scholarly journals Axial Compression Behavior of Ferrocement Geopolymer HSC Columns

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3789
Author(s):  
Taha Awadallah El-Sayed
Keyword(s):  
Axial Compression ◽  
Failure Load ◽  
Volume Fraction ◽  
Low Cost ◽  
Cementitious Materials ◽  
Concrete Cover ◽  
Wire Mesh ◽  
Ultimate Failure Load ◽  
Failure Loads ◽  
Ultimate Failure

Geopolymer concrete (GC) is a substantial sort that is created by utilizing metakaolin, ground granulated blast furnace slag (GGBS), silica fumes, fly ash, and other cementitious materials as binding ingredients. The current study concentrated on the structural behavior of the ferrocement geopolymer HSC-columns subjected to axial loading and produced using rice straw ash (RSA). The major goal of this research was to use the unique features of the ferrocement idea to manufacture members that function as columns bearing members. As they are more cost-effective and lower in weight, these designed elements can replace traditional RC members. The study also intended to reduce the cost of producing new parts by utilizing low-cost materials such as light weight expanded and welded wire meshes, polyethylene mesh (Tensar), and fiber glass mesh. For this purpose, an experimental plan was conducted and a finite element prototype with ANSYS2019-R1 was implemented. Nine geopolymer ferrocement columns of dimensions of 150 mm × 150 mm × 1600 mm with different volume-fraction and layers as well as a number of metallic and nonmetallic meshes were examined under axial compression loading until failure. The performance of the geopolymer columns was examined with consideration to the mid-span deflection, ultimate failure load, first crack load with various phases of loading, the cracking patterns, energy absorption and ductility index. Expanded or welded ferrocement geopolymer columns showed greater ultimate failure loads than the control column. Additionally, using expanded or welded columns had a considerable effect on ultimate failure loads, where the welded wire mesh exhibited almost 28.10% compared with the expanded wire mesh. Columns reinforced with one-layer of nonmetallic Tensar-mesh obtained a higher ultimate failure load than all tested columns without concrete cover spalling. The analytical and experimental results were in good agreement. The results displayed an accepted performance of the ferrocement geopolymer HSC-columns.

scholarly journals All Soft-suture Anchor versus Suture Bridge Construct for Insertional Achilles

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0006
Author(s):  
Kenneth Hunt ◽  
Pam Kumparatana ◽  
Sophia Anderson ◽  
Todd Baldini ◽  
Daniel Moon ◽  
...  
Keyword(s):  
Failure Load ◽  
Lateral Displacement ◽  
Clinical Failure ◽  
Suture Anchors ◽  
Suture Bridge ◽  
Ultimate Failure Load ◽  
Failure Loads ◽  
Tendon Thickness ◽  
Ultimate Failure ◽  
Group 2

