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1
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.
2
Ali, A., Z. Soomro, S. Iqbal, N. Bhatti e A. F. Abro. "Prediction of Corner Columns’ Load Capacity Using Composite Material Analogy". Engineering, Technology & Applied Science Research 8, n. 2 (19 aprile 2018): 2745–49. http://dx.doi.org/10.48084/etasr.1879.
Testo completoAbstract (sommario):
There are numerous reasons for which concrete has become the most widely used construction material in buildings, one of them being its availability in different types, such as fiber-reinforced, lightweight, high strength, conventional and self-compacting concrete. This advantage is specially realized in high-rise building construction, where common construction practice is to use concretes of different types or strength classes in slabs and columns. Columns in such structures are generally made from concrete which is higher in compressive strength than the one used in floors or slabs. This raises issue of selection of concrete strength that should be used for estimating column capacity. Current paper tries to address this issue by testing nine (09) sandwich column specimens under axial loading. The floor concrete portion of the sandwich column was made of normal strength concrete, whereas column portions from comparatively higher strength concrete. Test results show that aspect ratio (h/b) influences the effective concrete strength of such columns. A previously adopted methodology of composite material analogy with some modifications has been found to predict well the capacity of columns where variation in floor and concrete strength is significant.
3
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.
4
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.
5
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.
6
Szmigiera, Elżbieta. "INFLUENCE OF CONCRETE AND FIBRE CONCRETE ON THE LOAD‐CARRYING CAPACITY AND DEFORMABILITY OF COMPOSITE STEEL‐CONCRETE COLUMNS". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 13, n. 1 (31 marzo 2007): 55–61. http://dx.doi.org/10.3846/13923730.2007.9636419.
Testo completoAbstract (sommario):
The report presents the results of laboratories’ tests on steel columns strengthened by concrete casing. During testing of steel I‐shape column the strength of concrete casing and the way of the column loading were parameters subjected to changes. The possibility of increasing load capacity of columns by strengthening the supporting zones was checked, too. On the basis of tests performed, it has been stated that there is a considerable effect of concrete casing on the performance and capacity of steel columns. Possibility of increasing the load capacity of columns by making heads of fibre concrete has been shown.
7
Qi, Yue. "Experimental Research on Bearing Capacity of Concrete Columns with High Strength Concrete Core under Axial Compression Loading". Advanced Materials Research 479-481 (febbraio 2012): 2041–45. http://dx.doi.org/10.4028/www.scientific.net/amr.479-481.2041.
Testo completoAbstract (sommario):
Based on experimental research on plain concrete columns with high strength concrete core, the formula to predict the bearing capacity of concrete columns with high strength concrete core under axial compression loading was brought forward in previous paper, in order to verify the formula whether right, axial compression test including 3 concrete columns with high strength concrete core and 1 ordinary reinforced concrete column were completed, and the failure characteristic was analyzed additionally. According to experimental results, it can be shown that the failure modes of concrete columns with high strength concrete core are similar to that of ordinary reinforced concrete columns, however, the bearing capacity of concrete columns with high strength concrete core is significant higher compared with that of ordinary reinforced concrete column; the results of the bearing capacity obtained by the formula (2) was in good agreement with the experimental results.
8
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.
9
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.
10
Marques, M. G., A. P. A. R. Liserre, R. B. Gomes e G. N. Guimarães. "Analysis of the behavior of reinforced concrete columns strengthened with sleeve wedge bolts and a self compacting concrete layer". Revista IBRACON de Estruturas e Materiais 8, n. 2 (aprile 2015): 88–99. http://dx.doi.org/10.1590/s1983-41952015000200003.
Testo completoAbstract (sommario):
Strengthening of reinforced concrete columns by jacketing is one of the most common structural rehabilitation techniques in Brazil. For adequate performance, it is necessary, among others, to avoid detachment of the new concrete layer (strengthening material) from the old concrete substrate when the strengthened member is again in service conditions. This paper describes the test results of eight reinforced concrete rectangular columns subjected to combined compression and one-axis bending to evaluate the efficiency of using sleeve wedge bolts across the new concrete/old concrete interface to avoid detachment. The strengthening technique, in this case, consists of adding a layer of self-compacting concrete to one face of the column. Two columns tested were monolithic and named PO (original column) e PR (reference column). The other six 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 its results gave information about column behavior without the use of strengthening. Column PR had a 155mm by 250 mm rectangular cross section and its cross section dimensions matched the strengthened columns but it was cast monolithically. To improve bond conditions between the existing concrete and the new concrete, the concrete surface was roughened and the outermost aggregate was exposed using hydro jetting. Holes along the concrete surface were made to insert the wedge bolts responsible for increasing the bond between the two concrete surfaces. The difference among the six strengthened columns was the position and amount of bolts used. Results indicate that the position and amount of the bolts alters significantly the strength capacity of the columns, since premature rupture by concrete detachment was delayed.
11
Pei, Weichang, Daiyu Wang, Xuan Wang e Zhenyu Wang. "Axial monotonic and cyclic compressive behavior of square GFRP tube–confined steel-reinforced concrete composite columns". Advances in Structural Engineering 24, n. 1 (20 luglio 2020): 25–41. http://dx.doi.org/10.1177/1369433220934557.
