scholarly journals Mechanical Properties of Corroded-Damaged Reinforced Concrete Pile-supporting Wharves

2020 ◽  
Vol 6 (12) ◽  
pp. 2375-2396
Author(s):  
Cecielle N. Dacuan ◽  
Virgilio Abellana ◽  
Hana Astrid Canseco
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Cross Sectional Area ◽  
Constant Current ◽  
Sectional Area ◽  
Reinforced Concrete Structure ◽  
Cross Sectional ◽  
Constant Current Density ◽  
Remaining Service Life ◽  
Residual Capacity

Corrosion is one of the significant deteriorations of reinforced concrete structures. It accelerated the performance loss of the structures, leading to a cross-sectional reduction of steel, which affects its mechanical properties, particularly its tensile capacity and ductility. The purpose of this study is to assess the serviceability and safety of corroded-damaged structures, particularly those exposed to aggressive marine environments. A total of 54 pcs of 150 mm-diameter and 300mm-height of cylindrical specimen were cast. Small-scaled specimens were accelerated to corrosion using impressed current techniques with a constant current density of 200 µA/cm2. Samples were immersed in a simulated environment with a 5% solution of sodium bicarbonate during corrosion acceleration. Corrosion alters the surface configuration of the steel bar. Pitting corrosions due to chloride aggression causes the residual cross-sectional area of corroded rebars to no longer round and varies considerably along its circumference and length. The reduction of the steel cross-sectional area has a significant impact on the degradation of the strength and durability of reinforcing structures. The residual capacity of the corroded reinforcement decreases with the reduction of the cross-sectional area of the steel reinforcement. The rate of corrosion affects the extent of the remaining service life of a corroded reinforced concrete structure. Doi: 10.28991/cej-2020-03091624 Full Text: PDF

Comparison of the Cross Sectional Area, the Loss in Volume and the Mechanical Properties of LAE442 and MgCa0.8 as Resorbable Magnesium Alloy Implants after 12 Months Implantation Duration

2010 ◽  
Vol 638-642 ◽  
pp. 675-680 ◽  
Author(s):  
Martina Thomann ◽  
Nina von der Höh ◽  
Dirk Bormann ◽  
Dina Rittershaus ◽  
C. Krause ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Degradation Process ◽  
Cross Sectional Area ◽  
Bending Test ◽  
Sectional Area ◽  
Cross Sectional ◽  
Initial Strength ◽  
Three Point Bending ◽  
The Cross

Current research focuses on magnesium based alloys in the course of searching a resorbable osteosynthetic material which provides sufficient mechanical properties besides a good biocompatibility. Previous studies reported on a favorable biocompatibility of the alloys LAE442 and MgCa0.8. The present study compared the degradation process of cylindrical LAE442 and MgCa0.8 implants after 12 months implantation duration. Therefore, 10 extruded implants (2.5 x 25 mm, cross sectional area 4.9 mm²) of both alloys were implanted into the medullary cavity of both tibiae of rabbits for 12 months. After euthanization, the right bone-implant-compound was scanned in a µ-computed tomograph (µCT80, ScancoMedical) and nine uniformly distributed cross-sections of each implant were used to determine the residual implants´ cross sectional area (Software AxioVisionRelease 4.5, Zeiss). Left implants were taken out of the bone carefully. After weighing, a three-point bending test was carried out. LAE442 implants degraded obviously slower and more homogeneously than MgCa0.8. The mean residual cross sectional area of LAE442 implants was 4.7 ± 0.07 mm². MgCa0.8 showed an area of only 2.18 ± 1.03 mm². In contrast, the loss in volume of LAE442 pins was more obvious. They lost 64 % of their initial weight. The volume of MgCa0.8 reduced clearly to 54.4 % which corresponds to the cross sectional area results. Three point bending tests revealed that LAE442 showed a loss in strength of 71.2 % while MgCa0.8 lost 85.6 % of its initial strength. All results indicated that LAE442 implants degraded slowly, probably due to the formation of a very obvious degradation layer. Degradation of MgCa0.8 implants was far advanced.