Category: Ankle Introduction/Purpose: New techniques and anchors have been developed for the surgical treatment of insertional Achilles tendinopathy and rupture to allow for earlier return to postoperative weight bearing and accelerated rehabilitation. Two recently introduced soft tissue-to-bone anchor technology have purported advantages for insertional Achilles repairs. Knotless suture anchors allow suture tension to be precisely controlled with a ratcheting mechanism. The other is a suture bridge construct fastened with biotenodesis screws, increasing the soft tissue footprint and reducing the risk of suture pullout through the tendon. However, neither technology has been studied in a biomechanical model of Achilles tendon repair. We hypothesized that there would be no difference in the biomechanical characteristics of a single-row all-suture anchor repair to a double-row repair with knotless anchors and suture tape. Methods: Six matched-pairs of fresh-frozen lower leg cadaveric specimens (12 total) were obtained. All tendons were completely detached from their calcaneal insertions and tendon thickness was measured. Calcaneal exostectomies were performed (e.g., Haglunds removal) above the Achilles insertion. Group 1 was repaired with a single-row construct with two all-soft anchors. Group 2 was repaired with a double-row suture bridge construct with two knotless anchors distally and two suture tape anchors proximally. The repaired specimens were cyclically loaded from 10N to 100N at 1 Hz for 2,000 cycles then to failure at 1mm/sec. A motion capture system measured Achilles-calcaneal displacement at the medial and lateral anchors. Paired t-tests and linear mixed models (LMMs) were used to analyze the following outcomes: clinical failure load, ultimate failure load, Achilles-calcaneal medial and lateral displacement, distance at ultimate failure load, tendon thickness, footprint, and mode of failure. A p-value of <0.05 was considered statistically significant. Results: Group 2 showed significantly less Achilles-calcaneal overall medial and lateral displacement, 19.5% and 36.9% respectively (Table 1). Group 2 showed a statistical trend toward greater clinical and ultimate failure load, 23.8% and 34.2%, respectively (Table1). LMM analyses showed that a suture bridge repair over all-soft anchor repair was independently associated with a 50.24N increase in the load to clinical failure (p=0.0011). Higher clinical failure loads were associated with higher BMI (p<0.0001), thinner tendons (p<0.0001), and smaller tendon footprints on the calcaneus (p=0.0013). Higher absolute failure loads were associated with older age (p<0.0001), higher BMI (p<0.0001), thinner tendons (p=0.0028), and larger footprints (p<0.0001). Conclusion: These data suggest a trend toward higher clinical and ultimate failure loads in a suture bridge construct compared to all-soft suture anchors for insertional Achilles repair. Loads to failure in both groups were higher than previously reported pull-out strengths for most suture anchors (150-300 N), but are lower than typical loads at the Achilles insertion during walking activities. The use of the suture bridge repair method may result in superior loads to failure compared to all-soft anchors. Patient age, BMI and tendon thickness impact failure loads. Adequate healing should be allowed followed repair of complete Achilles detachment.

The evaluation of the failure loads of plane frames

1968 ◽  
Vol 306 (1486) ◽  
pp. 297-311 ◽  
Keyword(s):  
Failure Load ◽  
Plastic Hinge ◽  
Second Order ◽  
Order Effects ◽  
Deformation Characteristics ◽  
Computer Approach ◽  
Ultimate Failure Load ◽  
Plane Frames ◽  
Failure Loads ◽  
Ultimate Failure

The significance of the ultimate failure load of a structure is widely recognized, yet its determination has been a considerable task. Various propositions have been put forward since the formulation of the well-known plastic theory. These have been either of empirical nature such as the Merchant-Rankine formula or laborious such as the method of following the sequence of hinge formation. In this paper the main propositions are discussed briefly. A method is then presented to evaluate the failure loads of plane frames without following the sequence of plastic hinge formation. Instead the method utilizes the elastic as well as plastic load-deformation characteristics of frames, including the second-order effects involved in both. The theoretical validity of the proposed method is studied and illustrative examples are given. Comparisons are then made with experimental observations on frames loaded proportionally up to collapse. A summary of a computer approach is presented, but throughout the paper atten­tion is also paid to manual procedures.

scholarly journals Different Suture Materials for Arthroscopic Transtibial Pull-out Repair of Medial Meniscal Posterior Root Tears: A Human Biomechanical Study

2019 ◽  
Vol 7 (9) ◽  
pp. 232596711987327
Author(s):  
Gilberto Y. Nakama ◽  
Zachary S. Aman ◽  
Hunter W. Storaci ◽  
Alexander S. Kuczmarski ◽  
Joseph J. Krob ◽  
...  
Keyword(s):  
Medial Meniscus ◽  
Failure Load ◽  
Clinical Care ◽  
Posterior Root ◽  
Clinical Failure ◽  
Postoperative Rehabilitation ◽  
Pull Out ◽  
Ultimate Failure Load ◽  
Ultimate Failure ◽  
Suture Tape

