Search results for: concrete-filled double skin columns

Authors: Mohamed A. Shanan, Ashraf H. El-Zanaty, Kamal G. Metwally

Abstract:

This paper presents the effect of concrete compressive strength and rectangularity ratio on strength and ductility of normal and high strength reinforced concrete columns confined with transverse steel under axial compressive loading. Nineteen normal strength concrete rectangular columns with different variables tested in this research were used to study the effect of concrete compressive strength and rectangularity ratio on strength and ductility of columns. The paper also presents a nonlinear finite element analysis for these specimens and another twenty high strength concrete square columns tested by other researchers using ANSYS 15 finite element software. The results indicate that the axial force – axial strain relationship obtained from the analytical model using ANSYS are in good agreement with the experimental data. The comparison shows that the ANSYS is capable of modeling and predicting the actual nonlinear behavior of confined normal and high-strength concrete columns under concentric loading. The maximum applied load and the maximum strain have also been confirmed to be satisfactory. Depending on this agreement between the experimental and analytical results, a parametric numerical study was conducted by ANSYS 15 to clarify and evaluate the effect of each variable on strength and ductility of the columns.

Keywords: ANSYS, concrete compressive strength effect, ductility, rectangularity ratio, strength

Procedia PDF Downloads 480

Authors: Mohamed Z. Sayed-Ahmed, Ahmed M. Ahdy, Emad E. Younis, Sabry A. El-Khodary

Abstract:

Little research information is available on the prevalence of diseases of donkeys in Egypt. Across sectional study was undertaken between March 2009 and February 2010 to verify the prevalence of skin affection of donkeys. A total of 1134 donkeys in northern Egypt were investigated. A questionnaire was constructed to verify the number of infected contact animals as well as the associated factors. Physical examination was carried out, and the distribution of skin lesions was recorded. Skin scraping and biopsy were obtained to perform bacteriological, mycological, and histopathological examinations. Thirty-five (3.09%) out of 1134 noticed donkeys had skin affections including mange (18/35), dermatophytosis (6/35), bacterial dermatitis (6/35) urticaria (2/35) and allergic dermatitis (3/35). The present results indicate that mange and dermatophytosis are the prevalent skin diseases in donkeys. Contact with other animal species of contaminated environment may contribute to the occurrence of the diseases.

Keywords: donkeys, Egypt, prevalence, skin affection

Procedia PDF Downloads 162

Authors: Kirti, Samanta Sekhar Khora

Abstract:

Inflation serves different purposes in different organisms and adds beauty to their behavioral attributes. Pufferfishes are also known as blowfish, swellfish, and globefish due to their remarkable ability to puff themselves up like a balloon when threatened. This ability to inflate can be correlated with anatomical features that are unique to pufferfishes. Pufferfish skin provides a rigid framework to support the body contents and a flexible covering to allow whatever changes are necessary for remarkable inflation mechanism. Skin, the outer covering of animals is made up of collagen fibers arranged in more or less ordered arrays. The ventral skin of pufferfish stretches more than dorsal skin during inflation. So, this study is of much of the interest in comparing the structure and mechanical properties of these two skin regions. The collagen fibers were found to be arranged in different ordered arrays for ventral and dorsal skin and concentration of fibers were also found to be different for these two skin parts. Scanning electron microscopy studies of the ventral skin showed a unidirectional arrangement of the collagen fibers, which provide more stretching capacity. Dorsal skin, on the other hand, has an orthogonal arrangement of fibers. This provides more stiffness to the ventral skin at the time of inflation. In this study, the possible role of collagen fibers was determined which significantly contributed to the remarkable inflation mechanism of pufferfishes.

Keywords: collagen, histology, inflation, pufferfish, scanning electron microscopy, Small-Angle X-Ray Scattering (SAXS), transmission electron microscopy

Procedia PDF Downloads 275

Authors: Seyed Amin Vakili, Sahar Sadat Vakili, Seyed Ehsan Vakili, Nader Abdoli Yazdi

Abstract:

The purpose of this article is to analyze the finite displacement of Columns by applying the Modified Newmark Method. This research will be performed on Columns subjected to compressive axial load, therefore the non-linearity of the geometry is also considered. If the considered strut is perfect, the governing differential equation contains a branching point in the solution path. Investigation into the Elastica is a part of generalizing the developed method. It presents the ability of the Modified Newmark Method in treating non-linear differential equations Derived from elastic strut stability problems. These include not only an approximate polynomial solution for the Elastica problems, but can also recognize the branching point and the stable solution. However, this investigation deals with the post-buckling response of elastic and pin ended columns subjected to central or equally eccentric axial loads.