Testo completoAbstract (sommario):
Fiber-reinforced polymer tube–confined steel fiber–reinforced concrete column is a novel composite column proposed recently, which consists of a traditional steel-reinforced concrete column and an external glass fiber–reinforced plastic tube for lateral confinement. In order to investigate the axial compression behavior of steel fiber–reinforced concrete columns, a total of 16 square specimens were fabricated and tested under axial monotonic and cyclic compressive loading. Three different configurations of inner shaped steels, including cross-shaped, box-shaped with wielding, and box-shaped without wielding were considered. Two thicknesses of glass fiber–reinforced concrete tubes were also considered as the main experimental parameters. On the basis of test results, a thorough analysis of the failure process based on strain analysis was discussed. The test results showed that steel fiber–reinforced concrete columns exhibited higher ductility and load capacity compared with fiber-reinforced plastic–confined plain concrete columns. Two quantitative indexes were proposed to measure the confinement of steel fiber–reinforced concretes. The axial cyclic mechanical behaviors were discussed through comparative analysis with monotonic behaviors. The remnant strains and modulus of the cyclic behaviors were also discussed.
12
Ma, Li Jie, Jin Yu Zhang e Shao Jie Wang. "The Seismic Performance Study of Steel Pipe Concrete Column in the Absence of Beam Floor System". Advanced Materials Research 446-449 (gennaio 2012): 2331–35. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.2331.
Testo completoAbstract (sommario):
Architecture is the concrete columns with steel pipe flat floor slab, the 100mm × 100mm of steel pipe concrete column is in the center of the floor. The variation of moment and horizontal anti-force under horizontal displace of steel concrete columns are researched, and the steel columns working are analyzed, from that we can know steel concrete column in the slab-column structure has a good deformability under earthquake.
13
Sun, Heng, e Bai Shou Li. "Finite Element Analysis of Uniaxial Compression of Glazed Hollow Bead of Recycled Concrete Short Columns". Advanced Materials Research 898 (febbraio 2014): 399–402. http://dx.doi.org/10.4028/www.scientific.net/amr.898.399.
Testo completoAbstract (sommario):
For traditional ordinary concrete wall column prone to thermal bridges, posted outside the insulation board short life than the life of the building，in the glazed hollow bead of recycled concrete foundation with good thermal conductivity test and compressive strength of the proposed ,use glazed hollow bead of recycled concrete exterior wall column instead of the traditional ordinary concrete wall column ,and using the finite element software ANSYS simulation analysis the uniaxial compression of glazed hollow bead of recycled concrete short columns and ordinary concrete short columns. Comparative analysis showed the same intensity level glazed hollow bead of recycled concrete ultimate compressive bearing capacity of an analog value the same as ordinary concrete short columns. To validate the ANSYS simulation of concrete short columns under uniaxial compression condition .
14
Sidik Hasibuan, Samsul Abdul Rahman. "Revitalizing Infrastructure: Assessing Concrete Jacketing for Reinforced Concrete Column Rehabilitation". International Journal of Innovative Research in Computer Science and Technology 12, n. 1 (gennaio 2024): 40–44. http://dx.doi.org/10.55524/ijircst.2024.12.1.8.
Testo completoAbstract (sommario):
The rehabilitation of deteriorating civil engineering infrastructure, encompassing bridges, buildings, columns, beams, supporting beams, marine structures, and roads, presents a formidable challenge in contemporary engineering practice. As society's demand for upgraded infrastructure escalates, the imperative to address deteriorating structures becomes increasingly urgent. Consequently, the rehabilitation of existing infrastructure has been identified as a paramount concern warranting immediate attention. Among the myriad techniques employed, retrofitting columns with concrete jacketing stands out as one of the most prevalent methods for enhancing column strength. This investigation delves into the efficacy of concrete jacketing as a means of revitalizing reinforced concrete columns. The results evince a substantial augmentation in column capacity following retrofitting, underscoring the potential of such methods to bolster the load-bearing capabilities of reinforced concrete columns. Furthermore, the analysis reveals a more uniform stress distribution in retrofitted columns compared to their unmodified counterparts, thereby mitigating issues related to uneven stress distribution. In summation, the findings underscore the considerable promise of concrete jacketing in fortifying the strength, structural integrity, and longevity of deteriorated infrastructure.
15
Landović, Aleksandar, e Miroslav Bešević. "Experimental Research on Reinforced Concrete Columns Strengthened with Steel Jacket and Concrete Infill". Applied Sciences 11, n. 9 (29 aprile 2021): 4043. http://dx.doi.org/10.3390/app11094043.
Testo completoAbstract (sommario):
Experimental research on axially compressed columns made from reinforced concrete (RC) and RC columns strengthened with a steel jacket and additional fill concrete is presented in this paper. A premade squared cross-section RC column was placed inside a steel tube, and then the space between the column and the tube was filled with additional concrete. A total of fourteen stub axially compressed columns, including nine strengthened specimens and five plain reinforced concrete specimens, were experimentally tested. The main parameter that was varied in the experiment was the compressive strength of the filler concrete. Three different concrete compression strength classes were used. Test results showed that all three cross-section parts (the core column, the fill, and the steel jacket) worked together in the force-carrying process through all load levels, even if only the basic RC column was loaded. The strengthened columns exhibited pronounced ductile behavior compared to the plain RC columns. The influence of the test parameters on the axial compressive strength was investigated. In addition, the specimen failure modes, strain development, and load vs. deformation relations were registered. The applicability of three different design codes to predict the axial bearing capacity of the strengthened columns was also investigated.
16
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.
