Significant Loss Of Strength Research Articles

Seismic hybrid simulation of a nonductile RC building with severe damage to multiple columns

SummaryReinforced concrete frame structures built prior to the mid‐1970s are susceptible to brittle column failure under seismic action, potentially leading to progressive collapse of the structure. The behavior of columns susceptible to brittle shear‐axial failure has been studied previously but rarely has the interaction between damaged columns and the surrounding three‐dimensional structure been investigated experimentally and at full scale. In this study, as the second in a series of hybrid simulations, two full‐scale reinforced concrete columns of a representative pre‐1970s structure were tested at the Multi‐axial Full‐scale Substructure Testing and Simulation (MUST‐SIM) laboratory. Through the use of hybrid simulation, the interaction of the columns with the surrounding structure is studied under a severe seismic motion including vertical excitation.The computational model representing the remainder of the representative 10‐story structure is created in the computer program OpenSees. During the hybrid simulation, both physical specimens experience significant loss of shear and axial strength, and the effects of these failures on the surrounding system are described. The three‐dimensional computational model in OpenSees allowed for analytical flexural‐axial failure of a third column in the structure to occur. The effects of these multiple failures on the response of a full structural system under seismic action are quantified, and the progressive collapse resistance mechanisms are discussed. Copyright © 2016 John Wiley & Sons, Ltd.

INFLUENCE OF HEAT TREATMENTS ON THE MICROSTRUCTURE AND TENSILE BEHAVIOUR OF SELECTIVE LASER MELTING-PRODUCED TI-6AL-4V PARTS

In industry, post-process heat treatments of Ti-6Al-4V are performed with the aim of improving its tensile behaviour. While heat treatments of wrought Ti6Al4V have been standardised (e.g., Aerospace Material Specification H-81200), heat treatments of selective laser melting (SLM)-produced Ti-6Al-4V lacks research and understanding. Significant concern exists about SLM Ti6-Al-4V’s achievable ductility attributed to its martensitic (α’) phase. In this research, heat treatments at a range of temperatures are applied to SLM-produced Ti-6Al-4V tensile samples. Microstructural analysis (both optically and through electron backscatter diffraction) was used to identify links between heat treatments and microstructure. Subsequently, uniaxial tensile tests were performed to determine the respective tensile properties of all samples. Correlations in the data show a significant loss in strength with respect to an increase in annealing temperature due to grain growth, while no noticeable trend was observed for fracture strain with regard to annealing temperatures.Â

Does kraft hardwood and softwood pulp viscosity correlate to paper properties?

The impact of commercially prepared, fully bleached pulp viscosity variation on handsheet physical properties was evaluated at different levels of pulp refining. Hardwood pulps from the same brownstock species mix, cooking parameters, and kappa numbers were processed through two different commercial bleach plants: one with a D0(EP)D1D2 sequence and the second with an OD0(EOP)D1 sequence. Additionally, a commercial softwood (predominately Scotts pine) brownstock pulp bleached by an OD0(EP)D1D2 sequence was employed in this study. Pulps with viscosities ranging from 14 to 21 mPa∙s were refined in a Valley beater to two freeness levels, and the associated handsheet physical properties were measured in this study. Over the pulp viscosity range of 14 to 21 mPa∙s, no clear correlation was found to exist between pulp viscosity and related paper physical properties. Finally, a series of laboratory prepared bleached pulps were purposely prepared under non-ideal conditions to reduce their final viscosities to lower values. Handsheets made from these pulps were tested in their unbeaten condition for physical strength properties. Significant and rapid strength loss occurred when the measured pulp viscosity dropped below 12 mPa∙s; overall strength properties showed no correlation to viscosity above the critical 12 mPa∙s value.

Proximal row carpectomy on manual workers: 17 patients followed for an average of 6 years

