Magnitude Of Load Research Articles

A state-of-the-art review on reinforced concrete slabs strengthened by frp sheets under monotonic, impact and repeated loading

Composites made of fiber-reinforced polymer (FRP) have gained popularity as new high-performance material for concrete buildings in now days. The advantages of FRP composites include high strength, lightweight, and corrosion resistance. This paper’s primary objective is to assess the affect of FRP strips on the strengthening and repair of plain and reinforced concrete slabs. under the monotonic, impact, and repeated loading. According to studies’ observations, applying FRP strips to RC slabs significantly affects the final load and deflection. The number and positioning of FRP sheets improve the performance of slabs. The failure load magnitude of strengthened slabs would increase as slab thickness, concrete compressive strength, and sheet thickness increase. The ultimate load capacity was increased by (27-52%), depending on the FRP strengthening strategy used. GFRP sheets could be employed for improving or enhancing the impact strength of concrete structures. Externally attached GFRP sheets gave good resistance for reinforced concrete slabs against typical explosive blast.

Mechanism analysis of propeller-ice contact and rapid prediction of ice loads

To facilitate the rapid prediction of propeller ice loads, as well as to aid in the assessment of strength and optimal design of ice-class propellers, a state-based peridynamic (PD) method was utilized for mechanism analysis of propeller-ice contact and ice-loads sensitivity analysis. Both critical bond-stretch (CS) and critical energy (CE) damage criteria were implemented to determine whether sea ice is damaged. A verification example and comparison were given for a milling test. The design space for the propeller section was evaluated to perform the sensitivity analysis of ice loads to airfoil geometry and milling angle of attack. Based on the sensitivity results, a rapid-prediction method for propeller ice loads was proposed. As the airfoil mills ice with a slight angle (smaller than 7°), the CE criterion is more suitable than the stretch criterion. It was found that, by sensitivity analysis, there is little difference in the magnitude of ice loads applied on different airfoils with varying camber and thickness distribution and maximum thickness. Only the change in the maximum camber will make a difference in the transversal ice load. A propeller ice-loads calculation example shows the feasibility and convenience of the proposed prediction method, the error of which is only 4.5% compared with the experimental value.

Why we need to abandon fixed cutoffs for goodness-of-fit indices: An extensive simulation and possible solutions

To evaluate model fit in confirmatory factor analysis, researchers compare goodness-of-fit indices (GOFs) against fixed cutoff values (e.g., CFI > .950) derived from simulation studies. Methodologists have cautioned that cutoffs for GOFs are only valid for settings similar to the simulation scenarios from which cutoffs originated. Despite these warnings, fixed cutoffs for popular GOFs (i.e., χ2, χ2/df, CFI, RMSEA, SRMR) continue to be widely used in applied research. We (1) argue that the practice of using fixed cutoffs needs to be abandoned and (2) review time-honored and emerging alternatives to fixed cutoffs. We first present the most in-depth simulation study to date on the sensitivity of GOFs to model misspecification (i.e., misspecified factor dimensionality and unmodeled cross-loadings) and their susceptibility to further data and analysis characteristics (i.e., estimator, number of indicators, number and distribution of response options, loading magnitude, sample size, and factor correlation). We included all characteristics identified as influential in previous studies. Our simulation enabled us to replicate well-known influences on GOFs and establish hitherto unknown or underappreciated ones. In particular, the magnitude of the factor correlation turned out to moderate the effects of several characteristics on GOFs. Second, to address these problems, we discuss several strategies for assessing model fit that take the dependency of GOFs on the modeling context into account. We highlight tailored (or “dynamic”) cutoffs as a way forward. We provide convenient tables with scenario-specific cutoffs as well as regression formulae to predict cutoffs tailored to the empirical setting of interest.

Cyclic loading induces anabolic gene expression in ACLs in a load-dependent and sex-specific manner.