17
Lai, Zhi Peng, e Shao Hua Guo. "Mechanism Analysis on Concrete Column’s Recovery Strengthening". Advanced Materials Research 941-944 (giugno 2014): 707–11. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.707.
Testo completoAbstract (sommario):
This paper deals with the behavior of concrete columns actuated by SMA wires winding around the column’s cylindrical surface, when the concrete column are constrained and driven in circumferential direction by the SMA wires, the column’s ultimate bearing capacity and axial deformation are mainly studied. Both theoretical research and finite element simulation are carried out. The results indicate that, the SMA’s limited recovery in reverse transformation by heating can generate circumferential prestress, which will improve the concrete column’s ultimate bearing capacity and control its deformation, so as to realize the concrete column’s recovery strengthening.
18
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.
19
Liu, Xue Feng, Qing Xin Ren e Lian Guang Jia. "Temperature Field Analysis of Concrete Filled Steel Tube Reinforced Concrete Columns in Fire". Applied Mechanics and Materials 644-650 (settembre 2014): 5019–22. http://dx.doi.org/10.4028/www.scientific.net/amm.644-650.5019.
Testo completoAbstract (sommario):
In this paper, temperature field analysis of concrete filled steel tube reinforced concrete columns in fire has been carried on. A finite element model for concrete filled steel tube reinforced concrete columns in fire is developed by ABAQUS. The cross-sectional temperature field distribution regularity of concrete filled steel tube reinforced concrete columns in fire has been obtained. Parameter analysis such as fire duration time and steel ratio on the column section temperature field is conducted, and this provide the reference for the further analysis of concrete filled steel tube reinforced concrete columns.
20
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.
21
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.
22
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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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%.
24
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.
25
Yang, Yong, Xing Du, Yunlong Yu e Yongpu Pan. "Experimental study on the seismic performance of composite columns with an ultra-high-strength concrete-filled steel tube core". Advances in Structural Engineering 23, n. 4 (21 ottobre 2019): 794–809. http://dx.doi.org/10.1177/1369433219879805.
Testo completoAbstract (sommario):
The ultra-high-strength concrete-encased concrete-filled steel tube column consists of a concrete-filled steel tube core and a rectangle-shaped reinforced concrete encasement. This article presents the seismic performance analysis of ultra-high-strength concrete-encased concrete-filled steel tube columns subjected to cyclic loading. Based on the measured load-lateral displacement hysteresis curves of six ultra-high-strength concrete-encased concrete-filled steel tube columns and two conventional RC columns, the seismic behaviours, such as the ductility, energy dissipation, stiffness and load-bearing capacity, were analysed. The effects of the arrangement of the stirrups and the layout of the prestressed steel strips on the seismic performance of the composite columns were critically examined. The test results indicated that the ductility and energy dissipation performance of the ultra-high-strength concrete-encased concrete-filled steel tube columns were increased by 74.8% and 162.7%, respectively, compared with the conventional columns. The configuration of the prestressed steel strip increased the ductility of the composite column by 28.9%–63% and increased the energy consumption performance by 160.2%–263.3%. By reducing the stirrup spacing and using prestressed steel strips, the concrete-filled steel tube core columns could be effectively confined, leading to a great enhancement in ductility, energy dissipation, stiffness and load-bearing capacity.
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Li, Hongbing, Fangbo Wu, Liangtao Bu, Yong Liu e Jiang Yao. "Study on the compression performance of steel reactive powder concrete columns". Advances in Structural Engineering 23, n. 10 (16 febbraio 2020): 2018–29. http://dx.doi.org/10.1177/1369433220903986.
Testo completoAbstract (sommario):
In this study, the mechanical properties and failure characteristics of steel reactive powder concrete columns with different strength grades were investigated through compression testing. Six steel reactive powder concrete columns were tested; three columns underwent axial compression testing and three columns underwent eccentric compression testing. The results of the axial compression testing showed that steel and reactive powder concrete could work cooperatively at the initial stage, and the final column failure mode was primarily splitting failure at the end of the column, with the formation of a main crack in the longitudinal direction extending to the middle of the column. The results of the eccentric compression testing showed that the eccentrically loaded steel reactive powder concrete columns had comparatively strong deformability. The columns presented ductile failure mode under the eccentric load with 0.2 eccentricity. The final failure of the column involved a sudden increase in the horizontal crack width on the tension side, the steel flange on the tension side reached the yield state, the reactive powder concrete in the middle of the compressive side was crushed, and the reactive powder concrete surface layer burst open and partially spalled off. According to the test results and with reference to the relevant standards, equations for calculating the approximate ultimate bearing capacities of axially and eccentrically compressed reactive powder concrete columns were proposed.
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Yin, Zhan Zhong, Qiang Wang, Ya Xiong Liang e Zong Rui Hu. "The Ultimate Bearing Capacity of Partial Concrete Encased Steel Strengthened Column". Applied Mechanics and Materials 215-216 (novembre 2012): 796–99. http://dx.doi.org/10.4028/www.scientific.net/amm.215-216.796.
Testo completoAbstract (sommario):
The finite element modes of composite columns were built. The nonlinear analysis of the common steel column and the partial concrete encased steel composite columns were conducted. The load-displacement curves were getting. The strength of partial concrete encased steel Strengthened columns was much higher than the common steel column. Finally, Construction design suggestions and theory study of the type of partial concrete encased steel composite columns are advanced according to the results of analysis and computer simulation.
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Lahoud, Antoine E. "Slenderness effects in high-strength concrete columns". Canadian Journal of Civil Engineering 18, n. 5 (1 ottobre 1991): 765–71. http://dx.doi.org/10.1139/l91-093.