Proximal row carpectomy (PRC) is indicated for the treatment of SNAC or SLAC wrist with preservation of the midcarpal joint. Our hypothesis was that PRC is not appropriate for treating advanced wrist osteoarthritis in patients who carry out heavy manual work. Twenty-three PRCs were performed on 21 patients, 5 women and 16 men with an average age of 54 years (33–77). All patients performed manual work; 11 of them performed heavy manual work. Etiologies were: SLAC wrist in 14 cases (2 stage III, 11 stage II, and 1 stage I) and SNAC wrist in 9 cases (6 stage IIIB and 3 stage IIB). At an average 75 months’ follow-up (24–153), five patients were lost to follow-up. Radiocarpal arthrodesis was performed in one patient 10 years after the PRC. In the 17 remaining patients (18 wrists), pain (VAS) averaged 2.2, with residual pain of 5. Flexion–extension range was similar to preoperative levels (67% of contralateral wrist). Wrist strength was decreased by 34% compared to preoperative. The QuickDASH score averaged 26 points and the PRWE 20 points. Radiocapitate distance decreased by 0.3mm on average with joint line narrowing in 6 patients. The carpal translation index was 0.33mm, which was unchanged relative to preoperative values. Three patients had work-related limitations that required retraining and one patient had to be reassigned. PRC preserved the preoperative range of motion and reduced pain levels. However, significant loss of strength was observed, resulting in 23% of manual workers needing retraining or reassignment. Type of study/level of evidenceTherapeutic IV.

Steel-Reinforced Concrete Coupling Beams. II: Modeling

AbstractUsing test results presented in previous studies, design and modeling recommendations for steel-reinforced concrete (SRC) coupling beams are provided for both code-based (prescriptive) design approaches and performance-based design approaches. Procedures for computing both nominal and expected (upper bound) moment and shear strengths are described. For embedment, a capacity design approach is recommended in which the provided embedment strength exceeds the expected beam strength. Two approaches are recommended for determination of effective stiffness, one based on using a rigid beam (for flexure and shear) along with an interface rotational spring, since test results from the literature indicate that the majority of the coupling-beam deformations were associated with interface slip/extension, and an alternative approach where the effective stiffness is based on the beam aspect ratio or beam length. Additional parameters are provided to define deformation capacity at significant strength loss (to c...

Upper Limb Evaluation in Duchenne Muscular Dystrophy: Fat-Water Quantification by MRI, Muscle Force and Function Define Endpoints for Clinical Trials.

ObjectiveA number of promising experimental therapies for Duchenne muscular dystrophy (DMD) are emerging. Clinical trials currently rely on invasive biopsies or motivation-dependent functional tests to assess outcome. Quantitative muscle magnetic resonance imaging (MRI) could offer a valuable alternative and permit inclusion of non-ambulant DMD subjects. The aims of our study were to explore the responsiveness of upper-limb MRI muscle-fat measurement as a non-invasive objective endpoint for clinical trials in non-ambulant DMD, and to investigate the relationship of these MRI measures to those of muscle force and function.Methods15 non-ambulant DMD boys (mean age 13.3 y) and 10 age-gender matched healthy controls (mean age 14.6 y) were recruited. 3-Tesla MRI fat-water quantification was used to measure forearm muscle fat transformation in non-ambulant DMD boys compared with healthy controls. DMD boys were assessed at 4 time-points over 12 months, using 3-point Dixon MRI to measure muscle fat-fraction (f.f.). Images from ten forearm muscles were segmented and mean f.f. and cross-sectional area recorded. DMD subjects also underwent comprehensive upper limb function and force evaluation.ResultsOverall mean baseline forearm f.f. was higher in DMD than in healthy controls (p<0.001). A progressive f.f. increase was observed in DMD over 12 months, reaching significance from 6 months (p<0.001, n = 7), accompanied by a significant loss in pinch strength at 6 months (p<0.001, n = 9) and a loss of upper limb function and grip force observed over 12 months (p<0.001, n = 8).ConclusionsThese results support the use of MRI muscle f.f. as a biomarker to monitor disease progression in the upper limb in non-ambulant DMD, with sensitivity adequate to detect group-level change over time intervals practical for use in clinical trials. Clinical validity is supported by the association of the progressive fat transformation of muscle with loss of muscle force and function.

Simulated Total Wrist Fusion and its Influence on Hand Grip Function

Wrist fusion is still a common treatment for patients with advanced stage arthritis. Since patients are often intimidated by the functional limitations, we intended to evaluate the influence of the lack of wrist motion in different positions on the dynamic grip function and the grip strength of the hand. We simulated wrist fusion in 20° extension and 20° flexion and evaluated the following grip types: fist closure, 2 different power grips, pinch grip and precision grip. A TUB sensor glove was used, which allowed us to dynamically record the range of motion (ROM) of the finger joints as well as grip strength. Nineteen healthy subjects participated and all types of grips were performed using a standardised protocol with and without simulated wrist fusion. Lack of wrist motion in 20° extension had no relevant effect on the fingers' ROM, grip speed or strength. Simulated fusion in 20° flexion also had no influence on ROM or grip speed, rejecting our hypothesis that a tenodesis effect of the extensors in flexion would decrease ROM in the finger joints and grip speed. However, we were able to show a significant decrease of grip strength in flexion compared with extension or healthy wrists. The decrease averaged between 23 and 42% of healthy values, depending on the grip type. There was no change in strength distribution among the fingers. We didn't find any impact of lack of wrist motion on finger movement during forceful hand grip at normal speed. However, a significant loss of grip strength in flexed position of the wrist joint should be considered in patients with an indication for bilateral wrist fusion.