Keywords: columns, structural modeling, structures & structural stability, loads

Procedia PDF Downloads 278

Authors: R. Ziaie Moayed, A. Mahigir

Abstract:

Stone column technique has been successfully employed to improve the load-settlement characteristics of foundations. A series of finite element numerical analyses of harmonic dynamic loading have been conducted on strengthened raft footing to study the effects of single and group stone columns on settlement of circular footings. The settlement of circular raft footing that improved by single and group of stone columns are studied under harmonic dynamic loading. This loading is caused by heavy machinery foundations. A detailed numerical investigation on behavior of single column and group of stone columns is carried out by varying parameters like weight of machinery, loading frequency and period. The result implies that presence of single and group of stone columns enhanced dynamic behavior of the footing so that the maximum and residual settlement of footing significantly decreased. 

Keywords: finite element analysis, harmonic loading, settlement, stone column

Procedia PDF Downloads 350

Authors: Soner Guler, Eylem Guzel, Mustafa Gülen

Abstract:

Recently, concrete-filled steel tube columns are highly popular in high-rise buildings. The main aim of this study is to evaluate the axial load capacities of circular high strength concrete-filled steel tube columns according to Eurocode 4 (EC4) and American Concrete Institute (ACI) design codes. The axial load capacities of fifteen concrete-filled steel tubes stub columns were compared with design codes EU4 and ACI. The results showed that the EC4 overestimate the axial load capacity for all the specimens.

Keywords: concrete-filled steel tube column, axial load capacity, Eurocode 4, ACI design codes

Procedia PDF Downloads 360

Authors: Walid El Kamash

Abstract:

Sand columns (or granular piles) can be employed as soil strengthening for flexible constructions such as road embankments, oil storage tanks in addition to multistory structures. The challenge of embedding the sand columns in soft soil is that the surrounding soft soil cannot avail the enough confinement stress in order to keep the form of the sand column. Therefore, the sand columns which were installed in such soil will lose their ability to perform needed load-bearing capacity. The encasement, besides increasing the strength and stiffness of the sand column, prevents the lateral squeezing of sands when the column is installed even in extremely soft soils, thus enabling quicker and more economical installation. This paper investigates the improvement in load capacity of the sand column by encasement through a comprehensive parametric study using the 3-D finite difference analysis for the soft clay of soil in Egypt. Moreover, the study was extended to include a comparison study between encased sand column and Deep Mixed columns (DM). The study showed that confining the sand by geosynthetic resulted in an increment of shear strength. That result paid the attention to use encased sand stone rather than deep mixed columns due to relative high permeability of the first material.

Keywords: encased sand column, Deep mixed column, numerical analysis, improving soft soil

Procedia PDF Downloads 346

Authors: R. Ziaie Moayed, A. Khalili

Abstract:

Improvement and reinforcement of soils with poor strength and engineering properties for constructing low height structures or structures such as liquid storage tanks, bridge columns, and heavy structures have necessitated applying particular techniques. Stone columns are among the well-known methods applied in such soils. This method provides an economically justified way for improving engineering properties of soft clay and loose sandy soils. Stone column implementation in these soils increases their bearing capacity and reduces the settlement of foundation build on them. In the present study, the finite difference based FLAC3D software was used to investigate the performance and effect of soil reinforcement through stone columns without lining and those with geosynthetic lining with different levels of stiffness in horizontal and vertical modes in clayey soils. The results showed that soil improvement using stone columns with lining in vertical and horizontal modes results in improvement of bearing capacity and foundation settlement.

Keywords: bearing capacity, FLAC3D, geosynthetic, settlement, stone column

Procedia PDF Downloads 146

Authors: S. P. Sharma, Som Nath Saha

Abstract:

This study investigates the effect of Global Solar Radiation (GSR) on the performance of double flow corrugated absorber solar air heater. A mathematical model of a double flow solar air heater, in which air is flowing simultaneously over and under the absorbing plate is presented and solved by developing a computer program in C++ language. The performance evaluation is studied in terms of air temperature rise, energy, effective and exergy efficiencies. The performance of double flow corrugated absorber is compared with double flow flat plate and conventional solar air heaters. It is found that double flow effectively increases the air temperature rise and efficiencies in comparison to a conventional collector. However, corrugated absorber is more superior to that of flat plate double flow solar air heater. The results show that increasing the solar radiation leads to achieve higher air temperature rise and efficiencies.