Testo completoAbstract (sommario):
High-strength concretes are being increasingly used in the columns of high-rise buildings. Analytical studies of the slenderness effects in these columns have been very limited. The behavior of slender columns with normal- and high-strength concretes is studied using a finite element program. Differences and similarities in long-term and short-term behaviors between high-strength and normal-strength slender concrete columns are noted and discussed. Key words: columns, slenderness, high-strength concrete, creep, finite elements.
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More, Florence More Dattu Shanker, e Senthil Selvan Subramanian. "Experimental Investigation on the Axial Compressive Behaviour of Cold-Formed Steel-Concrete Composite Columns Infilled with Various Types of Fibre-Reinforced Concrete". Buildings 13, n. 1 (6 gennaio 2023): 151. http://dx.doi.org/10.3390/buildings13010151.
Testo completoAbstract (sommario):
The exceptional structural strength and low cost of steel-concrete composite columns make them a popular choice for civil engineering structures. Numerous forms of composite columns, including steel tubes filled with concrete, have been produced recently in response to various construction situations. Cold-formed steel tubular columns with concrete filling have higher strength and ductility due to their capacity to withstand inner buckling and postpone outward buckling. The objective of this research is to determine the ductile and strength performance of composite columns containing various forms of fibre-reinforced concrete when subjected to axial compression. Several different kinds of fibre-reinforced concrete (FRC) are employed as additives in hollow steel columns, including steel FRC, carbon FRC, glass FRC, coir FRC, jute FRC, and sisal FRC. Axial compression tests were performed on 24 columns, including three hollow steel columns and 21 composite columns. Three distinct slenderness ratios were developed and used. Axial bearing capacity, compressive stress-strain curves, ductility, peak strain, axial shortening, and toughness were among the topics covered by the axial compression test. Experimental findings demonstrated that all conventional composite columns experienced failure through overall buckling, Local buckling and crushing of concrete infill, which was transformed into more ductile failure using fibre-reinforced concrete infills. The test results revealed that fibre-reinforced concrete-infilled steel columns outperformed conventional composite columns in terms of strength, ductility, and energy absorption capacity. The percentage increase in load-carrying capacity was observed as 203.88%, 193.48% and 190.03% when compared to hollow cold-formed steel tubular columns in stub, short and medium columns, respectively. Under assessment of stub, short, and medium columns, the load-strain plots demonstrated that the steel fibre-reinforced concrete in-filled columns performed well in terms of ductility. Localized buckling and crushing of the concrete infill caused the composite columns with low slenderness ratios to fail. In contrast, concrete-filled steel tube columns with higher slenderness ratios showed column failure through the overall buckling of the composite column.
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Nhabih, Hussein Talab, Ahmed M. Hussein e Marwa Marza Salman. "Study a Structural Behavior of Eccentrically Loaded GFRP Reinforced Columns Made of Geopolymer Concrete". Civil Engineering Journal 6, n. 3 (1 marzo 2020): 563–75. http://dx.doi.org/10.28991/cej-2020-03091492.
Testo completoAbstract (sommario):
This study investigated a modern composite material, which is a short geopolymer concrete column (GPCC) reinforced by GFRP bars. The structural performances of GPCC subjected to eccentric load were studied and compared to the normal strength concrete column (NSCC) reinforced by steel bars. In this study, the primary experimental parameters were the reinforcement bars types, load eccentricity, and concrete types. Seven short columns were tested: three normal strength concrete columns reinforced by steel bars, three geopolymer concrete columns reinforced by GFRP bars and one normal strength concrete column without reinforcement. The model dimensions chosen in the present study was a square section of 130×130 mm and a total height of 850 mm. It was shown that the steel bars contribute about 16.47% of column capacity under concentric load. Comparing with the normal strength concrete column, a geopolymer concrete column reinforced by GFRP bars showed a little increase in ultimate load (5.17%) under concentric load. Under the load eccentricity of 130 mm, a geopolymer concrete column reinforced by GFRP bars showed a significant increase in the ultimate load (69.37%). Under large eccentricity, a geopolymer concrete column reinforced by GFRP bars has an outstanding effect on the columns' ultimate load capacity. Also, the sine form can be utilized for GPCC to find the lateral deflection along with the column high at different load values up to the failure.
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Nair, Anjaly, e Osama (Sam) Salem. "Experimental determination of the residual compressive strength of concrete columns subjected to different fire durations and load ratios". Journal of Structural Fire Engineering 11, n. 4 (27 luglio 2020): 529–43. http://dx.doi.org/10.1108/jsfe-10-2019-0034.
