scholarly journals Dynamic Characteristics of Lightweight Aggregate Self-Compacting Concrete by Impact Resonance Method

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Ning Li ◽  
Sisi Zhang ◽  
Guangcheng Long ◽  
Zuquan Jin ◽  
Yong Yu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Shear Modulus ◽  
Dynamic Loading ◽  
Damping Ratio ◽  
Resonance Method ◽  
Lightweight Aggregate ◽  
Damping Capacity ◽  
Self Compacting Concrete ◽  
Impact Resonance ◽  
Dynamic Loading Conditions

Understanding the dynamic behavior of Lightweight Aggregate Self-Compacting Concrete (LWASCC) is of importance to the safety of concrete structures serving in dynamic loading conditions. In this study, the fundamental dynamic properties of LWASCC with three types of LWA were investigated by the impact resonance method. Results show that the dynamic elastic and shear modulus generally decrease with the increase of LWA volume fraction, whereas three types of LWA exert limited influence on dynamic Poisson’s ratio. The dynamic elastic and shear modulus show good linear dependence upon compressive strength. The inclusion of three types of LWA significantly increases the damping ratio, indicating significantly enhanced damping capacity of LWASCC under dynamic loading conditions. The damping ratio of LWASCC is improved by 2.0%, 4.4%, and 2.9% when adding 1% (by volume) expanded clay, rubber, and expanded polystyrene, respectively. The compressive strength and dynamic performances of LWASCC are highly influenced by the intrinsic properties (elastic modulus, damping capacity, wettability, etc.) and geometrical characteristics (size, surface roughness, etc.) of LWA, as well as the LWA-matrix bonding capacity.

scholarly journals Dynamic Properties of Clean Sand Modified with Granulated Rubber

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Dervis Volkan Okur ◽  
Seyfettin Umut Umu
Keyword(s):  
Shear Modulus ◽  
Dynamic Characteristics ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Relative Size ◽  
Cyclic Behavior ◽  
Damping Capacity ◽  
Resonant Column ◽  
Strain Dependent

Waste automobile tires are used as additives or replacements instead of traditional materials in civil engineering works. In geotechnical engineering, tires are shredded to certain sizes and mixed with soil, especially used as backfill material behind retaining walls or fill material for roadway embankments. Compared to soil, rubber has high damping capacity and low shear modulus. Therefore, it requires the determination of the dynamic characteristics of rubber/soil mixtures. In this paper, the cyclic behavior of recycled tire rubber and clean sand was studied, considering the effects of the amount and particle size of the rubber and confining stresses. A total of 40 stress-controlled tests were performed on an integrated resonant column and dynamic torsional shear system. The effects of the relative size and proportion of the rubber on the dynamic characteristics of the mixtures are discussed. The dynamic properties, such as the maximum shear modulus, strain-dependent shear modulus, and damping ratio, are examined. For practical purposes, simple empirical relationships were formulated to estimate the maximum shear modulus and the damping ratio. The change in the shear modulus and damping ratio with respect to shear strain with 5% of rubber within the mixture was found to be close to the behavior of clean sand.

scholarly journals Effect of internal curing on performance of self-compacting concrete by using sustainable materials

2018 ◽  
Vol 162 ◽  
pp. 02017
Author(s):  
Nada Aljalawi ◽  
Amar Yahia AL-Awadi
Keyword(s):  
Compressive Strength ◽  
Lightweight Aggregate ◽  
Internal Curing ◽  
Modulus Of Rupture ◽  
Limestone Powder ◽  
Partial Replacement ◽  
Hardened Concrete ◽  
Self Compacting Concrete ◽  
Curing Conditions ◽  
Compressive Strength Test

