Level Of External Load Research Articles

Low-cycle fatigue properties and fracture location transition mechanism of dissimilar steel welded joints in towers of wind turbines

This study investigates the low-cycle fatigue (LCF) behavior of two types of dissimilar steel welded joints (DSWJs): AISI 1035 & S550Q and AISI 1020 & S550Q. Digital image correlation (DIC) and finite element analysis (FEA) were used to analyze the heterogeneous strain distribution. The results reveal that the location of maximum strain, which is load-dependent and related to strength mismatch, corresponds to the fracture location of the LCF specimens. Specifically, the crack initiation site shifts from the weld toe to the base metal as strain increases. Moreover, the weld reinforcement of the DSWJs significantly affects the failure site transition, introducing strain concentration at lower stress levels while enhancing deformation resistance at higher stress levels, as evidenced by DIC strain measurements and FEA. These findings highlight the importance of joint reinforcement profile, strength mismatch and external load level in designing DSWJs for wind turbine towers against LCF failure.

Investigating the impact of external load on muscle synergies during bipedal squats

PurposeA broad functional movement repertoire is crucial for engaging in physical activity and reducing the risk of injury, both of which are central aspects of lifelong health. As a fundamental exercise in both recreational and rehabilitative training regimes, the bipedal squat (SQBp) incorporates many everyday movement patterns. Crucially, SQBp can only be considered functional if the practitioner can meet the coordinative demands. Many factors affect coordinative aspects of an exercise, most notably external load. Since compound movements are assumed to be organized in a synergistic manner, we employed muscle synergy analysis to examine differences in muscle synergy properties between various external load levels during SQBp.MethodsTen healthy male recreational athletes were enrolled in the present study. Each participant performed three sets of ten SQBp on a smith machine at three submaximal load levels (50%, 62.5%, and 75% of 3 repetition maximum) across three non-consecutive days. Muscle activity was recorded from 12 prime movers of SQBp by way of electromyography (EMG). Muscle synergies were analyzed in terms of temporal activation patterns, i.e., waveform, as well as the relative input of each muscle into individual synergies, i.e., weight contribution.ResultsWaveforms of muscle synergies did not differ between loads. Weight contributions showed significant differences between load levels, albeit only for the gastrocnemius muscle in a single synergy.ConclusionTaken together, our results imply mostly stable spatiotemporal composition of muscle activity during SQBp, underlining the importance of technical competence during compound movement performance in athletic and rehabilitative settings.

Residual stresses in thick composites considering through-thickness temperature gradients during manufacturing

In the composite materials of wind turbine rotor blades, residual stresses form during manufacturing due to the different thermo-chemo-mechanical behaviors of the fibers and the matrix. These residual stresses decrease the ultimate and fatigue strength of the blade because the failure stress and cycles to failure are reached at lower levels of external loading. It is thus of utmost importance to consider residual stresses in the design stage to obtain reliable blade designs.This work deals with the prediction of residual stresses in a thick composite representative for a spar cap in a wind turbine rotor blade. A model is formulated for the thermo-chemo-mechanically coupled problem. An emphasis is given on the non-uniform and time-variable temperature distribution across the thickness of the composite. The different sources of residual stresses (e.g., chemical shrinkage, non-uniform distribution of different thermal expansion coefficients of fibers and matrix, exotherm, etc.) are analyzed, quantified, and compared. The impact of the time-dependent temperature distribution on the formation of residual stresses is highlighted by means of a representative numerical example.