Influence of Impact-Oscillatory Loading upon the Mechanical Properties of the VT-22 Titanium Alloy Sheet

This study shows the effect of the specific impact-oscillatory loading (Dynamical nonequilibrium process) on the VT-22 titanium α+β-type alloy mechanical properties and microstructure. Experiments were conducted using modified universal testing machine. Physical research revealed that significant microstructural refinement of the alloy is observed after such type of loading, as the result of which the fine grains are formed with subgrain refinement which takes place within the basis of alloy. It was found that overall plastic deformation of this alloy can be increased by a factor 2.75 compared with its initial state without significant loss of strength. Also we show that such process can be used as a preliminary microstructure refinement method for such alloy.

Differences among skeletal muscle mass indices derived from height-, weight-, and body mass index-adjusted models in assessing sarcopenia

Aging processes are inevitably accompanied by structural and functional changes in vital organs. Skeletal muscle, which accounts for 40% of total body weight, deteriorates quantitatively and qualitatively with aging. Skeletal muscle is known to play diverse crucial physical and metabolic roles in humans. Sarcopenia is a condition characterized by significant loss of muscle mass and strength. It is related to subsequent frailty and instability in the elderly population. Because muscle tissue is involved in multiple functions, sarcopenia is closely related to various adverse health outcomes. Along with increasing recognition of the clinical importance of sarcopenia, several international study groups have recently released their consensus on the definition and diagnosis of sarcopenia. In practical terms, various skeletal muscle mass indices have been suggested for assessing sarcopenia: appendicular skeletal muscle mass adjusted for height squared, weight, or body mass index. A different prevalence and different clinical implications of sarcopenia are highlighted by each definition. The discordances among these indices have emerged as an issue in defining sarcopenia, and a unifying definition for sarcopenia has not yet been attained. This review aims to compare these three operational definitions and to introduce an optimal skeletal muscle mass index that reflects the clinical implications of sarcopenia from a metabolic perspective.

Compression of Ulnar Nerve by Ganglionic Cyst in Guyon’s Canal: A Case Report

Ulnar nerve compression at guyon’s canal is rare and very few cases have been reported in literature. It can be missed due to its rarity. Symptoms vary from pain and paresthesia to wasting and significant loss of muscle strength, with significant deformities of the hand. The diagnosis is made by detailed history and examination, electromyography, nerve conduction velocity test, ultrasound and magnetic resonance imaging. Early decompression of nerve is treatment of choice. Here we are presenting a case of compression of ulnar nerve in guyon’s canal due to ganglionic cyst.

Anti-wrinkle and UV protective performance of cotton fabrics finished with 5-(carbonyloxy succinic)-benzene-1,2,4-tricarboxylic acid

1,2,3,4-Butane tetracarboxylic acid (BTCA) has been considered as one of the most promising crosslinking agent to replace dimethylol dihydroxy ethylene urea (DMDHEU) for anti-wrinkle finishing on cotton fabrics. However, it could cause significant strength loss of the treated fabrics. In this study, a 5-(carbonyloxy succinic)-benzene-1,2,4-tricarboxylic acid (BSTA) was synthesized and applied as an effective crosslinking agent. The results show that fabrics treated with BSTA present the same or even better anti-wrinkle properties as that with BTCA. FTIR was employed to analyze ester bond formation process on cellulose. Finishing conditions such as agent concentration, curing temperature, and bath pH were also discussed to evaluate crosslinking effect of cellulose. BSTA, as a derivative of photo-active conjugated compound, can absorb ultraviolet lights and offer ultraviolet (UV) protective property on treated materials. The treated fabrics showed excellent UV protection performance due to the addition of aromatic conjugated system on fabrics.