Keywords: corrugated absorber, double flow, flat plate, solar air heater

Procedia PDF Downloads 315

Authors: Bardia Khafaf, Mehrdad Ghaffari, Amir Hussein Samakar

Abstract:

It is currently desirable to use Hollow Square Sections (HSS) in moment resistant structures in construction of building because they offer fewer restrictions for designing and more useful space while adhering to build design codes. This paper present a through bolt connection in HSS column. This connection meets building code standards that require the moment resistant connections to deflect and absorb energy resulting from gravity and seismic loads. Connection through bolts is installed and pretension to provide the connection strength needed to make a beam–column moment rigid zone. A rigid joint is typically used to resist lateral forces by holding columns and beams fixed in relation to one another. With bolted moment frames using HSS columns, a through–bolt connection could be used to secure the beam and end plate to the column. However, when multiple columns and beams are used to span a length of building, the use of through-bolts would necessities aligning multiple beams simultaneously to the columns. In the case of a linear span, the assembly process requires the holes of a first beam end plate to be aligned with through bolt holes in a column and aligning the holes of a second, opposing beam plate with the column through bolt, then inserting the through bolts in each hole for tightening with nuts and washers. In moment resistant building, a problem arises when assembling beams to columns where multiple beams and columns are required. Through bolt, moment connections are among the economical, practical and not difficult rigid steel connection for HSS column building. In this paper, the results of numerous analytical studies performed for moment structures with HSS columns with through bolt based on AISC standard codes are shown.

Keywords: through bolt, moment resistant connection, HSS columns section, construction engineering

Procedia PDF Downloads 426

Authors: Vacharee Svamivastu

Abstract:

This research investigates the application of geometrical relationship to the ancient religious assembly hall (Vihara) housing a reclining Buddha statue of Thailand's Kamphaeng Phet Historical Park. The study utilizes the archaeological and wooden roof structure remains of the Vihara as the prima facie evidence, supplemented with evidence from other active archaeological sites with architectural kinship as well as Buddhist ideology. At present, the wooden roofs of the Vihara fell prey to the elements and there remain only the base, columns and enclosing walls. Unlike typical Viharas whose floor plan are of rectangular shape, the floor plan of the Vihara housing the reclining Buddha is of square configuration of 25x25m. Further observation has revealed the utilization of large laterite boulders as the principal construction material of the assembly hall (Vihara) columns. The laterite columns are of square shape (1x1m) and various heights (H), ranging from 3.50m to 5.50m. The erection of the Vihara required a total of 36 laterite columns. The pattern of columns arrangement is of two rows of inner columns, two rows of outer columns and two rows of verandah columns. The space between pairs of the verandah columns was stacked with laterite blocks of varying sizes to form the Vihara walls with small openings for ventilation. Upon applying the geometrical relationship-grid system to the Vihara, the results reveal that the placement of the columns was deliberately and masterfully undertaken such that the center of the square-shaped Vihara is conspicuously spacious so as to accommodate the sacred reclining Buddha statue. The elegance of the Vihara demonstrates the ingenious application of geometrical relationship to transforming a space into a structure (i.e. Vihara) of architectural and religious significance.

Keywords: geometrical relationship, the religious assembly hall, Vihara, Kamphaeng Phet School of Master Builder

Procedia PDF Downloads 246

Authors: P. S. Rajinikanth, Shobana Mariappan, Jestin Chellian

Abstract:

The objective of the study was to prepare and characterize a water-in-oil nano emulsion of 5-Fluorouracil (5FU) to enhance the skin penetration. The present study describes a nano emulsion of 5FU using Capyrol PGMC, Transcutol HP and PEG 400 as oil, surfactant and co-surfactant, respectively. The optimized formulations were further evaluated for heating cooling cycle, centrifugation studies, freeze thaw cycling, particle size distribution and zeta potential in order to confirm the stability of the optimized nano emulsions. The in-vitro characterization results showed that the droplets of prepared formulation were ~100 nm with ± 15 zeta potential. In vitro skin permeation studies was conducted in albino mice skin. Significant increase in permeability parameters was also observed in nano emulsion formulations (P<0.05). The steady-state flux (Jss), enhancement ration and permeability coefficient (Kp) for optimized nano emulsion formulation (FU2, FU1, 1:1 S mix were found to be 24.21 ±2.45 μg/cm2/h, 3.28±0.87 & 19.52±1.87 cm/h, respectively), which were significant compared with conventional gel. The in vitro and in vivo skin deposition studies in rat indicated that the amount of drug deposited from the nano emulsion (292.45 µg/cm2) in skin was significant (P<0.05) an increased as compared to a conventional 5FU gel (121.42 µg/cm2). The skin irritation study using rat skin showed that the mean irritation index of the nano emulsion reduced significantly (P<0.05) as compared with conventional gel contain 1% 5FU. The results from this study suggest that a water-in-oil nano emulsion could be safely used to promote skin penetration of 5FU following topical application.

