Global Displacement Research Articles

Full-scale fire tests on steel roof truss structures

This paper conducted nondestructive and destructive fire tests on a full-scale steel truss roof structure. The nondestructive trial fire tests adopted the diesel oil fire to simulate small-size localized fires, and the destructive fire test used wood cribs as the fuel. Test results including the test phenomenon, failure modes, thermal and structural responses, namely the temperature-time and displacement-time curves, were obtained. Small arching deformation was observed in the nondestructive fire tests, but no permanent damage that would influence the structural behavior occurred. After the destructive fire test, the failure modes of the specimen included massive global vertical displacement and buckling of the web members, while no damage of the joints was observed. Before the failure, the specimen presented obvious arching deformation. The homogeneous temperature assumption was conservative in the fire analysis of steel truss structures since the non-uniform temperature distribution existed in all of the tests, which was suggested to be considered by field simulation. The test results will also be a reference for the experimental verification of the fire monitoring system, which will be developed by the authors in the future.

Structural Shape Estimation by Mode Shapes Using Fiber Bragg Grating Sensors: A Genetic Algorithm Approach

Structural shape estimation is of great interest in many engineering fields including aerospace and civil engineering. During operation, however, the monitoring of structural displacements is often difficult. This article discusses structural shape estimation using a minimal number of fiber Bragg grating sensors. A strain to displacement transformation matrix is derived using mode shapes, to estimate the global displacement of a structure from measured discrete strain data. The number of sensors and sensor layout for the shape estimation is optimized using genetic algorithm. Static and dynamic displacement experiments are conducted on an aluminum plate to verify the algorithm. The deformation during static experiments is measured at nine different locations and estimation error was less than 0.5%. The deformation during dynamic excitation is measured at one selected location using a noncontact laser sensor. The shape estimation quality is better for resonance frequencies compared to off-resonance frequencies. The results show that the estimated displacements match well with those measured displacements.

The Silent Takeover of Power by the Far-Right

Annals of Social Sciences & Management studies are an international journal which focuses to spread a vast knowledge to the readers. ASM includes various topics which cover every part of Sociology and management studies like Philosophy & Public Affairs

Isogeometric Optimal Design of Compliant Mechanisms Using Finite Deformation Curved Beam Built-Up Structures

Abstract This paper presents a configuration and sizing design optimization method for large deformation planar compliant mechanisms, using a continuum-based adjoint design sensitivity analysis (DSA) approach for built-up structures. Under the total Lagrangian formulation, the Jaumann strain formulation using the discretization of the global displacement field is employed to account for the finite deformation of arbitrarily curved Kirchhoff beams. In multipatch models, a rotational junction continuity condition is imposed using penalty and Lagrange multiplier methods. The developed adjoint DSA method can handle nonconservative loading conditions, which lead to asymmetry of tangent operator. Performance measures are displacements and rotation angles, and neutral axis configuration and cross-sectional thickness are considered as design variables. Also, analytical design sensitivity expressions for the rotation continuity condition are derived. Various compliant mechanisms including path-generators and an angular rotator are synthesized to demonstrate the applicability of the proposed method.

Dynamic behavior of humid granular avalanches: Optical measurements to characterize the precursor activity.

Laboratory study of slope stability of granular media remains a challenge for modeling, understanding, and predicting natural hazards, such as avalanches and landslides, precursory signs of which are controlled by numerous physical parameters. The present work focuses on the impact of the humidity, in the range of 40-90%, on the stability of monodisperse dense packings of spherical beads. The beads are in a transparent box that is slowly and continuously tilted and allows simultaneous top and lateral optical measurements of global displacements of grains at the surface, defined as precursors. Humidity increases the cohesion between the grains. By performing successive avalanches that destabilize deeper granular layers, we assess the role of the exposure time to the high humidity rates in the diffusion process to reach the hygroscopic equilibrium inside the packing. We highlight an increase of the stability and first precursor angles, associated to a constant angle increment between two consecutive precursors, with a dependency with both the diameter (0.2,0.5, and 0.75mm) and the material (glass and polystyrene) of the grains.

