Improving the Impact Resistance of Reinforced Concrete

2014 ◽  
Vol 919-921 ◽  
pp. 1924-1929 ◽  
Author(s):  
Husain Abbas ◽  
Tarek Almusallam ◽  
Yousef Al-Salloum
Keyword(s):  
Reinforced Concrete ◽  
Split Hopkinson Pressure Bar ◽  
Impact Resistance ◽  
Concrete Structures ◽  
Material Behavior ◽  
Analytical Models ◽  
Impact Loads ◽  
Hopkinson Pressure Bar ◽  
Hybrid Fibers ◽  
The Impact

The strategic concrete structures are often required to resist impact loads arising from the projectile strike, falling weight, blast generated missile etc. The existing structures found deficient in resisting these loads are required to be retrofitted whereas the upcoming structures are required to be designed for expected impact loads. This paper explores the ways of strengthening existing reinforced concrete (RC) structures using externally bonded carbon fiber reinforced polymer (CFRP) sheets and improving the impact resistance of concrete by mixing hybrid fibers in its production. The impact response of concrete structures is assessed using experiments involving the impact of projectiles of different nose shapes on slab specimens. The material behavior at high strain rate is established using split Hopkinson pressure bar (SHPB) testing at varying strain rates. Analytical models are developed for predicting penetration depth, scabbing thickness, ballistic limit velocity and ejected mass. The experimental results were also validated through numerical modeling using LS-DYNA.

scholarly journals A new testing method for textile reinforced concrete under impact load

2018 ◽  
Vol 199 ◽  
pp. 11010 ◽  
Author(s):  
Marcus Hering ◽  
Manfred Curbach
Keyword(s):  
Reinforced Concrete ◽  
Large Scale ◽  
Impact Load ◽  
Impact Resistance ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Impact Loads ◽  
Textile Reinforced Concrete ◽  
Reinforcement Structure ◽  
Testing Method

Textile reinforced concrete, especially textile reinforced concrete with carbon fibres, was already been used for strengthening steel reinforced concrete structures under static loads up to now. The question is if the composite can also be used for strengthening structures against impact loads. The main goal of a current research project at the Technische Universität Dresden is the development and characterization of a reinforcement fabric with optimized impact resistance. But there is a challenge. There is the need to find the best combination of fibre material (glass, carbon, steel, basalt, …) and reinforcement structure (short fibres, 2D-fabrics, 3D-fabrics, …), but testing the large number of possible combinations is not possible with the established methods. In general, large-scale tests are necessary which are very expensive and time consuming. Therefore, a new testing method has been developed to deal with this large number of possible combinations of material and structural experiments. The following paper describes this new testing method to find the best fabric reinforcement for strengthening reinforced concrete structures against impact loads. The testing devise, which is located in the drop tower facility at the Otto Mohr Laboratory, and the test set-up are illustrated and described. The measurement equipment and the methods to evaluate the experimental results are explained in detail.

Strain Rate Effects in Porous Materials

1998 ◽  
Vol 521 ◽  
Author(s):  
J. Lankford ◽  
K. A. Dannemann
Keyword(s):  
Strain Rate ◽  
Gas Flow ◽  
Split Hopkinson Pressure Bar ◽  
Impact Resistance ◽  
Hopkinson Pressure Bar ◽  
Porous Metals ◽  
Strain Rate Effects ◽  
Open Cell ◽  
Rate Dependent ◽  
The Impact

ABSTRACTThe behavior of metal foams under rapid loading conditions is assessed. Dynamic loading experiments were conducted in our laboratory using a split Hopkinson pressure bar apparatus and a drop weight tester; strain rates ranged from 45 s−1 to 1200 s−1. The implications of these experiments on open-cell, porous metals, and closed- and open-cell polymer foams are described. It is shown that there are two possible strain-rate dependent contributors to the impact resistance of cellular metals: (i) elastic-plastic resistance of the cellular metal “skeleton,” and (ii) the gas pressure generated by gas flow within distorted open cells. A theoretical basis for these implications is presented.

Mitigating Impact Frailty of Concrete with Fiber Reinforcement

2011 ◽  
Vol 82 ◽  
pp. 26-35
Author(s):  
Nemy Banthia
Keyword(s):  
Reinforced Concrete ◽  
Historical Perspective ◽  
Dynamic Properties ◽  
Impact Resistance ◽  
Concrete Structures ◽  
Blast Loading ◽  
Fiber Reinforcement ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
The Impact

Since 9/11, there has been an increased interest in developing a better understanding of the properties of concrete structures under impact and blast loading. Although concrete, as a material, demonstrates extreme brittleness under dynamically applied loads, fortunately, fiber reinforcement significantly enhances such resistance. Yet, the dynamic properties of both concrete and fiber reinforced concrete (FRC) remain poorly understood. This paper provides a historical perspective of our efforts aimed at understanding the impact resistance of fiber reinforced concrete, highlights some of the issues and challenges encountered and identifies the emerging areas where further research is necessary.

