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Go to Editorial ManagerIn this paper, the cross section behavior of reinforced concrete columns made of normal and hybrid reactive powder concrete (hybrid by steel and polypropylene fibers) under concentric and eccentric vertical load was study. The casted columns were cured in two different type tap water for 28 days and chloride water for six months. Chloride salts with concentration was 8341.6 mg/l. Three variables were adopted in the experimental program; concrete type, curing type and the eccentricity of vertical load. Twenty (120x120x1200) mm columns were casted and tested depending on these variables. The different eccentricities were (0, 50,100 and 150) mm and where (e/h) were (0, 0.42, 0.83 and 1.25) respectively from the center of column, the other types of loading are tested the specimens as beam._x000D_ The experimental results showed increasing in ultimate load capacity and higher chlorides resisting for hybrid reactive powder concrete in comparison with normal concrete in both types of curing (tap and chloride water). Through studying load deflection, test results for Normal Strength Concrete (NSC) and Hybrid Fiber Reactive Powder Concrete (HFRPC) columns that deflection for columns cured in chloride water more than tap water when compared at the same load that also by increase eccentricity leads to an increase in deflection for both cured and The neutral axis depth for HFRPC columns is more than NSC at the same load also when eccentricity increases, the compression zone decreases and neutral axis also decrease by increase eccentricity. These results occur when columns are cured in tap and chloride water._x000D_
In term of sustainable practices, recycling plays a crucial role, particularly in the construction industry where the disposal of old structures generates significant waste. Recycling old concrete not only reduces the need for new natural resources but also eliminate waste accumulation. Numerous research study the behaviors of recycled aggregate concretes, practically focusing on the long term behaviours. A large number of studies have demonstrated that concrete made from recycled aggregate exhibits poorer long-term characteristics in comparison to aggregate from nature concrete. The long-term behaviour can be affected by three factor which is creep, shrinkage and tension stiffening. Greater management of these variables can enhance the RAC's long-term properties. The review will specifically focus on the influence of time dependent parameters i.e., creep, shrinkage, and loss of tension stiffening with time. Furthermore, it will explore the long-term deflection predicted from code used for deflection prediction, considering three codes: ACI, EC2, and the CSA code. The purpose of this paper is to enhance the understanding of long-term deflection of recycled aggregate concrete beam and evaluate the effectiveness of various factors that impact their structural performance.
In this paper an experimental works conducted to study the behavior of R.C. beam with large web opening at different locations and fortified with reactive powder composite (RPC) at the extreme tension zone (bottom edge of opening) and/or extreme compression zone (Top edge of opening). The experimental study is investigate the behavior of twelve beams and study the ability of using normal strength concrete together with RPC in the same section to exploit the advantages of these two materials in optimal way. The main variables are RPC layers locations in tension zone and/or in compression zone and the locations of openings. The ultimate loads, load mid-span deflection behavior and strain for steel and concrete were discussed. The experimental results showed that the ultimate strength was decreased with increasing number of opening about 4% for beams with two openings located in shear zone and 21% for beams with three openings, thus indicating that the stiffness decreases accordingly. The using RPC layers effectively enhanced performance of hybrid beams when compared with using the normal strength concrete layers only. The using RPC layers in compression and tension zones increased the ultimate load about 47 % for beams with two opening located in shear zone, when using RPC in the tension zone and normal strength concrete in the compression zone the ultimate flexural load and ultimate deflection increase little compared with normal concrete.
This research was conducted to investigate the effect of using internal steel plates for shear reinforcement on flexural behavior of SCC beams instead of using traditional reinforcement bars (stirrups) and to study the effect of their spacing and thickness on strength. The experimental work included destructive tests on six SCC beams under two-point load. The results showed that the yield loads in all of the beams with steel plates were lower than the reference beam by (5.21%) on average, the deflection at yield load was higher by (13.72%) on average and the ultimate loads were lower by (6.77%) on average except in one beam where it was higher by (0.37%). It was also found that the ultimate deflection in beams with internal shear steel plates was lower by (10.01%) on average except in the aforementioned beam where it was higher by (2.31%). Ductility in all beams with steel plates was lower by (20.08%) on average and the strain before a load of (200kN) was higher in the longitudinal reinforcement and lower in shear steel plates and vice versa after a load of (200kN). Theoretical analysis was also carried out for all beams using the finite element program ANSYS (version 15) where theoretical results of load versus mid-span deflection relations, longitudinal reinforcement strain, shear reinforcement strain, variations of neutral axis depths and cracks patterns showed good agreement with experimental ones. Finally, some specific further studies were recommended.