Anterior cruciate ligament (ACL) injuries are historically thought to be a result of a single acute overload or traumatic event. However, recent studies suggest that ACL failure may be a consequence of fatigue damage. Additionally, the remodeling response of ACLs to fatigue loading is unknown. Therefore, the objective of this study was to investigate the remodeling response of ACLs to cyclic loading. Furthermore, given that women have an increased rate of ACL rupture, we investigated whether this remodeling response is sex specific. ACLs were harvested from male and female New Zealand white rabbits and cyclically loaded in a tensile bioreactor mimicking the full range of physiological loading (2, 4, and 8 MPa). Expression of markers for anabolic and catabolic tissue remodeling, as well as inflammatory cytokines, was quantified using quantitative reverse transcriptionpolymerase chain reaction. We found that the expression of markers for tissue remodeling of the ACL is dependent on the magnitude of loading and is sex specific. Male ACLs activated an anabolic response to cyclic loading at 4 MPa but turned off remodeling at 8 MPa. These data support the hypothesis that noncontact ACL injury may be a consequence of failed tissue remodeling and inadequate repair of microtrauma resulting from elevated loading. Compared to males, female ACLs failed to increase anabolic gene expression with loading and exhibited higher expression of catabolic genes at all loading levels, which may explain the increased rate of ACL tears in women. Together, these data provide insight into load-induced ACL remodeling and potential causes of tissue rupture.

Mechanical stimuli activate gene expression via a cell envelope stress sensing pathway

Mechanosensitive mechanisms are often used to sense damage to tissue structure, stimulating matrix synthesis and repair. While this kind of mechanoregulatory process is well recognized in eukaryotic systems, it is not known whether such a process occurs in bacteria. In Vibrio cholerae, antibiotic-induced damage to the load-bearing cell wall promotes increased signaling by the two-component system VxrAB, which stimulates cell wall synthesis. Here we show that changes in mechanical stress within the cell envelope are sufficient to stimulate VxrAB signaling in the absence of antibiotics. We applied mechanical forces to individual bacteria using three distinct loading modalities: extrusion loading within a microfluidic device, direct compression and hydrostatic pressure. In all cases, VxrAB signaling, as indicated by a fluorescent protein reporter, was increased in cells submitted to greater magnitudes of mechanical loading, hence diverse forms of mechanical stimuli activate VxrAB signaling. Reduction in cell envelope stiffness following removal of the endopeptidase ShyA led to large increases in cell envelope deformation and substantially increased VxrAB response, further supporting the responsiveness of VxrAB. Our findings demonstrate a mechanosensitive gene regulatory system in bacteria and suggest that mechanical signals may contribute to the regulation of cell wall homeostasis.

Pollutant Burden on Pollution Sources in the Wai Batu Merah Watershed, Sirimau District, Ambon City

This study aims to identify sources of pollution and determine the magnitude of the potential pollution load from pollutant sources in the Wai Batu Merah watershed, Sirimau District, Ambon City. The method for identifying sources of pollution is carried out by using saturated or census sampling methods, calculating pollutant loads using direct methods for point source pollutant sources and indirect methods for non-point sources . The direct calculation method uses wastewater discharge data and the results of wastewater quality analysis results from measurements directly at the point source pollutant wastewater treatment plant (WWTP). The wastewater sampling technique uses the grab sampling method. While the indirect method uses effluent factors and supporting data from non-point source pollution sources that have been identified in the Wai Batu Merah watershed. The results showed that the pollutant sources found in the Wai Batu Merah watershed were point sources originating from hotel and health facility activities and non-point sources originating from domestic activities from residential areas, agricultural and livestock businesses, non-point source land (forest and open land), micro, small and medium enterprises (MSMEs), small scale industries and waste. The dominant pollutant source in the Wai Batu Merah watershed comes from domestic non-point sources. The highest point source pollution loads for BOD, COD and TSS parameters in the Wai Batu Merah watershed came from hotel activities in segment 6 with the contribution of each parameter of 17.82 kg/day, 23.82 kg/day and 0.029 kg/day. Meanwhile, the highest non-point source pollution load for BOD, COD and TSS parameters came from non-point source waste in segment 6 with the contribution of each parameter of 2825.3 kg/day, 3884.8 kg/day and 2684.03 kg/day.