Testo completoAbstract (sommario):
Purpose At elevated temperatures, concrete undergoes changes in its mechanical and thermal properties, which mainly cause degradation of strength and eventually may lead to the failure of the structure. Retrofitting is a desirable option to rehabilitate fire damaged concrete structures. However, to ensure safe reuse of fire-exposed buildings and to adopt proper retrofitting methods, it is essential to evaluate the residual load-bearing capacity of such fire-damaged reinforced concrete structures. The focus of the experimental study presented in this paper aims to investigate the fire performance of concrete columns exposed to a standard fire, and then evaluate its residual compressive strengths after fire exposure of different durations. Design/methodology/approach To effectively study the fire performance of such columns, eight identical 200 × 200 × 1,500-mm high reinforced concrete columns test specimens were subjected to two different fire exposure (1- and 2-h) while being loaded with two different load ratios (20% and 40% of the column ultimate design axial compressive load). In a subsequent stage and after complete cooling down, residual compressive strength capacity tests were performed on each fire exposed column. Findings Experimental results revealed that the columns never regain its original capacity after being subjected to a standard fire and that the residual compressive strength capacity dropped to almost 50% and 30% of its ambient temperature capacity for the columns exposed to 1- and 2-h fire durations, respectively. It was also noticed that, for the tested columns, the applied load ratio has much less effect on the column’s residual compressive strength compared to that of the fire duration. Originality/value According to the unique outcomes of this experimental study and, as the fire-damaged concrete columns possessed considerable residual compressive strength, in particular those exposed to shorter fire duration, it is anticipated that with proper retrofitting techniques such as fiber-reinforced polymers (FRP) wrapping, the fire-damaged columns can be rehabilitated to regain at least portion of its lost load-bearing capacities. Accordingly, the residual compressive resistance data obtained from this study can be effectively used but not directly to adopt optimal retrofitting strategies for such fire-damaged concrete columns, as well as to be used in validating numerical models that can be usefully used to account for the thermally-induced degradation of the mechanical properties of concrete material and ultimately predict the residual compressive strengths and deformations of concrete columns subjected to different load intensity ratios for various fire durations.
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Bao, Yanhong, Bowen Chen e Lei Xu. "Analysis of Concrete-Filled Steel Tube Reinforced Concrete Column-Steel Reinforced Concrete Beam Plane Frame Structure Subjected to Fire". Advances in Civil Engineering 2021 (7 aprile 2021): 1–12. http://dx.doi.org/10.1155/2021/6620030.
Testo completoAbstract (sommario):
The ABAQUS finite-element analysis platform was used to understand the mechanical behavior of concrete-filled steel tube reinforced concrete (CFSTRC) columns and steel reinforced concrete (SRC) beam plane frames under fire conditions. Thermal parameters and mechanical constitutive model of steel and concrete materials were reasonably selected, the correct boundary conditions were chosen, and a numerical model for the thermal mechanical coupling of CFSTRC columns and SRC beam plane frame structure was established. The finite-element model was verified from related experimental test results. The failure modes, deformation, and internal force distribution of the CFSTRC column and SRC beam plane frames were analyzed under ISO-834 standard fire conditions and with an external load. The influence of beam and column fire-load ratio on the fire resistance of the frame structure was established, and the fire-resistance differences between the plane frame structures and columns were compared. The CFSTRC column-steel reinforced concrete beam plane frame may undergo beam failure or the column and beam may fail simultaneously. The frame structure fire-resistance decreased with an increase of column and beam fire-load ratio. The column and beam fire-load ratio influence the fire resistance of the frames significantly. In this numerical example, the fire resistance of the frames is less than the single columns. It is suggested that the fire resistance of the frame structure should be considered when a fire-resistant structural engineering design is carried out.
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Liu, Jin Ming. "Construction Technology of Lift Slab with Concrete Filled Steel Tube Columns". Applied Mechanics and Materials 170-173 (maggio 2012): 3072–76. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.3072.
Testo completoAbstract (sommario):
Abstract. This paper discusses a lift slab building with concrete filled steel tube columns. Lift slab construction as a methodology has advanced on improvements in traditional lift slab construction technology. When concrete filled steel tube columns are used, the strength of the concrete in the tube is obviously enhanced by the hoop action derived from the steel tube. The section of the concrete filled steel tube column is smaller than the section of the reinforced concrete column, thus realizing cost savings in material and labor. Also, because the steel tube hasn’t been filled with concrete when it is assembled, the steel tube is much lighter than the traditional reinforced concrete column. Thus, the assembly of steel tube columns without concrete is easier and crane-lifting requirements are less. This paper describes the construction of a building utilizing current LSCSTC – Lift Slab Construction with Concrete filled Steel Tube Column technology.
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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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Salam, Mahmood A., Qiyao Wang e Jinbo Huang. "Experimental and Numerical Study on the Composite Column Behavior: Loess Soil Reinforced by Concrete-Stone Column". Civil Engineering Journal 8, n. 10 (1 ottobre 2022): 2022–37. http://dx.doi.org/10.28991/cej-2022-08-10-01.
Testo completoAbstract (sommario):
Stone columns are an effective approach to improving the bearing capacity of weak soils, which has led to increased interest in the improved soil method being further developed and expanded. In addition, enhancing the bearing capacity of stone columns has recently received great attention. This paper studies the effects of embedded concrete parts on the stone columns' bearing capacity and bulging failure. Moreover, arranging solutions to the problem of bulging failure and reduced bearing capacity of stone columns and understanding the stone columns' failure after reinforcement by comparing the results. Stone columns are either embedded in a solid concrete part or unreinforced were examined using large-scale laboratory experiments, and numerical simulation was performed using ABAQUS. The models test with a scale factor of 1:7 was employed. The results demonstrated that using a concrete part on the top of the stone column greatly increases its bearing capacity and the efficiency of the surrounding soil. Concrete-stone columns (CSCs) show stress concentration ratio (n) enhancement and significant resistance to bulging failure deformation. The concrete-stone column shows an enhancement related to increasing the concrete part length; also, the CSCs stiffness increases the surrounding loess soil capacity. The horizontal stresses of CSCs demonstrate the type of column failure behavior; the column may fail due to shear stress in a long concrete part case. Doi: 10.28991/CEJ-2022-08-10-01 Full Text: PDF
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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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Bagus Rai Widiarsa, Ida, e Ida Bagus Dharma Giri. "Influence of shape modification and stirrups on the axial capacity of concrete columns". MATEC Web of Conferences 195 (2018): 02020. http://dx.doi.org/10.1051/matecconf/201819502020.