Effect of the mineral spatial distribution heterogeneity on the tensile strength of granite: Insights from PFC3D-GBM numerical analysis

The mechanical characteristics of crystalline rocks are affected by the heterogeneity of the spatial distribution of minerals. In this paper, a novel three-dimensional (3D) grain-based model (GBM) based on particle flow code (PFC), i.e. PFC3D-GBM, is proposed. This model can accomplish the grouping of mineral grains at the 3D scale and then filling them. Then, the effect of the position distribution, geometric size, and volume composite of mineral grains on the cracking behaviour and macroscopic properties of granite are examined by conducting Brazilian splitting tests. The numerical results show that when an external load is applied to a sample, force chains will form around each contact, and the orientation distribution of the force chains is uniform, which is independent of the external load level. Furthermore, the number of high-strength force chains is proportional to the external load level, and the main orientation distribution is consistent with the external loading direction. The main orientation of the cracks is vertical to that of the high-strength force chains. The geometric size of the mineral grains controls the mechanical behaviours. As the average grain size increases, the number of transgranular contacts with higher bonding strength in the region connecting both loading points increases. The number of high-strength force chains increases, leading to an increase in the stress concentration value required for the macroscopic failure of the sample. Due to the highest bonding strength, the generation of transgranular cracks in quartz requires a higher concentrated stress value. With increasing volume composition of quartz, the number of transgranular cracks in quartz distributed in the region connecting both loading points increases, which requires many high-strength force chains. The load level rises, leading to an increase in the tensile strength of the numerical sample.

Evaluation of the Occurrence of Initial Failures from Stress Concentrators in Welded Joints and Structural Elements

Introduction. Data on the occurrence of initial failures obtained through testing on standard samples cannot always be extrapolated to real welded joints and structures. This is due to the difference between the concentrators in the joints, because after welding there is a significant structural and mechanical heterogeneity of the heat-affected and stress concentrator zone. Extended, deep concentrators are considered as crack-like defects, at whose vertices a volumetric, multiaxial stress state is formed. The paper addresses the issue of constructing critical diagrams of the onset of the limiting state at the concentrator vertex, which depends on the level of external load and the theoretical concentration coefficient.Materials and Methods. Analytical methods were used to study the stress state. The literature on the topic was analyzed. The features of proven physical models and patterns of behavior of materials were taken into account. The characteristics of steel alloys were taken from open sources and summarized in a tabulated form. Nonlinear equations were solved in Matlab applications. The diagrams constructed by the authors enable to track the correlation of the dangerous level of the theoretical stress concentration factor and the level of external load. Curve Fitting Toolbox Matlab was used to design the graphic part of the work.Results. The characteristic of damage from stress concentrators in welded joints was given. The crack propagation in the fusion zone was shown. The conditions stimulating and inhibiting destruction were indicated. The theoretical stress concentration factor α𝑇 was specified. It was shown how this indicator depended on the width, the height of the seam and the thickness of the welded part. Acute stress concentrators with theoretical concentration factor αт= 5…14 and more were studied. For this case, an approximating formula was given that took into account the maximum stress in the concentrator in the first half cycle, the initial deformation, and the load ratio. Through those elements, an indicator of an increase in maximum stresses was set depending on the number of loading cycles. The flow condition, the stress state, and the overvoltage factor, which took into account the increase in the first principal voltage for a combined stress state, were analytically shown. A model of the critical state at the apex of an acute stress macro concentrator was described. It was presented as the dependence of the relative stresses of the initiation of destruction σн𝑏𝑐/σ0,2 on the concentrator. Possible variations of this model were analyzed. The dependences of relative values σ𝐻𝑏𝑐⁄σ0,2 on the theoretical concentration factor α𝑇𝑏𝑐=α𝑇 were presented. To check the physical adequacy of this model, graphs were constructed that reflected changes in the relative stress of the external load at a critical state at the stress concentrator apex. The inevitability of bifurcation as a result of the studied processes was validated. Two directions of further development of events were indicated: brittle destruction and loss of stability of the stressed state with the transition to an increase in plastic deformations. The moment of bifurcation was defined as a critical state in the focus of the concentrator.Discussion and Conclusion. The analysis and calculations performed within the framework of the presented scientific work enabled, in particular, to draw conclusions about the role of key factors of the processes under study. It was established, for example, that the operation of a steel alloy at a high theoretical stress concentration factor depended on the characteristics of the stress state. In a rigid state, it was possible to inhibit shear deformation and the onset of the limiting state at a lower value of the theoretical stress concentration factor. With the usual strength of steel (in comparison to high), a greater impact of the volume of the stress state on the value of the theoretical stress concentration factor was recorded. The probability of failure depended on the resistance of the material to the growth of a macrocrack. In future research, it is possible to refine analytical models and results, evaluate effective stress concentration factors.

