Experimental and mesoscopic investigation on the dynamic properties of coral aggregate concrete in compression

Author(s):  
ZhangYu Wu ◽  
JinHua Zhang ◽  
HongFa Yu ◽  
Qin Fang ◽  
Li Chen ◽  
...  
2020 ◽  
Vol 5 (6) ◽  
pp. 702-707
Author(s):  
Fariborz M. Tehrani ◽  
Nazmieh A. Masswadi ◽  
Nathan M. Miller ◽  
Arezoo Sadrinezhad

This paper presents the results of an experimental study to investigate dynamic properties of polypropylene fiber-reinforced concrete beams with lightweight expanded shale (ES) and tire-derived aggregates (TDA). The mixture design followed past experiences in combining ES and TDA to enhance toughness and energy absorption in flexural behavior. The new mixture also contained 2% fiber by volume to improve such properties further. Experiments included compressive testing on cylindrical specimens as well as flexural testing on rectangular specimens to verify mechanical properties of fiber-reinforced tire-derived lightweight aggregate concrete (FRTDLWAC) subject to static loading. The results of these experiments confirmed reduction of mechanical strength due to addition of TDA and improvements in flexural strength due to fiber reinforcement. The dynamic testing included non-destructive impact loads applied to flexural specimens using a standard Schmidt hammer. A high-speed camera recorded the response of the system at 200 frames per second to allow detailed observations and measurements. Interpretation of energy-based dynamic results revealed that TDA enhances energy absorption through damping in flexural behavior. Results also indicated that fiber reinforcement reduces the amount of absorbed dynamic energy, even though; it enhances the absorbed strain energy due to crack bridging effect.


2015 ◽  
Vol 67 (6) ◽  
pp. 282-293 ◽  
Author(s):  
Linlin Shi ◽  
Licheng Wang ◽  
Yupu Song ◽  
Lu Shen

2017 ◽  
Vol 69 (6) ◽  
pp. 317-319
Author(s):  
Linlin Shi ◽  
Licheng Wang ◽  
Yupu Song ◽  
Lu Shen ◽  
José R. Martí-Vargas

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2004 ◽  
Author(s):  
Chonggang Zhou ◽  
Xingwang Pei ◽  
Wenlong Li ◽  
Yijun Liu

In this study, recycled aggregate concrete (RAC) modified with polypropylene fiber (PP) and air-entraining agent (AGA) was prepared, and the effects of PP and AGA on the static (compressive strength, Young’s modulus, and splitting tensile strength) and dynamic properties (dynamic modulus of elasticity and damping ratio) of RAC were investigated. The experimental results showed that the addition of an AGA and PP had a favorable effect on the damping ratio of the concrete, however, the addition of the AGA had a slightly negative effect on the mechanical performance of the concrete. The AGA and PP contents required to achieve the optimum damping ratio of the concrete with the least reduction in the mechanical performance were 0.02% and 0.10%, respectively. Furthermore, the addition of AGA was more effective than that of PP in improving the damping property of the concrete.


2021 ◽  
Vol 8 ◽  
pp. 56-61
Author(s):  
Shamsoon Fareed ◽  
Asad-ur-Rehman Khan ◽  
Samra Masood

Over the years the construction waste has enormously increased, this may be attributed to different factors such as (i) demolition (ii) accidents (iii) impact loads (iv) earthquakes. These activities have caused an increasing burden on already exhausted waste management system globally. As a result, the concrete waste produced in a large quantity has become a major issue to manage due to limited landfill sites. Therefore, the recycling of waste concrete can prove to be beneficial and necessary for the environmental preservation and effective utilization of natural resources. Number of studies have been conducted to study the static mechanical properties of recycled aggregate concrete; however, limited test data has been published which focused on the dynamic properties of the concrete prepared with recycled coarse aggregates. Therefore, in this investigation aim was to study the behavior of recycled aggregates concrete under increasing dynamic compressive loading. For this purpose, cylindrical specimens having a diameter of 100 mm and height of 200 mm were used. These specimens have been prepared with constant concrete mix ratio, having varying percentages of RA such as 0%, 30%, and 50% 70 % and 100%. The dynamic compressive behaviour was studied by using drop hammer system. The height drop hammer system consist of a frame having a maximum height of 15ft. Firstly, three samples (1, 1R, 2R) from each percentage replacement (0%, 30%, 50%, 70% and 100%) were tested on six different velocities of 2.44m/s, 3.45m/s, 4.23m/s, 4.89m/s, 5.46m/s and 7.45m/s with varying strain rates of 12.04/s, 17.00/s, 20.83/s, 24.08/s, 26.89/s and 36.73/s respectively. Weight of the drop hammer was 10 kg. Based on the detailed experimental investigation, it was found that the behaviour of the recycled aggregate concrete under dynamic loading differ significantly from the static loading.