High-speed 3D digital image correlation for rolling deformation of a tire sidewall and measuring dynamic contact patch length.

Tires play a vital role in a vehicle's operational stability, comfort, and security. However, due to the influence of test equipment and tire operating conditions, the perception of rolling tire characteristics is still in the stage of gradual improvement, especially the analysis of sidewall rolling deformation and dynamic contact peculiarities of tires/road interactions, which has restricted the analysis of rolling energy dissipation and the accurate observation of tire forces. In this paper, the high-speed stereo-vision system was created by high-speed cameras, and the relative rigid and flexible displacement, strain, and trajectory trend of marker points and the real-time global displacement field of the sidewall during the tire-rolling cycle were acquired utilizing the improved digital image correlation algorithm under different rolling velocities. Meanwhile, the periodic dissipation of the strain concentration region was observed, and the phenomenon of strain resonance appeared at the overlap of the periods. The relative flexibility strain and shear strain of the marker point were obtained on the plane element, which resulted in the relative flexibility major principle strain of the plane element, and then it achieved recognition of the leading and trailing points of the contact patch and the accurate measurement of dynamic contact patch length.

System reliability analysis of soil nail wall using random finite element method

Soil nail wall is a compound system which for safety margin determination, consideration of safety factors of its components and their correlations is required. In this paper, considering a real site using the random finite element method (RFEM), the reliability indices of global stability, lateral displacement stability, tensile strength, and pullout resistance stability as components of the soil nail wall system are obtained. In another section of the paper, using the sequential compounding method (SCM), the importance of the mentioned stability modes and their effects on system reliability and system probability of failure are represented. Results show that the most considerable interdependence is between the global and lateral displacement stabilities. Among the reliability indices of the components, the minimum one is attributed to the pullout resistance. Furthermore, the uppermost row of the nails has the most critical reliability index compared with the others. The locations of the slip surfaces and nail intersections varied from 0.05–0.90 of the nail length, which means that the uncertainty of the soil parameters has the most significant effect on the pullout resistance safety factor of the nails. The performance level of the soil nail wall decreases from below average to poor when the soil nail wall is considered to be a system with series components.

Extended Tension Chord Model for Boundary Elements of RC Walls Accounting for Anchorage Slip and Lap Splices Presence

This paper presents a mechanical model for the simulation of reinforced concrete (RC) wall boundary elements with lap splices, which builds on the tension chord model. The model is composed of an assembly of components, each one accounting for a different source of deformation. Namely: (i) an anchorage-slip element accounting for the strain penetration of the longitudinal reinforcement into the foundation; (ii) a basic tension chord element evaluating the response outside the lap splice zone; and (iii) a lap splice element describing the behaviour within the lap splice region. For an imposed global displacement, the model provides the steel and concrete stress and strain distributions, the crack distribution and opening, as well as the global resisting axial force. For spliced members, the ultimate displacement is computed through a semi-empirical relationship providing the average lap splice strain at failure. Validation is carried out against a series of uniaxial cyclic tests on RC wall boundary elements featuring both continuous and spliced reinforcement; different lap splice lengths and confining reinforcement are considered. Overall, a good match is obtained between numerical and experimental results in terms of crack width, rebar strain distribution along the splices and ultimate displacement.

