Rectilinear Shape Research Articles

Motion of a cylindrical net with a mass at the end

The motion of a semi-infinite cylindrical net with a mass at one end is examined. The cylindrical net, with a mass at one end, is initially stretched. Addressing the problem of wave propagation in deformable filament systems, accounting for significant deviations from their original rectilinear shape, presents considerable mathematical complexity, as the equations of motion constitute a system of nonlinear partial differential equations. The solution, derived using characteristic equations, reveals the occurrence of traveling waves. This solution is constructed by satisfying conditions at the point of contact between the net and the load. The results are presented in the form of graphs and tables.

Investigation of deformation of the spring tooth of agricultural implements from the action of the force applied to it

The relevance of the study lies in the need to investigate the dependence of the force applied to the spring tooth on its parameters, which is an important task due to the widespread use of spring teeth in agricultural implements, such as balers, reapers, rakes, etc. The purpose of the study is to establish an analytical description of the spring tooth deformation depending on the amount of applied force. For this purpose, the theory of bending rods from the resistance of materials was applied, without simplifying it, as is common in construction, where the deflection of a beam is small compared to its length. The calculation is based on the well-known dependence of the curvature of the elastic axis of the beam (tooth) on the applied moment and the stiffness of its cross-section. The study considers a cantilevered tooth, which at the point of pinching is a spring with several turns, followed by a smooth transition to a rectilinear shape. The tooth is divided into two parts along its length: curvilinear and rectilinear. Calculation of the deformation, i.e., finding the shape of the elastic axis after the action of the applied force, is carried out for both parts separately. The need for this approach is dictated by the fact that the curvature of the elastic axis of the tooth in the free state changes abruptly from the stable value of the curvilinear part to a zero value of the straight part. The main result of the study is to find the shape of the elastic axis of individual parts of the tooth under the action of the applied force and combine them into one whole. This helps to determine the amount of movement of the free end of the tooth depending on the amount of force applied to it. The application of the obtained data can help in the development of more efficient and productive agricultural tools, and increase their durability and efficiency when interacting with the soil

Highly Cooperative CO2 Adsorption via a Cation Crowding Mechanism on a Cesium-Exchanged Phillipsite Zeolite.

An understanding of the CO2 adsorption mechanisms on small-pore zeolites is of practical importance in the development of more efficient adsorbents for the separation of CO2 from N2 or CH4 . Here we report that the CO2 isotherms at 25-75 °C on cesium-exchanged phillipsite zeolite with a Si/Al ratio of 2.5 (Cs-PHI-2.5) are characterized by a rectilinear step shape: limited uptake at low CO2 pressure (PCO2 ) is followed by highly cooperative uptake at a critical pressure, above which adsorption rapidly approaches capacity (2.0 mmol g-1 ). Structural analysis reveals that this isotherm behavior is attributed to the high concentration and large size of Cs+ ions in dehydrated Cs-PHI-2.5. This results in Cs+ cation crowding and subsequent dispersal at a critical loading of CO2 , which allows the PHI framework to relax to its wide pore form and enables its pores to fill with CO2 over a very narrow range of PCO2 . Such a highly cooperative phenomenon has not been observed for other zeolites.

Highly Cooperative CO2 Adsorption via a Cation Crowding Mechanism on a Cesium‐Exchanged Phillipsite Zeolite

AbstractAn understanding of the CO2 adsorption mechanisms on small‐pore zeolites is of practical importance in the development of more efficient adsorbents for the separation of CO2 from N2 or CH4. Here we report that the CO2 isotherms at 25–75 °C on cesium‐exchanged phillipsite zeolite with a Si/Al ratio of 2.5 (Cs‐PHI‐2.5) are characterized by a rectilinear step shape: limited uptake at low CO2 pressure (PCO2) is followed by highly cooperative uptake at a critical pressure, above which adsorption rapidly approaches capacity (2.0 mmol g−1). Structural analysis reveals that this isotherm behavior is attributed to the high concentration and large size of Cs+ ions in dehydrated Cs‐PHI‐2.5. This results in Cs+ cation crowding and subsequent dispersal at a critical loading of CO2, which allows the PHI framework to relax to its wide pore form and enables its pores to fill with CO2 over a very narrow range of PCO2. Such a highly cooperative phenomenon has not been observed for other zeolites.

