penampang balok T dengan kondisi tumpuan jepit-jepit adalah yang paling mendekati lendutan hasil evaluasi secara eksperimental melalui uji beban

Performance Deterioration of Heavy-Haul Railway Bridges under Fatigue Loading Monitored by a Multisensor System

Heavy-haul railway bridges play an increasingly essential role in the transportation in China due to the increasing transport volume. The performance deterioration of the scale models of a typical heavy-haul railway bridge under fatigue loading is monitored in this work, based on a multisensor system including the fiber-reinforced polymer optical fiber Bragg grating and electrical resistance strain gauges, linear variable displacement transducer, and accelerometer. Specifically, by monitoring/observing on the failure mode, fatigue life, load-midspan deflection response, material strain development, and so forth, this work develops an S-N model by comparing the relationship between fatigue life and rebar stress range with that between fatigue life and load level and proposes a damage evolution model considering the coupling of the stiffness degradation and inelastic deformation of specimens. It is found that the fatigue life of specimens is determined by the fatigue life of the rebar at the bottom and it may be lower than 2.0 million cycles with a 30-ton axle weight when environmental factors are taken into account. The predictions of the models agree well with experimental results. Therefore, this work furthers the understanding of the fatigue performance deterioration of the bridges by using a multisensor system.

Static and vibration characteristics of thin-walled box beams: An experimental investigation

Static and vibration characteristics of thin-walled straight and curved box beams were investigated experimentally. Three different beam configurations were considered for the tests: one straight and two curved box beams. The load was applied at the centroid of the box section for the straight and one curved beam specimens. However, for the other curved specimen, the load was applied eccentrically to investigate its behavior under the additional torsion induced by the eccentricity. Displacements and strains were obtained using linear variable displacement transducer, one-directional and rosette strain gages. The specimens were excited using an impact at their free ends. The time history of strains was obtained to calculate natural frequencies and damping ratios. The experiment results were compared with those obtained from three-dimensional finite element analysis for all cases. The results obtained from implementing tests on the straight specimen were also used to validate an efficient numerical method recently developed by the authors.

Real-time setup to measure radon emission during rock deformation: implications for geochemical surveillance

Laboratory experiments can represent a valid approach to unravel the complex interplay between the geochemical behaviour of radon and rock deformation mechanisms. In light of this, we present a new real-time experimental setup for analysing in continuum the alpha-emitting 222Rn and 220Rn daughters over variable stress–strain regimes. The most innovative segment of this setup consists of the radon accumulation chamber obtained from a tough and durable material that can host large cylindrical rock samples. The accumulation chamber is connected, in a closed-loop configuration, to a gas-drying unit and to a RAD7 radon monitor. A recirculating pump moves the gas from the rock sample to a solid-state detector for alpha counting of radon and thoron progeny. The measured radon signal is enhanced by surrounding the accumulation chamber with a digitally controlled heating belt. As the temperature is increased, the number of effective collisions of radon atoms increases favouring the diffusion of radon through the material and reducing the analytical uncertainty. The accumulation chamber containing the sample is then placed into a uniaxial testing apparatus where the axial deformation is measured throughout a linear variable displacement transducer. A dedicated software allows obtaining a variety of stress–strain regimes from fast deformation rates to long-term creep tests. Experiments conducted with this new real-time setup have important ramifications for the interpretation of geochemical anomalies recorded prior to volcanic eruptions or earthquakes.