scholarly journals Strengthening Design of RC Columns with Direct Fastening Steel Jackets

2021 ◽  
Vol 11 (8) ◽  
pp. 3649
Author(s):  
Zhiwei Shan ◽  
Lijie Chen ◽  
Kun Liang ◽  
Ray Kai Leung Su ◽  
Zhao-Dong Xu
Keyword(s):  
Flexural Strength ◽  
Load Capacity ◽  
Design Procedure ◽  
Load Ratio ◽  
High Strength ◽  
Lateral Load ◽  
Steel Plates ◽  
Flexural Stiffness ◽  
Rc Columns ◽  
Strengthening Method

For non-seismically designed columns with insufficient strength and flexural stiffness, intense inter-story drift can be incurred during a strong earthquake event, potentially leading to the collapse of the entire building. Existing strengthening methods mainly focus on enhancing axial or flexural strength but not the flexural stiffness of columns. In response, a novel direct fastening steel jackets that can increase both flexural strength and stiffness is introduced. This novel strengthening method features straightforward installation and swift strengthening as direct fastening is used to connect steel plates together to form a steel jacketed column. This new connection method can quickly and stably connect two steel components together by driving high strength fasteners into them. In this paper, the design procedure of RC columns strengthened with this novel strengthening method is originally proposed, which includes five steps: (1) estimating lateral load capacity of damaged RC columns; (2) determining connection spacing of steel jacket; (3) estimating the lateral load capacity of strengthened RC column; (4) evaluating the axial load ratio (ALR) of strengthened RC columns; and (5) estimating effective stiffness of strengthened RC columns. Lastly, an example is presented to illustrate the application of the proposed design procedure.

BEHAVIOR OF DOUBLE SKIN FLAT COMPOSITE WALL UNDER LATERAL LOAD

2021 ◽  
Vol 12 (11) ◽  
pp. 314-317
Author(s):  
Cezar Dasi
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Tall Buildings ◽  
Shear Walls ◽  
High Strength ◽  
Lateral Load ◽  
Steel Plates ◽  
Double Skin ◽  
Composite Wall ◽  
Composite Shear

Shear walls are the primary lateral load-carrying elements in tall buildings. The composite shear walls with double steel plates and filled concrete are composed of two steel plates with studs inside, they were developed to enlarge the building space, and to delay the appearance of cracks by using the steel plates as formwork. Double skin composite wall panels can offer high strength and robustness while improving the convenience of construction, with great potential for application in nuclear power plants

Flexural behavior of fire-damaged reinforced concrete beams repaired with high-strength fiber reinforced mortar

2019 ◽  
Vol 10 (1) ◽  
pp. 56-75 ◽  
Author(s):  
Muhd Afiq Hizami Abdullah ◽  
Mohd Zulham Affandi Mohd Zahid ◽  
Afizah Ayob ◽  
Khairunnisa Muhamad
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Load Capacity ◽  
Peak Load ◽  
High Strength ◽  
Elastic Stiffness ◽  
Reinforced Concrete Beams ◽  
Repair Material ◽  
Content Type ◽  
High Strength Fiber

Purpose The purpose of this study is to investigate the effect on flexural strength of fire-damaged concrete repaired with high-strength mortar (HSM). Design/methodology/approach Reinforced concrete beams with dimension of 100 mm × 100 mm × 500 mm were used in this study. Beams were then heated to 400°C and overlaid with either HSM or high-strength fiber reinforced mortar (HSFM) to measure the effectiveness of repair material. Repaired beams of different material were then tested for flexural strength. Another group of beams was also repaired and tested by the same procedure but was heated at higher temperature of 600°C. Findings Repair of 400°C fire-damaged samples using HSM regained 72 per cent of its original flexural strength, 100.8 per cent of its original toughness and 56.9 per cent of its original elastic stiffness. Repair of 400°C fire-damaged samples using HSFM regained 113.5 per cent of its original flexural strength, 113 per cent of its original toughness and 85.1 per cent of its original elastic stiffness. Repair of 600°C fire-damaged samples using HSM regained 18.7 per cent of its original flexural strength, 25.9 per cent of its original peak load capacity, 26.1 per cent of its original toughness and 22 per cent of its original elastic stiffness. Repair of 600°C fire-damaged samples using HSFM regained 68.4 per cent of its original flexural strength, 96.5 per cent of its original peak load capacity, 71.2 per cent of its original toughness and 52.2 per cent of its original elastic stiffness. Research limitations/implications This research is limited to the size of the furnace. The beam specimen is limited to 500 mm of length and overall dimensions. This dimension is not practical in actual structure, hence it may cause exaggeration of deteriorating effect of heating on reinforced concrete beam. Practical implications This study may promote more investigation of using HSM as repair material for fire-damaged concrete. This will lead to real-world application and practical solution for fire-damaged structure. Social implications The aim of this research in using HSM mostly due to the material’s high workability which will ease its application and promote quality in repair of damaged structure. Originality/value There is a dearth of research on using HSM as repair material for fire-damaged concrete. Some research has been carried out using mortar but at lower strength compared to this research.