The nature of fracturing in the Mozyr salt uplift (Gomel region of Belarus)

The regularities of the internal structure of salt uplifts have not been studied enough at present. Analysis of the shape of the cavities obtained by sonar in the cavities blurred in the Mozyr dome in Belarus shows that their walls in some cases have a rectilinear shape, and the shape of the cavity in horizontal sections looks like a polygon. The experience of previous studies suggests that the appearance of rectilinear walls is associated not only with the presence of insoluble interlayers, but also with the preparation of crack systems. The relative location of fractures and cavities suggests the stress field that created them. The conducted experiments on the dissolution of salt dams confirm the great role of fractures in the formation of the relief of salt walls.

Comparison of Wound Surface Area Measurements Obtained Using Clinically Validated Artificial Intelligence-Based Technology Versus Manual Methods and the Effect of Measurement Method on Debridement Code Reimbursement Cost

Background. Evidence shows that ongoing accurate wound assessments using valid and reliable measurement methods is essential to effective wound monitoring and better wound care management. Relying on subjective interpretation in measuring wound dimensions and assuming a rectilinear shape of all wounds renders an inconsistent and inaccurate wound area measurement. Objective. The authors investigated the discrepancy in wound area measurements using a DWMS versus TPR methods and compared debridement codes submitted for reimbursement by assessment method. Methods. The width and length of 177 wounds in 56 patients were measured at an outpatient clinic in the United States using the TPR method (width × length formula) and a DWMS (traced wound dimensions). The maximal allowable payment for debridement was calculated for both methods using the reported CPT codes based on each 20-cm2 estimated surface area. Results. The average wound surface area was significantly higher with the TPR method than with the DWMS (20.20 and 12.81, respectively; P = .025). For patients with dark skin tones, ill-defined wound edges, irregular wound shapes, unhealthy tissues, and the presence of necrotic tissues, the use of the DWMS resulted in significantly lower mean differences in wound area measurements of 14.4 cm2 (P < .008), 8.2 cm2 (P = .040), 6.8 cm2 (P = .045), 13.1 cm2 (P = .036), and 7.6 cm2 (P = .043), respectively, compared with the TPR method. Use of the DWMS for wound surface area measurement resulted in a 10.6% lower reimbursement amount for debridement, with 82 fewer submitted codes, compared with the TPR method. Conclusions. Compared with the DWMS, TPR measurements overestimated wound area more than 36.6%. This overestimation was associated with dark skin tones and wounds with irregular edges, irregular shapes, and necrotic tissue.

SOME PROBLEMS OF OPTIMIZATION OF ROD SYSTEMS CONTAINING COMPRESSED ELEMENTS USING ADDITIONAL CONSTRAINTS

The article is devoted to the problem of increasing the stability of rod systems containing longitudinally compressed elements. The influence of the imposition of constraints on the behavior of such systems is investigated in order to determine such places for imposing constraints that provide the maximum stability of the system reinforced by the constraint. To get generality, the consideration includes such rod systems that allow various equilibrium configurations, for example, having internal ideal hinges, as well as an arbitrary distribution of longitudinal compressive forces, including leaving some areas free from compression. For the same purpose, the constraints are considered as generalized, producing a reaction with an arbitrary spatial distribution. The paper formulates some general results related to the influence of the introduction of generalized constraints on the critical forces of a rod system with some generalizations related to the extension of the class of rod systems under consideration. Particular attention is paid to the buckling modes in view of their important role as a basis for describing various configurations of the structure. It has been established that the shape of these modes, in particular, the position of their nodes, is essential for finding the optimal position of the constraint. For the case of constraint in the form of a concentrated hinged support, analytical expressions are obtained that represent the derivatives of the critical forces of the system with respect to the coordinate of the support. The case of a multiple critical force, when this derivative, generally speaking, does not exist, is especially considered. These expressions make it possible to qualitatively characterize the optimal position of the support. The application of some of the obtained results is demonstrated by the example of the problem of finding the optimal position of an intermediate hinged support of a two-span rod supported at the ends by elastic hinged supports. These positions are qualitatively described for various values of the stiffness coefficients of the end supports. It has been established that under certain conditions, the optimal positions of the intermediate support correspond to a special semi-curved mode of buckling, in which one of the spans does not bend, but retains its rectilinear equilibrium shape.