Background: Transtibial pull-out repair of the medial meniscal posterior root (MMPR) has been largely assessed through biomechanical studies. Biomechanically comparing different suture types would further optimize MMPR fixation and affect clinical care. Purpose/Hypothesis: The purpose of this study was to determine the optimal suture material for MMPR fixation. It was hypothesized that ultra high–molecular weight polyethylene (UHMWPE) suture tape would be biomechanically superior to UHMWPE suture and standard suture. Study Design: Controlled laboratory study. Methods: The MMPR attachment was divided in 24 human cadaveric knees and randomly assigned to 3 repair groups: UHMWPE suture tape, UHMWPE suture, and standard suture. Specimens were dissected down to the medial meniscus, and the posterior root attachments were sectioned off the tibia. Two-tunnel transtibial pull-out repair with 2 sutures, as determined by the testing group, was performed. The repair constructs were cyclically loaded between 10 and 30 N at 0.5 Hz for 1000 cycles to mimic the forces experienced on the medial meniscus during postoperative rehabilitation. Displacement was recorded at 1, 50, 100, 500, and 1000 cycles. Ultimate failure load, displacement at failure, and load at 3 mm of displacement (clinical failure) were also recorded. Results: UHMWPE suture tape had significantly less displacement of the medial meniscus when compared with standard suture at 1 (–0.22 mm [95% CI, –0.41 to –0.02]; P = .025) and 50 (–0.35 mm [95% CI, –0.67 to –0.03]; P = .029) cycles. There were no other significant differences observed in displacement between groups at any number of cycles. UHMWPE suture tape had significantly less displacement at the time of failure than standard suture (–3.71 mm [95% CI, –7.17 to –0.24]; P = .034). UHMWPE suture tape had a significantly higher load to reach the clinical failure displacement of 3 mm than UHMWPE suture (15.64 N [95% CI, 0.02 to 31.26]; P = .05). There were no significant differences in ultimate failure load between groups. Conclusion: The meniscal root repair construct with UHMWPE suture tape may be stronger and less prone to displacement than that with standard suture or UHMWPE suture. Clinical Relevance: UHMWPE suture tape may provide better clinical results compared with UHMWPE suture and standard suture.

scholarly journals Biomechanical evaluation of a novel double rip-stop technique with medial row knots for rotator cuff repair

2020 ◽  
Vol 9 (6) ◽  
pp. 285-292
Author(s):  
Zhanwen Wang ◽  
Hong Li ◽  
Zeling Long ◽  
Subin Lin ◽  
Andrew R. Thoreson ◽  
...  
Keyword(s):  
Rotator Cuff ◽  
Rotator Cuff Repair ◽  
Failure Modes ◽  
Failure Load ◽  
Biomechanical Properties ◽  
Gap Formation ◽  
Ultimate Failure Load ◽  
Fresh Frozen ◽  
Ultimate Failure ◽  
Cuff Repair

Aims Many biomechanical studies have shown that the weakest biomechanical point of a rotator cuff repair is the suture-tendon interface at the medial row. We developed a novel double rip-stop (DRS) technique to enhance the strength at the medial row for rotator cuff repair. The objective of this study was to evaluate the biomechanical properties of the DRS technique with the conventional suture-bridge (SB) technique and to evaluate the biomechanical performance of the DRS technique with medial row knots. Methods A total of 24 fresh-frozen porcine shoulders were used. The infraspinatus tendons were sharply dissected and randomly repaired by one of three techniques: SB repair (SB group), DRS repair (DRS group), and DRS with medial row knots repair (DRSK group). Specimens were tested to failure. In addition, 3 mm gap formation was measured and ultimate failure load, stiffness, and failure modes were recorded. Results The mean load to create a 3 mm gap formation in the DRSK and DRS groups was significantly higher than in the SB group. The DRSK group had the highest load to failure with a mean ultimate failure load of 395.0 N (SD 56.8) compared to the SB and DRS groups, which recorded 147.1 N (SD 34.3) and 285.9 N (SD 89.8), respectively (p < 0.001 for both). The DRS group showed a significantly higher mean failure load than the SB group (p = 0.006). Both the DRS and DRSK groups showed significantly higher mean stiffness than the SB group. Conclusion The biomechanical properties of the DRS technique were significantly improved compared to the SB technique. The DRS technique with medial row knots showed superior biomechanical performance than the DRS technique alone.