Influence of railway wheel tread damage on wheel–rail impact loads and the durability of wheelsets

Dynamic wheel–rail contact forces induced by a severe form of wheel tread damage have been measured by a wheel impact load detector during full-scale field tests at different vehicle speeds. Based on laser scanning, the measured three-dimensional damage geometry is employed in simulations of dynamic vehicle–track interaction to calibrate and verify a simulation model. The relation between the magnitude of the impact load and various operational parameters, such as vehicle speed, lateral position of wheel–rail contact, track stiffness and position of impact within a sleeper bay, is investigated. The calibrated model is later employed in simulations featuring other forms of tread damage; their effects on impact load and subsequent fatigue impact on bearings, wheel webs and subsurface initiated rolling contact fatigue of the wheel tread are assessed. The results quantify the effects of wheel tread defects and are valuable in a shift towards condition-based maintenance of running gear, and for general assessment of the severity of different types of railway wheel tread damage.

Metamaterial inspired electromagnetic bandgap filter for ultra-wide stopband screening devices of electromagnetic interference

Presented here is a reactively loaded microstrip transmission line that exhibit an ultra-wide bandgap. The reactive loading is periodically distributed along the transmission line, which is electromagnetically coupled. The reactive load consists of a circular shaped patch which is converted to a metamaterial structure by embedded on it two concentric slit-rings. The patch is connected to the ground plane with a via-hole. The resulting structure exhibits electromagnetic bandgap (EBG) properties. The size and gap between the slit-rings dictate the magnitude of the reactive loading. The structure was first theoretically modelled to gain insight of the characterizing parameters. The equivalent circuit was verified using a full-wave 3D electromagnetic (EM) solver. The measured results show the proposed EBG structure has a highly sharp 3-dB skirt and a very wide bandgap, which is substantially larger than any EBG structure reported to date. The bandgap rejection of the single EBG unit-cell is better than − 30 dB, and the five element EBG unit-cell is better than − 90 dB. The innovation can be used in various applications such as biomedical applications that are requiring sharp roll-off rates and high stopband rejection thus enabling efficient use of the EM spectrum. This can reduce guard band and thereby increase the channel capacity of wireless systems.

A Probable Approach to Reliability Assessment of Reinforced Plates

A scheme for solving the problem of determining the probability of failure and probabilistic (statistical) characteristics of the failure loading magnitude of a composite material plate is considered. The plate structure is a flat homogeneous matrix with stochastically distributed rigid rod inclusions. The geometric parameters of inclusions are considered independent random variables with given probability distribution laws. The expressions for the failure loading distribution function, the probability of failure, the mean value, and the dispersion of the failure loading were received and presented. Their dependence on the type of stress state, the inclusion number, and matrix Poisson’s ratio were studied graphically.

OPTIMIZATION ANALYSIS OF DETERMINING GENERATOR POWER CAPACITY IN MV SABUK NUSANTARA 71

Sabuk Nusantara 71 is a Indonesian passenger cargo ship with the Ambon – Tual route which has three generators. As is well known that the main generator of electrical power on a ship is a generator. The installed generator is expected to be able to supply the electric power needs of the ship optimally and efficiently. But in fact, the distribution of the load on the ship is still less than optimal and efficient. This results in excess fuel consumption. The purpose of this research is to find efficient load sharing so that the required fuel consumption is optimal. To achieve this, the research uses several stages. First, calculate the amount of electrical power needed on the ship. Second, look for the magnitude of the electric power load for each operating condition of the ship when leaning, sailing and maneuvering. Third, look for the fuel consumption of ship generators using the dynamic programming method which aims to get efficient generator fuel consumption. The results of this calculation simulation on MV. Nusantara Belt 71 operations with a voyage from Ambon – Tual (round trip) obtained an efficient fuel consumption of 20,724.77 liters by using generator 1 configuration for leaning, and generators 1 and 2 for maneuvering and sailing

Determining Magnitudes of Forces at Known Locations through a Strain Gauge Force Transducer.