Resettlement of Gumuz Communities Around Ethiopia’s Blue Nile Dam

This working paper presents preliminary conclusions from research carried out in Benishangul Gumuz and Amhara National Regional States of Ethiopia in November 2018 and January 2019. It explores the programme of resettlement of Gumuz farmers and others living at low altitude along the Nile and Beles rivers, whose home areas are expected to be flooded on completion of the Grand Ethiopian Renaissance Dam (GERD) and filling of a new reservoir. We focus on problems associated with access to social services and to common resources, notably water; on land, housing, property and compensation; on livelihoods impacts and prospects; on changes in social and community articulation; and on issues of planning, budgeting and coordination of responsibility among stakeholders. These findings, which indicate strong continuities with the well documented problems of global dam-induced displacement, and resettlement in Ethiopia’s past, suggest the potential for improving policy and institutional decision making by enhancing learning from existing experiences, rooted in a nuanced understanding of local conditions. The findings are designed both to inform the period to 2022, the currently projected conclusion of the GERD construction phase, and to encourage longer-term commitment and planning, once the dam is built, that would maximise shared benefits, in terms of social and economic development, locally, among the resettled Gumuz, and nationally and regionally.

Cardiovascular risk assessment in South and Middle-East Asians living in the Western countries.

Nearly a quarter of the world population lives in the South Asian region (India, Pakistan, Bangladesh, Sri Lanka, Nepal, Bhutan, and the Maldives). Due to rapid demographic and epidemiological transition in these countries, the burden of non-communicable diseases is growing, which is a serious public health concern. Particularly, the prevalence of pre-diabetes, diabetes and atherosclerotic cardiovascular disease (CVD) is increasing. South Asians living in the West have also substantially higher risk of CVD and mortality compared with white Europeans and Americans. Further, as a result of global displacement over the past three decades, Middle-Eastern immigrants now represent the largest group of non-European immigrants in Northern Europe. This vulnerable population has been less studied. Hence, the aim of the present review was to address cardiovascular risk assessment in South Asians (primarily people from India, Pakistan and Bangladesh), and Middle-East Asians living in Western countries compared with whites (Caucasians) and present results from some major intervention studies. A systematic search was conducted in PubMed to identify major cardiovascular health studies of South Asian and Middle-Eastern populations living in the West, relevant for this review. Results indicated an increased risk of CVD. In conclusion, both South Asian and Middle-Eastern populations living in the West carry significantly higher risk of diabetes and CVD compared with native white Europeans. Lifestyle interventions have been shown to have beneficial effects in terms of reduction in the risk of diabetes by increasing insulin sensitivity, weight loss as well as better glycemic and lipid control.

Effect of Random Strength Parameters of Flange Steel on Bending Resistance and Deflections of Girders with Corrugated Web

Abstract The study presents results of statistical investigations into random strength parameters of steel used to manufacture flanges of plate girders with corrugated web. In the case of plate girders with corrugated webs, flanges are manufactured from flat sheet steel S235JRG2 or S355J2+N or S275. The guaranteed yield strength Remin is determined on the basis of tests conducted on steel samples. It should be lower than yield strength of flat sheets obtained as the result of testing mechanical properties. This value at the same time should be regarded as the margin of resistance of girders. The material tests were performed on samples randomly collected from 20 girders with corrugated web and flange thickness of 15 and 20 mm, which had been already examined. Coefficients of variation of yield strength VRe =D(Re )/E(Re ) and partial factors of yield strength γm were selected on the basis of the conducted analysis of material tests. The obtained results were related to factors γm determined from the tests on thin flat sheets. The impact of yield strength and random cross-sectional area of flanges on bending resistance of girders with corrugated web was shown. Also the effect of the spread of the Young’s modulus values and semi-rigid connections on global displacements of tested plate girders with corrugated web was analyzed.