Prestressed concrete masonry walls subjected to uniform out-of-plane loading

1993 ◽  
Vol 20 (6) ◽  
pp. 969-979
Author(s):  
J. L. Dawe ◽  
G. G. Aridru
Keyword(s):  
Prestressed Concrete ◽  
Failure Load ◽  
Masonry Walls ◽  
Prestressing Force ◽  
Concrete Masonry ◽  
Ultimate Failure Load ◽  
Wall Stiffness ◽  
Out Of Plane ◽  
Ultimate Failure ◽  
Concrete Masonry Walls

Two series of post-tensioned concrete masonry walls subjected to uniform lateral loading were tested to investigate their flexural strength behaviour. Each series of walls consisted of four full-scale prestressed specimens, with varying levels of prestressing force, and one reinforced specimen. Of particular interest were the load–deflection curves, initial cracking loads, wall stiffness, crack patterns, and ultimate failure loads. An air bag test apparatus was used for applying lateral uniform pressures to the specimens. Results of this experimental investigation showed that, for a given wall thickness, increased prestressing force increases the cracking load, initial wall stiffness, and ultimate failure load. The results have established a linear relationship between increased prestressing force and initial cracking load, initial wall stiffness, and ultimate failure load. The proposed model, which takes into account changes in wall stiffness after initial cracking of the wall, accurately predicts wall behaviour. Key words: masonry, prestressed, walls, strength, behaviour, uniform, pressure, experimental, analytical.

scholarly journals Efficacy of Bone Marrow-Stimulating Technique in Rotator Cuff Repair

2017 ◽  
Vol 5 (2_suppl2) ◽  
pp. 2325967117S0008
Author(s):  
İsmail Kerem Bilsel ◽  
Fatih Yıldız ◽  
Mehmet Kapıcıoglu ◽  
Gokcer Uzer ◽  
Mehmet Elmadag ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Rotator Cuff ◽  
Failure Load ◽  
Tendon Healing ◽  
Histological Evaluation ◽  
Control Group ◽  
Time Interval ◽  
Lesser Tuberosity ◽  
Ultimate Failure Load ◽  
Ultimate Failure

Background: This study investigates the effect of microfracture as a bone marrow-stimulating(BMS) technique on rotatory cuff(RC) healing using a chronic RC tear model. Methods: Chronic retracted RC tendon tear model was created in the subscapularis(SSC) tendons of 20 New Zealand rabbits, bilaterally. The tendons were repaired after eight weeks using a single-row configuration with suture anchors. In right shoulders, tendons were repaired in a standard fashion(control group). In left shoulders, microfractures were performed on the SSC footprint before repair(microfracture group). The animals were sacrificed 8 and 16 weeks after repair. The repaired tendons were tested biomechanically for their ultimate failure load, linear stiffness and elongation at failure. Gross and histological evaluation of the tendon-to-bone healing was evaluated. Results: In every sample, the SSC tendon was attached to its footprint on the lesser tuberosity. In microfracture group, collagen fibers were organized in relatively ticker bundles at both time intervals. The mean ultimate failure load of microfracture was significantly greater than that of control group at 8 (148.4+31 N vs. 101.4+26 N; p=0.011) and 16 (155+30 N vs. 114.9+25 N; p=0.017) weeks after repair, respectively. There were no significant differences between the two groups at each time interval for linear stiffness (15.9+2.7N/mm vs. 15.8+1.3N/mm, p=0.798 and 16.9+4.3N/mm vs. 17.1+3.6N/mm, p=0.848, respectively) and elongation at failure (4.7+1.1 mm vs. 4.7+1.3 mm, p=0.848 and 4.8+1.5 mm vs. 4.9+0.9 mm, p=0.749, respectively). Conclusions: The BMS technique of microfracture on the tuberosity of the repaired chronic rotator cuff tear promotes the dynamic tendon healing with significant ultimate force to failure and apparent microscopic findings.

scholarly journals In Vitro Testing of 2 Adjustable-Loop Cortical Suspensory Fixation Systems Versus Interference Screw for Anterior Cruciate Ligament Reconstruction