A harmonic balance solution for the intrinsic 1D nonlinear equations of the beams

In this paper, a harmonic balance method is introduced to solve the intrinsic 1D nonlinear equations presented by Hodges for analyzing initially curved and twisted anisotropic rotating beams. First, the nonlinear first-order partial differential equations are discretized in space domain using the Galerkin approach. Then, the time response of the system of equations is approximated by using first and the second harmonic terms under the harmonic excitations applied to the structure. The harmonic balance algorithm has been developed for the linearized system of equations about the steady-state solution and for fully nonlinear equations. The differences between these two systems have been addressed under consideration of different levels of external loads. Fully analytical formulae have been presented for the HB solution of the linearized equations in this work. In the proposed approach for the nonlinear system, the Jacobian matrix utilized in the numerical solution part is obtained analytically to increase the time efficiency of the solution method. The results of the proposed approach for an initially twisted and curved blade are compared with a different algorithm based on a finite difference approach to discretize the equations and a time marching method to solve the system of equations in time domain. The comparison between the outputs of the harmonic balance method and the time marching method demonstrate high correlations between these distinct methods. It should be noted that the accuracy of the time marching method solution has been evaluated in another publication by the authors using the output of FLIGHTLAB for a blade with different types of boundary conditions. The proposed harmonic balance-based method delivers a very time-efficient approach for time analysis of twisted/curved beams and blades under harmonic loads in comparison with other employed methods. The developed approach can be a powerful computational tool for design optimization of composite blades.

Numerical investigation on the effect of intergranular contact bonding strength on the mechanical properties of granite using PFC3D‐GBM

AbstractIn rock materials, the intergranular structure is more affected by various external conditions than the transgranular structure, and then dominates the macroscopic mechanical properties of rocks. In this paper, an innovative three‐dimensional grain‐based model based on Particle Flow Code (PFC3D‐GBM) for reproducing granite crystalline structures was developed. Based on this model, the Brazilian splitting test was conducted to investigate the effects of intergranular contact (IC) bonding strength on the mechanical properties and micro‐cracking behavior of the granite. Additionally, in this paper, the force chains and the orientation distribution of the force chains are shown in the form of three‐dimensional rose diagrams. The results are compared to the numerical results obtained by an initial particle‐based model to demonstrate the superiority of the proposed PFC3D‐GBM. The results indicate that the stress–strain curve of the sample in the Brazilian splitting test can be classified into four distinct stages: initial compaction, linear elasticity, damage, and splitting failure. ICs fracture at a higher rate than transgranular contacts (TCs) under static loading, as evidenced by experimental results of laboratory tests; during the entire loading process, all force chains uniformly distribute in all directions of a sample. As the external load increases, the number of total force chains decreases and the number of cracks increases. The main orientation of the high‐strength force chains is consistent with the external loading direction and is vertical with respect to the main orientation of the cracks. Furthermore, the number of high‐strength force chains increases with the level of external load. The sample's failure mechanism in the Brazilian splitting test is always a tensile failure, and this characteristic is unaffected by the modeling method or the IC bonding strength. Both the tensile strength and peak strain increase as the IC bonding strength increases. In this process, the number of total cracks in PFC3D‐GBM decreases, the proportion of transgranular cracks (Tcs) increases, and the proportion of intergranular cracks (Ics) decreases. The micro‐cracking behavior described above based on the PFC3D‐GBM can be explained more rationally. As the bonding strength of the IC increases, the particles involved in sample deformation are subjected to a greater stress concentration prior to the sample experiencing macro‐fracture, leading to an increase in the number of high‐strength force chains, which is the fundamental reason for the increase of the sample's tensile strength.