Habitual loading results in tendon hypertrophy and increased stiffness of the human patellar tendon

2008 ◽  
Vol 105 (3) ◽  
pp. 805-810 ◽  
Author(s):  
C. Couppé ◽  
M. Kongsgaard ◽  
P. Aagaard ◽  
P. Hansen ◽  
J. Bojsen-Moller ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Patellar Tendon ◽  
Cross Sectional Area ◽  
Isometric Contractions ◽  
Sectional Area ◽  
Cross Sectional ◽  
Strength Difference ◽  
Distal Tendon

The purpose of this study was to examine patellar tendon (PT) size and mechanical properties in subjects with a side-to-side strength difference of ≥15% due to sport-induced loading. Seven elite fencers and badminton players were included. Cross-sectional area (CSA) of the PT obtained from MRI and ultrasonography-based measurement of tibial and patellar movement together with PT force during isometric contractions were used to estimate mechanical properties of the PT bilaterally. We found that distal tendon and PT, but not mid-tendon, CSA were greater on the lead extremity compared with the nonlead extremity (distal: 139 ± 11 vs. 116 ± 7 mm2; mid-tendon: 85 ± 5 vs. 77 ± 3 mm2; proximal: 106 ± 7 vs. 83 ± 4 mm2; P < 0.05). Distal tendon CSA was greater than proximal and mid-tendon CSA on both the lead and nonlead extremity ( P < 0.05). For a given common force, stress was lower on the lead extremity (52.9 ± 4.8 MPa) compared with the nonlead extremity (66.0 ± 8.0 MPa; P < 0.05). PT stiffness was also higher in the lead extremity (4,766 ± 716 N/mm) compared with the nonlead extremity (3,494 ± 446 N/mm) ( P < 0.05), whereas the modulus did not differ (lead 2.27 ± 0.27 GPa vs. nonlead 2.16 ± 0.28 GPa) at a common force. These data show that a habitual loading is associated with a significant increase in PT size and mechanical properties.

scholarly journals Sex Differences in the Morphological and Mechanical Properties of the Achilles Tendon

2021 ◽  
Vol 18 (17) ◽  
pp. 8974
Author(s):  
Xini Zhang ◽  
Liqin Deng ◽  
Songlin Xiao ◽  
Lu Li ◽  
Weijie Fu
Keyword(s):  
Mechanical Properties ◽  
Achilles Tendon ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Cross Sectional Area ◽  
Morphological Properties ◽  
Sectional Area ◽  
Cross Sectional ◽  
Force Peak ◽  
Strain Stress

Background: Patients with Achilles tendon (AT) injuries are often engaged in sedentary work because of decreasing tendon vascularisation. Furthermore, men are more likely to be exposed to AT tendinosis or ruptures. These conditions are related to the morphological and mechanical properties of AT, but the mechanism remains unclear. This study aimed to investigate the effects of sex on the morphological and mechanical properties of the AT in inactive individuals. Methods: In total, 30 inactive healthy participants (15 male participants and 15 female participants) were recruited. The AT morphological properties (cross-sectional area, thickness, and length) were captured by using an ultrasound device. The AT force–elongation characteristics were determined during isometric plantarflexion with the ultrasonic videos. The AT stiffness was determined at 50%–100% maximum voluntary contraction force. The AT strain, stress, and hysteresis were calculated. Results: Male participants had 15% longer AT length, 31% larger AT cross-sectional area and 21% thicker AT than female participants (p < 0.05). The plantarflexion torque, peak AT force, peak AT stress, and AT stiffness were significantly greater in male participants than in female participants (p < 0.05). However, no significant sex-specific differences were observed in peak AT strain and hysteresis (p > 0.05). Conclusions: In physically inactive adults, the morphological properties of AT were superior in men but were exposed to higher stress conditions. Moreover, no significant sex-specific differences were observed in peak AT strain and hysteresis, indicating that the AT of males did not store and return elastic energy more efficiently than that of females. Thus, the mechanical properties of the AT should be maintained and/or improved through physical exercise.