Keywords: nano emulsion, controlled release, 5 fluorouracil, skin penetration, skin irritation

Procedia PDF Downloads 471

Authors: Mehmet Alpaslan Köroğlu, Musa Hakan Arslan, Muslu Kazım Körez

Abstract:

Basic objective of this study is to create a regression analysis method that can estimate the length of a plastic hinge which is an important design parameter, by making use of the outcomes of (lateral load-lateral displacement hysteretic curves) the experimental studies conducted for the reinforced square concrete columns. For this aim, 170 different square reinforced concrete column tests results have been collected from the existing literature. The parameters which are thought affecting the plastic hinge length such as cross-section properties, features of material used, axial loading level, confinement of the column, longitudinal reinforcement bars in the columns etc. have been obtained from these 170 different square reinforced concrete column tests. In the study, when determining the length of plastic hinge, using the experimental test results, a regression analysis have been separately tested and compared with each other. In addition, the outcome of mentioned methods on determination of plastic hinge length of the reinforced concrete columns has been compared to other methods available in the literature.

Keywords: columns, plastic hinge length, regression analysis, reinforced concrete

Procedia PDF Downloads 448

Authors: Cherish Romina Prajitno, Sunisa Thaichinda

Abstract:

One indicator of facial aging is wrinkles. Not only that, but wrinkles are a key indicator in our world of facial aesthetics. Wrinkles occur where fault lines develop in aging skin. Nowadays, people are more motivated to keep up their appealing and young appearance. Many individuals are seeking a fast recovery time for their aesthetic procedures and are interested in non-invasive techniques that have a proven track record for successful outcomes. The purpose of this study is to see the efficacy of 100% (pure) grapeseed oil for reducing periorbital wrinkles. This study used the split-face, double-blind method, and this treatment was administered for three months at random to fifteen patients, with the grapeseed oil at one side of the face and the other side with the placebo. The main outcome measure was determined by conducting a comparative analysis of the participants' wrinkle results during each visit using the VIsioscan® VC98. Additionally, we evaluated the skin's elasticity and barrier function using the Cutometer® MP 530 and Tewameter® TM300. Furthermore, we administered a satisfaction score questionnaire to the patients in the 12th week. The findings of the study indicate that grapeseed oil exhibited a noteworthy effect in diminishing the appearance of wrinkles in the periorbital region, enhancing the viscoelastic properties of the periorbital skin, and improving the functionality of the skin barrier in the periorbital area.

Keywords: periorbital wrinkles, pure grapeseed oil, split-face method

Procedia PDF Downloads 39

Authors: Dipanshu Sur, Ratnabali Chakravorty

Abstract:

Background: Striae result from rapid expansion of the underlying tissue, e.g. during puberty, pregnancy or rapid weight gain. Prior data indicate that the incidence of stretch marks in Indian women is 77%.The hormonal and genetic factors are associated with their appearance. Recently that has been found skin extensibility, elasticity and rupture were strongly influenced by the water content of dermis and epidermis cells. Objective: The objectives were to assess the effects of topical treatments applied during pregnancy on the later development of stretch marks. Materials and methods: An open, prospective, randomized study was done on 120 pregnant women in whom skin elasticity and hydration as well as striae presence or apparition were measured at baseline and periodically until delivery. Patients were randomly assigned to application in wet skin cream, or in dry skin conditions. Results: The average basal hydration was 42 ±13 IU and the final was 46 ± 6 IU (P = 0.0325; 95% CI: -7.66 to -0.34), which difference was statistically significant. By measuring the moisture in the control region (forearm) a basal reading of 40 ± 9 IU and end of study of 38 ± 6; (p = 0.1547; 95% CI: -0.77 to 4.77) and this difference was considered to be not statistically significant. It was observed that at the end of the study, 55% women without ridges; mild ridges 5%; 36% moderate, and 4%, severe ridges. The proportion of women without grooves was 54% when the cream was applied studied wet skin and 45% when the cream was applied on dry skin. Conclusion: It was shown that cream under study increased hydration and elasticity of abdominal skin consequently in all subjects. This effect is more significant (54%) when the cream is applied to damp skin.

Keywords: striae gravidarum, skin moisturizer, skin hydration, skin elasticity

Procedia PDF Downloads 195

Authors: Elia Efraim, Boris Blostotsky

Abstract:

Testing of columns in sway mode is performed in order to determine the maximal allowable load limited by plastic deformations or their end connections and a critical load limited by columns stability. Motivation to determine accurate value of critical force is caused by its using as follow: - critical load is maximal allowable load for given column configuration and can be used as criterion of perfection; - it is used in calculation prescribed by standards for design of structural elements under combined action of compression and bending; - it is used for verification of theoretical analysis of stability at various end conditions of columns. In the present work a new non-destructive method for determination of columns critical buckling load in sway mode is proposed. The method allows performing measurements during the tests under loads that exceeds the columns critical load without losing its stability. The possibility of such loading is achieved by structure of the loading system. The system is performed as frame with rigid girder, one of the columns is the tested column and the other is additional two-hinged strut. Loading of the frame is carried out by the flexible traction element attached to the girder. The load applied on the tested column can achieve values that exceed the critical load by choice of parameters of the traction element and the additional strut. The system lateral stiffness and the column critical load are obtained by the dynamic method. The experiment planning and the comparison between the experimental and theoretical values were performed based on the developed dependency of lateral stiffness of the system on vertical load, taking into account semi-rigid connections of the column's ends. The agreement between the obtained results was established. The method can be used for testing of real full-size columns in industrial conditions.