Relation of transverse compression properties and the degree of brown rot biodeterioration of Pinus glabra in the soil block test

Abstract Improved methods are needed for detecting and quantifying the effect of decay fungi on wood products. The focus of the present paper is a soil block decay test with exposure to the brown rot fungus Gloeophyllum trabeum, where the changes in elasticity and strength were compared in both the radial and tangential directions as a function of the decay degree. The stress-strain analysis was employed by a transverse compression (transC) testing technique in which a load was applied over the specimen’s tangential or radial surface. It was found that early effects of decay were detected in either direction of loading, but the overall reduction in elasticity and compression strength after 7 days of exposure to the fungus was approximately two times greater in the radial direction. This difference is interpreted that decay occurs mainly in the earlywood (EW). Significant strength loss at 5% compression was detected after 2 days of exposure to the fungus. However, 3 days of exposure was required before significant strength loss was evident as a result of the reduction in modulus of elasticity (MOE) or mass loss (ML). In comparison to ML, the compression strength loss was found to be a more sensitive measure of wood decay.

A review of the influence of hydrogen on the mechanical properties of DP, TRIP, and TWIP advanced high-strength steels for auto construction

AbstractThe literature is reviewed regarding the influence of hydrogen on dual-phase (DP), transformation-induced plasticity (TRIP), and twinning-induced plasticity (TWIP) steels. Hydrogen influences DP steels by decreasing ductility while strengths are largely unaffected. TRIP steels may be susceptible to hydrogen embrittlement (HE) as indicated by the loss of ductility and some brittle fracture features. The literature on the influence of hydrogen on TWIP steels was inconsistent. Some researchers found no significant influence of hydrogen on TWIP steel properties and fully ductile fractures, whereas others found a significant loss of ductility and strength due to hydrogen and some brittle features. Possible countermeasures for HE are tempering for DP and TRIP steels and aluminum alloying for TWIP steels.

Investigation on Functional Properties of 1,2,3,4-Butanetetracarboxylic Acid Cross-Linked Fabrics Impacted by Molecular Structures and Chemical Affinity of Catalysts

1,2,3,4-Butanetetracarboxylic acid (BTCA), catalyzed by sodium hypophosphite (SHP), brings good antiwrinkle property to cotton fabrics and causes significant strength losses due to cross-linking and acidic degradation of cellulose simultaneously. Previous studies presented optimum pH values for different catalysts based on wrinkle recovery angle but without analyzing the tensile strength losses (TSL) of the treated fabrics. Here, the differences in TSL were analyzed from catalyst diffusibility and affinity to BTCA and cellulose based on anion sizes and Hansen solubility parameters of the corresponding acids of catalysts, respectively. Results showed that smaller catalyst anions such as the SHP anion would diffuse into the fibers more deeply, causing more TSL due to more cross-linking (TSLC). Besides, the lower affinity of the catalyst to BTCA and cellulose would accelerate the cross-linking reaction, also resulting in more TSLC. Connolly accessible area of an acid anion, catalyst anion concentration, and ...

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The aim of this study is to find a solution for the large volume of sludge produced in the wastewater treatment plants in Jordan in order to decrease the environmental pollution in the air , as well as to assess the strength of sludge concrete using treated water in concrete mix as a comparison with the strength of sludge concrete made by tap water. Many researchers have been trying to find suitable solutions to solve part of wastewater sludge problem. One of these solutions is to use sewage sludge in construction field (as the interlock bricks as an example of non structural elements made with sludge concrete) [1]. According to the results findings, no significant strength loss was observed when low organic dry sludge was used in making sludge concrete cube specimens as additive . The compressive strength of sludge concrete for treated water was compared with the strength of sludge concrete made by tap water. The results show that; using sludge concrete mixes decrease the strength of cube about (9.3%) when treated water was used .

Effect of latissimus dorsi flap breast reconstruction on the strength profile of the upper extremity

Objective: Dissection of the latissimus dorsi (LD) flap may have a distinct impact on upper extremity function and strength. To date, insufficient differentiation has been made between loss of muscular strength and shoulder function by dissection of the LD muscle per se and loss of function resulting from all excisional surgery, radiation therapy, and reconstructive procedures at the donor site and the recipient site that may have been combined near the shoulder region. Methods: This study determines the long-term effect of the LD breast reconstruction on the strength profiles of the upper extremity by measuring the isometric torque strength both in seven synergistic- and two contra-movement directions. The Biodex System 3 Pro (Biodex Medical Systems, New York, NY) was used in 12 patients at a mean of 3.5 years after surgery, and in 20 matched controls. Because loss of LD muscle may not result in significant impairment of activities of daily live (ADL) even in cases where objective measurements are decreased, this study simultaneously assessed the subjective function by use of the standardised Disability of Arm, Shoulder and Hand (DASH) questionnaire. Results: This study observed a significant long-term loss of 8.8 Nm or 19% LD torque strength in synergistic movement directions after transplantation of the LD muscle. This loss correlated significantly with an increase of the mean DASH score among the patients. Conclusions: Because no significant loss of contra-movement torque strength was observed, it was concluded that the loss of synergistic torque strength appears to result from the loss of LD function per se.

