scholarly journals Structural Response of Steel Jacket-UHPC Retrofitted Reinforced Concrete Columns under Blast Loading

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1521
Author(s):  
Mohammad Hanifehzadeh ◽  
Hadi Aryan ◽  
Bora Gencturk ◽  
Dovlet Akyniyazov
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Blast Resistance ◽  
Blast Loading ◽  
Concrete Columns ◽  
Ground Level ◽  
Fiber Reinforced Polymers ◽  
Fe Model ◽  
Building Collapse ◽  
Steel Jacket

The lateral capacity of exterior concrete columns subjected to a blast load is the key factor in the building collapse probability. Due to potentially severe consequences of the collapse, efforts have been made to improve the blast resistance of existing structures. One of the successful approaches is the use of ultra-high-performance-concrete (UHPC) jacketing for retrofitting a building’s columns. The columns on the first floor of a building normally have higher slenderness due to the higher first story. Since an explosion is more likely to take place at the ground level, retrofitting the columns of the lower floors is crucial to improve a building’s blast resistance. Casting a UHPC tube around a circular RC column can increase the moment of inertia of the column and improve the flexural strength. In this study, a retrofitting system consisting of a UHPC layer enclosed by a thin steel jacket is proposed to improve the blast resistance of buildings in service. Most of the previous research is focused on design aspects of blast-resistant columns and retrofitting systems are mostly based on fiber reinforced polymers or steel jackets. A validated FE model is used to investigate the effectiveness of this method. The results showed significant improvement both at the component and building system levels against combined gravity and blast loading.

Behaviour of Uniaxial Reinforced Concrete Columns Strengthened with Ultra-High Performance Concrete and Fiber Reinforced Polymers

2021 ◽  
Vol 28 (2) ◽  
pp. 54-72
Author(s):  
Abd-al-Salam Al-Hazragi ◽  
Assim Lateef
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Columns ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced Polymers ◽  
Tension Zone ◽  
Fiber Reinforced ◽  
Group A ◽  
Group B

This article investigates the behaviour of strengthened concrete columns using jacketing ultra-high-performance fiber reinforced concrete (UHPFRC) and carbon fiber-reinforced polymer (CFRP) under uniaxial loaded. The jacket was connected to the column core using shear connectors and (CFRP) fixed as a strip on the tension zone between the column cores and the jacketing. Seven column samples of square cross-section (120 x120) mm at the midsection with overall length of 1250 mm were cast using normal strength concrete (NSC) and having similar longitudinal and transverse reinforcement. The samples were made and tested under axial load at eccentricity equal to 120 mm up to failure. Test parameters were the thickness of jackets (25 and 35) mm and the width of CFRP (0,8, and 12) cm. Column specimens were tested, one of them was reference without any strengthening, and the other specimens divided into two groups (A, and B), and each group included three specimens based on the parameters. Group (A) has UHPFRC jacket thickness 25 mm and CFRP width (0,8, and 12) cm respectively, and group (B) has UHPFRC jacket thickness 35 mm and CFRP width (0,8, and 12) cm respectively. The outcomes of the article show that increasing the thickness of jacket, and width of CFRP lead to increase in the load carrying capacity about (110.5%,168.4%, and 184.2%) for group A, and (157.9%,226.3%, and 263.2%) for group B compared with the reference column due to delay in the appearance of cracks and their distribution. The mid-height lateral displacement of columns was decreased about (66.6%,42.3%, and 35.9%) for group A, and (46.15%,38.46%, and 32.3%) for group B, also the axial deformation of specimens decreased about (71.7%,60.86%, and 55.86%) for group A, and (65.5%,60.5%, and 53.4) for group B compared with the reference column. The ductility of columns that were strengthened with UHPFRC jacket only was increased about (13.67%,19.66%) for thickness(25,35) mm respectively, because of that UHPFRC jacket was contented on steel fibers, and the percentage decrease of ductility was about (5.1%,and 12%) for group (A), (1%,and 9.4%) for group (B) when bonded CFRP in the tension zone with width (8 ,and 12) cm respectively. The results show improvement in the initial and secant stiffness when, increased the thickness of jacket, and width of CFRP because of increase in the size of columns and improvement in the modulus of elasticity. The toughness increase was about (273.97%,301.55%, and 304.5%) for group A, and (453.69%,511.93%, and 524.28%) for group B compared with the reference column because of increase in the size of specimens and delay the appearance of cracks.