This research deals with the extent to which corrosion affects the behavior of buckling for 6061-T4 aluminum alloy under increasing compressive dynamic loads. Two types of columns, long, and intermediate were used.1% of the length column is the allowable lateral deflection. This is called the critical buckling of the columns. For the purpose of calculating the critical deflection, a digital dial gauge was used and set at a distance of 0.7 of column length from the fixed end condition for the column. The experimental analysis revealed that the corrosion time negatively affects the mechanical properties of materials such as the corroded specimens of 60 days (The least time to observe the corrosion of aluminum in the soil) which have approximately 2.7 % reduction in ultimate strength compared with the non-corroded specimen. Increasing the corrosion time reduces the critical load such as the maximum reduction will be 4.24% in critical buckling load for 60 days’ corrosion time. The results obtained were experimentally compared with the theoretical formulas of the Perry-Robertson and Euler-Johnson formula with the results of the ANSYS. It was found that the Perry-Robertson formula has a good agreement with the experimental results with a safety factor of 1.2, while the Euler-Johnson formula agreed with the experimental results taking a safety factor of 1.5. The ANSYS results showed a good agreement between the measured and calculated values by taking 1.1 factor of safety.
Reinforced concrete slab with plastic voids (Bubbled Deck system) is a new type of slabs which has two-dimensional arrangement of voids within the slab that is developed to decrease the slab self-weight while maintaining approximately the same load carrying capacity as compared with the solid slabs. Plastic voided slabs have the ability to reduce concrete amount by about 30 percent and this reduction is so important in terms of cost saving and enhancement the structural performance. In this research paper investigation is carried out to study the shear strength behavior of one-way bubble deck slab using self-compacting reinforced concrete. The experimental program consists of testing thirteen one-way slabs with dimensions of (1700 length, 700 width and 150 thick) mm. One of the tested slabs is a solid slab (without balls) is used as a reference, the remaining twelve bubbled slabs with ball diameter (73, 60) mm are divided into five groups according to the parameters of the experimental work, the parameters of the experimental work include: type of slab (bubble and solid slabs), ball diameter (73, 60) mm, shear reinforcement and spacing between balls. The experimental results showed that the bubbled slabs without shear reinforcement have a decrease in the ultimate load as compared to solid slab by about 3.7% to 14.3% and an increase in the deflection at ultimate load by about 10% to 22%, at the same time the first crack load decreases by about 15.3% to 42.4% as compared to solid slab due to decreases of moment of inertia of bubble slab compared to solid slab. Also, the results showed that the bubbled slabs withe shear reinforcement (multi-leg) have an increase in the ultimate load as compared to solid slab by about 35.4% to 57.3% and an increase in the deflection at ultimate load by about 1% to 15%, at the same time the first crack load decreases by about 2.8% to 27.4% as compared to solid slab.
Searching for an optimal alternative to normal cement concrete (NCC) is an urgent need nowadays in order to reduce carbon dioxide emissions, reduce energy, and reduce waste materials. Therefore, this research aims to examine zero cement concrete (ZCC) slabs under monotonic loads with several paramedic studies including slab thickness (60mm, 80mm, 100 mm), bar spacing (75mm, 150mm, and 225mm), and molarity concentration (6M, 8M, and 10M). The results showed the behavior of reinforced ZCC slabs is similar to or slightly lower than that of normal cement concrete. Increasing slab thickness from 60 mm to 80 mm and 100 mm enhanced the slab stiffness, increased the applied loads, and reduced the vertical mid-span deflection. Decreasing bar spacing by 33.33% and 66.67% relative to 225 mm reduced also the deflection. The energy absorption was increased due to increasing the slab thickness and bar spacing. When the load increased, the slabs eventually failed by a typically visible punching cone (punching shear).
In this work it had been focused on the possibility of replacement of steel spring in suspension system by fiber reinforced polymer composite that is responsible for light weight of spring which leads to reduces the weight of vehicle and improve fuel efficiency. This type of spring used in motor cycles, light weight vehicle. The design will be simulated by ANSYS workbench. Then, E-Glass fiber has been used to fabricate helical compression spring of 40% fiber volume fraction of glass. with polyester resin. The deflection of glass reinforced composite spring is more than steel spring but within permissible limit. weight of composite spring is reduced by 57% than of steel.
