The Effect of Steel Ring Width Variations as the External Confinement on Load-Moment Interaction Behavior of Reinforced Concrete Column

2016 ◽  
Vol 845 ◽  
pp. 188-192
Author(s):  
Endah Safitri ◽  
Iswandi Imran ◽  
Nuroji ◽  
Sholihin Asa'ad

Nowaday, we require higher capacity and ductility of structural member particulary in reinforced concret column in construction world. One way to improve the ductility and carrying capacity of concrete is confining the concrete. To investigate the effects of external confinement on column capacity, an analytical study is carried out. A steel ring external confinement is used in this study. The stress-strain diagrams design for confined concrete are developed by considering different proposed confined models based on width variations of the steel ring. The test results showed that steel ring are effective as external confinement in confining the concrete. Capability of concrete to support load simultaneously is increasing along the width of the ring. Its effect on column capacity is studied in terms of load – moment interaction diagram of column. The presence of external reinforcement expands the interaction diagram of the column particularly when it is in the compression-controlled region.

2010 ◽  
Vol 150-151 ◽  
pp. 441-446
Author(s):  
Jing Wu ◽  
Fa Zhou Wang ◽  
Wen Yang ◽  
Qing Jun Ding

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.


2015 ◽  
Vol 776 ◽  
pp. 47-52
Author(s):  
Endah Safitri ◽  
Iswandi Imran ◽  
Nuroji ◽  
Sholihin Asa'ad

Deformability of concrete decreases as its strength increases. The higher the concrete strength, the lower it’s failure strain which shows increase of brittleness. One way to improve the ductility and carrying capacity of concrete is by doing confinement of the concrete. A steel ring external confinement was used in this study. The steel ring is made of a steel cylindrical tube that is cut with a specific width (a) so similar to the ring. The steel ring is placed at a specific distance between the ring (b). With ring width variation (a = 28, 45 and 73 mm) and the distance between the steel ring is constant (b = 40 mm), gave the variation of the volumetric ratio which will afffect the confinement on the concrete. The test results showed that the steel ring was effective as external confinement of the concrete. The capability of concrete to support load increases in line with the width of the ring. Increased carrying capacity of concrete for 28, 45 and 73 mm ring width is respectively 115.382%, 131.792%, 150.253% and the maximum strain of concrete increases to 389.474%, 368.421% and 366.667%, respectively.


2006 ◽  
Vol 12 (2) ◽  
pp. 109-115 ◽  
Author(s):  
Mieczysław Kamiński ◽  
Tomasz Trapko

Strengthening of the reinforced concrete structures is one of the most difficult and important tasks of civil engineering. The paper presents the problem of strengthening of reinforced concrete structures. Experimental tests of load‐carrying capacity of reinforced concrete columns strengthened with CFRP strips and wraps have been carried out. The first objective of this research was to determine the influence of the type of reinforcement on load‐carrying capacity and strain. The second objective was to determine interdependence of the intensity of external reinforcement and load‐carrying capacity of element. Tests results have shown that the subject was worth investigating. Relations between external reinforcement ratio and load‐carrying capacity of small models of RC columns with various reinforcement ratio (from 1,4 % to 4,2 %) have been examined.


2020 ◽  
Vol 2 (1) ◽  
pp. 81-88
Author(s):  
Bikram Bhusal ◽  
Satish Paudel ◽  
Tek Bahadur Katuwal

This paper presents the relevance of using various material models to represent the inherent material non-linearity of the cross-section in generating moment curvature relationship. Further, confinement effects are imposed on geometry and P-M diagram is constructed of typical cross-section of column adopted in Nepal. Also, the modelling capability and user defined modelling aspects in terms of section, material behavior is assessed and suitability of modelling criteria to depict the actual displacement capacity is studied. It was observed the ultimate curvature of the un-confined concrete section considered was obtained approximately to be 0.16 per m while for studied confined material models the curvature was obtained approximately to be 0.66 per m. This increase in curvature is due to the confinement effect of the lateral ties. It was observed that the loss of strength of concrete in cover is compensated by use of the confinement since gain in axial and bending capacity of the confined concrete in comparison to unconfined one in compression control region. Hence, it is suggested to adopt the confined material model as user-defined for generating hinge property for non-linear analysis of the structures.


Author(s):  
Alex-Manuel Muresan ◽  
Daia Zwicky

When strengthening reinforced concrete slabs with textile reinforced mortars (TRM), the “correct” consideration of the global bond behaviour between textile and cementitious matrix is identified as the main challenge in determining the most appropriate global analytical model. The first model evaluated here is based on classical assumptions for structural concrete design. The second model, as another extreme assumption, is completely neglecting textile bond in the cracked zone, thus assuming it as unbonded, end-anchored, external reinforcement. The third model is based on the simplifying assumption of the textile reinforcement being only significantly activated when the internal steel reinforcement is yielding. Analytical results from these approaches are compared to a database containing more than 130 test results reported in literature, and are statistically evaluated.