A novel strain gauge force transducer was developed to minimize the number of strain gauges needed to determine the magnitudes of loads when the locations are known. This innovative methodology requires only one strain gauge for each force magnitude desired, reducing the complexity and cost associated with traditional approaches. The theory was verified with laboratory experiments. Seven uniaxial strain gauges were attached to the underside of a simply supported, slender, aluminum beam. One or more loads were applied either directly atop strain gauges or in known positions between strain gauges. Experiments were conducted on several different single and double-load configurations to evaluate the extent of the new methodology which yielded average errors under 5% for the cases where loads were direct atop strain gauges and 6.6% for the cases where the loads were between strain gauges. These findings indicate the potential of this novel strain gauge force transducer to revolutionize load measurement in scenarios where load locations are predetermined.

Bond stress distribution and suggestions for anchoring length of deformed steel bars in different types of cementitious grout

Eight sets of pull–out specimens were tested by considering four types of cementitious grout (CGM-380, CGM-340, CGM-300, and CGM-270) and two anchoring lengths (3d and 10d) in this study. Discussions were had on the failure modes, bond load–slip curves, stress distribution of steel bars, and bond stress distribution. Results indicated that the relationship between the magnitude of peak bond load of 3d–group specimens composed of different types of cementitious grout was shown as CGM-270>CGM-300>CGM-340>CGM-380. Simultaneously, the stress of the steel bars in specimens gradually increased with the increase in external load, and the steel bars were in the elastic stage. For the 10–group specimens, the peak bond load of each specimen was basically the same, and the steel bars had yielded when the specimen was damaged. In addition, the stress distribution of the steel bars was similar to that of 3d–group specimens before the steel bars yielding. After the load reached the yield load, however, the yield position gradually shifted toward the free end with the load further increased, and the yield section length of the steel bars gradually increased. Besides, in contrast to the unimodal bond stress distribution curves of the 3d–group specimens, the bond stress distribution curves of the 10d–group specimens were all in the shape of a multimodal distribution. The peak bond stress of 10d–group specimens were located near the loading end before the steel bars yielding. However, as the load was raised continuously after the steel bars yielded, the bond stress in the yield section dramatically dropped, the yield penetration depth progressively grew, and the peak bond stress gradually shifted towards the free end. Additionally, design suggestions for the critical anchoring length of steel bars in cementitious grout and the anchoring length of steel bars after yielding were provided.

Raw Acceleration from Wrist- and Hip-Worn Accelerometers Corresponds with Mechanical Loading in Children and Adolescents.

The purpose of this study was to investigate associations between peak magnitudes of raw acceleration (g) from wrist- and hip-worn accelerometers and ground reaction force (GRF) variables in a large sample of children and adolescents. A total of 269 participants (127 boys, 142 girls; age: 12.3 ± 2.0 yr) performed walking, running, jumping (<5 cm; >5 cm) and single-leg hopping on a force plate. A GENEActiv accelerometer was worn on the left wrist, and an Actigraph GT3X+ was worn on the right wrist and hip throughout. Mixed-effects linear regression was used to assess the relationships between peak magnitudes of raw acceleration and loading. Raw acceleration from both wrist and hip-worn accelerometers was strongly and significantly associated with loading (all p's < 0.05). Body mass and maturity status (pre/post-PHV) were also significantly associated with loading, whereas age, sex and height were not identified as significant predictors. The final models for the GENEActiv wrist, Actigraph wrist and Actigraph hip explained 81.1%, 81.9% and 79.9% of the variation in loading, respectively. This study demonstrates that wrist- and hip-worn accelerometers that output raw acceleration are appropriate for use to monitor the loading exerted on the skeleton and are able to detect short bursts of high-intensity activity that are pertinent to bone health.