Keywords: buckling, columns, dynamic method, end-fixity factor, sway mode

Procedia PDF Downloads 329

Authors: Hiba S. Ahmed, Abbas A. Allawi, Riyadh A. Hindi

Abstract:

Pultruded materials made of fiber-reinforced polymer (FRP) come in a broad range of shapes, such as bars, I-sections, C-sections, and other structural sections. These FRP materials are starting to compete with steel as structural materials because of their great resistance, low self-weight, and cheap maintenance costs-especially in corrosive conditions. This study aimed to evaluate the effectiveness of Glass Fiber Reinforced Polymer (GFRP) of the hybrid columns built by combining (GFRP) profiles with concrete columns because of their low cost and high structural efficiency. To achieve the aims of this study, nine circular columns with a diameter of (150 mm) and a height of (1000mm) were cast using normal concrete with compression strength equal to (35 MPa). The research involved three different types of reinforcement: hybrid circular columns type (IG) with GFRP I-section and 1% of the reinforcement ratio of steel bars, hybrid circular columns type (IS) with steel I-section and 1% of the reinforcement ratio of steel bars, (where the cross-section area of I-section for GFRP and steel was the same), compared with reference column (R) without I-section. To investigate the ultimate capacity, axial and lateral deformation, strain in longitudinal and transverse reinforcement, and failure mode of the circular column under different loading conditions (concentric and eccentric) with eccentricities of 25 mm and 50 mm, respectively. In the second part, an analytical finite element model will be performed using ABAQUS software to validate the experimental results.

Keywords: composite, columns, reinforced concrete, GFRP, axial load

Procedia PDF Downloads 21

Authors: Hansoo Kim, Seunghak Shin

Abstract:

The differential column shortening in tall buildings can be reduced by improving material and structural characteristics of the structural systems. This paper proposes structural methods to reduce differential column shortening in reinforced concrete tall buildings; connecting columns with rigidly jointed horizontal members, using outriggers, and placing additional reinforcement at the columns. The rigidly connected horizontal members including outriggers reduce the differential shortening between adjacent vertical members. The axial stiffness of columns with greater shortening can be effectively increased by placing additional reinforcement at the columns, thus the differential column shortening can be reduced in the design stage. The optimum distribution of additional reinforcement can be determined by applying a gradient based optimization technique.

Keywords: column shortening, long-term behavior, optimization, tall building

Procedia PDF Downloads 220

Authors: Boris Blostotsky, Elia Efraim

Abstract:

Testing of columns in sway mode is performed in order to determine the maximal allowable load limited by plastic deformations or their end connections and a critical load limited by columns stability. Motivation to determine accurate value of critical force is caused by its using as follow: - critical load is maximal allowable load for given column configuration and can be used as criterion of perfection; - it is used in calculation prescribed by standards for design of structural elements under combined action of compression and bending; - it is used for verification of theoretical analysis of stability at various end conditions of columns. In the present work a new non-destructive method for determination of columns critical buckling load in sway mode is proposed. The method allows performing measurements during the tests under loads that exceeds the columns critical load without losing its stability. The possibility of such loading is achieved by structure of the loading system. The system is performed as frame with rigid girder, one of the columns is the tested column and the other is additional two-hinged strut. Loading of the frame is carried out by the flexible traction element attached to the girder. The load applied on the tested column can achieve a values that exceed the critical load by choice of parameters of the traction element and the additional strut. The system lateral stiffness and the column critical load are obtained by the dynamic method. The experiment planning and the comparison between the experimental and theoretical values were performed based on the developed dependency of lateral stiffness of the system on vertical load, taking into account a semi-rigid connections of the column's ends. The agreement between the obtained results was established. The method can be used for testing of real full-size columns in industrial conditions.