Testo completoAbstract (sommario):
Columns as an important element of building structures support loads that work on slabs and beams and deliver the loads to the foundation. Concrete columns can experience strength degradation due to several reasons such as having less concrete strength than designed due to construction error or environmental damage. To restore the strength capacity of the columns, rehabilitation or retrofitting methods with steel plates or Fibre-Reinforced-Polymer (FRP) sheets are generally applied. This method is effective if the shape of the column is rounded. However, the shape of the column in the field is commonly rectangular or squared. Moreover, retrofitting using FRP is very expensive. Based on this background, this study examined the effect of shape modification and stirrup on the axial capacity of concrete columns. A total of 12 specimens of concrete columns were cast and tested. The specimens were grouped into 4, with variations in shape and stirrup spacing. The experimental results showed that the shape modification increased the axial capacity of the concrete column. Shape modification and addition of stirrups at the same time increased the axial capacity of the concrete columns more significantly. Furthermore, the shape modification and addition of stirrups improved the performance of the columns.
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Kim, Tae-Hoon, Young-Jin Kim, Hyeong-Taek Kang e Hyun Mock Shin. "Performance assessment of reinforced concrete bridge columns using a damage index". Canadian Journal of Civil Engineering 34, n. 7 (1 luglio 2007): 843–55. http://dx.doi.org/10.1139/l07-003.
Testo completoAbstract (sommario):
A procedure is presented for assessment of the performance of reinforced concrete bridge columns. Fourteen circular reinforced concrete bridge columns were tested under a constant axial load and a cyclically reversed horizontal load. A computer program, named RCAHEST (reinforced concrete analysis in higher evaluation system technology), was used to analyze these reinforced concrete structures. A damage index based on the predicted hysteretic behavior of a reinforced concrete bridge column was used. Damage indices aim to provide a means of quantifying numerically the performance level of reinforced concrete bridge columns under earthquake loading. The proposed numerical method for the performance assessment of reinforced concrete bridge columns was verified by comparison with the experimental results. Key words: assessment procedure, reinforced concrete bridge columns, damage index, hysteretic behavior, performance level.
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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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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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Zhang, Hua Zhi, Fang Pan, Zhen Hua Zhang e Cai Yun Cheng. "To Improve the Appearance Quality of Concrete Special-Shaped Frame Column". Applied Mechanics and Materials 351-352 (agosto 2013): 227–30. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.227.
Testo completoAbstract (sommario):
In order to meet the growing needs of people, many buildings are used in special-shaped frame column, but because of the size and shape of special-shaped columns and other causes of concrete appearance quality is not high, by the QC group activity, cause analysis of special-shaped frame column concrete surface defects, and how to guarantee and improve the appearance quality of concrete special-shaped columns is proposed to solve the method, to eliminate the common quality defects of concrete surface and special-shaped columns.
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Mhuder, Wathiq Jassim, e Samir M. Chassib. "Experimental Study of Strengthening of RC Columns with Steel Fiber Concrete". Materials Science Forum 1002 (luglio 2020): 551–64. http://dx.doi.org/10.4028/www.scientific.net/msf.1002.551.
Testo completoAbstract (sommario):
This study introduces an experimental program to investigate the performance of concrete wrapping jackets reinforced by steel fibers used for retrofitting of the square and circular RC columns under axial loads. Ten columns divided into two groups; the first group included seven square columns while the second group involved three circular columns. The experimental study included testing the columns with varied parameters such as cross-section shape, type and aspect ratio of steel fibres, jacket thickness, and using several techniques for retrofitting the column such as strengthening by plain and reinforced concrete jackets. The selected parameters affected the compressive behavior of confined columns high strength concrete jackets. The obtained results revealed that all strengthened columns with square cross-section appeared maximum strength greater than a circular one. Using several types of concrete jacketing promotes the load-capacity of the column with a clear improvement in the ductility. Increasing thickness appeared increasing in the load-carrying capacity in comparison with the reference column. Using the straight fibres showed better enhancement in the load capacity than the hooked ones. The main result was the failure mode was different from unstrengthen columns which showed more crushing in the concrete core with an increase in thickness.
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Yu, Feng, Chaochao Feng, Shilong Wang, Wei Huang, Yuan Fang e Shuangshuang Bu. "MECHANICAL PERFORMANCE OF RECYCLED AGGREGATE SELF-CONSOLIDATING CONCRETE COLUMN". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 27, n. 3 (22 marzo 2021): 188–202. http://dx.doi.org/10.3846/jcem.2021.14117.