Effects of cross-sessional area and aspect ratio coupled with orientation on mechanical properties and deformation behavior of Cu nanowires

2021 ◽  
Author(s):  
Hui Cao ◽  
Wenke Chen ◽  
Zhiyuan Rui ◽  
Changfeng Yan
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Cu Nanowires ◽  
The Cross

Abstract Metal nanomaterials exhibit excellent mechanical properties compared with corresponding bulk materials and have potential applications in various areas. Despite a number of studies of the size effect on Cu nanowires mechanical properties with square cross-sectional, investigations of them in rectangular cross-sectional with various sizes at constant volume are rare, and lack of multifactor coupling effect on mechanical properties and quantitative investigation. In this work, the dependence of mechanical properties and deformation mechanisms of Cu nanowires/nanoplates under tension on cross-sessional area, aspect ratio of cross-sectional coupled with orientation were investigated using molecular dynamics simulations and the semi-empirical expressions related to mechanical properties were proposed. The simulation results show that the Young’s modulus and the yield stress sharply increase with the aspect ratio except for the <110>{110}{001} Cu nanowires/nanoplates at the same cross-sectional area. And the Young’s modulus increases while the yield stress decreases with the cross-sectional area of Cu nanowires. However, both of them increase with the cross-sectional area of Cu nanoplates. Besides, the Young’s modulus increases with the cross-sectional area at all the orientations. The yield stress shows a mildly downward trend except for the <111> Cu nanowires with increased cross-sectional area. For the Cu nanowires with a small cross-sectional area, the surface force increases with the aspect ratio. In contrast, it decreases with the aspect ratio increase at a large cross-sectional area. At the cross-sectional area of 13.068 nm2, the surface force decreases with the aspect ratio of the <110> Cu nanowires while it increases at other orientations. The surface force is a linearly decreasing function of the cross-sectional area at different orientations. Quantitative studies show that Young’s modulus and yield stress to the aspect ratio of the Cu nanowires satisfy exponent relationship. In addition, the main deformation mechanism of Cu nanowires is the nucleation and propagation of partial dislocations while it is the twinning-dominated reorientation for Cu nanoplates.

Determinants of forced expiratory flows in newborn infants

1982 ◽  
Vol 53 (5) ◽  
pp. 1220-1227 ◽  
Author(s):  
L. M. Taussig ◽  
L. I. Landau ◽  
S. Godfrey ◽  
I. Arad
Keyword(s):  
Newborn Infants ◽  
Cross Sectional Area ◽  
Physiological Data ◽  
Sectional Area ◽  
Older Children ◽  
Cross Sectional ◽  
Thoracic Gas Volume ◽  
Residual Capacity ◽  
The Cross ◽  
Gas Volume

Maximal flows at functional residual capacity (VmaxFRC) from partial expiratory flow-volume (PEFV) curves (achieved with rapid compression of the chest) were obtained on 11 healthy newborn babies. Mean VmaxFRC, size corrected by dividing absolute values by measured thoracic gas volume, was 1.90 TGV's/s. Specific upstream conductances were high, and the cross-sectional area of the flow-limiting segment was estimated to be approximately 0.30 cm2 in the three infants on whom recoil pressures at FRC were also measured. The cross-sectional area of the major bronchi in the neonate is approximately 0.26–0.30 cm2. PEFV curves were convex to the volume axis. Many of the neonates increased their flows while breathing a helium-oxygen gas mixture. These results suggest 1) size-corrected flows are higher in the neonate than in older children or adults; 2) the site of the flow-limiting segment at FRC during maximal expiratory maneuvers is in large proximal airways, similar to the adult; and 3) the relationship of airway size to parenchymal size may be similar in neonates and adults or, in fact, airways may be larger, relative to parenchyma, in neonates. These physiological data do not support the hypothesis, based on pathological studies, that peripheral airways are disproportionately smaller (when compared with central airways) in infants than in adults.

scholarly journals Effects of Advanced Glycation Endproducts on the Mechanical Properties of Posterior Tibialis in Individuals with Diabetes Mellitus

2019 ◽  
Vol 4 (4) ◽  
pp. 2473011419S0045
Author(s):  
Jennifer A. Zellers ◽  
Jeremy Eekhoff ◽  
Remy Walk ◽  
Simon Y. Tang ◽  
Mary K. Hastings ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Mechanical Properties ◽  
Mechanical Testing ◽  
Advanced Glycation Endproducts ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Advanced Glycation ◽  
Cross Sectional ◽  
Glycation Endproducts ◽  
Wet Weight

