scholarly journals Impact Resistance of Concrete Structures

2015 ◽  
Vol 2015 ◽  
pp. 1-8
Author(s):  
R. Drathi
Keyword(s):  
High Pressures ◽  
Damage Model ◽  
Impact Resistance ◽  
Concrete Structures ◽  
Strain Rate Effects ◽  
Mesh Free ◽  
Mesh Free Method ◽  
The Impact ◽  
Impact Experiments ◽  
Geometric Correlation

We present simulations on the resistance of concrete structures due to impact loading. Therefore, a mesh-free method is exploited in combination with a viscous damage model that accounts for strain rate effects and high pressures that commonly occur in those events. In contrast to many other studies in the literature, we account for uncertainties in the material parameters by subjecting them to a probability distribution function. Furthermore, we also consider the geometric correlation inside the concrete and show that this geometric correlation has a minor influence on the predicted results. All numerical results are compared to the impact experiments performed by Hanchak and coworkers as well as our own impact experiments.

Experimental Research on the Vibration Reduction and Impact Resistance Performances of Offshore Structure Based on Magnetorheological Damper

2008 ◽  
Author(s):  
Zhongchao Deng ◽  
Dagang Zhang ◽  
Xiongliang Yao
Keyword(s):  
Vibration Reduction ◽  
Impact Resistance ◽  
Mr Damper ◽  
Magnetorheological Damper ◽  
Offshore Structure ◽  
Loading System ◽  
Vibration Experiment ◽  
Exciting Forces ◽  
The Impact ◽  
Impact Experiments

This paper presents a new kind of vibration reduction and impact resistance isolator system based on magnetorheological technique, and its experiment results. The vibration and impact experiments were designed using MTS hydraulic loading system. There were many load cases being applied in the experiment with different mass of the model, exciting forces, and controllable electricity of MR damper (Magnetorheological Damper). The experiment results indicate that this isolator system can control the vibration response very well, especially near the natural frequency of the system; and the isolator system has a good performance in the impact experiment too, the response acceleration was evidently reduced, but the characteristic of MR damper was different form its performance in vibration experiment.

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.

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.

scholarly journals Influence of Incremental Impact on the Damage of Coal-Rock under Unidirectional Constraint

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Hongbao Zhao ◽  
Huan Zhang ◽  
Jinyu Li ◽  
Nansong Ju ◽  
Zhijie Wen
Keyword(s):  
Impact Load ◽  
Damage Model ◽  
Impact Resistance ◽  
Cumulative Damage ◽  
Axial Pressure ◽  
Loading Test ◽  
Damage Degree ◽  
Coal Rock ◽  
The Impact ◽  
Pendulum Impact

Taking the briquette sample as research object, the influence of the incremental impulse (momentum) on the damage of coal-rock under different uniaxial axial pressure was studied by using the self-developed pendulum impact dynamic loading test device, cooperating with the ultrasonic detection device. Meanwhile, the influence of constant impulse on the damage degree of coal-rock was compared. The results show that the damage degree of coal-rock increases with the increase of the impulse, and the damage fitting curve is upward concave, indicating that the coal sample tends to accelerating failure. Moreover, with the increase of axial pressure, the variation gradient of the damage degree of coal-rock tends to moderate and the cumulative damage degree decreases under the same impulse, and the impact resistance of coal-rock increases. When the impulse is constant, the damage degree of coal-rock increases with the number of impact, and the damage curve is upward convex, indicating that coal-rock has a tendency to slow down the damage. The cumulative damage degree of coal-rock decreases with the increase of axial pressure, and the number of impact needed to destroy coal-rock is increased. In addition, the damage model of coal-rock was proposed, and the criterion of coal-rock damage was obtained, which shows that the damage degree of coal-rock increases with the increase of impact load and decreases with the increase of static axial load.

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.

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.    

scholarly journals Effect of SWCNT-Tuball Paper on the Lightning Strike Protection of CFRPs and Their Selected Mechanical Properties

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3140
Author(s):  
Kamil Dydek ◽  
Anna Boczkowska ◽  
Rafał Kozera ◽  
Paweł Durałek ◽  
Łukasz Sarniak ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Copper Foil ◽  
Impact Resistance ◽  
Mechanical Analysis ◽  
Lightning Strike ◽  
Single Wall Carbon Nanotubes ◽  
Carbon Fibre Reinforced Polymer ◽  
The Impact

The main aim of this work was the investigation of the possibility of replacing the heavy metallic meshes applied onto the composite structure in airplanes for lightning strike protection with a thin film of Tuball single-wall carbon nanotubes in the form of ultra-light, conductive paper. The Tuball paper studied contained 75 wt% or 90 wt% of carbon nanotubes and was applied on the top of carbon fibre reinforced polymer before fabrication of flat panels. First, the electrical conductivity, impact resistance and thermo-mechanical properties of modified laminates were measured and compared with the reference values. Then, flat panels with selected Tuball paper, expanded copper foil and reference panels were fabricated for lightning strike tests. The effectiveness of lightning strike protection was evaluated by using the ultrasonic phased-array technique. It was found that the introduction of Tuball paper on the laminates surface improved both the surface and the volume electrical conductivity by 8800% and 300%, respectively. The impact resistance was tested in two directions, perpendicular and parallel to the carbon fibres, and the values increased by 9.8% and 44%, respectively. The dynamic thermo-mechanical analysis showed higher stiffness and a slight increase in glass transition temperature of the modified laminates. Ultrasonic investigation after lightning strike tests showed that the effectiveness of Tuball paper is comparable to expanded copper foil.

Statistical micromechanical damage model for SH-SFRC under tensile load considering the interfacial slip-softening and matrix spalling effects

2021 ◽  
pp. 105678952110112
Author(s):  
Hehua Zhu ◽  
Xiangyang Wei ◽  
J Woody Ju ◽  
Qing Chen ◽  
Zhiguo Yan ◽  
...  
Keyword(s):  
Strain Hardening ◽  
Steel Fiber ◽  
Damage Model ◽  
Fiber Reinforced Concrete ◽  
Uniaxial Tensile ◽  
Interfacial Slip ◽  
Fiber Reinforced ◽  
Micromechanical Damage ◽  
The Impact ◽  
Micromechanical Damage Model

Strain hardening behavior can be observed in steel fiber reinforced concretes under tensile loads. In this paper, a statistical micromechanical damage framework is presented for the strain hardening steel fiber reinforced concrete (SH-SFRC) considering the interfacial slip-softening and matrix spalling effects. With a linear slip-softening interface law, an analytical model is developed for the single steel fiber pullout behavior. The crack bridging effects are reached by averaging the contribution of the fibers with different inclined angles. Afterwards, the traditional snubbing factor is modified by considering the fiber snubbing and the matrix spalling effects. By adopting the Weibull distribution, a statistical micromechanical damage model is established with the fracture mechanics based cracking criteria and the stress transfer distance. The comparison with the experimental results demonstrates that the proposed framework is capable of reproducing the SH-SFRC’s uniaxial tensile behavior well. Moreover, the impact of the interfacial slip-softening and matrix spalling effects are further discussed with the presented framework.

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