Papers by Keyword: Impact Load

Abstract: Sabo soil-cement has the advantages of reducing the amount of sediment transported, reducing costs by using local sediment, and a zero-emission construction method. In addition, the strength development of Sabo soil-cement is based on the interaction between soil compaction and cement hydration. The strength can be determined based on the compressive strength obtained from uniaxial compression tests. However, dynamic loads, such as debris flows, are not evaluated. In this study, an impact loading experiment is conducted on a Sabo soil-cement specimen to examine the impact resistance. In addition, the relationship between the dropping weight accumulation energy and the collapsed volume and the relationship between the dropping weight energy and compressive strength are evaluated to determine the impact resistance of Sabo soil-cement. The results show that the greater the compressive strength, the greater the accumulated weight energy. In addition, there is a proportional relationship between the collapsed volume and dropping weight accumulation energy, and the relationship between the maximum impact load and weight energy increases linearly until cracks occur in the specimen. The impact spectrum of the specimen with a low compressive strength reduces the impact load on the collision surface. Therefore, if the compressive strength of the Sabo soil-cement is high, it has a high impact resistance against the impact load on the collision surface. On the other hand, if the compressive strength is low, Sabo soil-cement absorbs the impact force.

Abstract: High strength Engineered Cementitious Composite (HS-ECC) is a promising material to be used in protective structures. Due to its high manufacturing efforts and cost compared to conventional concrete, nonlinear finite element (FE) simulation is performed to study the influence of replacing HS-ECC layers with concrete under drop weight impact load. Both materials are simulated using the MAT_72R3 material model impeded in LS-DYNA and verified with experimental results. Several FE slab models were developed to compare the impact responses of different configurations. This study as a whole will provide a guideline for researchers to carry out a performance and cost optimization for protective structure elements.

Abstract: The objective of this paper is to calculate the influential properties of concrete. These are the dynamic properties of sustainable concrete in the situation in which metal waste can found within its components. Growing the rate of pollution in the world, a fast decrease of the original resource, the requirement for utilization more areas of natural land, and increase the price of the newly available area are the reasons that make the researchers give great attention to the new concrete (green concrete) and destruction of unwanted material in the green mix. The concept of reuse aimed at sustainable structures was implemented within the current paper through consuming metal waste of cans and bottle caps in concrete. The waste materials were consumed in two modes; at 1^st mode, it was applied in the role of fibres and mixed using 15% by weight of cement. On the 2^nd mode, it was applied as coarse aggregate with 25% replaced by volume. The procedure includes testing 4 concrete mixes. The estimated properties were the flexural and compressive strengths, besides modulus of elasticity. Adding bottle caps (waste materials fibres) in concrete led to enhancement in strengths. The use of walls of cans (waste materials fibres) in concrete reduced the strengths. While in the case of compacted bottle caps plus pull-tab of cans (waste materials aggregate), concrete mechanical properties a little below the reference mix. The dynamic properties of concrete contain these types of waste under impact load were determined. As known, the dynamic properties are so helpful in the strategy that deals with civil constructions put in danger of impact loads like runways, gas explosion, etc. CEB-FIP (2010) code provides wide-ranging formulas to predict the strain change of concrete. The dynamic properties are determined by this code with consideration strain level between (10^-2-10⁰). In this range, dynamic loads in the civil constructions at the level of quasi-static strain were predicted.

Abstract: 10mm thickness AZ31B magnesium alloy was used as the friction stir welding object in this study. Different welding joints were obtained by setting different friction stir welding parameters. Metallographic analysis and impact loading test were carried out on the joint area. The experiment results show that (i) when the rotational speed of the stirring head is 600rpm and the welding speed is 120mm/min, the microstructure of the joint has the characteristics of compactness, thinning, and large-area twinning, which is beneficial to improve the plasticity of the joint area; (ii) the impact load of the joint is the highest, but lower than that of the base material, which is 95.5% of the base material; (iii) the fracture of impact specimen presents ductile fracture.

Abstract: This research focuses on studing the main points that concern on the behavior of reactive powder concrete (RPC) slab reinforced by smeared steel fibers subjected to impact load. The rectangular pulse force is used to represent an impact load. The material properties of the reactive powder concrete with the smeared reinforcement are simulated in the range of elastic behavior. The numerical modeling of the RPC slab structure with smeared steel fibers reinforcement is implemented by using ANSYS-LS-DYNA-software. The mode shapes and frequencies values of the RPC slab model are extracted by modal analysis. Impact load analysis of the RPC slab model with smeared steel fibers reinforcement is carried out for different cases. The effect of different amounts of smeared reinforcement and different locations of impact load are investigated. The results show that the first mode shape is governing impact load problems. Also, the effect of smeared reinforcement is so small within elastic range. In addition, it is observed there is a simple ratio between amount of smeared reinforcement and maximum displacement in force vibration.

