Concrete filled double skin circular tubes : a review
- Essopjee, Yoosuf, Dundu, Morgan
- Authors: Essopjee, Yoosuf , Dundu, Morgan
- Date: 2014
- Subjects: Prestressed concrete construction , Columns, Concrete , Plates, Iron and steel
- Type: Article
- Identifier: uj:5083 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13654
- Description: A review of the research conducted on the compressive strength of concrete filled double skin circular tubes (CFDSCT) columns is conducted. Variables of the CFDSCT considered in this review include the concrete strength, steel strength, inner and outer tube diameter, steel thickness and length of the stub columns. Test results show that the composite columns had compressive strengths of up to 41% higher than the sum of the individual strengths of the section. All the outer tubes of these composite columns by failed local buckling. A review of the design equations proposed are presented and discussed. The paper also identifies gaps for further research for these types of columns.
- Full Text:
- Authors: Essopjee, Yoosuf , Dundu, Morgan
- Date: 2014
- Subjects: Prestressed concrete construction , Columns, Concrete , Plates, Iron and steel
- Type: Article
- Identifier: uj:5083 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13654
- Description: A review of the research conducted on the compressive strength of concrete filled double skin circular tubes (CFDSCT) columns is conducted. Variables of the CFDSCT considered in this review include the concrete strength, steel strength, inner and outer tube diameter, steel thickness and length of the stub columns. Test results show that the composite columns had compressive strengths of up to 41% higher than the sum of the individual strengths of the section. All the outer tubes of these composite columns by failed local buckling. A review of the design equations proposed are presented and discussed. The paper also identifies gaps for further research for these types of columns.
- Full Text:
Repair of cracked reinforced concrete beams with adhesive bonded steel plates
- Authors: Ngidi, Sandile Daniel
- Date: 2017
- Subjects: Concrete beams - Maintenance and repair , Reinforced concrete construction , Plates, Iron and steel , Steel, Structural
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/269693 , uj:28652
- Description: M.Ing. (Civil Engineering) , Abstract: Concrete structures often suffer from cracking and deterioration caused by factors such as impact and dynamic loading, static overload and construction faults. This requires immediate repair to prevent further degradation and to restore structures integrity. Externally bonded steel plates are used to repair such damaged concrete structures in a number of projects in various parts of the World, but their overall performance is still not fully understood. The main objective of this study is to investigate the flexural behaviour of pre-cracked reinforced concrete beams, repaired by bonded steel plates on their soffit, using epoxy adhesives. This implied an experimental investigation, which took place in Material Laboratory of the Department of Civil Engineering Science at the University of Johannesburg. Twelve full-scale beams of 175 mm wide x 300 mm deep x 3200 mm long were pre-cracked, repaired with steel plates and tested to failure in flexure under a two-point loading. Two variables were included in this investigation, namely; plate size and loading conditions. The plate size was varied by changing its width, which ranged from 75 mm up to 175 mm, in increments of 25 mm and the beams were pre-cracking at serviceability load and at 85% of the maximum load. During the experiments, the following aspects were evaluated and recorded regarding the response of tested beams: flexural strength, stiffness, maximum deflections and failure modes. Externally bonding the steel plate to the pre-cracked reinforced concrete (RC) beams resulted in increased stiffnesses and maximum load capacities up to 153% and decreased in the maximum midspan deflections up to 38%. The strength and rigidity of the repaired beams were found to increase with increasing the width-to-thickness ratio of the steel plate from 12.5 to 29.17. The results also showed that bonded external steel plate can only enhance the maximum load capacity of the repaired beams to a limited extent. There exists a limit in the width-to-thickness ratio for which the load can increase. The experimental results showed that the structural integrity of the repaired beam not only can it be restored but also enhanced. The bonded external plate contributed more to the control of maximum load capacities than to the control of deflections.