Category: Diabetes Introduction/Purpose: Advanced glycation endproducts (AGEs) accumulate in tendon tissue in individuals with diabetes mellitus (DM). Although AGEs have been shown to impact tendon function by decreasing collagen sliding, this relationship has not been explored in humans with diabetes. Despite the prevalence of foot deformity in this population and implications of posterior tibialis dysfunction, the mechanical behavior of the posterior tibialis tendon has only been reported in a small (n=5), cadaveric study that did not report DM status. Therefore, the purpose of this study is to determine the effects of DM-associated AGEs accumulation on the mechanical properties of the posterior tibialis tendon. Methods: Posterior tibialis tendons were collected from individuals with and without DM undergoing lower extremity amputation. A 1-2 mm tendon transection was used for AGEs quantification. AGEs were quantified via fluorescence following papain digestion and hydrolyzation as described previously. Fluorescence was compared to a quinine standard to calculate AGEs content, which was normalized to sample wet weight. Tensile mechanical testing was completed with the remaining specimen (˜25 mm long). Tendon cross-sectional area was measured with a non-contact laser scanning device. Specimens were preloaded to 10 N and preconditioned for 10 cycles at 6% strain, subjected to stress-relaxation at 6% strain for 10 minutes, and loaded with a triangular waveform to a maximum of 10% strain at a rate of 1% strain per second. Individual values and group descriptive statistics are reported for AGEs content and mechanical testing. Relationships between AGEs content and various mechanical testing parameters were evaluated using Spearman correlation. Results: Six individuals (5 with DM, 4 male, mean(SD) age: 56(5)years) were included. AGEs content was increased in DM tendon (DM: 20.5(5.1), non-DM: 9.5 ng quinine/mg wet weight). Compared to non-DM tendon, DM tendons had larger cross-sectional area (DM: 44.3(4.9), non-DM: 11mm2). From stress relaxation, DM tendons had smaller peak (DM: 0.41(0.25), non-DM: 1.16 MPa) and equilibrium stress (DM: 0.23(0.13), non-DM: 0.83 MPa), and larger percent relaxation (DM: 46(6)%, non-DM: 29%)(Figure 1-A). DM tendons had decreased maximum stress at 10% strain (DM: 0.63(0.45), non-DM: 1.75 MPa), increased linear stiffness (DM: 35.2(27.6), non-DM: 19.2N/mm), and decreased linear modulus (DM: 8.5(7.0), non-DM: 20.1 MPa)(Figure 1-B, C) compared to non- DM tendon. Hysteresis (i.e., energy loss upon unloading) was higher in DM tendons (DM: 0.35(0.05), non-DM: 0.22), and positively correlated to AGEs (rho=0.943, p=0.005, Figure 1-D). Conclusion: Posterior tibialis tendons with DM exhibited increased AGEs content and altered mechanical properties. DM tendons were less stiff when accounting for cross-sectional area but had 2-4x the cross-sectional area of non-DM tendon, with inconsistent patterns in total tendon stiffness potentially attributable to several factors. DM tendons showed impaired energy storage and return, which was most strongly associated with AGEs. Non-DM samples were limited and the linear modulus was smaller than previously reported, however, all but one DM tendon had a modulus less than 50% of the non-DM sample. Future work will explore the mechanisms of AGEs-associated DM tendon impairments.

Effect of position and lung volume on upper airway geometry

1987 ◽  
Vol 63 (1) ◽  
pp. 375-380 ◽  
Author(s):  
J. M. Fouke ◽  
K. P. Strohl
Keyword(s):  
Lung Volume ◽  
Supine Position ◽  
Upper Airway ◽  
Upright Position ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Position Change ◽  
Cross Sectional ◽  
Acoustic Reflection ◽  
Residual Capacity