Influence of Spring Stiffness on the Loading Speed of the Falling Weight Deflectometer (FWD) in Bearing Capacity Evaluation of Cement Concrete Pavement

Introduction: The bearing capacity evaluation of cement concrete runway pavement is one of the most important contents in the airfield operation. Among the methods for estimating bearing capacity, the Falling Weight Deflectometer (FWD) is the most widely used method because it does not damage the pavement structure and spends so much time. The equipment for evaluation should have suitable parameters, such as. magnitude and loading speed, to the actual operating loads. Aims and Objectives: Currently, the equipment to assess the bearing capacity of cement concrete pavements of highways and airports by falling weight has been widely used in the world and is being applied in Vietnam. The loading system consists of a falling block through a spring system acting on the pressure plate under the pavement with a certain falling height. In particular, the spring system plays an important role in controlling the speed of the load on the pavement. In Vietnam, the test standards (Industry Standard 22TCN335-06, Vietnamese Standard TCVN 11365-2016) for assessing the pavement bearing capacity by FWD equipment do not specify the selection of spring stiffness corresponding to different operating speeds of the vehicle. Therefore, it is difficult to use the equipment for pavements with operating speeds different from the standard. In this paper, we study the effect of spring stiffness on the loading speed when considering different loading speeds corresponding to different speeds of vehicles moving in reality. This research is only limited to laboratory experiments. This study aims to determine the dependence of the loading magnitude and loading time on the damping spring stiffness of the dynamic loading equipment, that is, used as a basis for choosing the appropriate damping stiffness of FWD corresponding to actual vehicles. Methods: Among the methods for estimating the bearing capacity, the Falling Weight Deflectometer (FWD) is the most widely used method as it does not cause any damage to the pavement structure and spends much time. The equipment for evaluation should have suitable parameters, such as magnitude and loading speed, to the actual operating loads. Results: This paper presents the results of experimental research that determines the influence of the damping spring stiffness on the loading speed of the dynamic loading equipment on the model of the concrete slab in the laboratory. Conclusion: Based on the comparison of the FWD loading speed when using 02 damping springs with different stiffness, we propose the basis for choosing the damping system that conforms to the evaluation needs of different types of vehicles.

Stability of forming induced residual stresses in stainless steel components under mechanical load

Cold forward extrusion leads to the generation of residual stresses, which can have an advantageous or detrimental effect on the operating behavior of the formed components. In industrial practice, energy-intensive annealing steps are often used to remove unknown stress states and thus prevent unexpected failures. Residual stress-related knowledge can therefore help to save energy and resources. To be able to estimate the effects, not only sign and magnitude need to be known, but also the residual stress stability under typical operating loads. In this paper, stainless steel X6Cr17 (DIN 1.4016, AISI 430) is formed by forward rod extrusion at room temperature. The forming process leads to residual stresses in the formed components, which are subsequently subjected to mechanical testing. To represent different initial states, components with varied die opening angles are produced and tested. A modified 3-point bending setup is used to generate a defined tensile load stress in the part surface. The results show a behavior of the residual stresses, which is depending on the load magnitude, the initial stress state and the work hardening distribution in the part. While the number of cycles has an influence, the largest changes occur in the first stroke.

Digital shearography for NDT: Determination and demonstration of the size and the depth of the smallest detectable defect

This paper presents a methodology of digital shearography for determining the size of the smallest detectable defect and the depth under different loading magnitudes for the purpose of nondestructive testing. Digital Shearography, an interferometric nondestructive testing (NDT) technique, has been proven to be a useful tool for material inspections and evaluations, especially for detecting delaminations/disbonds in composite materials and honeycomb structures. A commonly asked question in the field of NDT is about measuring sensitivity - specifically, what is the smallest detectable delamination/disbond and how deep can these be detected? Although various attempts to find the smallest detectable defect by shearography have been made, a numerical model for determining the size of the smallest detectable defect and the depth has not yet been developed. This paper did a study in this aspect, especially for NDT of delamination and disbond in polymers and honeycomb structures. First, a mechanical model based on the thin plate theory to calculate the expected bending of close-to-surface defects was proposed; the model built a relationship among the deformation caused by a defect, the size and the depth of the defect, as well as the load and the material properties. Second, the relationship between the relative deformation measured by shearography and the deformation induced by a defect was established based on the optimized shearing amount and the sensitivity of digital shearography. Based on these analyses, relationships between the size of the smallest detectable defect and the depth under different load amounts were established for different defect shapes. Finally, experimental validation based on different sizes of prefabricated defects were conducted to verify these relationships. The experimental results show that the model developed can provide useful estimation for NDT by digital shearography, especially with helping test engineers estimate the size of the smallest detectable defect and the depth with corresponding loading magnitudes.

