Design method for concrete columns strengthened with prestressed CFRP sheets

2017 ◽  
Vol 151 ◽  
pp. 331-344 ◽  
Author(s):  
Donghui Cheng ◽  
Yanhong Yang
Keyword(s):  
Design Method ◽  
Concrete Columns ◽  
Cfrp Sheets ◽  
Prestressed Cfrp Sheets

Research on Interfacial Bond Behavior of Prestressed CFRP Sheets Strengthened SRC Beams under Symmetry Concentrated Loads

2011 ◽  
Vol 94-96 ◽  
pp. 1012-1017
Author(s):  
Na Ha ◽  
Shen Yuan Fu ◽  
Lian Guang Wang
Keyword(s):  
Interfacial Shear ◽  
Initial Strain ◽  
Concentrated Loads ◽  
Interfacial Bond ◽  
Steel Reinforced Concrete ◽  
Cfrp Sheets ◽  
Calculation Results ◽  
Minimum Potential ◽  
Effective Transfer ◽  
Prestressed Cfrp Sheets

The main form of interfacial bond stress between prestressed CFRP sheets and the beams of steel reinforced concrete(SRC) are interfacial shear and peel-off stress. The effective transfer of adhesive stress is the fundamental to ensure the structure bearing capacity improved after strengthened. According to the principle of minimum potential energy and combining with the mechanical behavior of prestressed CFRP sheets and the beams of SRC, the calculated formulas of interfacial shear and peel-off stress are deduced under symmetry concentrated loads. The influences of initial strain and the layer of CFRP sheets are discussed. The calculation results show that the effective availability of CFRP sheets is increased with the initial strain increasing under the load. And the interfacial shear and peel-off stress of beam-end are increased simultaneously with the initial strain and the layers of CFRP sheets increasing, which lead to the ends of beams occurred peel-off failure easily.

Analysis on Deformation of Pre-Splitting Steel Reinforced Concrete Beams Strengthened by Prestressed CFRP

2011 ◽  
Vol 243-249 ◽  
pp. 929-933
Author(s):  
Na Ha ◽  
Lian Guang Wang ◽  
Shen Yuan Fu
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Concrete Beams ◽  
Bending Moment ◽  
Reinforced Concrete Beams ◽  
Steel Reinforced Concrete ◽  
Cfrp Sheets ◽  
Deformation Curves ◽  
Prestressed Cfrp Sheets ◽  
Theoretical Results

In order to improve the bearing capacity of SRC which is related with deformation and stiffiness, SRC beams should be strengthened by CFRP. Based on the experiment of six pre-splitting steel reinforced concrete beams strengthened with (Prestressed) CFRP sheets, the deformation of beams are discussed. Load-deformation curves are obtained by the experiment. Considering the influence of intial bending moment on SRC beams, the calculated deformation formulas of SRC beams strengthened by (Prestressed) CFRP are deduced. The results showed that the load-deformation curves of normal and strengthened beams respectively showed three and two linear characteristics. The theoretical results which calculated by the formulas of deformation are well agreement with the experimental results.

Steel Core in Composite Steel-Concrete Columns

2016 ◽  
Vol 691 ◽  
pp. 195-206
Author(s):  
Juraj Frólo ◽  
Štefan Gramblička
Keyword(s):  
Cross Section ◽  
Design Method ◽  
High Strength ◽  
Concrete Columns ◽  
Steel Tube ◽  
Experimental Investigations ◽  
Composite Columns ◽  
Steel Core ◽  
Composite Steel ◽  
Simplified Design Method

This paper presents some results of theoretical and experimental investigations of composite steel-concrete columns with solid steel profiles - steel cores. Due to absence of simplified design method according to EN 1994-1-1 [1], design of these columns in practice is limited in general. Reasons for this are residual stresses in steel profile caused by fabrication process and limitation of strains in concrete. Recommendations have been determined for simplified design method according to EN 1994-1-1 for composite columns made of high strength concrete filled steel tube with central steel core. Results of experimental research on composite columns with the cross-section made of steel core covered by reinforced concrete are presented.

scholarly journals Influence of ties on the behavior of short reinforced concrete columns strengthened by external CFRP

2018 ◽  
Vol 162 ◽  
pp. 04005
Author(s):  
Kaiss Sarsam ◽  
Raid Khalel ◽  
Mohammed Hadi
Keyword(s):  
Carrying Capacity ◽  
Concrete Columns ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Load Carrying Capacity ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Load Carrying ◽  
The Difference ◽  
Normal Strength