scholarly journals Experimental and Modeling Studies of Stress Wave Propagation and Energy Dissipation Mechanism in Layered Composite Structures

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Youchun Zou ◽  
Chao Xiong ◽  
Junhui Yin ◽  
Huiyong Deng ◽  
Kaibo Cui ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Stress Wave ◽  
Composite Structures ◽  
Split Hopkinson Pressure Bar ◽  
Impact Resistance ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Stress Wave Propagation ◽  
Hopkinson Pressure Bar ◽  
Transmitted Waves ◽  
The Impact

Four composite structures (SiC/UHMWPE/TC4, SiC/TC4/UHMWPE, SiC/UHMWPE/MR/TC4, and SiC/TC4/MR/UHMWPE) were prepared using silicon carbide (SiC) ceramics, ultrahigh molecular weight polyethylene (UHMWPE), titanium alloy (TC4), and metal rubber (MR). The transmitted waves, failure forms, stress wave propagations, and energy dissipations of the composite structures were studied through Split Hopkinson Pressure Bar (SHPB) tests and numerical simulations. The results show that MR in composite structures can delay, attenuate, and smooth the stress wave, thereby reducing SiC damage. UHMWPE on the back of SiC provides cushioning for SiC, while TC4 on the back of SiC aggravates the damage of SiC. The composite structures with MR mainly dissipate the impact energy by reflecting energy, and the energy dissipation performance is better than that of composite structures without MR. A comprehensive comparison of transmitted waves, damage forms, stress wave propagations, and energy dissipations of the four composite structures shows that SiC/UHMWPE/MR/TC4 structure has the best impact resistance. Increasing the thickness of MR in the composite structures can improve the impact resistance, but there are also stress concentration and interface tensile stress.

scholarly journals Size Effect in the Split Hopkinson Pressure Bar Experiment

2022 ◽  
Vol 2160 (1) ◽  
pp. 012065
Author(s):  
Hailiang Nie ◽  
Weifeng Ma ◽  
Junjie Ren ◽  
Ke Wang ◽  
Jun Cao ◽  
...  
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Dynamic Testing ◽  
Impact Resistance ◽  
Dynamic Mechanical Properties ◽  
Experimental Results ◽  
Hopkinson Pressure Bar ◽  
Practical Engineering ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
The Impact

Abstract For many structures, their service environment is very strict, and the requirements for the impact resistance of materials are very high. Therefore, the dynamic testing method has important scientific significance and application value for practical engineering. Split Hopkinson pressure bar (SHPB) is one of the most common experimental methods for obtaining dynamic mechanical properties of materials. However, there is no uniform standard for the size of the bars and specimens used in the test. Theoretically, the size has little influence on the experimental results, but it has not been proved by experiments. This paper mainly studies the influence of device/specimen sizes of split Hopkinson pressure bar through experiments, it is demonstrated that the sizes of bars and specimen have little effect on experimental results.

scholarly journals Impact resistance of sisal fiber reinforced concrete

2018 ◽  
Vol 7 (2) ◽  
pp. 742
Author(s):  
Sabapathy Y K ◽  
Ramya Sajeevan ◽  
Rekha J ◽  
Vishal V ◽  
Sabarish S ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Impact Load ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Sisal Fiber ◽  
Impact Loads ◽  
Fiber Reinforced ◽  
Impact Machine ◽  
Sisal Fibers ◽  
The Impact

Concrete is typically a brittle material which is prone to damage when subjected to heavy impact loads. To overcome this weakness, concrete is reinforced with fibers as fibers are effective in withstanding heavy impact loads. The main objective of this experimental investigation is to study the influence of sisal fibers in concrete under impact load. The impact specimens are prepared using three grades of concrete- M20, M30 and M40 with five varying percentage of fibers- 0%, 0.5%, 1%, 1.5% and 2%. The mix designs of the respective grades of concrete are made as per the Indian standards. The specimens after curing for 28 days were subjected to impact loads using the standard drop weight impact machine confining to ASTM standards. Also cube and cylinder specimens are prepared and tested to ascertain the compressive and tensile strength of the sisal fiber reinforced concrete. The results indicated that the sisal fibers are effective in increasing the impact strength of concrete.