INTERPRETATION OF MORPHOLOGICAL PICTURE OBSERVED IN HISTOLOGICAL PREPARATIONS FROM THE POINT THE VIEW OF STEREOLOGY

The study of a biological microobject from the standpoint of three-dimensionality gives more correct and realistic vision. The study material included 8 preparations of the palatine and labial salivary glands of adult human individuals fixed in 4% glutaraldehyde solution in phosphate buffer (pH 7.4). Following pre-fixation, the object was cut into individual slices and fixed in a freshly prepared similar fixator adding 1% calcium chloride solution at 4 °C for 12 hours. The tissue was washed after the fixation and then processed according to the requirements for electron microscopy. Tissues enclosed in epoxy resin were used to obtain semi-thin series of histological sections for further graphic and plastic reconstruction of epithelial components (including tubular) glands. Semi-thin sections were stained with 0.1% toluidine blue in phosphate buffer with different pH (from 5.5 to 8.5). Spiral, corkscrew, tortuous, arched and other forms of biological tubular structures at the microscopic level are no exception and, as our study shows, are natural phenomena along with their rectilinear shape. It can be assumed that the interdependence between the shape of the tubular transport microchannels and the laminar motion of the fluid naturally reflects the elements of curvilinear symmetry and, in particular, its spiral property. Conclusion. Thus, we could assume that the tortuous shape of transport channels of human and animal tissues is a useful stereomorphological device, and their study and three-dimensional modelling is of great scientific interest, in particular, for understanding the mechanism of laminar fluid movement through biological tubes.

Numerical simulation of a viscoelastic pipeline vibration under pulsating fluid flow

PurposeThe purpose of this study is to create a mathematical model, a numerical algorithm and a computer program for studying the vibration of composite pipelines based on the theory of beams used in the oil and gas industry, agriculture and water management, housing and communal services and other areas.Design/methodology/approachA mathematical model of vibration of a viscoelastic pipeline based on the theory of beams with a pulsating fluid flowing through it was developed. Using the Bubnov-Galerkin method, based on the polynomial approximation of deflections, the problem is reduced to the study of systems of ordinary integro-differential equations, the solution of which is found by a numerical method. A computational algorithm was developed for solving problems of vibrations of composite pipelines conveying pulsating liquid.FindingsThe stability and amplitude-time characteristics of vibration of composite pipelines with a pulsating fluid flowing in it are studied for wide range of changes in the parameters of deformable systems and fluid flow. The critical velocities of fluid flow at which the viscoelastic pipe loses its rectilinear equilibrium shape are found. The effect of singularity in the kernels of heredity on the vibrations of structures with viscoelastic properties was numerically studied. It is shown that with an increase in the viscosity parameter of the pipeline material, the critical flow velocity decreases. It was determined that an increase in the value of the fluid pulsation frequency and the excitation coefficient leads to a decrease in the critical velocity of the fluid flow. It was established that an increase in the parameters of the Winkler foundation and the rigidity parameter of the continuous layer leads to an increase in the critical flow velocity.Originality/valueThe study of the vibration of pipelines made of composite materials is of great theoretical and applied interest. The solution to this problem is an effective application of the theory of viscoelasticity to real processes. Therefore, the methods and problems of pipeline vibrations attract much attention from researchers. This study is devoted to solving the above problems and therefore its subject is relevant. The paper considers the results of numerical simulation of the processes of vibration of a composite pipeline based on the theory of shells during the flow of a pulsating liquid through it. A mathematical model of vibration of a composite pipeline was developed. A computational algorithm was developed for solving problems of vibrations of composite pipelines conveying pulsating liquid.

Общая устойчивость балок двутаврового постоянного сечения. Развитие расчетных положений

The paper presents the derivation of formulas for the method of calculating bent elements for general stability, given in SP 16.13330, which is based on the theory of thin-walled elastic rods and the system of differential equations of V. Z. Vlasov. Formulas are given for a single-span beam with a hinged mounting of supports. A general equation has been compiled for calculating the bending stability coefficient φ_1, which allows adapting the requirements of SP16.13330 standards to various types of load action in the beam span. The results are presented for twenty-five different types of external load action. The formulas take into account the arbitrary location of the load along the height of the beam section, from the lower edge of the lower belt to the upper edge of the upper belt. The values of the critical moment M_cr, at which a new form of equilibrium state arises in the beam, are determined, according to the conclusions of the work [6]. The critical moment M_cr is calculated in the form of a stability problem of the first kind – the loss of a stable position of an element of a rectilinear shape (the load acts along the line of the bending center, the neutral axis of the beam is rectilinear, the material is elastic). The formulas of the presented table can be used to perform verification calculations.