The effects of steel X-brace retrofitting of RC frames on the seismic performance of frames and their elements

Steel X braces are used extensively to retrofit RC frames. When steel braces are added to an existing RC frame, the load paths through which the lateral forces are transferred change considerably, resulting in changes in demand on the frame and its elements. The present study attempts to examine the possible side effects of retrofitting RC frames with steel X braces, regarding their overall seismic performance such as global displacements, drifts and base shears, as well as, their individual members, including beams and joints. To this end, a large number of nonlinear time history seismic analyses are performed on retrofitted 2D, RC frames, being 4, 8 and 12 storeys high. It is found that, retrofitting an RC frame with steel X braces improves its global seismic response by reducing the maximum displacement, inter-storey drifts and demand base shear. However, the effectiveness of the bracing system in improving global responses is generally reduced as the height of the frame increases. Regarding the local effects on beams and joints, it is noted that although retrofitting, in general, reduces ductility demand in beams, and shear demand in joints, the reductions are not substantial in taller frames and in some beams and joints retrofitting may even have an adverse effect. Also, the connections between the steel X brace system and the RC frame cause the plastic hinges in beams and columns to relocate further away from the joint, resulting in a reduction in the effective length and possible increase in the level of plastic shear in these members. The local adverse effects of retrofitting an RC frame by steel X-braces may necessitate prior local strengthening of some members.

Morphological variability, biochemical parameters of Hippophae rhamnoides L. berries and implications for their targeted use in the food-processing industry

The results of studying the morphological and biochemical parameters of plants of sea buckthorn are presented. For the first time, genotypes of sea buckthorn ranked by ontogenetic and morphological characteristics and ecological features (relation to the level of soil moisture and humidity air, providing soil nutrients, its рН, amount and mode of precipitation, lighting, positive and negative temperatures) natural, semi-natural and anthropic coenopopulations genotypes of sea buckthorn be ranked by ecomorphic affiliation to certain climate ecotypes (рolissia, forest-steppe) and subecotypes (western-forest-steppe, northern-forest-steppe, рolissia–forest-steppe, central-forest-steppe). Biotypes, that have been a limited ability to carry soil and atmospheric drought (in which the root system is well developed, ground part with copious leaf cover), selected in natural and semi-natural places of growth appertain tо mesophytes (Ms). The genotypes, selected in catchment areas, the lowlands of Forest-Steppe, Polissia of Ukraine, appertain to mesohygrophytes (MsHg) (by morphological and physiological features characterized by weak drought and heat resistance – 6 points, require sufficient moisture and sufficient provision of organic and mineral substances, are weak frost resistant, but very resistant to temperature changes during the winter). A special group makes up widely ecological flexibility mesophyte plants of sea buckthorn – mesoxerophytes (wfMsKs) – are presented рolissia–forest-steppe subecotype, characterized by wide environmental plasticity, due to the high winter, drought and frost resistance, compared to others subecotype. Its have adapted to withstand prolonged of soil and air in the extreme phases of ontogeny, in particular, in the phase of fruit filling and ripening, giving high stable harvest. Particular breeding and economic value in terms of formation stably high yields under conditions of global climate change, its aridization and displacement borders zoning of fruit crops have xeromesophytes (KsMs) presented central forest-steppe subecotype – in view of the its relatively average demanding to soil and air moisture and resistance to moisture deficiency. Highlighted forms – sources of valuable economic features of sea buckthorn (large berry, firm skin, long berry peduncles and dry separation of berries and іts increased biological value, freezing capacity and making beverages, high yields.

Local zigzag effects and brittle delamination fracture of n-layered beams using a structural theory with three displacement variables

Equivalent single layer theories for layered beams effectively and accurately predict global displacements and internal force and moment resultants using a limited number of displacement variables. However, they cannot reproduce local effects due to material architecture or weak/imperfect bonding of the layers, such as zigzag displacement fields, displacement jumps at the layer interfaces and complex transverse stress fields, nor can they simulate delamination damage growth. In this work we will present some applications and discuss advantages and limitations of a recently formulated zigzag model. The model, through a modification of the equilibrium equations of an equivalent single layer theory, which maintains the same number of variables, reproduces local effects and delamination fracture under mode II dominant conditions. The approach is based on a local enrichment of the displacement field of first order shear deformation theory, the introduction of cohesive interfaces and homogenization.

