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1
Melero Carnero, Laura. "Francisco Ríos Álvarez y su «Mirada en la Lengua»: estructura, temas e ideologías lingüísticas en sus Columnas sobre la lengua (CSL) en La Voz de Galicia". Revista de Investigación Lingüística 25 (31 dicembre 2022): 129–54. http://dx.doi.org/10.6018/ril.524511.
Testo completoAbstract (sommario):
This article analyses Francisco Ríos Álvarez’s newspaper columns. The aim is to define this columnist’s writing style and its evolution, as well as his linguistic ideology. The study is framed within a line of research that investigates a subgenre of journalistic column called language columns. These are journalistic texts regularly published in a written newspaper, signed by a person of renown and dealing with analyses of language usage (Marimón, 2019b: 13). In order to analyse columns by the said author, a corpus was compiled consisting of 44 texts selected from the three series of columns that he authored. The findings reveal a stylistic, ideological and thematic evolution. Este trabajo analiza las columnas periodísticas de Francisco Ríos Álvarez, con el fin de definir el estilo de escritura y su evolución y la ideología lingüística del columnista. Esta investigación se enmarca dentro del estudio de un subgénero de columna periodística llamada Columnas sobre la lengua: un texto periodístico que se publica regularmente en un periódico escrito, firmadas por una persona de reconocido prestigio y en el que se explican los usos de la lengua (Marimón, 2019b: 13). Para analizar sus columnas, se ha creado un corpus con 44 columnas seleccionadas de las tres series que escribió. Los resultados obtenidos mostraron que existe una evolución estilística e ideológica en sus columnas y en los temas sobre los que escribe.
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VIRGENS, J. P., R. B. GOMES, L. M. TRAUTWEIN, G. N. GUIMARÃES e A. P. R. VAZ. "Experimental analysis of eccentrically loaded reinforced concrete columns with an added jacket of self-compacting concrete". Revista IBRACON de Estruturas e Materiais 12, n. 2 (aprile 2019): 329–36. http://dx.doi.org/10.1590/s1983-41952019000200007.
Testo completoAbstract (sommario):
Abstract This paper presents the experimental study of eccentrically loaded reinforced concrete columns with an added 35 mm self-compacting concrete jacket attached to the column’s most compressed face using wedge bolts. Nine columns with a 2000 mm height were tested under compression and one-way bending until failure. Columns were denominated as original column (PO) with a cross section of 120 mm x 250 mm; reference column (PR) with a cross section of 155 mm x 250 mm, and seven columns with an initial cross section of 120 mm x 250 mm and later reinforced by the addition of 35 mm self-compacting concrete layer and various configurations of wedge bolts. Except for the original column PO, the columns were submitted to a 42.5 mm load eccentricity due to the added concrete layer at the compressed face. Although failure of the wedge bolts did not occur, it was not possible to prevent detachment of the added layer. The results indicate that it is possible to structurally rehabilitate reinforce concrete columns with the use of the strengthening methodology used in this research, resulting in average ultimate load capacity gains of 271% compared to original column’s ultimate load.
3
Schmidt, Jon A. "Design of Mill Building Columns Using Notional Loads". Engineering Journal 38, n. 2 (30 giugno 2001): 90–99. http://dx.doi.org/10.62913/engj.v38i2.753.
Testo completoAbstract (sommario):
Structural engineers have long recognized that mill building columns constitute a unique design situation. These columns typically support both the roof of the building at the top and one or more crane rails at an intermediate elevation. They accomplish this by taking the form of one of four common configurations (Fisher, 1993): a uniform column with a cantilevered bracket, a stepped column, separate laced columns, or separate battened columns (Figure 1). The last three options involve the use of a stronger and stiffer column section below the crane rail elevation by providing a larger section or a combination of two sections tied together for composite action. The presence of applied crane loads and, often, a transition of section properties at a point within the in-plane unbraced length of the overall column presents special challenges to the designer attempting to assess the member's strength and stability. Traditionally, determination of the load capacity of a steel column requires the calculation of an effective length factor, K. This value, when multiplied by the column's actual unbraced length, estimates the length of an equivalent pin-ended column with the same buckling load as the actual column. To be reasonably accurate, the effective length factor must account for various influences on the column's behavior, including initial material and geometrical imperfections, inelasticity, end restraint characteristics, and both horizontal and vertical interaction among the columns in the frame being analyzed. Over the years, engineers have developed several special procedures for establishing effective length factors for mill building columns that reflect their unique loading and geometry.
4
Shaat, Amr, e Amir Fam. "Axial loading tests on short and long hollow structural steel columns retrofitted using carbon fibre reinforced polymers". Canadian Journal of Civil Engineering 33, n. 4 (1 aprile 2006): 458–70. http://dx.doi.org/10.1139/l05-042.
Testo completoAbstract (sommario):
This paper describes the behaviour of axially loaded short and long square hollow structural section (HSS) columns, strengthened with carbon fibre reinforced polymer (CFRP) sheets. Twenty-seven short-column and five long-column HSS specimens were tested. The effect of CFRP sheet orientation in the longitudinal and transverse directions was studied for short columns. For long columns, CFRP sheets were oriented in the longitudinal direction only. A maximum strength gain of 18% was achieved for short columns with two transverse CFRP layers. For long columns, the maximum strength gain of 23% was achieved with three longitudinal CFRP layers applied on four sides. In all CFRP-strengthened long columns, lateral deflections were reduced. Strength gain in long columns was highly dependent on the column's imperfection. As such, no correlation was established between strength gain and number of CFRP layers. CAN/CSA 16-01 equation was modified to account for CFRP through transformed section analysis so that they could be used to predict the axial-load capacity of long columns.Key words: retrofit, steel, HSS, column, FRP, carbon, buckling, strength, stiffness.
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Rahbar-Kelishami, Ahmad, Hossein Bahmanyar e Zahra Hajamini. "A novel approach for calculating packed column height based on new correlation of mass transfer coefficient". Polish Journal of Chemical Technology 17, n. 1 (1 marzo 2015): 48–54. http://dx.doi.org/10.1515/pjct-2015-0008.
Testo completoAbstract (sommario):
Abstract The calculation of column’s height plays an important role in packed columns precise design. This research is based on experimentally measurement of mass transfer coefficients in different heights of packed column to predict its height. The objective of presented work is to introduce a novel conceptual method to predict column height via new correlation for mass transfer coefficient. As the mass transfer coefficient is decreased with increase of column height, the HTU’s are not constant figures along the column so this new approach is called increasing HTU’s. The results of the proposed idea were compared with other correlations and the conventional method i.e. constant HTU’s. Since the results are in very good agreement with experimental data comparing to conventional method, it seems this approach can be a turning point in design of all differential columns like packed columns. Making use of this method is suggested for design of differential columns.
6
Luo, Wen Wen, Ying Min Li, Ni Na Zheng e Na Chen. "Numerical Analysis of Seismic Behavior of Masonry Walls Confined by Precast Tie-Columns". Applied Mechanics and Materials 166-169 (maggio 2012): 2429–35. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.2429.
Testo completoAbstract (sommario):
In order to improve the seismic behavior of the rural masonry buildings and reduce the cost and be convenient for construction, a precast tie-column system was put forward, which was suitable for masonry buildings, constructed by fired common bricks or porous bricks. The uniaxial compression constitutive relation of brick masonry was used for simulating the precast tie-column. And this paper analyzed the difference of the seismic behavior of masonry walls which bearing different vertical compressive stress, and confined by cast-in-place tie-columns or precast tie-columns, and whether contain windows or not. The results show that the uniaxial compression constitutive relation used for simulating precast tie-column is reasonable and the seismic behavior of masonry walls confined by precast tie-columns is better than the wall without tie-colums, and equal to those confined by cast-in-place tie-columns.
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Belakhdar, Ahmed Rafik, Mohamed Salah Dimia e Mohamed Baghdadi. "Post-fire behavior of RC columns repaired with square hollow section steel tube and RC concrete jackets". Journal of Engineering and Exact Sciences 9, n. 6 (20 luglio 2023): 161456–01. http://dx.doi.org/10.18540/jcecvl9iss6pp161456-01e.
Testo completoAbstract (sommario):
This paper investigates numerically fire-exposed reinforced concrete (RC) columns. As a first step, the study examined the effects of exposing the columns to fire for 60 minutes according to the ISO 834 fire standard on the column's residual load-bearing capacity by considering some decisive geometrical parameters such as the column height and its cross-sectional area. The second step consisted of investigating the effectiveness of the strengthening technique utilized by incorporating composite jackets, considering different strengths of concrete, in order to improve the post-fire behavior of these columns. The results showed that the longer the column is exposed to fire, the lower its bearing capacity. However, it was also found that increasing the column cross-sectional area can reduce the percentage of load-bearing capacity. Finally, it was revealed that the strengthening method used herein allowed restoring the capacity of the columns exposed to fire for a period of one hour by up to 180%.