Numerical study on bending response of precast segmental concrete beams externally prestressed with FRP tendons

This study numerically investigates the bending response of dry key-jointed precast segmental concrete girders/beams (PSCBs) prestressed with external fiber reinforced polymer (FRP) tendons by using commercial finite element analysis (FEA) software Abaqus/CAE. The experimentally-validated model was used to conduct an intensive parametric analysis with a focus on the second-order effect. There has not been a similar numerical study of PSCBs with external FRP tendons in the published literature yet. The results showed that due to the rectilinear rigid-body bending shape, the behavior of PSCBs with external tendons was similar to that with internal tendons only if placing the deviators next to the opening joints. The second-order effect on the beam’s behavior and the harping effect on the tendon stress at deviators became more obvious when the deviators were located away from the opening joints. Both the second-order and harping effect were proportionate to the beam’s displacement. Therefore, using a high reinforcing index (ω) or a low span-to-depth ratio (L/dp) could mitigate the second-order and harping effect at the ultimate stage because the ultimate displacement of the beam decreased when increasing ω or reducing L/dp. Commonly-used CFRP tendons (Young’s modulus Ep = 145 GPa) were found to be the optimum to replace steel tendons in PSCBs with external tendons because they offered the PSCBs similar strength and ductility compared to steel tendons. The use of high-modulus CFRP tendons (e.g. Ep = 200 GPa) improved the stiffness and strength of PSCBs but greatly reduced the beam’s ductility. Lastly, the analytical analyses showed that the existing models yielded unconservative estimations of the effective depth (dpu) and stress (fpu) of external FRP tendons at the ultimate stage in PSCBs.

Textural and oceanographic aspects of the sandy beaches of South coast of Santa Catarina, Brazil

This study aims to describe the textural and oceanographic aspects of the foreshore zone of the beaches located between the municipalities of Passo de Torres and Balneario Rincao, at South coast of Santa Catarina. Oceanographic and textural parameters were collected at 41 sites, arranged on 22 beaches that extend out on 77,4 km of coastline. The field work was conducted in December 2007. The Sysgran software analyzed the textural data, revealing high homogeneity of grain size, predominance of fine sand, with quartzose sediments, reddish brown color (2.5YR5/3) in 66% of the samples and brown color (10YR5/3) in 34% of the samples, besides reducing amount of organic matter and biodetritic carbonate. In general, the sediments are well sorted, mesokurtic and with skewness approximately symmetrical. Regarding the source area, it should be noted that the coastal plain of the South coast of Santa Catarina comprises a wide barrier-lagoon depositional system of Holocene age, in which the sediments in general show high maturity. Regarding the coastal oceanographic aspects, the rectilinear shape of the coastline, as well as the predominant dissipative morphodynamic stage and a system of well-developed coastal dunes in most of the sites examined, corroborate with the textural and compositional homogeneity resulting from the frequency and intensity of the marine dynamic agents, winds and supply of lithoclastic sediments.

Investigation of thermal-structural characteristics at two-way shape memory effect of rapid quenched laminated amorphous-crystalline ribbons of Ti50Ni25Cu25 alloy

The work is devoted to the study of processes of structural changes leading to the realization of the two-way shape memory effect (TWSME) in the rapid quenched amorphous-crystalline alloy Ti50Ni25Cu25. The object of the study was a rapid quenched laminated amorphous-crystalline Ti50Ni25Cu25 alloy ribbon with a thickness of about 39 um and with a thickness of surface crystal layer about 10 μm was present on the non-contact side relative to the quenching wheel. In the ribbon under study, without any additional heat treatments the TWSME with bending deformation from a rectilinear shape during heating and cooling in the range of martensitic transformation is manifested. The samples were characterized by means: scanning and transmission electron microscopy; X-ray diffraction analysis; differential scanning calorimetry; measuring the characteristics of the crystalline layer during the implementation of TWSME and the temperature dependence of the form change. It was shown that the formation of a laminated amorphous-crystalline composite occurs due to the martensitic transformation of B2∼B19 in the crystal layer and the accompanying TWSME as a result of which the crystal layer is reduced.