A statistics-based discrete element modeling method coupled with the strength reduction method for the stability analysis of jointed rock slopes

The stability of jointed rock slopes can be effectively analyzed using the discrete element method (DEM). However, the criteria for terminating the DEM iterative calculation process and determining the factor of safety (FOS) are not well defined. In this paper, a displacement-statistics-based discrete element modeling method (DSDM) is proposed to analyze the stability of jointed rock slopes by coupling with the shear strength reduction method (SRM). In the presented DSDM, two important criteria are defined: (1) a statistics-based criterion for terminating the iterative calculation process of the DEM modeling in the stability analysis of jointed rock slopes, and (2) a statistics-based criterion for determining the FOS of a jointed rock slope when coupling DEM and SRM. The novelty of the proposed DSDM is that statistical information of the global displacements around the potential slip surface of the jointed slope, rather than the local displacements of several characteristic points, are utilized to define the criteria for terminating the DEM iterative calculation process and determining the FOS. To verify the effectiveness of the proposed DSDM, the FOS of a simplified jointed rock slope is first calculated using the proposed DSDM, and then compared with the FOS obtained using the finite difference method (FDM). Moreover, the proposed DSDM is applied to analyze the stability of a real high-steep bedding rock slope. The numerical simulation results for the real rock slope are consistent with the in-situ observations. The proposed DSDM is thus capable of effectively analyzing the stability of jointed slopes with potential slip surfaces.

Unfavourable seismic behaviour of reinforced concrete structures due to soil structure interaction

The soil-structure interaction (SSI) effects can substantially alter the behaviour of structures during earthquakes. Implementation of SSI within the seismic analysis often leads to lower stresses in the structure and therefore a more economical design. The recently introduced provisions in European and American codes allow for this type of approach. However, consideration of SSI can also lead to the observation of unfavourable effects (undetectable in a fixed-base analysis) due to the modification of the structure’s dynamic properties. Examples of unfavourable effects include higher global displacements or story drifts, increases of the base or story shear forces, higher post-elastic demands in the structural members or the collision of adjacent buildings separated by an insufficient structural joint. These unfavourable effects can be related to various parameters such as the structural system (frames or shear walls), foundation type (shallow or piles), geometry of the foundation, height of the building, soil type, seismic input, presence of adjacent buildings, etc. Under these circumstances, the integration of SSI into the current structural design becomes essential. As the mathematical formulation of the phenomenon is very complex and involves many parameters, the definition of complete numerical models is difficult. The provisions in the codes are often general and do not give the practicing engineers clear modelling solutions. An analysis of the current situation in the field of SSI is carried out, with a focus on the design of reinforced concrete structures. Based on an extensive literature review, the unfavourable seismic effects and the main parameters that determine them are identified. Conclusions are drawn regarding the situations when SSI should be mandatory and on the different possibilities of implementing SSI in the structural design.

Refugee and Asylum-Seeking Children: Interrupted Child Development and Unfulfilled Child Rights.

The 21st century phenomenon of “global displacement” is particularly concerning when it comes to children. Childhood is a critical period of accelerated growth and development. These processes can be negatively affected by the many stressors to which refugee and asylum-seeking children are subjected. The United Nations Convention on the Rights of the Child (CRC) is the most ratified human rights treaty in history, with 196 States Parties (SPs). The CRC provides a framework of 54 articles outlining government responsibilities to ensure the protection, promotion, and fulfillment of rights of all children within their jurisdictions. Among these are the rights of refugee and asylum-seeking children, declared under Article 22 of the CRC. Refugee and asylum-seeking children, similarly to all other children, are entitled to their rights under the CRC and do not forgo any right by virtue of moving between borders. The hosting governments, as SPs to the CRC, are the primary duty bearers to fulfill these rights for the children entering their country. This manuscript provides an overview of the health and developmental ramification of being displaced for refugee and asylum-seeking children. Then, an in-depth analysis of the provisions under Article 22 is presented and the responsibilities of SPs under this article are described. The paper provides some international examples of strengths and shortcomings relating to these responsibilities and closes with a few concluding remarks and recommendations.