- Full Text:
- Authors: Ngidi, Sandile Daniel
- Date: 2017
- Subjects: Concrete beams - Maintenance and repair , Reinforced concrete construction , Plates, Iron and steel , Steel, Structural
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/269693 , uj:28652
- Description: M.Ing. (Civil Engineering) , Abstract: Concrete structures often suffer from cracking and deterioration caused by factors such as impact and dynamic loading, static overload and construction faults. This requires immediate repair to prevent further degradation and to restore structures integrity. Externally bonded steel plates are used to repair such damaged concrete structures in a number of projects in various parts of the World, but their overall performance is still not fully understood. The main objective of this study is to investigate the flexural behaviour of pre-cracked reinforced concrete beams, repaired by bonded steel plates on their soffit, using epoxy adhesives. This implied an experimental investigation, which took place in Material Laboratory of the Department of Civil Engineering Science at the University of Johannesburg. Twelve full-scale beams of 175 mm wide x 300 mm deep x 3200 mm long were pre-cracked, repaired with steel plates and tested to failure in flexure under a two-point loading. Two variables were included in this investigation, namely; plate size and loading conditions. The plate size was varied by changing its width, which ranged from 75 mm up to 175 mm, in increments of 25 mm and the beams were pre-cracking at serviceability load and at 85% of the maximum load. During the experiments, the following aspects were evaluated and recorded regarding the response of tested beams: flexural strength, stiffness, maximum deflections and failure modes. Externally bonding the steel plate to the pre-cracked reinforced concrete (RC) beams resulted in increased stiffnesses and maximum load capacities up to 153% and decreased in the maximum midspan deflections up to 38%. The strength and rigidity of the repaired beams were found to increase with increasing the width-to-thickness ratio of the steel plate from 12.5 to 29.17. The results also showed that bonded external steel plate can only enhance the maximum load capacity of the repaired beams to a limited extent. There exists a limit in the width-to-thickness ratio for which the load can increase. The experimental results showed that the structural integrity of the repaired beam not only can it be restored but also enhanced. The bonded external plate contributed more to the control of maximum load capacities than to the control of deflections.
- Full Text:
Methods for flexural strengthening of reinforced concrete elements using steel plates
- Olajumoke, Akinropo Musiliu, Dundu, Morgan
- Authors: Olajumoke, Akinropo Musiliu , Dundu, Morgan
- Date: 2014
- Subjects: Concrete beams , Plates, Iron and steel , Reinforced concrete , Flexure
- Type: Article
- Identifier: http://ujcontent.uj.ac.za8080/10210/380017 , uj:5078 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13649
- Description: When reinforced concrete elements are incapable of safely sustaining the anticipated load, flexural strengthening may be necessary. Two major construction methods have been reported in literature for strengthening reinforced concrete (RC) elements in bending. These methods include Externally Bonded Reinforcement (EBR) and Near Surface Mounting (NSM). The aim of this paper is review these methods, including the extensive surface preparation that must be performed on bonded elements. Previous investigations have shown that these techniques are effective in salvaging old and distressed reinforced concrete structures. This paper identifies the problems associated with the utilisation of steel plates as strengthening material for RC elements in EBR and NSM techniques.
- Full Text:
- Authors: Olajumoke, Akinropo Musiliu , Dundu, Morgan
- Date: 2014
- Subjects: Concrete beams , Plates, Iron and steel , Reinforced concrete , Flexure
- Type: Article
- Identifier: http://ujcontent.uj.ac.za8080/10210/380017 , uj:5078 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13649
- Description: When reinforced concrete elements are incapable of safely sustaining the anticipated load, flexural strengthening may be necessary. Two major construction methods have been reported in literature for strengthening reinforced concrete (RC) elements in bending. These methods include Externally Bonded Reinforcement (EBR) and Near Surface Mounting (NSM). The aim of this paper is review these methods, including the extensive surface preparation that must be performed on bonded elements. Previous investigations have shown that these techniques are effective in salvaging old and distressed reinforced concrete structures. This paper identifies the problems associated with the utilisation of steel plates as strengthening material for RC elements in EBR and NSM techniques.
- Full Text:
Flexural failure modes of steel plate-strengthened reinforced concrete elements
- Olajumoke, Akinropo Musiliu, Dundu, Morgan
- Authors: Olajumoke, Akinropo Musiliu , Dundu, Morgan
- Date: 2014
- Subjects: Reinforced concrete , Composite materials - Bonding - Congresses , Concrete beams - Maintenance and repair , Plates, Iron and steel
- Type: Article
- Identifier: uj:5071 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13642
- Description: Failure of plate strengthened flexural reinforced concrete (RC) member can be crushing of the concrete at the compression face or premature debonding of the plate from the concrete element at the tension face. Debonding can be classified into three groups; namely, intermediate crack debonding (ICD), delamination and plate-end debonding (PED). Intermediate crack debonding is caused by flexural or flexural-shear stress, and plate-end debonding and delamination are caused by interfacial stress. This paper reviews the failure modes of flexural strengthened RC elements in bending, using epoxy-bonded steel plates. It also attempts to establish the width-to-thickness ratios of plates that can achieve the full flexural strengths of the strengthened element and promote a ductile failure.