scholarly journals Investigate the Structural Response of Ultra High Performance Concrete Column under the High Explosion

2021 ◽  
Vol 71 (2) ◽  
pp. 256-264
Author(s):  
Viet-Chinh Mai ◽  
Xuan-Bach Luu ◽  
Cong-Binh Dao ◽  
Dinh-Viet Le
Keyword(s):  
Cross Section ◽  
High Performance ◽  
High Performance Concrete ◽  
Blast Resistance ◽  
Load Capacity ◽  
Structural Response ◽  
Blast Loading ◽  
Frame Structure ◽  
Ultra High Performance Concrete ◽  
Main Concept

Most of the structures that are damaged by an explosion are not initially designed to resist this kind of load. In the overall structure of any building, columns play an important role to prevent the collapse of frame structure under blast impact. Hence, the main concept in the blast resistance design of the structure is to improve the blast load capacity of the column. In this study, dynamic analysis and numerical model of Ultra High Performance Concrete (UHPC) column under high explosive load, is presented. Based on the Johnson Holmquist 2 damage model and the subroutine in the ABAQUS platform, a total of twenty UHPC model of the column were calculated. The objective of the article is to investigate the structural response of the UHPC column and locate the most vulnerable scenarios to propose necessary recommendations for the UHPC column in the blast loading resistance design. The input parameters, including the effect of various shapes of cross-section, scaled distance, steel reinforcement ratio, and cross-section area, are analyzed to clarify the dynamic behavior of the UHPC column subjected to blast loading. Details of the numerical data, and the discussion on the important obtained results, are also provided in this paper.

scholarly journals Behaviour of Uniaxial Reinforced Concrete Columns Strengthened with Ultra-High Performance Concrete and Fiber Reinforced Polymers

2021 ◽  
Vol 28 (2) ◽  
pp. 54-72
Author(s):  
Abd-al-Salam Al-Hazragi ◽  
Assim Lateef
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Concrete Columns ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced Polymers ◽  
Tension Zone ◽  
Fiber Reinforced ◽  
Group A ◽  
Group B

This article investigates the behaviour of strengthened concrete columns using jacketing ultra-high-performance fiber reinforced concrete (UHPFRC) and carbon fiber-reinforced polymer (CFRP) under uniaxial loaded. The jacket was connected to the column core using shear connectors and (CFRP) fixed as a strip on the tension zone between the column cores and the jacketing. Seven column samples of square cross-section (120 x120) mm at the midsection with overall length of 1250 mm were cast using normal strength concrete (NSC) and having similar longitudinal and transverse reinforcement. The samples were made and tested under axial load at eccentricity equal to 120 mm up to failure. Test parameters were the thickness of jackets (25 and 35) mm and the width of CFRP (0,8, and 12) cm. Column specimens were tested, one of them was reference without any strengthening, and the other specimens divided into two groups (A, and B), and each group included three specimens based on the parameters. Group (A) has UHPFRC jacket thickness 25 mm and CFRP width (0,8, and 12) cm respectively, and group (B) has UHPFRC jacket thickness 35 mm and CFRP width (0,8, and 12) cm respectively. The outcomes of the article show that increasing the thickness of jacket, and width of CFRP lead to increase in the load carrying capacity about (110.5%,168.4%, and 184.2%) for group A, and (157.9%,226.3%, and 263.2%) for group B compared with the reference column due to delay in the appearance of cracks and their distribution. The mid-height lateral displacement of columns was decreased about (66.6%,42.3%, and 35.9%) for group A, and (46.15%,38.46%, and 32.3%) for group B, also the axial deformation of specimens decreased about (71.7%,60.86%, and 55.86%) for group A, and (65.5%,60.5%, and 53.4) for group B compared with the reference column. The ductility of columns that were strengthened with UHPFRC jacket only was increased about (13.67%,19.66%) for thickness(25,35) mm respectively, because of that UHPFRC jacket was contented on steel fibers, and the percentage decrease of ductility was about (5.1%,and 12%) for group (A), (1%,and 9.4%) for group (B) when bonded CFRP in the tension zone with width (8 ,and 12) cm respectively. The results show improvement in the initial and secant stiffness when, increased the thickness of jacket, and width of CFRP because of increase in the size of columns and improvement in the modulus of elasticity. The toughness increase was about (273.97%,301.55%, and 304.5%) for group A, and (453.69%,511.93%, and 524.28%) for group B compared with the reference column because of increase in the size of specimens and delay the appearance of cracks.