Inflation experiments and inverse finite element modelling of posterior human sclera

The complexity of inverse finite element modelling methods used in ocular biomechanics research has significantly increased in recent years in order to produce material parameters that capture microscale tissue behaviour. This study presents a more accessible method for researchers to optimise sclera material parameters for use in finite element studies where macroscale sclera displacements are required.Five human donor sclerae aged between 36 and 72 years were subjected to cycles of internal pressure up to 61 mmHg using a custom-built inflation rig. Displacements were measured using a laser beam and two cameras through a digital image correlation algorithm. Specimen-specific finite element models incorporating regional thickness variation and sclera surface topography were divided into six circumferential regions. An inverse finite element procedure was used to optimise Ogden material parameters for each region.The maximum root mean squared (RMS) error between the numerical and experimental displacements within individual specimens was 17.5 µm. The optimised material parameters indicate a gradual reduction in material stiffness (as measured by the tangent modulus) from the equator to the posterior region at low-stress levels up to 0.005 MPa. The variation in stiffness between adjacent regions became gradually less apparent and statistically insignificant at higher stresses.The study demonstrated how inflation testing combined with inverse modelling could be used to effectively characterise regional material properties capable of reproducing global sclera displacements. The material properties were found to vary between specimens, and it is expected that age could be a contributing factor behind this variation.

A hierarchical spline based isogeometric topology optimization using moving morphable components

This paper presents a hierarchical spline based isogeometric topology optimization using moving morphable components (HITO-MMC). In this work, the adaptive isogeometric analysis implemented by hierarchical B-spline is adopted to efficiently and accurately assess the structural performance. An ersatz material model is derived from the Gaussian points of the hierarchy computational mesh to relate the geometric design variables with the objective and constraint of TO. To determine the iterative steps performing local refinement and the elements to be locally refined, a mark strategy is put forward based on the relative error of objective function and the value of topological description function (TDF). The mathematic model of HITO-MMC is reformulated by mapping the global displacement vector into the local displacement vector of the active elements on each level of the hierarchy computational mesh. The proposed HITO-MMC approach has twofold merits: (a) the optimization can be started from a relative coarse computational mesh and the mesh is locally refined during the course of TO, which result into a highly computational efficiency; (b) more accurate results are obtained due to the use of high continuous hierarchical basis functions and denser mesh on structural boundary. Besides, continuous refinement is more effective to generate the optimal design than fixed NURBS mesh, and hierarchical local refinement is superior to continuous global refinement. The effectiveness of the proposed HITO-MMC is validated by a series of 2D and 3D numerical benchmarks.

Global unsustainable virtual water flows in agricultural trade

Recent studies have highlighted the reliance of global food production on unsustainable irrigation practices, which deplete freshwater stocks and environmental flows, and consequently impair aquatic ecosystems. Unsustainable irrigation is driven by domestic and international demand for agricultural products. Research on the environmental consequences of trade has often concentrated on the global displacement of pollution and land use, while the effect of trade on water sustainability and the drying of over-depleted watercourses has seldom been recognized and quantified. Here we evaluate unsustainable irrigation water consumption (UWC) associated with global crop production and determine the share of UWC embedded in international trade. We find that, while about 52% of global irrigation is unsustainable, 15% of it is virtually exported, with an average 18% increase between year 2000 and 2015. About 60% of global virtual transfers of UWC are driven by exports of cotton, sugar cane, fruits, and vegetables. One third of UWC in Mexico, Spain, Turkmenistan, South Africa, Morocco, and Australia is associated with demand from the export markets. The globalization of water through trade contributes to running rivers dry, an environmental externality commonly overlooked by trade policies. By identifying the producing and consuming countries that are responsible for unsustainable irrigation embedded in virtual water trade, this study highlights trade links in which policies are needed to achieve sustainable water and food security goals in the coming decades.