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Ibraheem, Rawaa S., e Alaa H. Al-Zuhairi. "A Comparative Study on Behavior of RC Columns Strengthened by CFRP and Steel Jacket". E3S Web of Conferences 318 (2021): 03002. http://dx.doi.org/10.1051/e3sconf/202131803002.
Testo completoAbstract (sommario):
This paper studies the behavior of axially loaded RC columns which are confined with carbon fiber reinforced polymers’ sheet (CFRP) and steel jackets (SJ). The study is based on twelve axially loaded RC columns tested up to failure. It is divided into three schemes based on its strengthening type; each scheme has four columns. The main parameters in this study were the compressive strength of the concrete and steel reinforcement ratio. Furthermore, the results of the experimental test showed a substantial enhancement in the column's load-carrying capacity. When compared to the original columns, the CFRP sheet had a significant effect on improving the ductility of the column by increasing the axial deformation by about 59.2 to 95.7%. On the other hand, the SJ contributed mostly to the column load-carrying capacity, which increased the capacity of RC concrete from 75 to 107%; because of its composite action comparing with the CFRP sheet action in which unidirectional lateral confinement is provided. Both methods produced completely different failure modes. The columns strengthened with CFRP sheet failed by rupture occurring in the sheet fibers. The strengthened with SJ failed due to the buckling that occurred in the steel angles due to the direct contact with the head of the column, and crushing in the concrete has occurred.
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Zacarese, Lawrence M. "A column about columns". Campus Security Report 21, n. 2 (15 maggio 2024): 1–3. http://dx.doi.org/10.1002/casr.31261.
Testo completoAbstract (sommario):
I was chatting with my youngest son the other day while driving him to wrestling practice and playing “Daddy Uber.” I mentioned to him that I needed to work on writing my column, and he asked me what it was about. I mentioned I had a few ideas, but there were so many things going on in higher education, many that I have written extensively about, that I wasn’t sure which direction I was headed yet. He suggested that I take a page out of John Grogan's book.
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Niu, Jiangang, Wenming Xu, Jingjun Li e Jian Liang. "Influence of Cross-Sectional Shape on the Mechanical Properties of Concrete Canvas and CFRP-Reinforced Columns". Advances in Materials Science and Engineering 2021 (11 maggio 2021): 1–14. http://dx.doi.org/10.1155/2021/5541587.
Testo completoAbstract (sommario):
Fiber-reinforced polymer (FRP) wrapping has become an attractive strengthening technique for concrete columns. However, the ingress of corrosion into the concrete through the gap of CFRP fiber greatly reduces the durability of concrete and the bearing capacity of specimens. Concrete canvas, a kind of corrosion-resistant and refractory material, is a promising method to enhance durability and carrying capacity. In this study, the concrete canvas (CC) and carbon fiber-reinforced polymer (CFRP) were used to jointly reinforce columns with square cross section, octagonal cross section, circular cross section, and elliptical cross section. The influence of section shape on the strengthening effect of the axial compression column was investigated by the axial compression test. The results showed that the section shape had a significant influence on the reinforcement effect of the axial compression column. The carrying load capacity and ductility coefficient of different columns follow this order: square column < oval-shaped columns < octagonal columns < circle columns. The increased amplitude of bearing capacity for the different columns with the increase of CC layers follows this order: square columns < oval-shaped columns < circle column < octagonal columns. Compared with the unconstraint columns, the bearing capacity of adopting two-layer CC columns increased by 129%, 155%, 150%, and 139% for the square, octagonal, circular, and elliptical columns, respectively. The octagonal column has the largest increase range. Compared with the unconstraint columns, the bearing capacity of adopting two-layer CC columns increased by 348%, 318%, 310%, and 296% for the square, octagonal, elliptical, and circular columns, respectively. The square column has the largest increase range. The stress concentration phenomenon of all section shapes was weakened after the CC was used. The application of the CC on CFRP-reinforced columns improves column ductility significantly, with some degree of increase in bearing capacity.
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Al-Shwaiter, Abdullah, e Ziyad Al-Gaboby. "Behavior of Rubberized Concrete-Filled Square Steel Tube Under Axial Loading". Journal of Science and Technology 24, n. 1 (30 giugno 2019): 23–39. http://dx.doi.org/10.20428/jst.v24i1.1572.
Testo completoAbstract (sommario):
The purpose of this paper is to investigate the behavior of rubberized concrete-filled steel tube (RuCFST)analytically by using ABAQUS 6.12-1 software for square columns under axial loading. Twelve specimens modeled with various variables which are rubber content as replacement percentage from natural aggregate (0%, 5% and 15%), tube thickness (3mm and 6mm) and columns’ length (1.5m and 3.0m). The results showed an adoption model of RuCFST columns subjected to axial force in elastic and plastic properties of steel and concrete gives a good agreement between numerical and references experimental results. Also, the results showed a reduction in column capacity with increasing rubber content. In contrast, the results showed an increase in the columns’ compression capacity with increasing the thickness from 3 to 6mm. In addition, columns’ lengths have no significant effect on compression capacity, although the corresponding shortening increased with increase column’s length.
Keywords: Rubberized concrete, Infilled steel tube, Finite element, Axial loading and ABAQUS.
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Al-Shwaiter, Abdullah, e Ziyad Al-Gaboby. "Behavior of Rubberized Concrete-Filled Square Steel Tube Under Axial Loading". Journal of Science and Technology 24, n. 1 (30 giugno 2019): 23–39. http://dx.doi.org/10.20428/jst.24.1.2.
Testo completoAbstract (sommario):
The purpose of this paper is to investigate the behavior of rubberized concrete-filled steel tube (RuCFST)analytically by using ABAQUS 6.12-1 software for square columns under axial loading. Twelve specimens modeled with various variables which are rubber content as replacement percentage from natural aggregate (0%, 5% and 15%), tube thickness (3mm and 6mm) and columns’ length (1.5m and 3.0m). The results showed an adoption model of RuCFST columns subjected to axial force in elastic and plastic properties of steel and concrete gives a good agreement between numerical and references experimental results. Also, the results showed a reduction in column capacity with increasing rubber content. In contrast, the results showed an increase in the columns’ compression capacity with increasing the thickness from 3 to 6mm. In addition, columns’ lengths have no significant effect on compression capacity, although the corresponding shortening increased with increase column’s length.
Keywords: Rubberized concrete, Infilled steel tube, Finite element, Axial loading and ABAQUS.
13
Zhang, Xun Zhong, Ru Heng Wang e Wei Hu. "Analysis on Seismic Performance of Frame Columns Reinforced with Wing Walls". Applied Mechanics and Materials 166-169 (maggio 2012): 1691–95. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.1691.
Testo completoAbstract (sommario):
Through the ANSYS finite element method, the seismic performance of frame columns reinforced with wing walls has been analyzed, indicating that the wing wall reinforcement can effectively improve the lateral stiffness and remarkably increase the bearing capacity of columns. With the wing wall reinforcement, the envelop area of the column’s hysteresis curve increases, and the bearing capacity improves, however, the shrinking phenomena of the curve suggests that the ductility of the section reduces. When the centerline of the additional wing wall coincides with that of the original column, the hysteresis curve inclines to be full, thus advising overlapping the centerline of the wing wall with that of the original column.
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Patel, Nishiben, Krishna R. Gupta e Milind J. Umekar. "An Overview of Monolithic Column: Types, Parameters and Applications". Journal of Drug Delivery and Therapeutics 12, n. 4-S (15 agosto 2022): 223–31. http://dx.doi.org/10.22270/jddt.v12i4-s.5521.
Testo completoAbstract (sommario):
The column is the main component for chromatographic separation. Nowadays, monolithic columns are graining more popularity in the field of separation media for liquid chromatography. The monolith columns possess great potential as compared to the conventional packed column in terms of preparing complex mixtures. These columns provide various properties like higher permeability, high-efficiency fast separations, high flow rate with lower backpressure, fast mass transfer kinetics with a high binding capacity. It is categories into three columns and they are organic monolithic column, inorganic monolithic column and hybrid monolithic column and all three types of monolithic column differ through their porous properties. In this review, the various advantage of the high-efficiency monolithic column with recent advances, the origin of the concept, the various parameter of the monolithic stationary phase and the application of monolithic columns are illustrated. It is better column in comparison of selectivity, reproducibility and performance.