Impact of external biaxial compressive loading on the fire spalling behavior of normal-strength concrete

Explosive spalling of concrete exposed to fire consists in the expulsion of shards from the heated face during rapid heating. The phenomenon can seriously jeopardize the integrity of reinforced concrete structures due to the reduction of the cross-sectional area of the structural elements and even lead to the direct exposure of reinforcing bars to flames. The literature shows that various parameters influence the occurrence of fire spalling, such as heating rate, specimen geometry and boundary conditions, concrete grade, and external loads. In this regard, the present study aims at highlighting the role of external loading in combination with the effects of pore pressure and thermo-mechanical stresses in triggering spalling in normal-strength concrete (fc28days ≈ 45 MPa). Unreinforced concrete slabs (size: 800 × 800 × 100 mm3) were subjected to a standard (ISO 834–1) fire curve under seven different levels of external membrane biaxial compressive load. The experimental results clearly show that compressive loading significantly increases spalling propensity and severity.

Eutrophication decreases Halophila beccarii plant organic carbon contribution to sequestration potential

Seagrass ecosystems rank among the most effective blue carbon sinks in climate change mitigation and greenhouse gas removal. Nutrient pollution has emerged as a leading threat to seagrass decline and has diminished the carbon sequestration potential in recent decades. Changes in the nutrient regime can also impact the organic carbon compositions (labile and refractory organic carbon compositions) of seagrass tissues, with important implications for determining the quantity and quality of carbon sequestration. However, there is still little information about the impact of nutrient loading on seagrass plant refractory organic carbon composition (ROC), which hinders our ability to reveal the driving mechanisms of anthropogenic factors that decrease seagrass organic carbon sequestration capability. Here, a multidisciplinary approach was employed to investigate the organic carbon variations of Halophila beccarii at five seagrass meadows with contrasting nutrient loading levels. The results showed that H. beccarii plant nitrogen (N) content ranged from 2.21% to 5.65%, which well reflected the external nutrient loading levels. High nutrient loading elevated labile organic carbon content, like free amino acids and soluble sugars. Nevertheless, ROC content (cellulose-associated organic matter) decreased with increasing nutrient loading, which presented a significant negative linear correlation with plant N content. These results provide evidence that eutrophic conditions enhance H. beccarii plant quality (high N and labile organic carbon) and consequently decrease plant ROC sequestration potential. This suggests that reducing nitrogen input to seagrass meadows would aid in increasing seagrass carbon storage.

An approach to predict soil particle breakage and gradation evolution for carbonate sands

This paper proposed an approach to predict particle breakage and gradation evolution for carbonate sands, based on single-particle compression and confined bulk compression tests. Two key concepts, i.e. ‘Breakage ratio’ and ‘Evolution Distribution Matrix’ were developed in this study, to address two central questions (1) what is the portion of the original particles that will break under different level of external loading, and (2) what are the relative proportions of new particles resulted from the larger broken particles. The calculation parameters in this prediction approach can be calibrated through the single-particle compression and uniformly-graded sample bulk compression tests conducted in this study. Compression tests by using non-uniformly graded samples were further carried out and the prediction approach was used to compare the test results. The good agreement demonstrated the feasibility and effectiveness of the proposed prediction approach.

How the Direction of Screws Affects the Primary Stability of a Posterior Malleolus Osteosynthesis under Torsional Loading: A Biomechanical Study