Numerical study of the effect of viscoelastic properties of the material and bases on vibration fatigue of pipelines conveying pulsating fluid flow

The article presents the results of mathematical and computer modeling of the oscillatory processes of viscoelastic pipelines considering stationary external loads. A mathematical model of viscoelastic pipeline vibrations based on the theory of beams was developed when a pulsating fluid flows through it. Using the Bubnov-Galerkin method, based on a polynomial approximation of deflections, the problem was reduced to the study of a system of ordinary integro-differential equations, the solution of which was found numerically. A computational algorithm has been developed to solve vibration problems of composite pipelines conveying pulsating fluid. Stability and amplitude-time characteristics of vibrations of composite pipelines conveying pulsating fluid were studied at wide range of parameters variation of deformable systems and fluid flow. Critical fluid flow rates were found at which a viscoelastic pipe lost its rectilinear equilibrium shape. A singularity effect in hereditary kernels on vibrations of structures with viscoelastic properties was numerically studied. It was shown that with an increase in viscosity parameter of the pipeline material, the critical flow rate decreases. It was revealed that an increase in fluid pulsation frequency and excitation coefficient led to a decrease in the fluid flow critical rate. It was stated that an increase in Winkler bases parameters and the rigidity parameter of a continuous layer led to an increase in the critical flow rate.

Potential of new innovative confinement for square reinforced concrete columns

The most popular shape of column section used in reinforced concrete buildings is square or rectangle. Besides longitudinal bars, it is normally reinforced with traditional rectilinear or square shape of transverse steel (stirrups) or confinement. It is well known that circular spiral of reinforcing bars used in circular columns serve better ductility or performance compared to rectilinear stirrups in rectangular columns. Up to present, the use of spiral is limited only to circular columns. This is because for rectangular or square columns, it is not easy to shape the spiral on site during construction. The study focuses on the potential application of new innovative rectilinear or square spiral when used for rectangular or square concrete columns. The result of the study is that the proposed new innovative confinement which introduces the use of rectilinear or square spiral without any discontinuity or seismic hooks like those in the stirrups, as well as the introduction of interlocking system has successfully improved the ductility and performance of the columns. With this new innovative confinement, the confined core area is increased, the congestion can be avoided (no seismic hooks), and effectiveness of confining influence is improved (overlapped confining area through interlocking system).

A Robust Performance Evaluation Metric for Extracted Building Boundaries From Remote Sensing Data

Various methods for automatic building extraction from remote sensing data including light detection and ranging (LiDAR) data have been proposed over the last two decades but a standard metric for evaluation of the extracted building boundary has not been found yet. An extracted building boundary from LiDAR data usually has a zigzag pattern with missing detail, which makes it hard to compare the boundary with its reference. The existing metrics do not consider the significant point (e.g., corner) correspondences, therefore, cannot identify individual extralap and underlap areas in the extracted boundary. This article proposes an evaluation metric for the extracted boundary based on a newly proposed robust corner correspondence algorithm that finds one-to-one true corner correspondences between the reference and extracted boundaries. Assuming a building has a rectilinear shape, corners and lines are first detected for the extracted boundary. Then, corner correspondences are obtained between the extracted and reference boundaries. Each corner has two corresponding lines on its two sides that ideally are perpendicular to each other. The corner correspondences are finally ranked based on their distance, angle, and parallelism of corresponding lines. The metric is defined as the average minimum distance $d_{\mathrm{avg}}$ from the extracted boundary points to their corresponding reference lines. Extralap and underlap areas are identified by comparing the point distances with $d_{\mathrm{avg}}$ . In experiments, the proposed metric performs more realistic than the existing metrics and finds the individual extralap and underlap areas effectively.

On numerical solving of junction problem for semirigid and Timoshenko inclusions in elastic body

The paper considers an example of mathematical modeling of the process of deformation of a structure made of fiber-composite material. Timoshenko’s theory of thin beams is used to describe the reinforcing fiber model. The paper concerns a numerical solving of the equilibrium problem for a two-dimensional elastic body with a thin Timoshenko elastic inclusion and a thin semirigid inclusion. Both inclusions are of a rectilinear shape and delaminate from the elastic matrix. Therefore, the problem is posed in the domain with a cut and conditions of the form of inequalities are specified at the edges of the crack, as on a part of the boundary. These conditions exclude mutual penetration of the crack edges into each other. At the same time, such a formulation leads to the nonlinearity of the problem and the need to use additional mathematical methods to construct an algorithm for the numerical solution of the problem. The inclusions have a joint point at which junction conditions are written out. For the numerical solving of the problem in a domain with a cut, a variational formulation is used using the domain decomposition method and the Uzawa algorithm. To obtain an approximate solution that satisfies the conditions of semirigid inclusion, an additional algorithm is built using methods of mathematical analysis, an example with calculations is given.