Keywords: buckling, columns, dynamic method, semi-rigid connections, sway mode

Procedia PDF Downloads 289

Authors: SunWoo Lee, TaeBum Lee, YoonHwa Park, YooJeong Kim

Abstract:

Solar lentigines appear predominantly on chronically sun-exposed areas of skin, such as the face and the back of the hands. Among the several ways to lentigines treatment, quality-switched lasers are well-known effective treatment for removing solar lentigines. The present pilot study was therefore designed to assess the efficacy of quality-switched ruby laser treatment of such lentigines compare between pretreatment and posttreatment of skin brightness. Twenty-two adults with chronic sun-damaged skin (mean age 52.8 years, range 37–74 years) were treated at the Korean site. A 694 nm Q-switched ruby laser was used, with the energy density set from 1.4 to 12.5 J/cm2, to treat solar lentigines. Average brightness of skin color before ruby laser treatment was 137.3 and its skin color was brightened after ruby laser treatment by 150.5. Also, standard deviation of skin color was decreased from 17.8 to 16.4. Regarding the multivariate model, age and energy were identified as significant factors for skin color brightness change in lentigo depigmentation by ruby laser treatment. Their respective odds ratios were 1.082 (95% CI, 1.007–1.163), and 1.431 (95% CI, 1.051–1.946). Lentigo depigmentation treatment using ruby lasers resulted in a high performance in skin color brightness. Among the relative factors involve with ruby laser treatment, age and energy were the most effective factors which skin color change to brighter than pretreatment.

Keywords: depigmentation, lentigine, quality switched ruby laser, skin color

Procedia PDF Downloads 218

Authors: Suresh Prasad Sharma, Som Nath Saha

Abstract:

This paper deals with the effect of Global Solar Radiation (GSR) on the performance of double flow solar air heater having corrugated plate as an absorber. An analytical model of a double flow solar air heater has been presented, and a computer program in C++ language has been developed to calculate the outlet air temperature, heat gain, pressure drop for estimating the thermal and thermohydraulic efficiencies. The performance of double flow corrugated absorber is compared with double flow flat plate and conventional solar air heaters. It is found that the double flow arrangement effectively increases the air temperature rise and efficiencies in comparison to a conventional collector. However, corrugated absorber is more superior to that of flat plate double flow solar air heater. The results indicate that increasing the solar radiation leads to achieve higher air temperature rise and efficiencies.

Keywords: corrugated absorber, double flow, flat plate, solar air heater

Procedia PDF Downloads 250

Authors: S. Chandrakaran, G. Govind

Abstract:

Stone columns are effectively used to improve bearing strength of soils and also for many geotechnical applications. In soft soils when stone columns are loaded they undergo large settlements due to insufficient lateral confinement. Use of geosynthetics encasement has proved to be a solution for this problem. In this paper, results of a laboratory experimental study carried out with model stone columns with and without encasement. Sand was used for making test beds, and grain size of soil varies from 0.075mm to 4.75mm. Woven geotextiles produced by Gareware ropes India with mass per unit area of 240gm/M2 and having tensile strength of 52KN/m is used for the present investigation. Tests were performed with large scale direct shear box and also using scaled laboratory plate load tests. Stone column of 50mm and 75mm is used for the present investigation. Diameter of stone column, size of stones used for making stone columns is varied in making stone column in the present study. Two types of stone were used namely small and bigger in size. Results indicate that there is an increase in angle of internal friction and also an increase in the shear strength of soil when stone columns are encased. With stone columns with 50mm dia, an average increase of 7% in shear strength and 4.6 % in angle of internal friction was achieved. When large stones were used increase in the shear strength was 12.2%, and angle of internal friction was increased to 5.4%. When the stone column diameter has increased to 75mm increase in shear strength and angle of internal friction was increased with smaller size of stones to 7.9 and 7.5%, and with large size stones, it was 7.7 and 5.48% respectively. Similar results are obtained in plate load tests, also.

Keywords: stone columns, encasement, shear strength, plate load test

Procedia PDF Downloads 211

Authors: Mahmoud F. Awad-Allah, Mohammed Rabeih, Eman Abdel Baseer

Abstract:

Soft to very soft soil deposits are widely speared in some areas of Egypt such as East Port Said, Damietta, Kafr El-Sheik, Alexandria, etc. The construction projects in these areas have faced the challenge of the presence of extended deep layers of soft and very soft clays which reach to depths of 40 to 60 m from the ground level. Stone columns are commonly used to support structures overlying soft ground soils and surcharged by embankment type loading. Therefore, this paper introduces a wide comparison numerical study between the ordinary stone columns (OSC) versus the geosynthetic encased stone columns (ESC) installed in soft clay soil deposit using finite element method (FEM). Parametric study of an embankment on soft soils reinforced with stone columns is performed using commercial computer program based on the finite element technique (PLAXIS 2D). The investigation will present the influence of the following parameters: diameter of stone columns, stiffness of geosynthetic encasement, embedded depth of stone column from ground level, and the length encasement of the stone column on the consolidation time, vertical settlement, and lateral displacement of soft clay soil formations.