Insufficient fixation of a posterior malleolus fracture (PM) can lead to posttraumatic complications such as osteoarthritis and chronic pain. The purpose of this biomechanical study was to test the hypothesis of whether the direction of PM screw fixation has an impact on the primary stability of osteosynthesis of a PM under torsional loading. PM fractures of 7 pairs human cadaveric lower leg specimens were stabilized with posterior to anterior (p.a.) or anterior to posterior (a.p.) screw fixation. Stability of the osteosynthesis was biomechanically tested using cyclic external torsional loading levels, in 2 Nm steps from 2 Nm up to 12 Nm, under constant monitoring with 3D ultrasonic marker (Zebris). The primary stability does not differ between both stabilizations (p = 0.378) with a medium effect size (η2p = 0.065). The movement of the PM tends to be marginally greater for the osteosynthesis with a.p. screws than with p.a. screws. Whether a.p. screws or the alternative p.a. screw fixation is performed does not seem to have an influence on the primary stability of the osteosynthesis of the PM fixation under torsional loading. Although osteosynthesis from posterior seems to be more stable, the biomechanical results in the torsional test show quite equivalent stabilities. If there is no significant dislocation of the PM, a.p. screw fixation could be a minimally invasive but stable surgical strategy.

The effect of external load on ultrasonic wave attenuation in steel bars under bending stresses

The stress state in deformed solids has a significant impact on the attenuation of an ultrasonic wave propagating through the medium. Measuring a signal with certain attenuation characteristics can therefore provide useful diagnostic information about the stress state in the structure. In this work, basic principles behind a novel attenuation-based diagnostic framework are introduced. An experimental study on steel bars under three-point bending was carried out, and finite element analyses were used to numerically model the experiments. Obtained test results showed a strong correlation between the external load and the ultrasonic signal energy, which decreases with increasing load. A similar but positive correlation appeared between the level of attenuation of longitudinal ultrasonic wave signals and the external load, which allowed for efficient estimation of the mid-span bending moment. Upon proper calibration of testing equipment, the change in ultrasonic signal energy can therefore be used as an indicator of the external load level. As a result, this effect has potential applications in non-destructive structural health monitoring frameworks.

METHODOLOGY AND RESULTS OF THE SERIES P-2 GLASS SLABS DURABILITY TEST

The paper presents the results of studies of glass plates of series P-2 for durability, which were made of float glass sheets, the methodology of experimental studies of glass plates for durability, as well as the design of the test facility. The analysis of literature sources on the subject made it possible to study the main factors of application of glass slabs as load-bearing structures. Glass is characterized by high strength, but glass structures are not widely used because of the possibility of their sudden brittle fracture and the lack of reliable calculation methods. The strength and reliability of glass structures depend on the type and strength of glass, manufacturing technology, the magnitude of external load and the duration of its action. Glass structures are characterized by the phenomenon of rheology and sudden brittle fracture, so the study of their durability, at different levels of external static load will ensure their reliable operation for the required time. Durability of a structure is the time from the beginning of static load action, which does not exceed the destructive load, with its further endurance until the destruction of the structure. For experimental studies of the durability of glass slabs, there was a need to create a research technique to ensure the stability of the external static load during the entire experiment with the possibility to record the growth of the deflection of the glass slab, the time and the nature of the failure up to the very moment of their sudden brittle failure. The paper describes the methodology and presents the initial results of the experimental study of glass beam slabs for durability. The slabs were hinged to two supports and operated as a single-span beam under a steady static load. Based on the experimental data obtained on the fracture of glass slabs during the action of a steady static load, we can try to predict their durability.

Safety evaluation of truss bridges using continuous Bayesian networks

Truss structures have been widely used in railway and highway bridges. However, it is difficult to evaluate the safety states of truss bridges due to a large number of members, high system redundancy, and insufficient monitoring data caused by limited sensors. Due to this, a new method based on continuous Bayesian Networks (BNs) is proposed to perform the safety evaluation on truss bridges, where the external loads and member stresses are assigned with two types of nodes in the BN. First, the BN topologies are established by combining the mechanical relationship of truss members to avoid the negative influence of redundant and missing edges in large-scale topology learning. Then, since the monitoring data in real-world civil structures are usually insufficient, a completed numerical sample set is adopted for parameter learning to obtain the conditional probability distributions. Subsequently, multiple BN models corresponding to different external load levels are established. A monitoring data-based matching approach is presented for model screening to find the optimal BN model. After that, the data from a few truss members are used to simulate the insufficient data in actual situations, and they are input into the optimal BN model to infer the external loads and the stresses of the remaining members. The inference ability using insufficient information well accords with the demand in engineering practice. Furthermore, two safety indices representing system states and failure probabilities are defined to evaluate the safety states of truss bridges. Finally, the feasibility of the proposed method has been successfully verified against both numerical and experimental truss bridge models.