Keywords: Monolithic column, Packed columns, Inorganic and organic monolithic column, Column parameters, Pharmaceutical Applications
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Ahmed, Ali, Ahmed Mohammed Youssef Mohammed e Koichi Maekawa. "Performance Comparison of High Strength Reinforced Concrete Circular and Square Columns Subjected to Flexural Controlled Cyclic Loading". Civil Engineering Journal 7, n. 1 (1 gennaio 2021): 83–97. http://dx.doi.org/10.28991/cej-2021-03091639.
Testo completoAbstract (sommario):
In existing design practices selection of circular or square column shape mostly depends upon architectural needs rather than structural behavior. The behavior of equivalent area (circular and square), high strength reinforced concrete columns is reported to be same under monotonic loading conditions but their behavior under fatigue loading is not well-established. This paper presents the comparison of high strength reinforced concrete circular and square equivalent area columns’ performance (load-deflection behavior) under fatigue loading. Columns were casted in four configurations: square and circular shapes and with and without shear stirrups. Experimental results showed that in case of columns without shear stirrups, the square column resisted 38% more loading cycles as compared to circular column while the maximum deflection was 78% more than the circular column. Similarly, in case of columns with shear stirrups, square shaped column resisted 55% more loading cycles with only 5% more maximum deflections as compared to circular column. The results show that the square columns might be considered more ductile as compared to circular columns under the application of cyclic loading conditions like wind forces or seismic forces. Therefore, it might be concluded that square columns should be recommended for highly seismic regions as compared to circular columns with equivalent area. Doi: 10.28991/cej-2021-03091639 Full Text: PDF
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Fenollosa, Ernesto, Iván Cabrera, Verónica Llopis e Adolfo Alonso. "Non-linear Analysis of Slender High Strength Concrete Column". Civil Engineering Journal 5, n. 7 (18 luglio 2019): 1440–51. http://dx.doi.org/10.28991/cej-2019-03091343.
Testo completoAbstract (sommario):
This article shows the influence of axial force eccentricity on high strength concrete columns design. The behavior of columns made of normal, middle and high strength concrete with slenderness values between 20 and 60 under an eccentric axial force has been studied. Structural analysis has been developed by means of software which considers both geometrical and mechanical non-linearity. The sequence of points defined by increasing values of axial force and bending moment produced by eccentricity has been represented on the cross-section interaction diagram until failure for each tested column. Then, diagrams depicting the relationship between failure axial force and column's slenderness have been drawn. The loss of bearing capacity of the member for normal and middle strength columns when compared with the bearing capacity of their cross-section is more noticeable as axial force eccentricity assumes higher values. However, this situation reverses for high strength columns with high slenderness values. On the basis of results obtained, the accuracy level for the moment magnifier method was checked. Despite the good concordance in most of the cases, it was verified that the moment magnifier method leads to excessively tight results for high strength concrete columns with high slenderness values. In these specific cases, a coefficient which amends the column rigidity is proposed so as to obtain safer values.
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Nguyen Thai, Linh, Manh Nguyen Duc e Ha Nguyen Hai. "Analysis of impacting factors for soil-cement column combined high strength geogrid". Transport and Communications Science Journal 72, n. 1 (25 gennaio 2021): 9–15. http://dx.doi.org/10.47869/tcsj.72.1.2.
Testo completoAbstract (sommario):
Soil-cement column combined with geogrid on top or Geogrid Reinforced Pile Supported (GRPS), is used to construct structures on soft ground. Because of its high tensile capacity, the geogrid is spread on the top of the soil-cement column to form a soft transmission layer, increasing the capacity transferred to the columns, reducing a part of the load transmitted to the soft soil between the columns. The numerical analysis results of the GRPS with a high strength geogrid showed four major factors affecting transmission the efficacy of the column (Ef) and the tensile force of the geogrid including effective vertical load (v’); the ratio of the distance between the columns and the column’s diameter (s/D); the ratio of the elastic modulus of the soil-cement column to the deformation modulus of soil (Ec/Es); the tensile stiffness of the geogrid (J). The efficacy of the column (Ef) increases rapidly with an increase in effective vertical load (v’) from 0.23 to 0.44. In contrast, the transmission efficiency (Ef) decreases from 0.60 to 0.37 when s/D increased. When the ratio Ec/Es > 150 and J > 8000 kN/m, the tensile force of the geogrid tends not to change much.
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Propika, Jaka, Dita Kamarul Fitriyah e Yanisfa Septiarsilia. "Analisa Perbandingan Kolom Komposit Inside Steel dan Outside Steel terhadap Kapasitas Tahanan Aksial dan Momen". Reka Buana : Jurnal Ilmiah Teknik Sipil dan Teknik Kimia 5, n. 2 (22 settembre 2020): 62. http://dx.doi.org/10.33366/rekabuana.v5i2.1947.
Testo completoAbstract (sommario):
ABSTRAK Penggunaan kolom komposit telah banyak digunakan di berbagai bangunan bangunan tinggi. Dan pada umumnya, Kolom komposit dibagi menjadi 2 macam, yaitu kolom komposit inside steel dan outside steel dengan struktur baja terbungkus oleh beton disebut dengan kolom inside steel atau bisa saja disebut Concrete Encased Column. Sedangkan untuk baja yang berisi beton disebut dengan kolom outside steel atau juga disebut Concrete Filled Column. Penggunaan struktur kolom komposit outside steel sebagai kolom utama dalam mendukung beban lateral pada struktur rangka bangunan belum lazim digunakan dalam perkembangan konstruksi saat ini. Oleh karena itu, perlu dilakukan analisa kekuatan dari 2 macam kolom komposit agar diketahui jenis kolom komposit yang paling efektif dan memiliki kekuatan paling tinggi. Perhitungan yang dilakukan dengan menggunakan perhitungan manual pada kolom komposit inside steel dan outside steel yang berbentuk kotak, sedangkan untuk perhitungan dengan menggunakan program CSICOL dilakukan pada seluruh kolom komposit. Hasil nilai ØPn dan ØMn kemudian dibandingkan antara perhitungan manual dengan program CSICOL. Hasil perhitungan menunjukan bahwa kemampuan kolom komposit outside steel lebih baik dibandingkan kolom komposit inside steel dengan menggunakan standar volume dari ukuran kolom komposit inside steel kotak 400x400 mm. Kolom komposit outside steel berbentuk bundar dengan diameter 431 mm lebih unggul sebesar 17 % dalam menahan gaya aksial nominal (ØPn) dibandingkan semua tipe kolom komposit yang lain. Sedangkan kolom komposit outside steel berbentuk kotak dengan ukuran 405.70x405.70 mm lebih unggul menahan momen nominal (ØMn) sebesar 10,5 % dibandingkan semua tipe kolom komposit yang lain.Kata kunci : kolom komposit; inside steel (concrete- encased column); outside steel (concrete-filled column)ABSTRACT The use of composite columns has been widely used in various high-rise buildings. Composite columns are generally divided into two types: composite columns inside steel and outside steel columns with a steel structure wrapped in concrete called an inside steel column (concrete encased column), while steel containing concrete is called an outside steel column (concrete-filled column). The use of a composite column structure outside steel as the main column in supporting lateral loads in the building frame structure is not yet commonly used in current construction developments. Therefore, it is necessary to consider the strengths of 2 types of composite columns to know which type of composite column is the most effective and has the highest strength. Calculations are performed using manual calculations on composite columns inside steel and outside steel in the form of a box, while calculations using the CSiCOL program are carried out on all composite columns. The results of the ØPn and ØMn values are then compared between manual calculations and the CSiCOL program. The calculation results show that the composite outside steel column's ability is better than the inside steel composite column by using a standard volume from the size of the composite column inside steel box 400x400 mm. The round composite outside steel column with a 431 mm diameter is 17% superior in withstanding nominal axial force (ØPn) than all other composite column types. While the outside steel composite column in the form of a box with a size of 405.70x405.70 mm is superior to withstand the little moment (ØMn) by 10.5% compared to all other types of composite columns.
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AlJallad, Sadjad Amir, e Haitham Al-Thairy. "EFFECT OF WEB OPENING ON THE AXIAL LOAD CAPACITY OF STEEL COLUMNS WITH COLD FORMED THIN WALLED SECTION (CFS)". Kufa Journal of Engineering 7, n. 3 (9 ottobre 2016): 13–26. http://dx.doi.org/10.30572/2018/kje/731200.