Numerical and experimental study of comb-teeth metallic yielding dampers

In this paper, a new type of metallic yielding damper called comb-teeth damper, CTD, is introduced. CTD is made of steel plates and includes a number of teeth that dissipate energy through in-plane flexural yielding. An optimum geometry of teeth is suggested, which assures uniform distribution of stress along them and prevents strain localization. Finite element modeling is used to verify the design of proposed damper and to study nonlinear behavior of the damper subjected to monotonic as well as cyclic loading. Three full scale specimens have also been made and tested under cyclic loading. In order to restrict out-ofplane buckling of damper teeth, a special clamp has been designed. A numerical study has elaborated the effects of these clamps in comparison to increasing the thickness of individual tooth. The tested samples have tolerated considerable cumulative displacement in their hysteresis cycles without any significant loss of strength.

Effects of acid diffusibility and affinity to cellulose on strength loss of polycarboxylic acid crosslinked fabrics

1,2,3,4-Butanetetracarboxylic acid (BTCA) imparts good anti-wrinkle property to cotton fabrics and results in significant strength loss due to cross-linking and acid degradation of cellulose simultaneously. However, benzophenone-3,3′,4,4′- tetracarboxylic acid (BPTCA), an aromatic acid, crosslinks cellulose effectively but causes less strength loss to the products under similar conditions. The difference in damages to cellulose fibers was analyzed by using diffusibility and corresponding affinity of the acids to cellulose fibers, which were estimated by their molecular sizes and Hansen solubility parameters (HSP). Both experimental results and theoretical speculations revealed consistent agreement, indicating that smaller acid molecules could diffuse into cellulose fiber more rapidly and deeply, resulting in more acid degradation. Besides, the aliphatic acid such as BTCA has higher molecular affinity than BPTCA to cellulose, causing additional more degradation of cellulose. Both factors are potential reasons of the observed more severe tensile strength loss of the BTCA treated cotton fabrics.

Walking-induced muscle fatigue impairs postural control in adolescents with unilateral spastic cerebral palsy

BackgroundFatigue is likely to be an important limiting factor in adolescents with spastic cerebral palsy (CP). AimsTo determine the effects of walking-induced fatigue on postural control adjustments in adolescents with unilateral CP and their typically developing (TD) peers. MethodsTen adolescents with CP (14.2±1.7yr) and 10 age-, weight- and height-matched TD adolescents (14.1±1.9yr) walked for 15min on a treadmill at their preferred walking speed. Before and after this task, voluntary strength capacity of knee extensors (MVC) and postural control were evaluated in 3 conditions: eyes open (EO), eyes closed (EC) and with dual cognitive task (EODT). ResultsAfter walking, MVC decreased significantly in CP (−11%, P<0.05) but not in TD. The CoP area was only significantly increased in CP (90%, 34% and 60% for EO, EC and EODT conditions, respectively). The CoP length was significantly increased in the EO condition in CP and TD (20% and 21%) and was significantly increased in the EODT condition by 18% in CP only. ConclusionsUnlike TD adolescents, treadmill walking for 15min at their preferred speed lead to significant knee extensor strength losses and impairments in postural control in adolescents with unilateral spastic CP.

Atomic layer deposited TiO2 protects porous ceramic foams from grain boundary corrosion

Intergranular corrosion causes a significant loss of compressive strength in highly porous TiO2 foams. In this study, the resistance of conformal atomic layer deposited (ALD) coatings against intergranular corrosion has been investigated. ALD coated TiO2 foams maintained 107%±20% and 94%±10% of their initial compressive strength for films deposited at 150°C and 250°C, respectively. After an immersion period of 28 days in 1mM HCl, amorphous films showed greater potential in corrosion protection of polycrystalline TiO2 foams. However, anatase coatings with sufficient protection may be more beneficial for cell-material interactions.