Deformations of steel end‐plate beam‐to‐column joint when subject to simulated steady‐state and transient‐state fire heating regimes

AbstractThe bearing capacity and rigidity of selected steel end‐plate beam‐to‐column joint are analysed in the paper. Those properties are determined numerically, based on the fire conditions simulated for this node. For comparison, two alternative heating regimes, typical for steady‐state and transient‐state scenarios, are considered. In the first case, an initially statically preloaded joint is evenly heated up to a predetermined temperature and subsequently, in this temperature, subjected to monotonously increasing static load until reaching the ultimate bearing capacity. In the second scenario, the same joint, subjected to the same preliminary static load, is subsequently statically loaded to reach a predetermined ratio of its ultimate bearing capacity and then, during the time of simulated fire, monotonously heated until failure. During the analysis it is assumed, that the steel is heated at a low rate, not affecting its material properties at given temperature. A cluster of curves depicted in the bending moment vs. effective rotation angle system of coordinates is a result of the first analysis. Each of these curves corresponds to a selected steel temperature. In the second case, the deformability of the joint, increasing with temperature, is expressed by a set of relationships between joint rotation and the corresponding temperature of steel. Thus a single relationship of this type corresponds to a selected level of external load applied at the node.

Different volumes of repetitions and workloads in the pressor responses of hypertensive elderly: A systematic review

Objective: To synthesize the findings of chronic effects and the differences between the volume of repetitions and levels of external loads in the pressure responses of elderly hypertensive patients. Methods: The study followed the proposals of PRISMA (Preferred Reporting Items are Systematic Reviews and Metanalysis). As searches for the selected articles on the Medline, Pub Med, Cochrane, and Periodical platforms, between August and December 2020. The same studies were found using several words according to the proposed theme. ("Resistance training" and "elderly") ("Resistance training" and "blood pressure") ("Resistance training" and "cardiovascular and elderly") ("Resistance training" and "blood pressure" and "elderly") ("Resistance training" and "blood pressure" and "older"). Results: 2,698 articles were identified with these keywords. Title, abstract, duplicates excluded studies and after reading in full. Finally, ten studies were selected to read the integration, and four were selected for final analysis. Conclusion: This systematic review study uses low repetition and repetition to reduce similar magnitudes' blood pressure. The levels of external loads did not interfere in large proportions in hypertensive older adults' pressure responses. However, studies on the post-exercise resistance hypotensive effect and its variables are still scarce, making further studies on the subject necessary.

Physiological and physical effect on U-12 and U-15 football players, with the manipulation of task constraints: field size and goalkeeper in small-sided games of 4x4 players.

Our study aimed to verify whether the manipulation of task constraints has different effects according to age group. Another objective was to verify the physiological and physical responses in the different formats of small-sided games (SSG). Each team in the SSGs was composed of 4 players (4x4). The participants in the research are young football players U-12 (n=8) and U-15 (n=8), affiliated with a club certified as a training entity, and competed in the regional football championship of 7 and 9 players and the national championship of Portugal, respectively. The internal and external load data were collected in 5 formats of SSGs with three field size and in 2 used goalkeepers. We used the WIMU PROTM inertial device for data collection. The registration of the internal charge, using heart rate (HR), was performed with the use by the players of Garmin bands, which send the data to WIMU PROTM devices, through of Ant+ technology. The variance analysis (ANOVA) was used to verify the differences between SSGs and the effect size was determined by calculating partial eta-square). Comparisons between the two age groups were evaluated using standardized differences with combined variance (Cohen’s d). The results show that the manipulation of the playing areas and the use of goalkeepers promoted different effects in the two age groups in terms of distance, explosive distance, accelerations/decelerations and maximum sprint. As for the comparison between SSGs we found differences in the level of external load (distance, accelerations/decelerations and maximum sprint). At the level of internal load, the effects were more evident with field areas above 100m2. We can conclude that the manipulation of the task conditions, playing area and goalkeeper, promote different physical and physiological responses, and the coach should consider this fact, as well as the effects promoted in the age groups.