Keywords: finite element method, geosynthetic, lateral displacement, settlement, soft clay

Procedia PDF Downloads 172

Authors: Jung Yoon Kim

Abstract:

Introduction: Wounds inevitably cause patients to experience discomfort, distress, and consequentially reduced quality of life due to entailed pain, maceration, and foul odor. The dressing has been a universal wound care method in which wounds are covered and protected, and an optimum environment for healing is provided. This study aimed to investigate Korean nurses’ level of awareness of pain and skin tearing in wound beds and/or peri-wound skin at dressing change. Methods: A descriptive study was performed. Convenience sampling was employed, and registered nurses were recruited from attendees of continuing education program. A total of 399 participants (RN) completed the questionnaire. Data were collected from September to November 2022. Results: Many of them perceived skin tearing and wound-related pain associated with dressing changes, but most of them did not assess and record pain and skin tearing at dressing change. More than half of the respondents reported that they did not provide nursing intervention to prevent pain and skin tearing. Many of them reported that a systematic educational program for preventing pain and skin tearing at dressing changes was needed. Discussion: Many of the respondents were aware of pain and skin tearing at dressing change but did not take any further necessary measures, including nursing intervention, for the most appropriate, systematic pain and skin tearing management. Therefore, this study suggested that a systematic and comprehensive educational program for Korean healthcare professionals needs to be developed and implemented in Korea’s hospital settings.

Keywords: skin tearing, pain, dressing change, nurses

Procedia PDF Downloads 76

Authors: Zahra Abdi, Roghayeh Alipour, Babak Farahi Ghasraboonasr

Abstract:

Introduction: Diabetes is a serious medical condition that requires constant care. People with type 2 diabetes may also be likely to experience dry, itchy skin and poor wound healing. Some people with diabetes will have a skin problems at some time in their lives and for those not yet diagnosed with diabetes, a skin problem can be an indication of the disease. our purpose was to assess the capability and knowledge of students of Shiraz University of Medical Sciences about prevent from skin complications in diabetes type 2. Methods: In this descriptive cross-sectional study, knowledge of 360 students of Shiraz University of Medical Sciences was evaluated about different ways to avoid skin complications in diabetes type 2. Data were analyzed by spss19.(P<0.05) was considered significant. Results: 360 students of Shiraz University of Medical Sciences participated in this study. 45% of students agree with the effect of Moisturize skin daily, If Diabetics have sensitive skin, choose a fragrance-free, dye-free moisturizer that won’t irritate skin. 52% believe that Protect skin from sun can be so useful, Sun exposure is drying and aging. Use sunscreen with SPF 30 or higher whenever you’re outside. Wear gloves when doing yardwork to protect the skin on your hands. 62% of students strongly agree with Carefully clean any cuts and scrapes, If diabetics notice any sign of infection skin that’s red, swollen, or warm to the touch, or has a foul-smelling drainage or pus should consulting with a doctor immediately. Diabetics should be careful about any injury that takes longer than normal to heal and they should consulting with doctor about them too. 72% of students believe that diabetics should be diligent about daily foot care. Clean and moisturize feet each day and check each foot closely, top and bottom, for wounds even a tiny cut, blisters, or cracked skin. Conclusions: The risk of getting these diabetes complications can be lessened by controlling blood sugar. Skin complications can cause serious consequences. Taking care of skin is so important and using these tips are remarkable effective and help diabetics to look after their skin easier.

Keywords: skin complications, diabetes type 2, Shiraz University of Medical Sciences, diabetics

Procedia PDF Downloads 325

Authors: Jeong Hong Kim, Ju Wan Kang

Abstract:

Objective: Histamine skin prick testing is most commonly used to diagnose immunoglobulin E (IgE)-mediated allergic diseases, and histamine reactivity is used as a standardized positive control in the interpretation of a skin prick test. However, reactivity to histamine differs among individuals for reasons that are poorly understood. The present study aimed to evaluate the potential association between body mass index (BMI) and histamine skin reactivity in children. Methods: A total of 451 children (246 boys, 205 girls) aged 7–8 years were enrolled in this study. The skin prick test was performed with 26 aeroallergens commonly found in Korea. Other information was collected, including sex, age, BMI, parental allergy history, and parental smoking status. Multivariate analysis was used to confirm the association between histamine skin reactivity and BMI. Results: The histamine wheal size was revealed to be associated with BMI (Spearman's Rho 0.161, p < 0.001). This association was confirmed by multivariate analysis, after adjusting for sex, age, parental allergy history, parental smoking status, and allergic sensitization (coefficient B 0.071, 95% confidence interval 0.030–0.112). Conclusions: Skin responses to histamine were primarily correlated with increased BMI. Further studies are needed to understand the clinical implication of BMI when interpreting the results of skin prick test.