Testo completoAbstract (sommario):
In this paper, an experimental study has been presented to investigate the effects of web opening on the behavior and failure of steel columns with cold formed thin walled sections (CFS) subjected to axial compressive load. Twenty small scale steel columns with cold formed box and channel sections and a total length of 500 mm have been considered in the experimental tests. Ten of the tested steel columns specimens have a box section with dimensions of (100×100×2) mm (height × width× thickness), and the other ten columns specimens have a channel sections with dimensions of (100×50×2) mm (height × width× thickness). To investigate the effect of the number and the shape of web opening on the axial compressive strength of steel columns, each ten columns with same cross section shape was divided into three groups of three columns in addition to the reference column which has no web openings. All groups of columns have same opening area which is located at the web of the section, but each group has a different opening shape (square, rectangular, and circular shapes), and each steel column within each group has different numbers of opening distributed along column length (one, two, and three openings). Each steel column specimens was subjected to an increasing static load up to column failure which indicated by the reloading of the test machine. The study has shown that for most of the tested columns, increasing the numbers of web openings results in decreasing the column axial strength compared to the reference steel column. The maximum percentage of the reduction in the columns axial compressive strength caused by the presence of web opening was found to be about 30% and 45% of the reference columns strength for columns with box and channel shape sections, respectively. It has also been found that the reduction in the axial compressive strength of the column specimens caused by the presence of web openings is lower for the circular shape openings compared to that for rectangular and/or square shape web openings.
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Yarovyy, S., Y. Yarovyy e D. Mazur. "DETERMINATION OF THE CALCULATED LENGTH OF THE COLUMNS TAKING INTO ACCOUNT THEIR FORM OF DEFORMATION AND UNEQUAL LOADING IN THE FRAME COMPOSITIOND". Scientific Bulletin of Building, n. 110 (27 giugno 2024): 96–101. http://dx.doi.org/10.33042/2311-7257.2024.110.1.14.
Testo completoAbstract (sommario):
The coefficient of expansion of the columns, which are used in the warehouse of one-span frames with crane attachments, must depend on the shape of their deformation and the unequal attachment of the columns. At this time, the peculiarity of the current development of the frame is the fact that the most likely objectives can be achieved by only one column in the warehouse. If one of the columns (which has a heavy tap with a vantage) is subject to the maximum influx of constant force at the moment, then the longitudinal column of the same cut allows for the influx of significantly less force. The overall rigidity of the columns in the warehouse frame plays a vital role in the stability of the columns. In a transverse direction, two columns of one span of the workshop are connected by a crossbar into a frame system. The development of significant plastic deformations in one of the columns does not cause a loss of the column’s strength. The protruding column is becoming increasingly important. The regulation of the efficient operation of columns in warehouses allows for more rational design in accordance with current standards. The arrangement of the crazy work of unequally attractive columns in the warehouse can be characterized as a refinement of the first form of deformation. Meanwhile, under active pressure, the frame is deformed according to a mixed shape, which in addition to the first appears in the form of warehouses and other types of normative, effective form of deformation in action. The form of deformation of the frame is stimulated by the following main factors, and, as a rule, does not coincide with the first moisture form and does not predict it. Essentially, the structured combination includes a vantage that stimulates different moisture forms, and a vantage that fits on a similar frame that can be laid out in warehouses that stimulates a variety of moisture forms. The resulting form, due to the resistance of permanent forces in the plastic elements and the elasticity of the material, is a linear combination of warehouse forms and this form can be called mixed. The established principle of independence of action of forces can be distributed on the rod or rod system of storage in the warehouse, where the skin storage force is stimulated by those and other moisture forms. A method has been developed for assessing the durability of steel-curved columns of steel frames with crane attachments, which ensures the effective operation of differently attached columns in the warehouse and the shape of deformation under the action of active forces. The calculated lengths of the columns, determined for cross-sections with crane loads according to the proposed method, are smaller than the calculated lengths determined according to the standard method by 8-20%. Keywords: squeezed columns, gauge length, deformed form, making a column in a frame.
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Redecki, Michał, e Bronisław Gosowski. "The influence of the torsional restraint of crane column brackets on their critical load capacity". MATEC Web of Conferences 262 (2019): 09009. http://dx.doi.org/10.1051/matecconf/201926209009.
Testo completoAbstract (sommario):
The paper presents the results of numerical parametric studies conducted on laterally restrained steel I-columns with a single stepped asymmetric change in their cross-section. Such elements are used as a part of the outermost columns in the transversal system of steel halls with cranes. The columns are usually braced along their length with wall girts, which in a properly structured hall system have a significant effect on the columns’ load bearing capacity and determine their axis of rotation. The main aim of the presented studies is to determine the impact of parameters, such as longitudinal load distribution on the upper and lower segment of the column, the number of pointed lateral bracings and their distance to a column's external flange, and also the application of torsional restraint on the critical load capacity. Results are presented as surfaces or contour maps, in which the ordinates represent the critical loads with regards to the analysed parameters. The paper ends with practical conclusions.
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Liu, Shihao, Wenhua Ye, Peihuang Lou, Weifang Chen, Jungui Huang e Lili Xiao. "Bionic Design for Column of Gantry Machining Center to Improve the Static and Dynamic Performance". Shock and Vibration 19, n. 4 (2012): 493–504. http://dx.doi.org/10.1155/2012/545931.
Testo completoAbstract (sommario):
In order to improve the machining accuracy of a gantry machining center, structural bionic design for column was conducted. Firstly, the bionic design method for stiffener plate structure was established based on distribution principles of gingko root system. The bionic design method was used to improve column structure of the gantry machining center, and three kinds of bionic columns were put forward. The finite element analysis on original and bionic columns indicates that the mass of the column with the best bionic stiffener plate structure is reduced by 2.74% and the first five order natural frequencies are increased by 6.62% on average. The correctness of column's bionic design method proposed in this paper was verified by the static and dynamic experiments. Finally, the bionic principles for stiffener plate of column were concluded, which provides a new idea for updating traditional design concepts and achieving lightweight structure of machine tool components.
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Lei, Min, Zihao Wang, Penghui Li, Liyi Zeng, Hongyao Liu, Zhidong Zhang e Huicheng Su. "Experimental Investigation on Short Concrete Columns Reinforced by Bamboo Scrimber under Axial Compression Loads". Advances in Civil Engineering 2020 (29 settembre 2020): 1–12. http://dx.doi.org/10.1155/2020/8886384.
Testo completoAbstract (sommario):
The paper presents bamboo scrimber bars as a reinforcing material instead of steel reinforcement in low-strength concrete columns. Twelve short concrete columns with different reinforcements are tested under axial compression load to study the axial compressive behavior of short concrete columns reinforced by bamboo scrimber. Three columns are reinforced concrete columns, and the other nine columns are bamboo scrimber reinforced concrete columns. The failure process, bearing capacity, axial deformation, and strain of the specimens are compared and analyzed. The results show that the bonding performance between the bamboo scrimber bars by surface treatment and low-strength concrete is excellent. In low-strength concrete columns, the material properties of bamboo bars play more thoroughly than those of steel bars. When the bamboo reinforcement ratio is increased, the concrete column ductility is significantly improved, but the bearing capacity of the concrete column is not increased. The bamboo scrimber bars with the size of 10 mm × 10 mm or 15 mm × 15 mm can be used as longitudinal bars of low-strength concrete columns. The ductility of the short concrete column with 2.56% bamboo scrimber reinforcement is close to that of the short concrete column with 0.72% steel reinforcement.
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Wu, Jing, Fa Zhou Wang, Wen Yang e Qing Jun Ding. "Load Carrying Capacity Analysis of Multi-Spiral Reinforced Concrete Column". Advanced Materials Research 150-151 (ottobre 2010): 441–46. http://dx.doi.org/10.4028/www.scientific.net/amr.150-151.441.
Testo completoAbstract (sommario):
The behavior of confined concrete is highly dependent on the confinement type of transverse reinforcement, spiral hoops are generally believed to have better confined effect in concrete than rectangular hoops. It is verified through experiments and the oretical calculations that multi-spiral confined concrete columns have better mechanical properties than single spiral columns, the multi-spiral significantly increase the column’s strength, plasticity, ductility and anti-seismic capability. Based on the three-direction stress law of confined concrete, the load carrying capacity of the rectangular cross section concrete column with multi-spiral is analysed in this paper, and the calculated equation of the load carrying capacity is proposed, which provide a theory and calculation basis for multi-spiral confined concrete column design and research.