This paper is devoted to investigate the effect of internal curing technique on the properties of self-compacting concrete. In this study, self-compacting concrete is produced by using limestone powder as partial replacement by weight of cement with percentage of (5%), sand is partially replaced by volume with saturated fine lightweight aggregate which is thermostone aggregate as internal curing material in three percentages of (5%, 10%, 15%) for self-compacting concrete, and the use of two external curing conditions which are water and air. The experimental work was divided into three parts: in the first part, the workability tests of fresh self-compacting concrete were conducted. The second part included conducting compressive strength test and modulus of rupture test at ages of (7, 28 and 90) days. The third part included doing the shrinkage test at age of (7, 14, 21, 28) days. The results show that internally cured self-compacting concrete has the best workability and the best properties of hardened concrete which include (compressive strength, modulus of rupture) of externally cured self-compacting concrete with both water and air as compared with reference concretes. Also, the hardened properties of internally cured self-compacting concrete with percentage of (5%) with thermostone aggregate is the best as compared with that of percentages (10% and 15%) in both external curing conditions. In general, the results of shrinkage test have shown reduction in shrinkage of internally cured self-compacting concrete as compared with reference concretes and this reduction increases with increase in the thermostone aggregate content-within-self-compacting-concrete.

Experimental Study of FRP Rubber Bearing

2010 ◽  
Vol 168-170 ◽  
pp. 1621-1624 ◽  
Author(s):  
Hua Zhang ◽  
Tian Bo Peng ◽  
Jian Zhong Li ◽  
Wen Xiao Li
Keyword(s):  
Experimental Study ◽  
Shear Modulus ◽  
Damping Ratio ◽  
Compression Modulus ◽  
Damping Capacity ◽  
Fiber Reinforce Polymer ◽  
Damping Property ◽  
Rubber Bearing ◽  
Laminated Rubber Bearing ◽  
Fiber Reinforce

FRP (fiber reinforce polymer) rubber bearing is a novel isolator improved from traditional laminated rubber bearing. Several specimens were manufactured to study the mechanic properties of FRP rubber bearing. Vertical experiments are conducted to study the compression capacity and compression modulus of the bearing and horizontal experiments are conducted to study the shear modulus and damping property of the bearing. Hysteretic curve and damping ratio of each specimen are derived from the experiments. The results show that the performance of FRP rubber bearing matches that of multiplayer rubber bearing but have good damping capacity.

scholarly journals The Effect of Styrofoam Artificial Lightweight Aggregate (ALWA) on Compressive Strength of Self Compacting Concrete (SCC)

2018 ◽  
Vol 4 (9) ◽  
pp. 2111 ◽  
Author(s):  
Dhiafah Hera Darayani ◽  
Tavio Tavio ◽  
I G. P. Raka ◽  
Puryanto Puryanto
Keyword(s):  
Compressive Strength ◽  
Modulus Of Elasticity ◽  
Coarse Aggregate ◽  
Lightweight Aggregate ◽  
Structural Members ◽  
Self Compacting Concrete ◽  
Conventional Concrete ◽  
Concrete Material ◽  
Compressive Strength Test ◽  
The Impact

Self-compacting concrete (SCC) is a fresh concrete that is able to flow and fill up the formwork by itself without the need of a vibrator to compact it. One of the reasons that causes the damage of a building structure during an earthquake is the heavy weight of its structural members which are from the high density of the material used such concrete material. Lightweight aggregate is one of the solutions to reduce the weight of the structure. Therefore, the SCC using the artificial lightweight aggregate (ALWA) is one of the solutions to reduce the self-weight (dead load) of a structure. This research was conducted to investigate the impact of the use of ALWA in conventional concrete and SCC in terms of its compressive strength and modulus of elasticity. To study the impact of the use of ALWA in SCC, several variation of percentage of ALWA as a substitution to the natural coarse aggregate was examined. The proportions of ALWA as a replacement to the coarse aggregate were 0%, 15%, 50%, and 100%. The test specimens were the cylindrical concrete of 200 mm in height and 100 mm in diameter for both compressive strength and modulus of elasticity tests. The results of the compressive strength test indicated that the higher the percentage of ALWA used in SCC, the lower the compressive strength of the concrete. The addition of ALWA as a substitution to the natural coarse aggregate to conventional concrete and SCC was found optimum at 15% replacement with the compressive strength of conventional concrete and SCC of 21.13 and 28.33 MPa, respectively. Whereas, the modulus of elasticity of the conventional concrete and SCC were found to be 20,843.99 and 23,717.77 MPa, respectively.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

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