Experimental Investigation on Soft-Story RC Frames Retrofitted by Hybrid Wall Technique

2011 ◽  
Vol 82 ◽  
pp. 612-617
Author(s):  
Tomomi Sunagawa ◽  
Pasha Javadi ◽  
Koki Maeda ◽  
Tetsuo Yamakawa
Keyword(s):  
Experimental Investigation ◽  
High Strength ◽  
Steel Plates ◽  
Structural Performance ◽  
Experimental Investigations ◽  
Rc Columns ◽  
Soft Story ◽  
Rc Frames ◽  
Hybrid Walls

In this paper, a new retrofit method, which is called “Hybrid Wall Technique”, is proposed for retrofitting soft-story RC frames. In the proposed technique, steel plates encase the boundary RC columns, and connect to additional steel plates at the bay of the frame with the help of high-strength bolts. After installation of steel plates and high-strength bolts, which are also used as formworks, the additional concrete is cast. Structural performance of the proposed metho­­­d is verified by experimental investigations conducted on one-bay one-story RC frames. One non-retrofitted frame and three frames retrofitted by thick or thin hybrid walls were evaluated experimentally.

scholarly journals High-Strength Concrete Circular Columns with TRC-TSR Dual Internal Confinement

Buildings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 218
Author(s):  
Rami Eid ◽  
Avi Cohen ◽  
Reuven Guma ◽  
Eliav Ifrach ◽  
Netanel Levi ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
High Strength Concrete ◽  
Large Scale ◽  
Load Capacity ◽  
High Strength ◽  
Construction Method ◽  
Textile Reinforced Concrete ◽  
Rc Columns ◽  
Strength Concrete ◽  
Ductile Behavior

The standard requirements for transverse steel reinforcement (TSR) confinement in reinforced-concrete (RC) columns are mainly to provide the following: ductile behavior, minimum axial load capacity of the column’s core, and prevention of longitudinal bars buckling. It is well-known that the passive confinement due the TSR action is less effective in high-strength concrete (HSC) compared to normal-strength concrete (NSC). Therefore, the TSR amounts required by the standards for HSC columns are high, and in some cases, especially in the lower stories columns of high-rise buildings, are impractical. This paper presents a new construction method using textile-reinforced concrete (TRC) as internal confinement together with reduced TSR amounts. Moreover, comparison of the proposed method with RC columns casted in fiber-reinforced polymer (FRP) stay-in-place forms as additional external confinement, is presented. Eleven large-scale column specimens were tested under axial compression. The results give an insight on the application feasibility of the proposed construction method. It is shown that the TRC-TSR dual internal confinement action can be an option to reduce the standard required TSR amounts while maintaining similar levels of ductile behavior.

Experimental Study of Strengthening of RC Columns with Steel Fiber Concrete

2020 ◽  
Vol 1002 ◽  
pp. 551-564
Author(s):  
Wathiq Jassim Mhuder ◽  
Samir M. Chassib
Keyword(s):  
Experimental Study ◽  
Cross Section ◽  
Load Capacity ◽  
High Strength ◽  
Experimental Program ◽  
Axial Loads ◽  
Concrete Core ◽  
Rc Columns ◽  
Load Carrying ◽  
Steel Fiber Concrete

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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