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FERREIRA, D. B., R. B. GOMES, A. L. CARVALHO e G. N. GUIMARÃES. "Behavior of reinforced concrete columns strenghtened by partial jacketing". Revista IBRACON de Estruturas e Materiais 9, n. 1 (febbraio 2016): 1–21. http://dx.doi.org/10.1590/s1983-41952016000100002.
Testo completoAbstract (sommario):
This article presents the study of reinforced concrete columns strengthened using a partial jacket consisting of a 35mm self-compacting concrete layer added to its most compressed face and tested in combined compression and uniaxial bending until rupture. Wedge bolt connectors were used to increase bond at the interface between the two concrete layers of different ages. Seven 2000 mm long columns were tested. Two columns were cast monolithically and named PO (original column) e PR (reference column). The other five columns were strengthened using a new 35 mm thick self-compacting concrete layer attached to the column face subjected to highest compressive stresses. Column PO had a 120mm by 250 mm rectangular cross section and other columns had a 155 mm by 250mm cross section after the strengthening procedure. Results show that the ultimate resistance of the strengthened columns was more than three times the ultimate resistance of the original column PO, indicating the effectiveness of the strengthening procedure. Detachment of the new concrete layer with concrete crushing and steel yielding occurred in the strengthened columns.
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Halding, Philip Skov. "Reduction of the Carbon Footprint of Precast Columns by Combining Normal and Light Aggregate Concrete". Buildings 12, n. 2 (15 febbraio 2022): 215. http://dx.doi.org/10.3390/buildings12020215.
Testo completoAbstract (sommario):
To reduce the global emission of CO2 from the building industry, researchers, architects and manufacturers must consider new ways of constructing precast concrete buildings. Modern concrete columns and walls are not optimized to the applied load, and there is potential to save material. By creating a stronger column core and a lightweight concrete cover, it is possible to reduce the carbon footprint. A method is proposed to calculate such eccentrically loaded columns of two or more materials. The analytical method is developed for straight columns and columns with Entasis. Production of curved Entasis columns is possible by using textile molds due to the low mold pressure from the light aggregate concrete. Two column types are load tested to confirm the method. The CO2 emission is calculated for some column examples, and it shows that an optimized column geometry often leads to a reduced carbon footprint compared to regular columns. The concept is especially efficient for slender columns. Furthermore, the external light aggregate concrete layer ensures protection against fire if high-strength concrete is applied as the column core.
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Li, Kai Wen, Zhi Yang Li, Xin Wan e Fei Liu. "Non-Linear Numerical Simulation on Hysteretic Behavior of SRC Columns". Applied Mechanics and Materials 723 (gennaio 2015): 382–86. http://dx.doi.org/10.4028/www.scientific.net/amm.723.382.
Testo completoAbstract (sommario):
In order to study the mechanics properties to of concrete columns with embedded steel, two groups contrasting analysis models referring to SRC column and RC column are established by using finite element software ABAQUS. Both Static and cycle force are conducted. Analytical results show that bearing capacity and deformation ability of steel embedded reinforced concrete columns (SRC) under static loading are obviously higher than those of the reinforced concrete column (RC). Under the cycle force, the hysteresis circles of the SRC columns are fuller than RC column. The capability of energy consumption of the SRC columns is almost 1.4 times more than the RC columns. Further axial pressure coefficient and stirrup ratio are considered as parameters to study hysteresis characteristics, energy dissipation and the influence of the skeleton curve of SRC columns. The analytical results demonstrate that the hysteresis characteristics and energy dissipationare different with the changes of axial pressure coefficient. Meanwhile, the stirrup ratio of SRC column has little effect on energy dissipation. The study results have some value on the design and application of the SRC columns.
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Goswami, A., e S. Deka. "Study of the Effect of Installation of Stone Columns on the Stability of Soil Slopes using Finite Element Method". IOP Conference Series: Materials Science and Engineering 1282, n. 1 (1 ottobre 2023): 012020. http://dx.doi.org/10.1088/1757-899x/1282/1/012020.
Testo completoAbstract (sommario):
Abstract There are several ways to mitigate the failure of a soil slope. The installation of stone columns for this purpose, is easy as well as economical. As their strength is greater than that of soil, they disrupt the slip surfaces. Also being more porous, they dissipate the pore pressure generated in the soil in the vicinity of the stone columns to a certain extent. This paper illustrates 2D finite element analyses carried out to simulate the behavior of stone columns in cohesive soil using the computer program PLAXIS. Parametric study was conducted to analyze the effect of number, length and diameter of the stone columns on the Factor of Safety of the soil slope. The F.O.S. of the soil slope was predicted using prediction models created using artificial neural networks (ANN) considering slope geometry like slope angle and height, material properties like cohesion and angle and internal friction of soil as well as granular material used in the columns, and the stone column parameters like the stone column’s number, length, diameter and the centre to centre (c/c) distance between two adjacent columns as input parameters. It was found that introduction of stone columns significantly improved the stability of the soil slopes. Further, it was seen that all the parameters considered in the study influenced the Factor of Safety of the soil slope.
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İnce, Elif Gökçe, e Fatih Mehmet Özkal. "Optimization of Structural Steel Used in Concrete-Encased Steel Composite Columns via Topology Optimization". Applied Sciences 14, n. 3 (30 gennaio 2024): 1170. http://dx.doi.org/10.3390/app14031170.
Testo completoAbstract (sommario):
Concrete-encased steel composite columns are preferred for their exceptional ductility and strength, particularly in high-rise buildings. This research aims to enhance both the strength and ductility of these composite columns by increasing the height of the steel profile. Typically, hexagonal or circular openings, referred to as castellated elements, are incorporated into the steel profile to achieve this height increase. This study employed a topology optimization method to identify the ideal opening shape for the steel profile in concrete-encased steel composite columns. The analysis revealed a sinusoidal-like opening shape, which was then refined for manufacturing. The optimal opening shape was used to increase the height of the existing steel profile, and nonlinear analyses were conducted to evaluate the effectiveness of this new optimized steel profile in concrete-encased steel composite columns. Two concrete-encased steel composite columns were designed: one with the optimal steel profile and the other with a standard steel I profile. ANSYS APDL 19.0 software was used to simulate an experiment based on an existing concrete-encased steel column to validate the nonlinear analysis. The verification analysis demonstrated a remarkable similarity between the experimental and numerical load–displacement graphs, indicating that the numerical analysis was reliable. In the analysis of the composite columns, both axial and lateral forces were applied in the nonlinear analyses. The axial force was applied at 15% of the column’s capacity, while the lateral force was applied until the composite column reached a state of failure. The results of the nonlinear analyses allowed for a comparison of load–displacement curves and the performance of the composite columns. In comparison to the standard steel I profile, the steel profile with the optimal opening shape increased load-carrying capacity by approximately 19% and energy absorption capacity by approximately 24%.
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Thejarathnam, T., M. H. Prashanth e Imran Kuttagola. "Study on the effectiveness of prefabricated cage system reinforcement in columns". IOP Conference Series: Earth and Environmental Science 1149, n. 1 (1 maggio 2023): 012010. http://dx.doi.org/10.1088/1755-1315/1149/1/012010.
Testo completoAbstract (sommario):
Abstract The concrete is the primary vertical load bearing component in a reinforced concrete column whereas the steel cage provides additional vertical load carrying capacity along with the confinement of core concrete. The research paper will focus on the performance of Prefabricated Cage System (PCS) Reinforcement in square columns. Eight columns were casted and tested, out of which two are rebar reinforced columns and six are PCS reinforced columns. There were two test groups, each group containing one rebar column and three PCS columns. In this study work is done to compare the performance of a PCS reinforced column to a rebar reinforced column, in addition comparing PCS cages of differently sized grid openings. The objective is to theoretically, experimentally, and numerically investigate the PCS column for its load carrying capacity and displacement capacity. From the results it is observed that as the size of opening of a PCS reinforced column increase, the load carrying capacity increases as the concrete running through the openings can strengthen the connection. Hence to improve the effectiveness of the PCS columns the spacing of openings should be increased. Further, the stiffness and energy absorption are more in rebar reinforced column compared to all PCS columns.
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Shukla, Shubham, e M. V. Waghmare. "Strengthening of RC Column Using GFRP". International Journal for Research in Applied Science and Engineering Technology 10, n. 3 (31 marzo 2022): 1217–24. http://dx.doi.org/10.22214/ijraset.2022.40866.