Author(s):  
Takaaki OHKUBO ◽  
Takuya HASEGAWA ◽  
Hitoshi HAMASAKI ◽  
Hisashi SUGIYAMA ◽  
Katsuro KAMIMURA ◽  
...  

2021 ◽  
Vol 247 ◽  
pp. 107636
Author(s):  
Zhangyu Wu ◽  
Jinhua Zhang ◽  
Qin Fang ◽  
Hongfa Yu ◽  
Haiyan Ma

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhiqing Zhao

For the purpose of studying the dynamic properties of lightweight aggregate concrete, dynamic performance tests under uniaxial compression were conducted by considering 10 different strain rates ranging from 10−5/s to 10−1/s, from which the stress-strain curves under various compressive loads were obtained. From the stress-strain curves, parameters including peak stress, peak strain, and elastic modulus of lightweight aggregate concrete, as well as the concrete failure mode, were determined and examined. By reviewing the relevant literature on ordinary concrete, the dynamic properties of lightweight aggregate concrete were analyzed accordingly. Meanwhile, by applying the dynamic elastoplastic damage constitutive model, the effect of dynamic rate on lightweight aggregate concrete was calculated. The experimental results showed that the damage mode of lightweight aggregate concrete under the static and dynamic strain rates belonged to shear failure, which is different from that of ordinary concrete (binding material failure). On the other hand, it was also found that the peak stress and elastic modulus of lightweight aggregate concrete could be increased by 54.48% and 28.75%, respectively, with the increase of strain rate, suggesting that the loading strain rate has a stronger influence on lightweight aggregate concrete than on ordinary concrete. Based on the experimental data, both the peak stress and nondimensionalized elastic modulus are in linear relationship with the logarithm of the nondimensionalized strain rate. Moreover, the established constitutive model had been verified as an effective and reliable tool for simulating the dynamic rate effect of lightweight aggregate concrete.


Author(s):  
R.F. Stump ◽  
J.R. Pfeiffer ◽  
JC. Seagrave ◽  
D. Huskisson ◽  
J.M. Oliver

In RBL-2H3 rat basophilic leukemia cells, antigen binding to cell surface IgE-receptor complexes stimulates the release of inflammatory mediators and initiates a series of membrane and cytoskeletal events including a transformation of the cell surface from a microvillous to a lamellar topography. It is likely that dynamic properties of the IgE receptor contribute to the activation of these responses. Fewtrell and Metzger have established that limited crosslinking of IgE-receptor complexes is essential to trigger secretion. In addition, Baird and colleagues have reported that antigen binding causes a rapid immobilization of IgE-receptor complexes, and we have demonstrated an apparent increase with time in the affinity of IgE-receptor complexes for antigen.


2006 ◽  
Vol 73 ◽  
pp. 109-119 ◽  
Author(s):  
Chris Stockdale ◽  
Michael Bruno ◽  
Helder Ferreira ◽  
Elisa Garcia-Wilson ◽  
Nicola Wiechens ◽  
...  

In the 30 years since the discovery of the nucleosome, our picture of it has come into sharp focus. The recent high-resolution structures have provided a wealth of insight into the function of the nucleosome, but they are inherently static. Our current knowledge of how nucleosomes can be reconfigured dynamically is at a much earlier stage. Here, recent advances in the understanding of chromatin structure and dynamics are highlighted. The ways in which different modes of nucleosome reconfiguration are likely to influence each other are discussed, and some of the factors likely to regulate the dynamic properties of nucleosomes are considered.


Sign in / Sign up

Export Citation Format

Share Document