2021 ◽  
Vol 9 (9) ◽  
pp. 232596712110316
Author(s):  
Gerardo L. Garcés ◽  
Oscar Martel ◽  
Alejandro Yánez ◽  
Ignacio Manchado-Herrera ◽  
Luci M. Motta
Keyword(s):  
Anterior Cruciate Ligament ◽  
Acl Reconstruction ◽  
Failure Load ◽  
Cruciate Ligament ◽  
Interference Screw ◽  
Yield Load ◽  
Ultimate Failure Load ◽  
Significant Difference ◽  
Ultimate Failure ◽  
Anterior Cruciate

Background: It is not clear whether the mechanical strength of adjustable-loop suspension devices (ALDs) in anterior cruciate ligament (ACL) reconstruction is device dependent and if these constructs are different from those of an interference screw. Purpose: To compare the biomechanical differences of 2 types of ALDs versus an interference screw. Study Design: Controlled laboratory study. Methods: ACL reconstruction was performed on porcine femurs and bovine extensor tendons with 3 types of fixation devices: interference screw, UltraButton (UB) ALD, and TightRope (TR) ALD (n = 10 for each). In addition to specimen testing, isolated testing of the 2 ALDs was performed. The loading protocol consisted of 3 stages: preload (static 150 N load for 5 minutes), cyclic load (50-250 N at 1 Hz for 1000 cycles), and load to failure (crosshead speed 50 mm/min). Displacement at different cycles, ultimate failure load, yield load, stiffness, and failure mode were recorded. Results: In specimen testing, displacement of the ALDs at the 1000th cycle was similar (3.42 ± 1.34 mm for TR and 3.39 ± 0.92 mm for UB), but both were significantly lower than that of the interference screw (7.54 ± 3.18 mm) ( P < .001 for both). The yield load of the UB (547 ± 173 N) was higher than that of the TR (420 ± 72 N) ( P = .033) or the interference screw (386 ± 51 N; P = .013), with no significant difference between the latter 2. In isolated device testing, the ultimate failure load of the TR (862 ± 64 N) was significantly lower than that of the UB (1879 ± 126 N) ( P < .001). Conclusion: Both ALDs showed significantly less displacement in cyclic loading at ultimate failure than the interference screw. The yield load of the UB was significantly higher than that of the other 2. The ultimate failure occurred at a significantly higher load for UB than it did for TR in isolated device testing. Clinical Relevance: Both UB and TR provided stronger fixation than an interference screw. Although difficult to assess, intrinsic differences in the mechanical properties of these ALDs may affect clinical outcomes.

scholarly journals Fracture damage of integrated composite joint for fuselage structure under tensile loading

2021 ◽  
Vol 39 (4) ◽  
pp. 739-746
Author(s):  
Yong Du ◽  
Yu'e Ma ◽  
Junwu Liu
Keyword(s):  
Failure Load ◽  
Failure Process ◽  
Tensile Load ◽  
Interface Debonding ◽  
Load Drop ◽  
Complex Load ◽  
Damage Initiation ◽  
Composite Joint ◽  
Ultimate Failure Load ◽  
Ultimate Failure

In order to solve the complex load transfer and structural design of the joint structures including skin, longeron and frame in the composite fuselage, the adhesively bonded integrated composite joint was designed. Static tensile test was performed and the strain-load curves and damage modes were obtained. Then the numerical simulation model of integrated composite joint was built. The damage initiation, propagation and failure process of integrated composite joint under tensile load were simulated and analyzed. Results show that: the first load drop and the ultimate failure load of the joint are 120.82 kN and 168.11 kN respectively; the initial damage occurs at the corner bend region of the lower-left corner-shaped preform, and extends across the radius bend region among short flange, long flange and web, and leads to the interface debonding of the upper and lower corner-shaped preform and the delamination of corner-shaped preform and L-shaped preform. Compared with the experimental results, the errors of the first load drop and the ultimate failure load from numerical calculated results are 6.68% and 2.61% respectively, which agree with each other very well.

scholarly journals Structural Performance of uPVC Confined Concrete Equivalent Cylinders Under Axial Compression Loads

Buildings ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 82 ◽  
Author(s):  
Abraham Mengesha Woldemariam ◽  
Walter O. Oyawa ◽  
Timothy Nyomboi
Keyword(s):  
Energy Absorption ◽  
Axial Compression ◽  
Construction Materials ◽  
Strain Curve ◽  
Fire Risk ◽  
Resistance Mechanisms ◽  
Concrete Cover ◽  
Wire Mesh ◽  
Aspect Ratios ◽  
Innovative System