Structural Design and Experimental Verification of Precast Columns from High Performance Concrete

2015 ◽  
Vol 1106 ◽  
pp. 110-113 ◽  
Author(s):  
Ctislav Fiala ◽  
Jaroslav Hejl ◽  
Vladimira Tomalova ◽  
Vlastimil Bilek ◽  
Tereza Pavlu ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Experimental Verification ◽  
High Performance ◽  
Energy Savings ◽  
High Performance Concrete ◽  
Concrete Columns ◽  
Building Envelope ◽  
Structural Elements ◽  
Reinforced Concrete Columns ◽  
Common Solution

Paper presents some results of long-term research of a new optimized subtle precast construction system based on high performance silicate composites. The system is particularly aimed for building construction in passive or zero-energy standard. Subtle structural elements from high performance concrete (HPC) can be integrated into building envelope of energy efficient buildings with significant reduction of envelope structure and avoiding risk of thermal bridges. Significant advantages of subtle elements are material and energy savings during production, transport, manipulation and construction on building site.Paper presents experimental verification of connection between columns and beams ensured by Peikko ́s PCs corbels. Moreover, production of two prototypes of high performance fibre reinforced columns over two floors is presented. Prototypes were casted in ŽPSV a.s. plant, Litice nad Orlicí in June 2014. Complex LCA analysis of three various reinforced concrete columns was performed. Analysis covers construction life phase. Consequently, environmental impacts of assessed variants were compared and evaluated. Results show that it is possible to reduce some impacts on the environment from 16 up to 65% in comparison with common solution of reinforced concrete columns due to the utilization of excellent mechanical properties of high performance concrete that enables the design of subtle structural elements.

Experimental Analysis of Slender Concrete Columns at the Loss of Stability

2016 ◽  
Vol 249 ◽  
pp. 203-208
Author(s):  
Peter Kendický ◽  
Vladimír Benko ◽  
Tomáš Gúcky
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
Compressive Strain ◽  
Concrete Columns ◽  
Design Methods ◽  
Critical Cross Section ◽  
Loss Of Stability ◽  
Reinforced Concrete Columns ◽  
Non Linear

The use of non-linear methods for design of slender concrete columns by European standards. For the verification of non-linear design methods it is important to compare their results with results of experiments. Within the applied research of the Faculty of Civil Engineering at Slovak University of Technology in Bratislava in cooperation with the company ZIPP Bratislava LTD the experimental verification of the slender reinforced concrete columns was realized. In the paper the authors present the preparation and process one of three series of slender reinforced concrete columns, which were made to verify the reliability of various design methods. Columns of planned second series were designed from high performance concrete C100/115, but the material tests showed that the strength class of concrete was C70/85. The columns, subjected to axial force and bending moment were designed to fail due to loss of stability before the resistance of the critical cross-section is reached. The expected compressive strain in concrete was 1,5 ‰.

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