Abstract: The impact resistance of micro-steel fiber-reinforced and hybrid fiber-reinforced reactive powder concrete is investigated in this study. Six groups of specimens were prepared with 2.5% volumetric contents of different combinations of fibers. For this purpose, micro-steel fibers with 6 and 15 mm length in addition to polypropylene fibers were used. Each group includes 12 identical specimens. The impact tests were conducted using the repeated drop-weight impact test of ACI 544-2R. However, higher drop-height (700 mm) and drop-weight (10 kg) were adopted to accelerate the failure and reduce the effort required to crack the specimens. The test results showed that the use of only 15 mm micro-steel fiber led to much higher impact resistance than other micro-steel fiber combinations. The recorded number of blows for the group with SF15 was 247, while those of SF6 and combined SF6 and SF15 were 127 and 112, respectively. The replacement of 0.5% of micro-steel fiber by 0.5% of PP fiber was found to reduce the impact resistance regardless of the type or combination of the used micro-steel fiber.

Abstract: A group of concrete spilitting tensile test was carried out by using the drop test machine Studying on the inertial effect on the dynamic tensile strength of concrete under different working conditions. The result show:with the increase of the drop height and quailty, peak load, loading rate of the concrete are increasing gradually.peak load of the test group is slightly higher than control group, The inertia effect has a certain influence on the dynamic tensile strength of concrete.

Abstract: The current research addresses the effect of impact load on Reinforced Concrete (RC) slabs strengthened by Expanded Polystyrene (EPS) and/ or Glass Fiber Reinforced Polymer (GFRP) sheets. A total of five slabs were tested; one control specimen without EPS or GFRP, two slabs with two EPS panels with different densities on their impact side, one slab with GFRP sheet on impact side and finally one slab with EPS panel on impact side and GFRP on the tension side. To test the effect of the presence of EPS panels and GFRP sheets, the RC slabs were supported on a table centered below a drop tower. A weight of 3.245 kg was dropped freely from the drop tower to hit the slab. The energy that the slab could withstand was calculated based on the weight, height and number of drops. Results varied according to the variation of parameters; the combination of EPS on the impact side and GFRP on the tension side yielded double the energy the specimen could withstand compared to the control specimen. Results also showed that EPS acted like a cushion that is capable of absorbing a portion of the impact energy. Another finding is that the higher the density of the EPS the more energy it can absorb. This paper proves that EPS is a promising material that could be utilized in reducing the effects of impact loads on concrete structures.

Abstract: Building collapses from the seismic pounding of two adjacent buildings have been found in many past earthquakes. For the two buildings with different story height, the pounding induces impact load and local stress at column mid-height where the provided column reinforcement is normally lesser than the column’s edge. This paper aims to investigate the impact responses of reinforced concrete columns with different axial load and shear capacity by using numerical simulation method. Sixteen reinforced concretes columns were subjected to an impact load created by dropping 300 kg hammer at the height of 1,200 mm above the mid-span of the column. Every specimen has an identical cross section of 220 mm by 220 mm, with 3,000 mm of clear span length. Both ends of the column were fully restrained. The magnitude of the axial load varies from 0% to 40% of the ultimate axial capacity of the concrete section. Shear reinforcement spacing varies from @200 mm to @60 mm. It is found that the axial loads have a great effect on the impact responses of the RC columns. The specimens with high axial load yield higher peak impact force value and less mid-span deflection. Shear cracks were observed on the specimens with low axial force, but the cracks were relatively decreased when increasing the axial load.

Abstract: Aluminum tubes are efficient energy absorbing components and are widely used in the automobile industry. In the previous report, the authors investigated the influence of cross-sectional shape on axially compressed aluminum tube by numerical analysis. However, there are only a few reports on length of aluminum tube. This paper deals with the influence of axial length and reinforcing rib on dynamic axially compressed aluminum polygonal tube in order to obtain the basic data of buckling and impact resistance. A numerical analysis of the dynamic deformation process of the polygonal tube was made with a finite element method. The result shows that even if the axial length was changed, there was no difference in the trend of the load-displacement curve in each cross-sectional shape. However, the maximum load part on load-displacement curve was changed. The buckling was generated partially and the deformation was larger at the corners in each axial length and cross-sectional shape.