Review on impact response of reinforced concrete beams: Contemporary understanding and unsolved problems

2021 ◽  
pp. 136943322199771
Author(s):  
Thong M Pham ◽  
Wensu Chen ◽  
Hong Hao
Keyword(s):  
Reinforced Concrete ◽  
Experimental Testing ◽  
Structural Response ◽  
Impact Testing ◽  
Reinforced Concrete Beams ◽  
Impact Response ◽  
Analytical Models ◽  
Impact Loads ◽  
Rc Beams ◽  
The Impact

Designing protective reinforced concrete (RC) beams against impact loadings is a challenging task. It requires a comprehensive understanding of the structural response of RC beams subjected to impact loads. Significant research efforts have been spent to unveil the impact response of RC beams by using analytical models, experimental testing, or numerical investigations. However, these studies used various assumptions in the analytical derivations and different test setups in the impact testing, which led to significantly different responses and observations of similar structures and similar loading conditions. For example, a minor change in contact surface can triple the maximum impact force of identical RC beams. This study provides a review of the contemporary understandings of the RC beam responses to impact loads, and explains the different observations and conclusions. Some unsolved issues for protective structures, that is, RC beams to resist impulsive loads are also discussed. It is suggested that future studies should take into consideration the conditions of the test setup, simplifications and assumptions made in analytical derivations for better interpretations of the obtained results.

SHPB Dynamic Experiment on Silica Fume Concrete

2013 ◽  
Vol 631-632 ◽  
pp. 771-775 ◽  
Author(s):  
Rong Jun Chen ◽  
Hong Wei Liu ◽  
Rui Zeng
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Silica Fume ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Impact Resistance ◽  
Dynamic Mechanical Properties ◽  
Hopkinson Pressure Bar ◽  
The Impact

Dynamic mechanical properties of silica fume concrete in a number of strain rate under the conditions of dynamic compression mechanical properties subjected to various strain rates were studied, and gained the stress versus strain curves, details of an experimental investigation using 74 mm-diameter split Hopkinson pressure bar(SHPB) apparatus were presented. The results showed that: The admixture of silica fume concrete impact resistance, especially under the impact of the performance of high-speed has a very important influence, with the impact velocity increased, the strain rate increase, and its impact more obvious.

Effect of combined drink cans and steel fibers on the impact resistance and mechanical properties of concrete

2020 ◽  
Vol 14 (2) ◽  
pp. 6734-6742
Author(s):  
A. Syamsir ◽  
S. M. Mubin ◽  
N. M. Nor ◽  
V. Anggraini ◽  
S. Nagappan ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Reinforced Concrete ◽  
Impact Resistance ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Fiber Reinforced ◽  
Indirect Tensile ◽  
The Impact

This study investigated the combine effect of 0.2 % drink cans and steel fibers with volume fractions of 0%, 0.5%, 1%, 1.5%, 2%, 2.5% and 3% to the mechanical properties and impact resistance of concrete. Hooked-end steel fiber with 30 mm and 0.75 mm length and diameter, respectively was selected for this study.  The drinks cans fiber were twisted manually in order to increase friction between fiber and concrete. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the strength performance of concrete, especially the compressive strength, flexural strength and indirect tensile strength. The results of the experiment showed that the combination of steel fibers and drink cans fibers improved the compressive strength, flexural strength and indirect tensile strength by 2.3, 7, and 2 times as compare to batch 1, respectively. Moreover, the impact resistance of fiber reinforced concrete has increase by 7 times as compared to non-fiber concretes. Moreover, the impact resistance of fiber reinforced concrete consistently gave better results as compared to non-fiber concretes. The fiber reinforced concrete turned more ductile as the dosage of fibers was increased and ductility started to decrease slightly after optimum fiber dosage was reached. It was found that concrete with combination of 2% steel and 0.2% drink cans fibers showed the highest compressive, split tensile, flexural as well as impact strength.    

Analysis of the Impact of the Frequency Range of the Tensometer Bridge and Projectile Geometry on the Results of Measurements by the Split Hopkinson Pressure Bar Method

2013 ◽  
Vol 20 (4) ◽  
pp. 555-564 ◽  
Author(s):  
Wojciech Moćko
Keyword(s):  
Test Bench ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Deformation ◽  
Spectral Width ◽  
Hopkinson Pressure Bar ◽  
Computing Environment ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
The Impact ◽  
Bench Model

Abstract The paper presents the results of the analysis of the striker shape impact on the shape of the mechanical elastic wave generated in the Hopkinson bar. The influence of the tensometer amplifier bandwidth on the stress-strain characteristics obtained in this method was analyzed too. For the purposes of analyzing under the computing environment ABAQUS / Explicit the test bench model was created, and then the analysis of the process of dynamic deformation of the specimen with specific mechanical parameters was carried out. Based on those tests, it was found that the geometry of the end of the striker has an effect on the form of the loading wave and the spectral width of the signal of that wave. Reduction of the striker end diameter reduces unwanted oscillations, however, adversely affects the time of strain rate stabilization. It was determined for the assumed test bench configuration that a tensometric measurement system with a bandwidth equal to 50 kHz is sufficient

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