Forced vibration has been experimentally investigated on a model consists of circular pipe with1.6m length. The pipe built in tank (1.2m length, 0.6m height and 0.6m width) horizontally at 0.4m height with two different diameters d=15mm and d=35mm. The pipe conveying laminar flow in the fully developed region, of Reynolds number equals 2000. The experimental results of span pipe conveying water at five stations of forced excitation vibration were studied. The harmonic forced vibration with two different excitation frequencies (10 Hz and 15 Hz) are imposed at all of the five locations. The distance between two stations is (0.2m). Two conditions of pipe environment have been applied, the first in air and the other was immersed in water. It is concluded that the effect of flow induced vibration due to the pipe conveying fluid increases the maximum deflection when the fluid speed increases. The water surrounds the pipes reduce the effect of excitation vibration about (33 – 46%). The effect difference between the excitation frequencies was about (4 – 7%).
ESAR feet are prosthetic feet with carbon fiber parts that store mechanical energy while standing and release it during propulsion. It is believed to reduce the metabolic energy needed for walking, and to promote the economy of walking. However, there is little scientific evidence to support this claim. This study aimed to compare the energy storage properties of two prosthetic feet made of carbon fiber using the P-Walk, G-Walk, and Podium devices developed for gait analysis, which is a systematic examination of human movement, enabling phasing, estimation of musculoskeletal performance, and determination of kinematic and motor parameters. The amount of energy was calculated for each of the feet using the load deflection test, and the results showed that the new artificial foot with an energy of 6.186 joules showed a great improvement in the results of the tests compared to the old artificial foot with an energy of 3.403 joules. The Podium device tests showed a significant improvement in walking patterns and pressure distribution after using a new foot. The pressure distribution became almost equal on both sides, and the angular deviation of COP decreased from -7 to 1.3 degrees. Ground reaction force vector tilt results also improved, with a body angle of 0 degrees and inclination varying slightly depending on the tibiofemoral angle for males. P-Walk results reveal left-sided static test pressure distribution, exposing amputees to osteoarthritis risk and revealing lack of confidence in prosthetic foot. After use the new prosthetic foot, amputees press more on right foot, indicating balance restoration. The G-Walk device shows the effectiveness of both healthy left and prosthetic foot when walking on an amputated right leg when use the new prosthetic foot. The amputated side's performance is similar to a healthy limb, with minimal difference and within normal limits. Walking cadence and speed values are within normal ranges, while stride length and step length are outside normal ranges for both sides. Obliquity results show a small difference in pelvic angles due to weak pelvic muscles, but these are close to standard values for prosthetic foot use. The amputee's opinions about the evaluation of the new prosthetic foot were good when using the T-score by 61.0 with a rate of 86.4%. It was a significant improvement compared to the old foot with an evaluation of 53.6 by 63.9%.
In this study a numerical examples and solutions has been obtained by using three system of beam resting on elastic foundation (BOEF) which was adopted previously by three different engineering software. The first part of this paper was related to verify the model of (BOEF) by using ETABS2015 by make a comparison with previous results by determination the maximum settlements at the mid of span which show a good agreement between ETABS2015 and other results, where the total differences was vary from 2.13 % to 3.27%. . The second part of this study was highlighted on the settlement of BOEF with different parametric study (beam thickness, soil subgrade reaction(KS) and the load location), case (1) was selected for this goal. In this paper it is found that the differential settlement along the beam are decrease as increasing in the beam stiffness in addition to possibility to obtain uplift (positive settlement ) for some type of changing in the load location specially for higher thick beam . It was noticed that the settlement are increased significantly as reducing in the (KS). Finally this study show a different form of deflection by combination two of parametric study.
This paper presents a numerical investigation to study the effect of variations in displacement history sequence and magnitude on cyclic response of RC tapered (haunched) beams (RCHBs).Five simply supported RCHBs (four haunched and one prismatic) were selected from experimental work carried out by Aranda et al. The selected variables included were five loading history types. The first part of this study focused to verify the finite element analysis with selected experimental work and the second part of this study focused too studying the effect of varying in loading history to the response of RCHBs. The finite element code Abaqus was used in the modeling. The adopted cyclic simulation performance of the selected beams using the plastic- damage model for concrete developed by Lubliner and Lee & Fenves. The constitutive model of plain concrete describing the uniaxial compression response under cyclic loading proposed by Thorenfeldt, and the uniaxial tension response follows the softening law proposed by Hordijk was used in the modeling. Menegotto-Pinto model was used to simulate the steel response. Model verification has shown A good agreement to the selected experimental work. The variations in loading history will decrease the ultimate load and corresponding deflection with increase in the number of cycles at ultimate load.