Testo completoAbstract (sommario):
Abstract: In construction industry, engineers try to find new, better, economical material. Today there are several new techniques observed in the industry. In recent years, the construction industry has seen an increasing demand to reinstate, rejuvenate, strengthen and upgrade existing concrete structures. This may be attributed to various causes such as environment degradation, design inadequacies, poor construction practices, lack of regular maintenance, revision of codes of practice, increase in loads and seismic conditions etc. One of the technique used is the wrapping of damaged and newly constructed columns with GFRP. As GFRP has the properties like high strength, light weight, resistance towards chemicals and salt water, it can be moulded into complex shapes, requires low maintenance etc. The behaviour of fibre reinforced polymer on different shapes of column has been extensively studied, but much less is known about concrete in FRP confined damaged columns. In this project a total of 21 columns are casted, out of which 3 columns are conventional columns, 9 columns are damaged & 9 are newly constructed columns. The columns are wrapped with single, double and triple layer of GFRP. An average increase of 33.21% is observed in damaged single layer wrapped GFRP column and 51.64% in damaged double layer wrapped GFRP column and 62% in damaged triple layer wrapped GFRP column. Similarly, 46.93% of increase in newly constructed single layer wrapped GFRP column and 72.56% of increase in newly constructed double layer wrapped GFRP column and 90.23% of increase in newly constructed triple layer wrapped GFRP column. Keywords: GFRP, damaged column, newly constructed column.
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Krishna, Himanshu, e Prince Yadav. "Study the Seismic Behavior of Special Columns in Multi-Story (G+4) Building for Seismic Zone III". International Journal for Research in Applied Science and Engineering Technology 10, n. 8 (31 agosto 2022): 749–53. http://dx.doi.org/10.22214/ijraset.2022.46215.
Testo completoAbstract (sommario):
Abstract: Columns are RC building structural elements that are primarily subjected to axial load and moments as they transport them from the superstructure to the substructure. Columns of various shapes and sizes are used. Popular column shapes include square, rectangular, and circular columns, as well as L-shaped, T-shaped, and (+) shaped columns, which are uncommon but provide more interior space than commonly used column shapes. This study aims to examine the seismic performance of multistory G+4 buildings with Rectangular columns and building with specially shaped columns. According to IS Code 1893(part 1):2016, the proposed buildings are analyzed using equivalent static analysis for zone III in soil condition 3. ETABs are used to analyze the models. After analysis, we conclude that buildings having special columns are safer and have more space as compared to the regular shaped column buildings
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Krishna, Himanshu. "Study the Behavior of Special Columns on Multi Storey Building for Seismic Ground Motions". International Journal for Research in Applied Science and Engineering Technology 10, n. 7 (31 luglio 2022): 2011–14. http://dx.doi.org/10.22214/ijraset.2022.45642.
Testo completoAbstract (sommario):
ABSTRACT: Columns are RC building structural elements that are primarily subjected to axial load and moments as they transport them from the superstructure to the substructure. Columns of various shapes and sizes are used. Popular column shapes include square, rectangular, and circular columns, as well as L-shaped, T-shaped, and (+) shaped columns, which are uncommon but provide more interior space than commonly used column shapes. This study aims to examine the seismic performance of multistorey G+10 buildings with Rectangular columns and building with specially shaped columns. According to IS Code 1893(part 1):2016, the proposed buildings are analyzed using equivalent static analysis for zone IV. ETABs are used to analyze the models. After analysis, we conclude that buildings having special columns are safer and have more space as compared to the regular shaped column buildings
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Yusuf, Hamzah, Akhmad Azis, Sugiarto Badaruddin, Andi Muhammad Subhan Saiby, Zulvyah Faisal e Zubair Saing. "Physical modeling of sand columns application in recharge reservoir to prevent seawater intrusion". Water Supply 22, n. 2 (26 ottobre 2021): 2170–78. http://dx.doi.org/10.2166/ws.2021.365.
Testo completoAbstract (sommario):
Abstract This study aims to provide visual evidence by the physical simulation to demonstrate the sand column performance of a recharge reservoir to control seawater encroachment and confirm some previous studies. In this analysis, a two-dimensional sand tank illustrates the sand column's role in overcoming seawater intrusion. Besides using dyes, the sand tank is also fitted with sensors to observe the length of seawater penetration. Furthermore, the simulation using SEAWAT numerical modeling is used as a reference in this analysis. The criteria analyzed were the number of sand columns, the reservoir water level, and the isochlors concentration. The results revealed a reasonably close match between physical and computational modeling. It was also found that the more sand columns and the higher the reservoir water level, resulted in the decrease of seawater penetration length that occurred. Physical and computational modeling findings indicated that the optimal results are derived using three sand columns with an RMSE value of 0.76. The seawater infiltration length decreased to 84.72% relative to sand column-free conditions at a reservoir water level of 15.0 cm.
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Li, Xiaozhong, Sumei Zhang, Yu Tao e Bing Zhang. "Numerical Study on the Axial Compressive Behavior of Steel-Tube-Confined Concrete-Filled Steel Tubes". Materials 17, n. 1 (27 dicembre 2023): 155. http://dx.doi.org/10.3390/ma17010155.
Testo completoAbstract (sommario):
To improve the concrete confinement and mechanical properties of concrete-filled steel tube (CFST) columns, a new configuration of steel-tube-confined concrete-filled steel tube (T-CFST) columns has recently been developed, in which an outer steel tube is employed externally, and the additional tube does not sustain the axial load directly. This preliminary experimental study revealed that, due to the effective concrete confinement by the outer steel tube, the T-CFST column achieves higher compressive strength and more ductile deformation compared to the CFST columns of the same steel ratio. In this study, two finite element (FE) models were developed for the T-CFST cross-section and stub column, respectively. The numerical study results revealed that the concrete can be constrained by the outer steel tube at the beginning of loading and the outer steel tube hoop stress can reach its yield strength at the column’s compressive strength, showing its effective confinement to the concrete. Numerous data were generated by the developed FE model to cover a wide range of parameters. Based on that, the calculation methods for the stress components of the inner and outer steel tubes are proposed. Finally, a suitable prediction method is proposed, utilizing the superposition method to determine the compressive strength of the T-CFST stub column, and the results of the calculation method and FE model agree well with each other. This research is the basis for promoting further research of T-CFST columns.
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Xu, Ying, e Bi Qin Dong. "An Industrialized Multi-Layer Precast Concrete Frame Building with Middle-Joint Beams and Columns". Advanced Materials Research 163-167 (dicembre 2010): 1849–53. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.1849.
Testo completoAbstract (sommario):
An industrialized multi-layer precast concrete building with middle-joint beams and columns frame system has been developed by China VANKE CO., LTD. The building is the first industrialized multi-layer precast concrete building for experimental purpose in China. A middle-joint beams and columns method has been utilized with beams and columns split in the middle place. The whole frame structure is then integrated into a unity through precast beams, precast columns, and reliable cast-in-place column-column and beam-beam joints. This paper presents the key points and difficulties during the building design process, introduces the structural design of column-column and beam-beam joints, and analyses the advantages and weaknesses of middle-joint beams and columns frame system.
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Teddy, Livian, Gagoek Hardiman, N. Nuroji e Sri Tudjono. "The New Method in Calculating Columns and Beams Dimensions That Meets Requirements of The Strong Column-Weak Beam and Non-Soft Story". Journal of Architectural Design and Urbanism 1, n. 2 (27 marzo 2019): 1. http://dx.doi.org/10.14710/jadu.v1i2.4492.
Testo completoAbstract (sommario):
Situated at an earthquake prone area, buildings planning in Indonesia must implement earthquake resistant building principles. One of these principles is determining dimensions of columns and beams in the process of architectural designing.This act eventually affects the behaviour of the strong column-weak beam and the probability of bending failure due to soft story. At present time, there are no simple rules architects can use in calculating the dimensions of beams and columns that meet the criteria for strong column-weak beam and non-soft story. This paper is an effort to provide an input to the architects in designing the dimensions of the columns and beams. This research is a review result of three theories namely: 1). The theory of columns and beams preliminary design, 2). The theory of the strong column-weak beam concept, and 3). The theory of soft story and column slenderness. Those theories were then synthesized into a spreadsheet. To meet the criteria for strong column-weak beam and non-soft story, the following procedures must be done : 1). Determine the columns’ dimensions according to 0.15% of the columns’ cumulative tributary area, 2). Determine the beams’ dimensions according to 1/12 of the beams’ span and the beams’ plastic modulus, 3). Determine the columns’ dimensions and the columns’plastic modulus, 4). Determine the columns’ height based on the column slenderness criteria, and 5). Compare the columns plastic modulus and the beams plastic modulus and check whether they meet the criteria “the columns’plastic modulus ≥ 1.2 * the beams’ plastic modulus”.