- Full Text:
- Authors: Olajumoke, Akinropo Musiliu , Dundu, Morgan
- Date: 2014
- Subjects: Reinforced concrete , Composite materials - Bonding - Congresses , Concrete beams - Maintenance and repair , Plates, Iron and steel
- Type: Article
- Identifier: uj:5071 , ISBN 9781614994657 , ISBN 9781614994664 , http://hdl.handle.net/10210/13642
- Description: Failure of plate strengthened flexural reinforced concrete (RC) member can be crushing of the concrete at the compression face or premature debonding of the plate from the concrete element at the tension face. Debonding can be classified into three groups; namely, intermediate crack debonding (ICD), delamination and plate-end debonding (PED). Intermediate crack debonding is caused by flexural or flexural-shear stress, and plate-end debonding and delamination are caused by interfacial stress. This paper reviews the failure modes of flexural strengthened RC elements in bending, using epoxy-bonded steel plates. It also attempts to establish the width-to-thickness ratios of plates that can achieve the full flexural strengths of the strengthened element and promote a ductile failure.
- Full Text:
Effects of the width-to-thickness ratios of steel plates bonded to the soffit of reinforced concrete beams
- Rakgate, Sylvester Mokgokone
- Authors: Rakgate, Sylvester Mokgokone
- Date: 2017
- Subjects: Plates, Iron and steel , Concrete beams , Steel, Structural , Flexure
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/242353 , uj:24994
- Description: M.Ing. (Civil Engineering) , Abstract: The use of epoxy-bonded steel plate (EBSP) is becoming a well-known solution in the field of civil engineering around the world for strengthening structural elements such as beams, columns and slabs. This thesis presents an experimental study aimed at investigating the flexural behaviour (structural behaviour) of simply supported under-reinforced concrete (URC) beams, strengthened in flexure by externally-bonded steel plates (EBSP) with varying width-to-thickness ratio. This required an experimental investigation, which took place at the material laboratories at the University of Johannesburg (UJ), South Africa. The experimental program was carried out on 17, 175 x 300 x 3200 mm rectangular reinforced concrete (RC) beams. Two beams were not strengthened with steel plates and they were considered as control specimens, whilst the remaining beams were categorised into three groups with five (5) beams in each group. The first group of beams was externally strengthened with 4 mm steel plates, the second group was externally strengthened with 6 mm steel plates and the third group was externally strengthened with 8 mm steel plates, in flexure. Furthermore, in each group, the width of the bonded steel plate varied from 75 mm to 175 mm, with increments of 25 mm. All the beams were tested simply supported under two-point static loadings until failure over a clear span of 3000 mm. To achieve the goals of this experimental investigation, the load-deflection response, strain distribution at the mid-span of the bonded steel plate, cracking load, crack patterns and associated failure modes of the tested specimens were recorded. From the experimental results, it is observed that the externally bonded steel plates led to an increase in flexural stiffness, maximum load carrying capacity, cracking load, decrease in vertical deflections and crack-widths as compared to the control beams. Furthermore, there is a limit to width-to-thickness ratio of the steel plate which the premature shear or bond failure occurs without beams achieving their full flexural capacity.
- Full Text:
- Authors: Rakgate, Sylvester Mokgokone
- Date: 2017
- Subjects: Plates, Iron and steel , Concrete beams , Steel, Structural , Flexure
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/242353 , uj:24994
- Description: M.Ing. (Civil Engineering) , Abstract: The use of epoxy-bonded steel plate (EBSP) is becoming a well-known solution in the field of civil engineering around the world for strengthening structural elements such as beams, columns and slabs. This thesis presents an experimental study aimed at investigating the flexural behaviour (structural behaviour) of simply supported under-reinforced concrete (URC) beams, strengthened in flexure by externally-bonded steel plates (EBSP) with varying width-to-thickness ratio. This required an experimental investigation, which took place at the material laboratories at the University of Johannesburg (UJ), South Africa. The experimental program was carried out on 17, 175 x 300 x 3200 mm rectangular reinforced concrete (RC) beams. Two beams were not strengthened with steel plates and they were considered as control specimens, whilst the remaining beams were categorised into three groups with five (5) beams in each group. The first group of beams was externally strengthened with 4 mm steel plates, the second group was externally strengthened with 6 mm steel plates and the third group was externally strengthened with 8 mm steel plates, in flexure. Furthermore, in each group, the width of the bonded steel plate varied from 75 mm to 175 mm, with increments of 25 mm. All the beams were tested simply supported under two-point static loadings until failure over a clear span of 3000 mm. To achieve the goals of this experimental investigation, the load-deflection response, strain distribution at the mid-span of the bonded steel plate, cracking load, crack patterns and associated failure modes of the tested specimens were recorded. From the experimental results, it is observed that the externally bonded steel plates led to an increase in flexural stiffness, maximum load carrying capacity, cracking load, decrease in vertical deflections and crack-widths as compared to the control beams. Furthermore, there is a limit to width-to-thickness ratio of the steel plate which the premature shear or bond failure occurs without beams achieving their full flexural capacity.
- Full Text:
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