Propeller-Ice Contact modelling with Peridynamics

Ice loads pose a significant threat to ice-class propellers in frozen waters, making it crucial to analyse the magnitude of ice loads. However, the complex mechanical properties of ice and its failure process make it challenging to investigate the correlation between ice-propeller contact phenomena and ice loads. This paper uses a PC3 class propeller blade to study the propeller-ice contact process. This study involves developing ice failure and propeller blade models based on ordinary and non-ordinary state-based peridynamics theory and validating them using experimental. Convergence analysis was performed before blade ice loads evaluation. Additionally, we investigate the effect of the pitch angle on the ice-milling process.

Lateral response of a pile group embedded in the transversely isotropic saturated soil due to surcharge loads

This paper investigates the behavior of pile groups in the transversely isotropic saturated soil under an adjacent surcharge load using a coupling method. The analytical layer-element theory is utilized to the transversely isotropic saturated soil model, and the fundamental solutions of the soil are applied to derive the soil flexibility matrices. And the FEM is used for the piles modeled as Bernoulli–Euler beams considering pile–pile interaction. Then, the dynamic response equations of pile groups are derived by using the FEM–BEM coupled method and considering pile-soil boundary coordination condition. The results of the present model compared well with those in existing solutions. Numerical examples are presented to examine the influences of the soils’ transverse isotropy, the magnitude of the surcharge load, the pile's physical properties and the distance between the load and the pile on the behavior of pile groups. It is observed that as the surcharge load grows, the position of the pile maximum displacement response changes from the middle of the soft soil layer to the top of the pile. The impact of the surcharge load is not significant when the loading action distance is greater than twice the thickness of soft soil layer. Furthermore, relatively large bending moments appear in the middle of the soft soil layer and at the interface of the soil layers.

Transient Response of Turbocharged Compression Ignition Engine under Different Load Conditions

&lt;div&gt;In urban roads the engine speed and the load vary suddenly and frequently, resulting in increased exhaust emissions. In such operations, the effect of air injection technique to access the transient response of the engine is of great interest. The effectiveness of air injection technique in improving the transient response under speed transient is investigated in detail [&lt;span&gt;1&lt;/span&gt;]; however, it is not evaluated for the load transients. Load step demand of the engine is another important event that limits the transient response of the turbocharger. In the present study, response of a heavy-duty turbocharged diesel engine is investigated for different load conditions. Three cases of load transients are considered: constant load, load magnitude variation, and load scheduling. Air injection technique is simulated and after optimization of injection pressure based on orifice diameter, its effect on the transient response is presented. The results reveal that air injection into the intake manifold is an effective technique to improve the turbo lag of a heavy-duty turbocharged diesel engine under the transient conditions of load.&lt;/div&gt;

EFFCT OF HOOPS AND COLUMN AXIAL LOAD ON SHEAR STRENGTH OF HIGH-STRENGTH FIBER REINFORCED BEAM-COLUMN JOINTS

A reinforced concrete frame is referred as "RIGID FRAMES". However, researches indicate that the Beam-Column joint (BCJ) is definitely not rigid. In addition, extensive research shows that failure may occur at the joint instead of in the beam or the column. Joint failure is known to be a catastrophic type which is difficult to repair. This study was carried out to investigate the effect of hoops and column axial load on the shear strength of high-strength fiber reinforced Beam-Column Joints by using a numerical model based on finite element method using computer program ANSYS (Version 11.0). The variables are: diameter of hoops and magnitude of column axial load. The theoretical results obtained from ANSYS program are in a good agreement with previous experimental results.