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Yuan, Haofeng, Lichang Fang e Shiji Song. "A Reinforcement-Learning-Based Multiple-Column Selection Strategy for Column Generation". Proceedings of the AAAI Conference on Artificial Intelligence 38, n. 8 (24 marzo 2024): 8209–16. http://dx.doi.org/10.1609/aaai.v38i8.28661.
Testo completoAbstract (sommario):
Column generation (CG) is one of the most successful approaches for solving large-scale linear programming (LP) problems. Given an LP with a prohibitively large number of variables (i.e., columns), the idea of CG is to explicitly consider only a subset of columns and iteratively add potential columns to improve the objective value. While adding the column with the most negative reduced cost can guarantee the convergence of CG, it has been shown that adding multiple columns per iteration rather than a single column can lead to faster convergence. However, it remains a challenge to design a multiple-column selection strategy to select the most promising columns from a large number of candidate columns. In this paper, we propose a novel reinforcement-learning-based (RL) multiple-column selection strategy. To the best of our knowledge, it is the first RL-based multiple-column selection strategy for CG. The effectiveness of our approach is evaluated on two sets of problems: the cutting stock problem and the graph coloring problem. Compared to several widely used single-column and multiple-column selection strategies, our RL-based multiple-column selection strategy leads to faster convergence and achieves remarkable reductions in the number of CG iterations and runtime.
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Masia, Mark J., e Nigel G. Shrive. "Carbon fibre reinforced polymer wrapping for the rehabilitation of masonry columns". Canadian Journal of Civil Engineering 30, n. 4 (1 agosto 2003): 734–44. http://dx.doi.org/10.1139/l03-015.
Testo completoAbstract (sommario):
The use of carbon fibre reinforced polymer (CFRP) wrapping to strengthen existing cracked masonry columns was investigated experimentally. The study was aimed at quantifying the increase in strength that can be achieved and assessing the effect of column size on the strength increase. Eighteen columns were tested, with three different square cross-sectional sizes (290 mm × 290 mm, 390 mm × 390 mm, 490 mm × 490 mm) and two different types of clay masonry unit. Six columns were constructed in each size, two columns using unit type 1 and four columns using unit type 2. Strengthening was achieved by wrapping the square section columns directly with a single-layer CFRP laminate or by wrapping the columns after first casting a circular concrete jacket around the column. The latter treatment was applied to two of the small-sized columns and two of the intermediate-sized columns. All other square section columns were wrapped directly. Significant strength increases were achieved, particularly when the columns were provided with the cylindrical concrete jacket. These preliminary tests indicate that the use of CFRP wrapping is an effective technique for rehabilitating damaged masonry columns. Decisive conclusions could not be made regarding the effect of column size (cross-sectional area) on the strength increase achieved. Further tests together with nonlinear finite element modelling aimed at duplicating the experimental observations would greatly enhance the information provided by the current tests.Key words: masonry, columns, rehabilitation, strengthening, fibre reinforced polymer, experimental.
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Shendrik, V. A. "STRUCTURAL EVALUATION OF REINFORCED CONCRETE COLUMN WITH COMPOSITE GFRP SHELL -- A STRUCTURAL ELEMENTOF BRIDGE PIER". Russian Journal of Building Construction and Architecture, n. 2(50) (21 maggio 2021): 74–84. http://dx.doi.org/10.36622/vstu.2021.50.2.006.
Testo completoAbstract (sommario):
Statement of the problem. It’s considered the problem of developing a methodology for structural evaluation of hybrid design - a reinforced concrete column combined with external composite GFRP (glass-fiber-reinforced-plastic) shell. This hybrid design is intended for bridge piers. Results. As a result of a study, theoretical relationships were formulated to determine the longitudinal and transverse stresses and relative deformations of hybrid column structural elements. The developed formulas take into account the cooperation of triaxial compressed concrete core and an anisotropic composite GFRP shell. Conclusions. The obtained theoretical dependences of the hybrid column’s elements behavior make it possible to develop a structural evaluation methodology of bridge piers hybrid columns. The findings of the investigation are proposed to be applied in the structural evaluations of the bridges piers hybrid columns with composite GFRP elements.
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Sivakumar, V., D. McKelvey, J. Graham e D. Hughes. "Triaxial tests on model sand columns in clay". Canadian Geotechnical Journal 41, n. 2 (1 aprile 2004): 299–312. http://dx.doi.org/10.1139/t03-097.
Testo completoAbstract (sommario):
Vibro-stone columns can improve the bearing capacity and reduce the settlement of foundations. Their performance depends on the strength of the column material, reinforcement method of column installation, type of in situ soil, area replacement ratio, and column length. This paper examines the behaviour of small laboratory specimens of soft clay (undrained shear strength ≈ 30 kPa) reinforced with sand columns when tested under known boundary stress conditions. Two series of tests were carried out on kaolin specimens (diameter 100 mm, height 200 mm) in a triaxial cell. In the first series, specimens were reinforced with a 32 mm diameter column of sand, 80, 120, 160, or 200 mm long. Columns were installed by (i) compacting moist sand into a prebored hole or (ii) freezing a column of moist sand before inserting it into a prebored hole. In the second series, columns were reinforced with geo-grids before installation. The specimens were subjected to (i) uniform loading in which the load was applied over the entire surface area of the specimen or (ii) foundation-type loading in which only a small area in the centre of the specimen was loaded. Under uniform loading, the specimens containing a full-depth column were significantly stronger than specimens without columns. Specimens with single, partially penetrating columns installed by wet compaction were weaker than specimens without columns. When frozen columns were installed, strengths increased progressively. Under foundation-type loading, bearing capacities increased with an increase in column length. Geo-grid reinforcement produced significant increases in load-carrying capacity.Key words: ground improvement, undrained shear strength, consolidation, stress path.
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Mohamed Sayed, Ahmed, Mohamed Mohamed Rashwan e Mohamed Emad Helmy. "Experimental Behavior of Cracked Reinforced Concrete Columns Strengthened with Reinforced Concrete Jacketing". Materials 13, n. 12 (24 giugno 2020): 2832. http://dx.doi.org/10.3390/ma13122832.
Testo completoAbstract (sommario):
Reinforced concrete (RC) columns often need to be strengthened or rehabilitated to allow them to carry the loads applied to them. In previous studies, RC columns have been strengthened by jacketing, without considering the occurrence of cracking. In this study, the behavior of RC columns strengthened externally by jacketing after cracking is analyzed. The accuracy of the existing models was verified by analyzing the performance of fifteen RC columns with different cross-sections to determine the effect of new variables, such as the column size, amount of steel reinforcement, and whether the column was cracked or not, on the effectiveness of strengthening. The analysis demonstrated that this strengthening technique could effectively improve both the ductility and strength of RC column cross-sections. The results indicate that the model suggested by the ACI-318 code can predict the ultimate load capacity of RC columns without strengthening, or strengthened by RC jacketing before or after cracking, with higher accuracy and material efficiency. The RC columns without strengthening met the safety limit of the ACI-318 model. However, for strengthened columns, a reduction coefficient must be used to enable the columns to meet the safety limit, with values of 94% and 76% for columns strengthened before and after cracking, respectively. Furthermore, strengthening after cracking affects the ultimate load capacity of the column, with 15.7%, 14.1%, and 13.5% lower loads for square, rectangular, and circular columns than those strengthened before cracking, respectively.
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Marzon, Marzon, Mukhlis Islam e Elhusna Elhusna. "ANALISIS PENAMPANG KOLOM BETON BERTULANG PERSEGI PANJANG BERLUBANG". Inersia, Jurnal Teknik Sipil 10, n. 2 (29 gennaio 2019): 1–12. http://dx.doi.org/10.33369/ijts.10.2.1-12.
Testo completoAbstract (sommario):
Installation of pipes (conduit) in the building columns often found in reinforced concrete structures. The installation of pipes inside the columns is utilized as sanitary and mechanical electrical pipes. The case research in this study is to analyze the rectangular column with the applied research type (applied/pratical research). This research aims to analyze the impact of the holes on square rectangular columns. This calculation consists of 675 samples with differentconcrete compression strength (f'c), reinforcement area, holes area, and the dimensions of the column. Analysis of the calculation of hollow rectangular columns using the stress-strain relationship equation developed by Hognestaad. The results of the analysis on hollow rectangular columns resulted in a decrease column capacity. The largest decrease of the rectangular column capacity occurred on holes area of 7%, with concrete compression strength 30 MPa, and dimensions of the column 450 x 1800 mm which is 16.97%.