Testo completoAbstract (sommario):
The utilization of recycled concrete aggregate (RCA) can reduce the environmental impact and decreases the cost of concrete. In this study, a comprehensive assessment of self-consolidating concrete (SCC) using RCA as partial or total replacement of coarse aggregate was conducted. Recycled concrete aggregate self-consolidating concrete (RCA-SCC) mixtures with varied water-to-cement (W/C) ratios (0.28–0.46), sand-to-aggregate (S/A) ratios (48–52%), fly ash (FA) contents (20–40%), RCA replacement ratios (0–100%), and water reducer contents (0–1.5%) were designed and tested. 5 groups of the RCA-SCC columns with different W/C and replacement ratios of RCA were also investigated. The slump flow, the J-ring flow and the cubic compressive strength, and the compressive behaviors of the RCA-SCC columns were studied. Results indicated that W/C ratio was the dominant parameter in RCA-SCC mixture, and the failure modes of the RCA-SCC columns were similar to those of the conventional concrete columns. Based on the experimental results, the mechanical performance of RCA-SCC columns was evaluated quantitatively, and a stress–strain relation model for predicting the axial compressive behavior of RCA-SCC column was proposed. This study will provide a reference for the engineering application of the environment-friendly SCC using RCA that are derived from tested or returned concretes with better performance.
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Swarnkar, Jagriti. "Examining Seismic Response for Rigid Building Frame Having Composite Column". International Journal for Research in Applied Science and Engineering Technology 10, n. 7 (31 luglio 2022): 3647–53. http://dx.doi.org/10.22214/ijraset.2022.45821.
Testo completoAbstract (sommario):
Abstract: Concrete filled steel tubes are generally used in Beams, Columns, Piers and caissons for deep foundations. The steel tube functions as the formwork for casting the concrete and hence, construction cost is reduced. The prime focus of the present work is to study the behavior of RCC structure under the effect of seismic loads provided with composite columns. This research study comprises of seismic analysis with the design of rigid frame with Reinforced Concrete column, Concrete encased steel and steel tube encasing concrete columns. These cases are designed based on IS 1893:2016 using ETABS software. The result shows that steel encased concrete is performing better than conventional column. The construction practices is the only difficulty arises in such of composite column.
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R, Ramasubramani. "Study on the Behavior of Axially Loaded Coconut Shell Concrete Column Using M-Sand in Its Place of R-Sand". ECS Transactions 107, n. 1 (24 aprile 2022): 1723–35. http://dx.doi.org/10.1149/10701.1723ecst.
Testo completoAbstract (sommario):
In Current Construction Industry many developments are happening towards green concept,where the waste materials are reused to avoid the accumulation of Waste and reducing the conception or destroying the environment.In Line with the same green concept this study is done such that Manufacture Sand called as M-Sand has been used as the replacement for Fine Aggregate. Coconut Shell has been used as replacement for Coarse Aggregate. M-Sand are produced by crushing the rocks that are obtained from hills and mountains. The Coconut shell has been used as the aggregates for producing lightweight concrete. As the Coconut shell has the properties of storing water this helps in internal curing of the Concrete. In this research have done the analysis of short column and long column with normal concrete and coconut shell concrete using M-sand in its place of R-sand. 12 Columns with different reinforcements have casted and tested. 6 columns for Short Columns and 6 for long columns. In the short columns both normal concrete and coconut shell concrete are casted with 3 different types of reinforcements. The same different types of reinforcements are done for long column too. columns are casted and cured using gunny bags for 28 days. At the end of the study it was observed that the load carrying capacity of columns replaced by coconut shells with M-sand are only 5% lesser when compared to conventional concrete with M-sand. The stiffness of the concrete produced by coconut shells are only 8% lesser when compared to conventional Concrete.
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Hudoba, Igor. "Composite C-C Columns by Utilizing of UHPFRC". Key Engineering Materials 691 (maggio 2016): 108–18. http://dx.doi.org/10.4028/www.scientific.net/kem.691.108.
Testo completoAbstract (sommario):
Main advantage of composite concrete columns, in comparison with traditional reinforced concrete columns, is its increased load-bearing capacity by using of solid steel reinforcing core. Ordinary type of such a steel-concrete (S-C) composite column consists of normal concrete and different type of solid steel core. In last decades high quality concrete is more and more used for load-bearing structural members exposed compression like columns. Present knowledge level in the area of ultra-high quality of concrete open a new chance for utilization of this progressive structural material in concrete building industry. This paper presents some new information and laboratory test results of concrete-concrete (C-C) composite columns by utilizing of UHPFRC.
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Zhang, Xihong, Hong Hao e Chao Li. "The effect of concrete shear key on the performance of segmental columns subjected to impact loading". Advances in Structural Engineering 20, n. 3 (28 luglio 2016): 352–73. http://dx.doi.org/10.1177/1369433216650210.
Testo completoAbstract (sommario):
Conventional precast segmental columns with seismic resistance design consist of only flat concrete segments with prestress tendon. This is because friction between adjacent segments is sufficient to resist the lateral forces from earthquake-induced actions. However, the friction between segments is not necessarily sufficient to resist lateral impact loads such as vehicle impact the column might experience during its service life. This article investigates the effectiveness of using concrete shear key in segments of precast segmental column in resisting the lateral impact loading. The precast reinforced concrete segments were designed with concrete shear keys to improve the column shear resistance capacity and minimize the relative displacement between adjacent segments. Two groups of segmental columns with and without shear key were designed and tested using a pendulum impact system. The effectiveness of shear key in resisting lateral impact loads was analysed by comparing the performance of the two groups of segmental columns. The testing results revealed that by introducing concrete shear key to segmental column, the relative displacement between adjacent segments could be effectively reduced. However, the large concrete shear key increased stress concentration in the concrete segments. Relatively, more severe damages to concrete segments were found on the columns with shear key. Further improvements on shear key designs should be made for better performance of segmental columns against impact loading.