Theoretical foundations of design optimization ship's control, decision-making systems and information processing

Problem setting. The problems of optimizing the protection parameters of REA structures operating under complex mechanical influences, their diagnostics of quality, reliability and strength, as well as structural and parametric synthesis in the last decade are devoted to the work [1 9]. However, these works do not consider the issues of optimisation of vibration prote ction parameters and strength of structures on the basis of determination of functional dependencies of forces against deformation and damping against deformation rate for vibration insulation systems and structural elements included in the instrument. The main results given in these works relate to the determination, at best, of resonant frequencies, which is insufficient to optimize vibration protection parameters and diagnose the reliability of devices. The aim. Develop a methodological basis for the use of quality and durability control and diagnostics methods to improve the reliability of the operation of ship information and control systems in extreme operating conditions by optimizing their vibration protection. Results. The basics of modeling the designs of radio-electronic equipment devices for various mechanical influencing factors are described. Description of models and mathematical peculiarities of organization of initial data for modeling is given. When comparing design stresses and allowable stresses, the strength of the product is determined. Allowable stresses are obtained using endurance curves for each material of the device design. Simulation of the panel instrument design under vibration impact is considered and processing of its results is presented. When creating a typical product operation model, the main operating modes and levels of external influencing factors and loads of each mode are determined. The example of the console instrument shows the procedure for modeling strength and determining the value of failure-free operation. It has been found that for a given console device the most complex effect is vibration, since it creates a multi-cycle loading of the structure, which affects the strength of the product as a whole. Practical significance. The proposed approach to determination of structural strength makes it possible to find the number of loading cycles under vibration impact for each element and time operating time, as well as the calculated value of failure-free operation of the console device. This simulation can be performed at any stage of the instrument design.

Calculation of Bearing Capacity of Augercast Tapered Piles in Clayey Soils

The article presents a new method for determining the bearing capacity of augercast tapered piles in clayey soils by considering the various factors such as the level of external load, the sequence of operations in the installation of piles, and variations in the physical and mechanical characteristics of soils in the pile space that are responsible for effective performance of piles. This method is also recommended for designing free-standing pile and girder foundations.

The impact of climate change on a Mediterranean shallow lake: insights based on catchment and lake modelling

Shallow lakes in the semi-arid climate zone of the Mediterranean are sensitive to drought due to the low annual precipitation and high evaporation. Changes in precipitation and temperature as projected by climate change scenarios will have an effect on the hydrology of these shallow lakes with secondary effects on nutrient dynamics and ecological state. In this study, we used a combined modelling approach that included the catchment model Soil and Water Assessment Tool (SWAT) and the lake model PCLake to study the possible effects of several climate scenarios on a shallow lake in semi-arid central Anatolia, Turkey. Our results show that lower precipitation and higher temperatures may reduce inflow rates and water levels drastically. Diffuse nutrient loading depended highly on precipitation and thus decreased as well. The lake model predicts an interaction between external nutrient loading and water levels. Low water levels benefited submerged macrophytes if nutrient concentrations were low, but low inflow rates and high evaporation during dry periods increased in-lake nutrient concentrations and chlorophyll-a. Cyanobacteria biomass was also higher in the drier and warmer scenarios. Overall, the results show that lower hydraulic loads and reduced flushing rates as a result of drier and warmer conditions lead to lower water levels and higher in-lake nutrient concentrations unless nutrient loading decreased as well. This implies that catchment-scale nutrient management is essential to maintain low nutrient concentrations in the lakes with increasing temperature and decreasing precipitation in a dry climate.