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Hashemi, Fereshteh, e Faezeh Jafari. "Finite element analysis and neural network investigation of box columns under climate change". Pollack Periodica 16, n. 1 (25 marzo 2021): 83–89. http://dx.doi.org/10.1556/606.2020.00085.
Testo completoAbstract (sommario):
AbstractThe behavior of box-shaped columns under heating is investigated. For this purpose, the various sections of thin-wall box-shaped columns were modeled and verified in different temperature ranges by ABAQUS software. The results of this research showed that increasing the thickness leads to increase the buckling stability of column under temperature change. Since the behavior of column will be better than thinner columns under climate change because of the increase in the modulus of elasticity. The solid columns have better buckling stability than hollow columns in normal conditions.
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A, Akhil Kumar, e Narendra Kumar B. "Amplifying Column Resilience and Retrofitting of Nano Defects: A Profound Review of Advanced Wrapping Methodologies". NanoNEXT 4, n. 3 (25 settembre 2023): 1–7. http://dx.doi.org/10.54392/nnxt2331.
Testo completoAbstract (sommario):
In order to sustain the vertical load and guarantee the stability of various constructed environments, structural columns are essential. These columns can lose their integrity over time as a result of things like age, corrosion, seismic activity, or modifications in the conditions under which they are loaded unlike designed results in nano defects. If this is the case, conventional techniques of rehabilitation and strengthening might not be adequate to help them return to their prior levels of performance. Nowadays, wrapping techniques have become one of the most efficient and cutting-edge methods for improving the load-bearing capacity, ductility, and longevity of columns. The numerous wrapping techniques used to strengthen and refit columns to lengthen their useful lives are thoroughly analyzed in this paper. The objective is to provide a complete understanding of the concepts, elements, and practical uses related to different wrapping strategies. Steel, fiber-reinforced polymers (FRP), soft computing methods, and hybrid materials are some of the strategies that are currently being looked at. The fundamental physics of column wrapping, such as stress redistribution, confinement, and interactions between the material used for wrapping and the host column's structure are listed. The review additionally emphasizes how important suitable design, material selection, installation strategies, and quality control methods are to the successful implementation of column wrapping techniques. Numerous kinds of factors, such as the environment, loading patterns, and long-term performance, have been taken into account to shed light on the resilience and sustainability of wrapped columns. The detailed examination of wrapping techniques in this article offers a comprehensive picture of the most significant present progress and potential in the field of column strengthening, improving the overall toughness and resilience of built structures.
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Tantrapongsaton, Warakorn, e Chayanon Hansapinyo. "Impact Response of Reinforced Concrete Columns with Different Axial Load under Low-Velocity Impact Loading". Key Engineering Materials 803 (maggio 2019): 322–30. http://dx.doi.org/10.4028/www.scientific.net/kem.803.322.
Testo completoAbstract (sommario):
Building collapses from the seismic pounding of two adjacent buildings have been found in many past earthquakes. For the two buildings with different story height, the pounding induces impact load and local stress at column mid-height where the provided column reinforcement is normally lesser than the column’s edge. This paper aims to investigate the impact responses of reinforced concrete columns with different axial load and shear capacity by using numerical simulation method. Sixteen reinforced concretes columns were subjected to an impact load created by dropping 300 kg hammer at the height of 1,200 mm above the mid-span of the column. Every specimen has an identical cross section of 220 mm by 220 mm, with 3,000 mm of clear span length. Both ends of the column were fully restrained. The magnitude of the axial load varies from 0% to 40% of the ultimate axial capacity of the concrete section. Shear reinforcement spacing varies from @200 mm to @60 mm. It is found that the axial loads have a great effect on the impact responses of the RC columns. The specimens with high axial load yield higher peak impact force value and less mid-span deflection. Shear cracks were observed on the specimens with low axial force, but the cracks were relatively decreased when increasing the axial load.
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Fiorelia, Natashya Evangeline, Anthony Dharma Wibowo, Natanael Leonard Lae, Allison Ang e Oki Krisbianto. "Types of High-Performance Liquid Chromatography (HPLC) Columns: A Review". FoodTech: Jurnal Teknologi Pangan 5, n. 1 (25 maggio 2022): 1. http://dx.doi.org/10.26418/jft.v5i1.57334.
Testo completoAbstract (sommario):
Some chemical analysts, especially those working in the food sector, often find it difficult to choose the HPLC columns for their research. Every so often they tend to modify their method to fit whatever HPLC column available in their laboratory instead of looking for the column type best suited to their experiments. Other than that, HPLC column types are often very limited discussed in the class. This is particularly disadvantageous for those who have sufficient access to select the HPLC column they need for the best result. The lack of insight into the types of HPLC columns available in the market also influenced their decision to select the right column in their analysis to a large extent. This article briefly reviews the differences between the commonly used Particle-Packed Columns with the newer yet less frequently used Monolithic Columns. The types of HPLC columns based on polarity, molecular size, and the electrical charge will be described further, along with the working principle of the columns in brief and various examples of options available on the market. Lastly, the uses of HPLC columns in the food industries are also described. This review is expected to contribute to the field of chemical analysis, such as food analysis.
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Moitinho, Maria da Luz Ribeiro, e Cláudio Santos Ferreira. "Sedimentation in parasitological coproscopy". Revista do Instituto de Medicina Tropical de São Paulo 34, n. 3 (giugno 1992): 255–58. http://dx.doi.org/10.1590/s0036-46651992000300013.
Testo completoAbstract (sommario):
A sedimentation technique is described, in which a fecal suspension is placed on top of an aqueous sucrose solution of specific gravity 1.015 g/cm³. Using 100 by 15 mm test tubes, duplicate gravity sedimentation experiments were made using homogenized fecal suspensions (single-columns) and fecal suspensions placed on top of clear columns (double-columns). Egg- and cyst-counts, and turbidity determinations were made in the sediments obtained after definite time intervals. Most Ascaris lumbricoides, Trichuris trichiura and Ancylostomidae eggs sedimented within 20 minutes in single - and between 30 and 60 minutes in double-columns. Giardia duodenalis cysts required longer periods to sediment in double - than in single-columns; after 180 minutes (the maximum period of observation), double-column sediments produced 60.0% of the counts of single-columns. Double-column sediments were consistently less turbid than single-column ones
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Zhao, Jin You, e Shi Chang Teng. "Design Method of Horizontal Braces Unlocated at Middle of Columns with Fixed-Ended Column Base". Applied Mechanics and Materials 351-352 (agosto 2013): 803–7. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.803.
Testo completoAbstract (sommario):
A large number of column-bracing systems for the horizontal braces unlocated at middle of columns with fixed-ended column base were modeled and analyzed by second-order analysis using finite element method, in which the random combination of the initial imperfections between columns and horizontal braces was well considered by Monte Carlo method. According to the analysis results, two kinds of instability modes of column-bracing system have been found, probability density function of the horizontal bracing forces unlocated at middle of columns with fixed-ended column base is established based on probability statistics, and the design formula of horizontal braces unlocated at middle of columns are also proposed.
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Al-Mashaykhi, Mustafa, Belal Alsubari, Mazin Abdulrahman e Aayat Hussein. "Punching Strength of Reactive Powder Reinforced Concrete Flat Slabs". TJES: Vol. 28, No.3 28, n. 3 (7 aprile 2021): 35–74. http://dx.doi.org/10.25130/tjes.28.3.03.
Testo completoAbstract (sommario):
This research is devoted to investigating experimentally the punching shear strength of reactive powder concrete slabs under monotonic loading. All slabs have the same flexural reinforcement and same dimensions (1000mm length,600mm width,50mm thickness). The experimental program includes casting and testing of sixteen slabs tested under monotonic loading. The major parameters adopted in the current research include the shape of column (circle, square), column size (twocolumn sizes), number of columns (one, two), and the distance between two columns (3d,5d,7d). Results showed that, the slabs with circular column sections have slightly higher ultimate load than those with square column sections. An increasing column area increases the load of punching shear failure. It was found that the ultimate failure load for slabs with two columns is greater than the slabs with one column. Related to the effect of distance between the two columns for monotonic, it was found that the slabs maximum load reaches the maximum value at distance between the two columns equal to(7d) for a circular section with a diameter of 85mm and 113mm and square section with dimensions of (100*100)mm. While the maximum failure load reaches the maximum value when the distance between two columns (d) for a square section with the dimension of (75*75)mm. Related to the crack patterns, it was noticed that for slabs with larger columns sections with the distance between columns equal to 7d, the failure zone extended (in a large direction) to the slab sides.