An experimental study was carried out to investigate the behavior of normal strength reinforce concret (RC) circular short column strengthned with “carbon fiber reinforced polymer (CFRP) sheets”. Three series comprising totally of (15) specimens loaded until failure under concentric compresion load. Strengthening was varied by changing the number of CFRP strips, spacing and wrapping methods. The findings of this research can be summarized as follows: for the columns without CFRP, the influence of the tie spacing was significant: compared with 130 mm tie spacing, dropping the spacing to 100 mm and 70 mm increased the load carrying capacity by 18% and 26%, respectively. The columns with less internal confinement (lesser amount of ties) were strengthened more significantly by the CFRP than the ones with greater amount of internal ties. As an example of the varying effectiveness of the fully wrapped CFRP, the column with ties at 130 mm was strengthened by 90% with the CFRP. In contrast, the ones with 70 mm spaced ties only increased in strength with CFRP by 66%. Compared with the control specimen (no CFRP), the same amount of CFRP when used as hoop strips led to more strengthening than using CFRP as a spiral strip- the former led to nearly 9% more strengthening than the latter in the case of 130 mm spaced internal steel ties. In the case of 100 mm internal steel ties, the difference (between the hoops & spiral CFRP strengthening) is close to 4%. In contrast, there is no difference between the two methods of strengthening in the heavily tied columns (70 mm tied spacing).

Flexural behaviour of concrete beams strengthened with prestressed carbon fibre reinforced polymer sheets subjected to sustained loading and low temperature

2004 ◽  
Vol 31 (2) ◽  
pp. 239-252 ◽  
Author(s):  
Raafat El-Hacha ◽  
Mark F Green ◽  
R Gordon Wight
Keyword(s):  
Low Temperature ◽  
Carbon Fibre ◽  
Flexural Behaviour ◽  
Prestress Losses ◽  
Cfrp Sheets ◽  
Reinforced Polymer ◽  
Carbon Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Prestressed Cfrp Sheets

This paper presents results of an experimental investigation that examined concrete beams post-tensioned with bonded carbon fibre reinforced polymer (CFRP) sheets and then exposed to either room (+22 °C) or low (-28 °C) temperatures. The primary objective of this investigation was to assess the flexural behaviour of the strengthened beams after sustained loadings at both room and low temperatures. The strengthened beams showed significant increases in flexural stiffness and ultimate capacity as compared with the control-unstrengthened beams. Failure of the strengthened beams was by tensile rupture of the prestressed CFRP sheets. Test results showed that the long-term and low temperature effects did not adversely affect the strength of the beams. Long-term loading and low temperature exposure caused prestress losses in the CFRP sheets. The load–deflection behaviour of the long-term beams was predicted accurately by an analytical model. These results suggest that bonded prestressed CFRP sheets could be used to increase the strength of damaged prestressed concrete girders under extreme environmental conditions.Key words: strengthening, anchorage, low temperature, long-term, prestress losses, sustained load, carbon fibre reinforced polymer sheet.

Slenderness Influence on the Behavior of Composite Columns

2016 ◽  
Vol 691 ◽  
pp. 40-50
Author(s):  
Štefan Gramblička ◽  
Andrea Hrusovska
Keyword(s):  
Cross Sections ◽  
Design Method ◽  
Tall Buildings ◽  
Concrete Columns ◽  
Order Theory ◽  
Second Order ◽  
Order Effects ◽  
Composite Columns ◽  
Steel Members ◽  
Composite Steel

Composite steel and concrete columns have been used in the tall buildings due theirs high-resistance and the possibility to reduce cross sections when we compered composite columns with reinforced concrete columns. There are a lot of types of composite columns. We are concerned with columns, which are completely or partially concrete-encased steel members. In practice, a lot of composite columns are relatively slender and in design the second - order effects will usually need to be included. A partially concrete encased steel cross-section was selected for laboratory tests of composite columns. According to the results of the experiments (total of 18 columns were tested in two series), we analyzed the effects of the second - order theory. The experimental results were compared with theoretical results obtained from the model developed in the non-linear software. The evaluation of the results is also shown in comparison with the general design method according to Eurocode 4, Design of composite steel and concrete structures - Part 1.1 General rules and rules for buildings.

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