Development of construction and analysis of the elastic shells packet stability of the device for well trajectory management

Overview of equipment for management of a trajectory of directional and horizontal wells during drill process was done in the article. Both domestic and foreign equipment are described. Based on the critical analyses, most promising designs were chosen and were described their base disadvantage: restriction of range of changing of curvature angle of deflecting tool through some design features. Based on mentioned above, modern device for management of directional and horizontal wells trajectory was suggested. Advanced unit for curvature of deflecting tool’s axle is fundamentals of construction. Using of the elastic shells packet that loses stability by critical axial load and gets small longitudinal deformation is the main innovation. Further, it is a reason of unlocking the mutual movement of specific elements of the device and buckling of its axis on preset angle. That’s why angle of deflecting tool curvature does not depend of absolute longitudinal deformation of the elastic shells packet and, as result, is not restricted by them. Deflecting tool’s axis gets the rectilinear shape after a drill string is torn off from a downhole. So, there is possible to manage a well axis during drilling process using stretching and compression of the deflecting tool. The elastic shells packet that consists of variable quantity of shells is used for setting necessary compression force that switches device in regime of curvature. Stability of the packet was analyzed by 3D-modeling and finite element method. The magnitude of critical force is determined depending on the number of shells in the packet. Was mentioned, this dependence is rectilinear. There is a possibility, by selecting the number of shells in the elastic shells packet, to manage magnitude of axial compression force that causes bend of the deflecting tool’s axis considering needed bit load.

Experimental studies of the performance of the heat-shielding layer of composite pipelines during cooling with liquid hydrogen

The development of technology for aircraft and rocket engines more efficient and environmentally friendly cryogenic fuels in the form of liquefied gases: hydrogen (vinyl), oxygen (oxide), natural gas (methane), required the creation of pipelines from modern composite materials, as well as new thermal insulation coatings (TIC), providing reliable protection of these highways from external heat leakage. Fuel out-of-flight manifolds of reusable aircraft require a particularly reliable TIC, since during the operation of the product, their multi-cycle cooling down occurs when pouring cryogenic fuel into the pipelines and heating at the discharge. Thermally insulating coatings in the form of polyurethane foam (PUF), applied to the surface of the protected product, by spraying or pouring a mixture of the constituent components, which are widely used at the present time, are not fully suitable for cryogenic pipelines due to the deterioration of their heat insulating properties in the process of cyclic cooling. The aim of the work is to create a new design and technological solution that ensures the performance of the TIC in the conditions of high-cycle thermal loading. In connection with the prospect of using cryogenic fuels in an aviation (reusable) technology, ensuring the performance of a TIC in such conditions is relevant. For the developed technology, experimental determination of the main parameters of the TIC was carried out. Composite pipelines of curvilinear and rectilinear shape were used as objects of research. The pipeline design included a sealing film sheath, a power sheath made of a polymer composite material, a foam heat insulating coating and metal connecting flanges. On model composite samples of cryogenic pipelines, cyclic tests for cooling with liquid hydrogen (filling of fuel lines) and heating to ambient temperature (draining components) were carried out. During the tests, the pipeline was first cooled with hydrogen gas for one hour. Then, for one hour, liquid hydrogen was poured into the internal cavity, after which natural warming up to a normal temperature was carried out for an hour. The obtained results allowed to determine the dependence of temperature and heat flow of the shell with TIC on the number of cooling cycles, to propose a design and technological solution for a significant reduction of the cryopump at large temperature differences in the TIC, to show the effectiveness of cyclic cooling of foam porosity with closed porosity of the “Vikort-3M”

Appraisal of Vernacular Stone Housing Typology of Tigrai, Ethiopia

Tigrai vernacular housing mainly characterized by a stone architecture called hidmo, which is an astonishing feature of the country and the region. The hidmo house does not only mean a flat roofed vernacular house, but it is becoming an architectural style since thousands years ago at the beginning of Aksumite civilization. The objective of this paper is to appraise the vernacular housing typology and their spatial relationship in Tigrai, Ethiopia. Using field visit, observation, non-structured interview, cross-checking different data sources are used for qualitative data collection and the collected data are synthesized and categorized. According to the research study the Tigrai vernacular housing has mainly three housing typology namely, the Tigrai farmer house commonly called hidmo house, Tigrai chief house that is housed for the rich, clerks and leaders and the third is Agudo dwelling unit a house for common people. In the Tigrai farmer house we could have variations and labeling such as Merebae and Sekela house. All the housing typology have rectilinear shape, form and use the same building material that is a stone wall, mud and timber roof, but Agudo dwelling unit and Tigrai chief house have circular plan and conical thatched roof. The very nature of the Tigrai housing typology has the potential to respond the sustainability of the climate and the availability of abundant materials, mainly stone and the ‘Monkey head construction’ system.