2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Bedaso Ahmed ◽  
Kefiyalew Zerfu ◽  
Elmer C. Agon

Slender reinforced concrete column may fail in material failure or instability failure. Instability failure is a common problem which cannot be analyzed with first-order analysis. So, second-order analysis is required to analyze instability failure of slender RC column. The main objective of this study was to construct uniaxial interaction diagram for slender reinforced concrete column based on nonlinear finite element analysis (FEA) software. The key parameters which were studied in this study were eccentricity, slenderness ratio, steel ratio, and shape of the column. Concrete damage plasticity (CDP) was utilized in modeling the concrete. Material nonlinearity, geometric nonlinearity, effect of cracking, and tension stiffening effect were included in the modeling. The results reveal that, as slenderness ratio increases, the balanced moment also increases, but the corresponding axial load was decreased. However, increasing the amount of steel reinforcement to the column increases the stability of the column and reduces the effect of slenderness ratio. Also, the capacity of square slender RC column is larger than rectangular slender RC column with equivalent cross section. However, the result is close to each other as slenderness ratio increased. Finally, validation was conducted by taking a benchmark experiment, and it shows that FEA result agrees with the experimental by 85.581%.


Buildings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 355
Author(s):  
Qudeer Hussain ◽  
Anat Ruangrassamee ◽  
Somnuk Tangtermsirikul ◽  
Panuwat Joyklad ◽  
Anil C. Wijeyewickrema

This research investigates the behavior of square concrete columns externally wrapped by low-cost and easily available fiber rope reinforced polymer (FRRP) composites. This study mainly aims to explore the axial stress-strain relationships of FRRP-confined square columns. Another objective is to assess suitable predictive models for the ultimate strength and strain of FRRP-confined square columns. A total of 60 square concrete columns were cast, strengthened, and tested under compression. The parameters were the corner radii of square columns (0, 13, and 26 mm) and different materials of FRRP composites (polyester, hemp, and cotton FRRP composites). The strength and deformability of FRRP-confined specimens were observed to be higher than the unconfined specimens. It was observed that strength gains of FRRP-confined concrete columns and corner radii were directly proportional. The accuracy of ultimate strength and strain models developed for synthetic FRRP-confined square columns was assessed using the test results of this study, showing the need for the development of improved predictive models for FRRP-confined square columns. Newly developed unified models were found to be accurate in predicting the ultimate strength and strain of FRRP-confined columns.


2020 ◽  
Vol 44 (3) ◽  
pp. 151-158
Author(s):  
S. Tomilov

Так как в настоящее время в эксплуатации находится достаточно много автодорожных мостов, запроектированных и построенных в различные периоды, их, как и всю дорожную сеть, необходимо поддерживать в состоянии, соответствующем нормативам, а для этого проводить ремонт с использованием элементов усиления несущих конструкций. При качественном возведении и надлежащем уходе высокая степень сохранности мостов позволяет продлить срок их службы путем решения ряда конструктивных вопросов, наиболее актуальным из которых считают обеспечение нормативной грузоподъемности. Усиление с целью повышения грузоподъемности эксплуатируемых мостов достигается путем добавления элементов внешних или внедренных в состав существующего конструктива в зависимости от типа сооружения, его состояния и доступной технологии производства. Однако не только грузоподъемность, но и подверженность конструкций деформациям определяет транспортно-эксплуатационные параметры сооружения, характеризующие послеремонтное состояния моста. Цель настоящего исследования – анализ известного и широко востребованного способа усиления железобетонных балок внешним армированием как обеспечивающего минимальное вмешательство в существующие основные конструкции, технологичного и доступного в исполнении. Впервые дана оценка влияния стадийности включения в работу элементов усиления на общие деформации – прогибы главных балок. Ключевые слова: главная балка, грузоподъемность, усиление, внешняя арматура, свободная затяжка, стадийность работы, относительная деформация, прогиб. Currently, there are quite a lot of road bridges in operation, designed and built in different periods. It is necessary to maintain the road network including bridge structures in a condition that meets up-to-date standards, and for this repair should be carried out using reinforcing elements of the supporting structures. With high-quality construction and proper maintenance, a high degree of safety of bridges allows to extend their service life by solving a number of design issues, the most important of which is considered to be the provision of standard load capacity. Strengthening in order to increase the carrying capacity of operated bridges is achieved by adding elements external or incorporated into the existing structure, depending on the type of structure, its condition and available production technology. However, not only the carrying capacity, but also the susceptibility of structures to deformations determines the transport and operational parameters of the structure, which characterize the post-repair state of the bridge. The purpose of this study is to analyze the well-known and widely demanded method of reinforcing reinforced concrete beams with external reinforcement as providing minimal interference with the existing basic structures, technological and affordable in execution. For the first time, an assessment of the influence of the staging of the inclusion of reinforcement elements in the work on the general deformations – deflections of the main beams. Keywords: main beam, carrying capacity, reinforcement, external reinforcement, free rod, staging of work, relative deformation, deflection.


2013 ◽  
Vol 790 ◽  
pp. 227-230
Author(s):  
Jian Feng Su ◽  
Yu Feng Xu

Floor slab static load test is a important method to judge the performance and carrying capacity of the slab. This paper, with the background of a factory frame-structure slab, introduced the testing scheme, the details of the testing process as well as the test results. The testing cases provide a useful reference for the same type of project.


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