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Kado, Bishir, Shahrin Mohammad, Yeong Huei Lee, Poi Ngian Shek e Mariyana Aida Ab Kadir. "EXPERIMENTAL STUDY ON BEHAVIOR OF UNPROTECTED FOAMED CONCRETE FILLED STEEL HOLLOW COLUMN UNDER FIRE". Journal of Civil Engineering, Science and Technology 12, n. 2 (30 settembre 2021): 189–202. http://dx.doi.org/10.33736/jcest.3983.2021.
Testo completoAbstract (sommario):
Reduction in self-weight and achievement of full fire resistance requirements are some of the important considerations in the design of high-rise structures. Lightweight concrete filled steel tube (CFST) column provides an alternative method to serve these purposes. Recent studies on lightweight CFST columns at ambient temperature have revealed that foamed concrete can be a beneficial and innovative alternative material. Hence, this study investigates the potential of using foamed concrete in circular hollow steel columns for improving fire resistance. A series of nine fire test on circular unfilled hollow and foamed concrete filled hollow section column were carried out. ISO 834 standard fire exposure test were carried out to investigate the structural response of these columns under fire. The main parameters considered are load level and foamed concrete density; foamed concrete density used are 1500 kg/m3 and 1800 kg/m3 at 15%, 20%, and 25% load level. All the columns tested are without any external fire protection, with concentrically applied load under fixed-fixed boundary conditions. The columns dimension was 2400 mm long, 139.7 mm diameter and steel tube thickness of 6 mm. The fire test result showed that foamed concrete increases the fire resistance of steel hollow column up to an additional 16 minutes. The improvement is more at load level above 15%, and the gain in fire resistance is about 71% when 1500 kg/m3 density foamed concrete is used. Generally, foamed concrete filled steel hollow column demonstrate a good structural fire behavior, based on the applied load and foamed concrete density. Also, inward local buckling was averted by filling the steel hollow column with foamed concrete. General method for composite column design in Eurocode 4 adopted to calculate the axial buckling load of 1500 kg/m3 foamed concrete filled columns. These type of columns can be used for structures like airports, schools, and stadiums; taking the advantage of exposed steel for aesthetic purpose and high fire resistance. It can also be used for high rise structures; taking advantage of high fire resistance and reduction in self-weight of a structure.
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Shehab, Hamdy, Ahmed Eisa, Ahmed Mohamed Wahba, Peter Sabol e Dušan Katunský. "Strengthening of Reinforced Concrete Columns Using Ultra-High Performance Fiber-Reinforced Concrete Jacket". Buildings 13, n. 8 (9 agosto 2023): 2036. http://dx.doi.org/10.3390/buildings13082036.
Testo completoAbstract (sommario):
The use of Ultra-High Performance Fiber Reinforced Concrete (UHPFRC) increased in the field of civil engineering throughout the last few decades. UHPFRC is being used considerably on a large scale in megastructure applications. High compressive and tensile strength permits reconstruction and optimization of the structural members. At the same time, its improved durability properties make it easier to extend the life of the design and can be used as thin layers, cladding, repairs, and column coverings. Although UHPC has an extremely high compressive strength, it exhibits very brittle fracture behavior compared to normal strength concrete (NSC). Since the ductility and fracture toughness of UHPC can be enhanced by adding fibers, the addition of fibers to production adds innovative features to UHPFRC structures and opens up new application areas for UHPFRC. The aim of this study is to investigate the axial behavior of square reinforced concrete (RC) columns strengthened with UHPFRC jackets. Nineteen specimens were cast (1000 mm in height and a cross-sectional area of 150 × 150 mm, whose interface treatment methods were prepared through vertical grooving (VG), horizontal grooving (HG), and without grooving (NG), with the jacket thickness (20 mm and 40 mm) and the number of strengthened sides of the column (two, three, and four sides). The results show a brittle failure for all strengthened specimens. The UHPFRC-reinforced RC columns with vertical grooving (VG) showed a higher ultimate load capacity compared to the columns with horizontal grooving (HG) and the columns without grooving (NG). The horizontal grooving (HG) gives a better result than the jacket without grooving (NG) and increases the cohesion area between the jacket and the column for two and three of the RC columns’ strengthened sides. But, in the case of strengthening the columns on four sides, the effect of confining the jacket to the column appears, and the grooving causes weakness in the body of the original column so that the jacket without grooving (NG) gives a better result than the jacket with horizontal grooving (HG).
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Omar, M. Y. M., R. B. Gomes e A. P. A. Reis. "Experimental analysis of reinforced concrete columns strengthened with Self-Compacting concrete". Revista IBRACON de Estruturas e Materiais 3, n. 3 (settembre 2010): 271–83. http://dx.doi.org/10.1590/s1983-41952010000300002.
Testo completoAbstract (sommario):
This paper presents the results of reinforced concrete columns strengthened by addition of a self-compacting concrete overlay at the compressed and at the tensioned face of the member, with and without addition of longitudinal steel bars. Eight columns were submit- ted to loading with an initial eccentricity of 60 mm . These columns had 120 mm x 250 mm of rectangular cross section, 2000 mm in length and four longitudinal reinforcement steel bars with 10 mm in diameter. Reference columns P1 and P2 were tested to failure without any type of rehabilitation. Columns P3 to P8 were loaded to a predefined load (close to the initial yield point of tension reinforce- ment), then unloaded and strengthened for a subsequent test until failure. Results showed that the method of rehabilitation used was effective, increasing the loading capacity of the strengthened pieces by 2 to 5 times the ultimate load of the reference column.