The occurrence of upper airway obstruction during sleep and with anesthesia suggests the possibility that upper airway size might be compromised by the gravitational effects of the supine position. We used an acoustic reflection technique to image airway geometry and made 180 estimates of effective cross-sectional area as a function of distance along the airway in 10 healthy volunteers while they were supine and also while they were seated upright. We calculated z-scores along the airway and found that pharyngeal cross-sectional area was smaller in the supine than in the upright position in 9 of the 10 subjects. For all subjects, pharyngeal cross-sectional area was 23 +/- 8% smaller in the supine than in the upright position (P less than or equal to 0.05), whereas glottic and tracheal areas were not significantly altered. Because changing from the upright to the supine position causes a decrease in functional residual capacity (FRC), six of these subjects were placed in an Emerson cuirass, which was evacuated producing a positive transrespiratory pressure so as to restore end-expiratory lung volume to that seen before the position change. In the supine posture an increase in end-expiratory lung volume did not change the cross-sectional area at any point along the airway. We conclude that pharyngeal cross-sectional area decreases as a result of a change from the upright to the supine position and that the mechanism of this change is independent of the change in FRC.

Analysis of pulmonary vascular interdependence in excised dog lobes

1980 ◽  
Vol 48 (3) ◽  
pp. 450-467 ◽  
Author(s):  
J. C. Smith ◽  
W. Mitzner
Keyword(s):  
Cross Sectional Area ◽  
Sectional Area ◽  
Mechanical Interaction ◽  
Elasticity Solution ◽  
Cross Sectional ◽  
Lung Inflation ◽  
Residual Capacity ◽  
Stress And Deformation ◽  
Arteries And Veins

The pressure-volume behavior of intraparenchymal extra-alveolar arteries and veins was measured at various lung inflation states by inflating and deflating the vasculatures with air. The vascular volumes at specific vascular pressures (Pv) and transpulmonary pressures (Ptp) were partitioned into components of axial length and cross-sectional area. An analysis of the interrelationships between the perivascular pressure (Px), the vascular pressure vs. cross-sectional area behavior, and the Ptp is presented. For in vivo values of Pv, at functional residual capacity, the vascular-parenchymal mechanical interaction was small and values of arterial and venous Px approximately Ppl. With increasing Ptp to 30 cmH2O, values of both the arterial and venous Px relative to Ppl (Px - Ppl) decreased to approximately -5 cmH2O, indicating that the magnitude of the vascular-parenchymal interaction with increasing Ptp is similar for both arteries and veins in the in vivo state. At any fixed Ptp, values of arterial and venous Px - Ppl decreased nearly linearly with decreasing vascular cross-sectional area. These results were generally consistent with a linear continuum elasticity solution relating stress and deformation in the perivascular parenchyma.

scholarly journals ANALISIS KOLOM BETON BERTULANG PADA PENAMPANG PERSEGI BERLUBANG

2019 ◽  
Vol 11 (1) ◽  
pp. 19-26
Author(s):  
Amrun Nasution ◽  
Mukhlis Islam
Keyword(s):  
Reinforced Concrete ◽  
Axial Force ◽  
Analytical Method ◽  
Concrete Columns ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Power Difference ◽  
Strain Relationship ◽  
Spread Sheet

Installation of the pipe in the column (conduit) such as electrical and sanitary plumbing installations are found in the structure of reinforced concrete columns. This causes it to be a hollow column. The existence of holes cause a reduction in cross sectional area of the column and can result in reduced strength of a column. The purpose of this study was to know the  power  difference  hollow concrete  columns  with  concrete  columns  are not hollow and produce an analysis of the interaction in the form graphics axial force (Pn) and nominal torque (Mn). The analytical method developed by using square column spread sheet applications and use the stress-strain relationship hognestad. Analysis of the hollow square column in this study as many as 720 samples. This study used 300x300-600x600 mm dimensions with an increase of 100 mm. Quality concrete (f'c) used was 25-30 MPa to 2.5 MPa rise. Quality reinforcement (fy) used was 400 MPa and the ratio of the reinforcement taken from 1% -8% with an increase of 2% of the cross sectional area of the column, with the amount of reinforcement as much as 12-20 pieces of reinforcement to rise 4 pieces. Widely used hole that is 3% -7%, with an increase of 1%. The analysis showed a decrease in Pn-Mn hollow column to column was not perforated. The decrease Pn maximum of 7.20% in the area of hole 7% by eccentricity to d amounting to 8.01% and the maximum Mn decrease of 10.91% in the area of hole 7% by eccentricity to d amounting to 20.51%.

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