There is always a need for more durable, ductile, and robust materials for buildings, bridges, and other infrastructure due to the drawbacks of existing construction materials. Some of the drawbacks are the corrosion of steel, the brittle failure of concrete, and the performance instabilities that are caused when exposed to different environments. Thus, an innovative system is required to improve the performance and retain the integrity of structures in a harsh environment. To alleviate the situation, Un-plasticized polyvinyl chloride (uPVC) tubes are used as a confining material and their performance was experimentally evaluated by testing uPVC confined equivalent cylinders. Accordingly, unconfined and uPVC confined equivalent concrete cylinders for five different concrete classes, four types of uPVC tube sizes, and the aspect ratios of two (h/D = 2) were prepared and tested under axial compression loads. The result shows that the uPVC confinement increased the strength, ductility factor, and energy absorption in between 1.28–2.35, 1.84–15.3, and 11–243 times the unconfined levels, respectively. The confinement performed well for lower concrete classes and higher thickness to diameter ratios (2t/D). The post-peak behavior of the stress-strain curve was affected by the 2t/D ratio and the absolute value of the slope decreased as the 2t/D ratio increased. Additionally, the uPVC tube has shown several advantages, such as acting as a permanent formwork, protecting the concrete from chemical attacks, preventing the segregation of concrete, preventing peeling, and taking off concrete cover, decreasing the cross-section, and resulting in lighter sections. The uPVC confinement provided a remarkable improvement on the strength, ductility, energy absorption, and post-peak behavior of concrete. Therefore, uPVC tubes can be used as confining material for bridge piers, piles, electric poles, and highway signboards, where the fire risk is very small, though additional research is required on fire resistance mechanisms, such as wire-mesh reinforced mortar cover.

Comparison of Two Proximal Osteotomies for the Treatment of Hallux Valgus

1998 ◽  
Vol 19 (7) ◽  
pp. 425-429 ◽  
Author(s):  
Mark Earll ◽  
Jennifer Wayne ◽  
Paul Caldwell ◽  
Robert Adelaar
Keyword(s):  
Hallux Valgus ◽  
Polyurethane Foam ◽  
Mechanical Characteristics ◽  
Failure Load ◽  
Testing Machine ◽  
Area Under The Curve ◽  
Metatarsal Osteotomy ◽  
Ultimate Failure Load ◽  
Initial Fixation ◽  
Ultimate Failure

Moderate to severe deformities of hallux valgus can be corrected with combination procedures, such as a proximal crescentic metatarsal osteotomy and a distal soft tissue procedure. Because crescentic osteotomy allows for motion in all planes, inadvertent metatarsal elevation can result in metatarsalgia. The crescentic shelf osteotomy (CSO) provides a plantar shelf, decreasing the complication of dorsiflexion fixation. Eighteen polyurethane foam specimens in three groups were prepared and tested to failure on a servohydraulic Instron testing machine. The mechanical characteristics of stiffness, deformation, ultimate failure load, and stored energy were compared between single-screw fixation crescentic osteotomies and single- and dual-screw CSOs in molded polyurethane foam metatarsal sawbones. In addition, 12 cadaver specimens were randomly divided, and a CSO or crescentic osteotomy was performed. Preosteotomy and postosteotomy intermetatarsal, dorsiflexion, and pronation angles were compared from radiograph measurements. The results showed comparable mechanical characteristics among the groups, as measured by the area under the curve ( P = 0.95), ultimate failure load ( P = 0.35), deformation ( P = 0.63), and stiffness ( P = 0.21). Greater improvements were seen in the CSO group compared with the crescentic osteotomy group in correction of the intermetatarsal angle (4.8° compared with 3.2°) and of the first metatarsal plantarflexion (2.3° compared with 3.2° of dorsiflexion). However, these differences were insignificant ( P = 0.10 and P = 0.41) with the numbers available. Compared with the crescentic osteotomy, a CSO may possibly provide easier initial fixation but similar mechanical properties.

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