Keywords: allergy, body mass index, histamine, skin prick test

Procedia PDF Downloads 330

Authors: Bambang Piscesa, Mario M. Attard, Dwi Presetya, Ali K. Samani

Abstract:

A numerical strategy formulated using a plasticity approach is presented to model spalling of the concrete cover in reinforced concrete columns. The stage at which the concrete cover within reinforced concrete column spalls has a direct bearing on the load capacity. The concrete cover can prematurely spall before the full cross-section can be utilized if the concrete is very brittle under compression such as for very high strength concretes. If the confinement to the core is high enough, the column can achieve a higher peak load by utilizing the core. A numerical strategy is presented to model spalling of the concrete cover. Various numerical strategies are employed to model the behavior of reinforced concrete columns which include: (1) adjusting the material properties to incorporate restrained shrinkage; (2) modifying the plastic dilation rate in the presence of the tensile pressure; (3) adding a tension cut-off failure surface and (4) giving the concrete cover region and the column core different material properties. Numerical comparisons against experimental results are carried out that shown excellent agreement with the experimental results and justify the use of the proposed strategies to predict the axial load capacity of reinforce concrete columns.

Keywords: spalling, concrete, plastic dilation, reinforced concrete columns

Procedia PDF Downloads 125

Authors: Seyed Abolhasan Naeini, Saeideh Mohammadi

Abstract:

Embankment settlement on soft clays has always been problematic due to the high compaction and low shear strength of the soil. Deep soil mixing and geosynthetics are two soil improvement methods in such fields. Here, a numerical study is conducted on the embankment performance on the soft ground improved by deep soil mixing columns and geosynthetics based on the data of a real project. For this purpose, the finite element method is used in the Plaxis 2D software. The Soft Soil Creep model considers the creep phenomenon in the soft clay layer while the Mohr-Columb model simulates other soil layers. Results are verified using the data of an experimental embankment built on deep mixing columns. The effect of depth and diameter of deep mixing columns and the stiffness of geogrid on the vertical and horizontal movements of embankment on clay subsoil will be investigated in the following.

Keywords: PLAXIS 2D, embankment settlement, horizontal movement, deep soil mixing column, geogrid

Procedia PDF Downloads 141

Authors: Riya Roy, Anjana Bhasi

Abstract:

Column-supported embankments provide a practical and efficient solution for construction on soft soil due to the low cost and short construction times. In the recent years, geosynthetic have been used in combination with column systems to support embankments. The load transfer mechanism in these systems is a combination of soil arching effect, which occurs between columns and membrane effect of the geosynthetic. This paper aims at the study of soil arching effect on columnar embankments using finite element software, ABAQUS. An axisymmetric finite element model is generated and using this model, parametric studies are carried out. Thus the effects of various factors such as height of embankment fill, elastic modulus of pile and tensile stiffness of geosynthetic, on soil arching have been studied. The development of negative skin friction along the pile-soil interface have also been studied and the results obtained from this study are compared with the current design methods.

Keywords: ABAQUS, geosynthetic, negative skin friction, soil arching

Procedia PDF Downloads 346

Authors: Luai Z. Hasoun, Steven W. Bailey, Kitti K. Outlaw, June E. Ayling

Abstract:

Human skin color is thought to have evolved to balance sufficient photochemical synthesis of vitamin D versus the need to protect not only DNA but also folate from degradation by ultraviolet light (UV). Although the risk of DNA damage and subsequent skin cancer is related to light skin color, the effect of UV on skin folate of any species is unknown. Here we show that UVA irradiation at 13 mW/cm2 for a total exposure of 187 J/cm2 (similar to a maximal daily equatorial dose) induced a significant loss of total folate in epidermis of ex vivo white skin. No loss was observed in black skin samples, or in the dermis of either color. Interestingly, while the concentration of 5 methyltetrahydrofolate (5-MTHF) fell in white epidermis, a concomitant increase of tetrahydrofolic acid was found, though not enough to maintain the total pool. These results demonstrate that UVA indeed not only decreases folate in skin, but also rearranges the pool components. This could be due in part to the reported increase of NADPH oxidase activity upon UV irradiation, which in turn depletes the NADPH needed for 5-MTHF biosynthesis by 5,10-methylenetetrahydrofolate reductase. The increased tetrahydrofolic acid might further support production of the nucleotide bases needed for DNA repair. However, total folate was lost at a rate that could, with strong or continuous enough exposure to ultraviolet radiation, substantially deplete light colored skin locally, and also put pressure on total body stores for individuals with low intake of folate.

Keywords: depletion, folate, human skin, ultraviolet

Procedia PDF Downloads 356