scholarly journals Numerical Evaluation of Reinforced Concrete Columns Retrofitted with FRP for Blast Mitigation

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Jing Dong ◽  
Junhai Zhao ◽  
Dongfang Zhang
Keyword(s):  
High Strength ◽  
Element Model ◽  
Blast Mitigation ◽  
Rc Columns ◽  
Existing Structures ◽  
Frp Composites ◽  
Blast Response ◽  
Proposed Model ◽  
Comprehensive Comparison ◽  
Result Analysis

Fiber reinforced polymer (FRP) material is commonly applied in retrofitting structures due to the advantages of high strength and well corrosion resistance. Previous studies indicated that retrofitting with FRP sheet was an effective way for protecting the existing structures to resist the blast loads, but little research made comprehensive comparison study on the blast response of RC columns with different retrofitting strategies. This paper proposed a series of FRP retrofitting strategies and evaluated their effect on blast mitigation using numerical analysis approach. Comparison studies were conducted on the effect of FRP type, FRP thickness, and retrofitting mode on blast mitigation. A finite element model of RC columns retrofitted with FRP under blast loading was developed. The model considered the strain rate effect of steel and concrete and the orthotropic property of FRP composites. The reliability of the proposed model was validated against the data from a field blast test. Based on the verified model, the blast responses of RC columns with different retrofitting strategies were numerically investigated. According to the result analysis, appropriate FRP type, FRP thickness, retrofitting mode, and retrofitting length were recommended.

scholarly journals Some Key Aspects in the Mechanics of Stress Transfer Between SRG and Masonry

2020 ◽  
Vol 10 (20) ◽  
pp. 7303
Author(s):  
Giulia Baietti ◽  
Tommaso D’Antino ◽  
Christian Carloni
Keyword(s):  
Stress Transfer ◽  
High Strength ◽  
Active Role ◽  
Fiber Reinforced ◽  
Suitable Alternative ◽  
Existing Structures ◽  
Direct Shear Tests ◽  
Frp Composites ◽  
Mortar Matrix

The use of composite materials to strengthen masonry structures has become common practice within the civil engineering community. Steel-reinforced grout (SRG), which comprises high-strength steel fibers embedded in a mortar matrix, is part of the family of the fiber-reinforced cementitious matrix (FRCM) composites that represent a suitable alternative to fiber-reinforced polymer (FRP) composites for strengthening existing structures. Although studies on FRCMs have already reached a certain level of maturity, some key issues remain open, such as the role of matrix type and layout, substrate properties, and test rate. This paper focuses on some of these issues. The results of single-lap direct shear tests on masonry blocks strengthened with SRGs are presented to analyze the bond behavior between the composite material and the substrate. Four aspects are considered: (1) the change in the width of the SRG mortar matrix while keeping the width of the fiber sheet fixed; (2) the type of mortar used for the SRG; (3) the influence of the test rate, and (4) the type of substrate (i.e., concrete vs. masonry). The results obtained indicate the active role of the matrix layout and the importance of the test rate, encouraging further investigations to clarify these aspects.

scholarly journals Finite element modelling of rectangular concrete-filled steel tube stub columns incorporating high strength and ultra-high strength materials under concentric axial compression

2021 ◽  
Vol 15 (4) ◽  
pp. 74-87
Author(s):  
Thai Son ◽  
Cuong Ngo-Huu ◽  
Dinh Van Thuat
Keyword(s):  
Finite Element ◽  
Axial Compression ◽  
Geometrical Nonlinearity ◽  
Initial Imperfection ◽  
High Strength ◽  
Element Model ◽  
Steel Tube ◽  
Stress Strain Relation ◽  
Proposed Model ◽  
Stub Columns

This study presents a unified approach to simulate the behavior of rectangular concrete-filled steel stub columns incorporating high strength and ultra-high strength materials subjected to concentric axial compression. The finite element model is developed based on Abaqus software, which is capable of accounting for geometrical nonlinearity, material plasticity, and interaction between multi-physics. The proposed model incorporates the influences of residual stress for welded-box steel sections and initial imperfection. A novel stress-strain relation of confined concrete is proposed to account for the composite action, which might increase the strength and ductility of infilled concrete under multi-axial compressive conditions. Various verification examples are conducted with wide ranges of geometrical and material properties. The simulation results show that the proposed model can accurately predict the ultimate strength, load-deformation relations, and failure mode of the experimental specimens.

scholarly journals Numerical Investigation of Behavior of RC Columns Strengtheneg with RC Jacket

2019 ◽  
Vol 2 (2) ◽  
pp. 257-264
Author(s):  
M. Burhan Navdar ◽  
Naci Caglar
Keyword(s):  
Load Capacity ◽  
Concrete Strength ◽  
Experimental Studies ◽  
Element Model ◽  
Transverse Reinforcement ◽  
Structural Elements ◽  
Rc Columns ◽  
Existing Structures ◽  
Laboratory Facilities ◽  
Earthquake Performance

Strengthening of structural elements which are insufficient in terms of earthquake performance is very important for the safety of existing structures. Nowadays, one of the most commonly used methods is strengthening such members with RC jacketing. Several experimental studies have been conducted in the literature to investigate behavior of structural elements reinforced with RC jacketing. Moreover, numerical studies are frequently preferred due to the high cost of experimental studies and the limited availability of laboratory facilities. In this study, a finite element model has been created with OpenSees program in order to investigate the behavior of strengthened RC columns with jacketing. Later, the accuracy of the model has been verified successful by the experimental results selected from the literature. By using that verified model, the effects of concrete strength and amount of spacing of transverse reinforcement used on the jacketing part on reinforced column behavior were investigated. As a result of the study, it is deduced that the change in the concrete strength and amount of transverse reinforcement results in a significant change in ductility, load capacity and rigidity of the reinforced concrete columns.

Experimental Investigation of Glass and Carbon FRCM Composite Materials Applied onto Concrete Supports

2016 ◽  
Vol 847 ◽  
pp. 60-67 ◽  
Author(s):  
Tommaso D'Antino ◽  
Jaime Gonzalez ◽  
Carlo Pellegrino ◽  
Christian Carloni ◽  
Lesley H. Sneed
Keyword(s):  
High Strength ◽  
Shear Strengthening ◽  
Existing Structures ◽  
Direct Shear Tests ◽  
Frp Composites ◽  
Load Response ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Concrete Joints ◽  
Fibre Reinforced Composites

In recent decades the growing need for strengthening and retrofitting existing structures has led to the development of innovative strengthening materials. Fibre reinforced composites have been shown to be an effective strengthening solution for flexural and shear strengthening and for confinement of axially/eccentrically loaded elements. Fibre Reinforced Cementitious Matrix (FRCM) composites, comprised of high-strength fibres and an inorganic matrix, are a newly-developed type of composite that has better resistance to high temperature and compatibility with the substrate than traditional fibre reinforced polymer (FRP) composites. This paper investigates the behaviour of FRCM composites comprised of a glass or carbon fibre net tested using single-lap direct-shear tests. Observations regarding the load response and failure mode of FRCM-concrete joints with different geometrical and mechanical characteristics are provided.

scholarly journals Internal Force on and Deformation of Steel Assembled Supporting Structure of Foundation Pit under Thermal Stress

2021 ◽  
Vol 11 (5) ◽  
pp. 2225
Author(s):  
Fu Wang ◽  
Guijun Shi ◽  
Wenbo Zhai ◽  
Bin Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
High Strength ◽  
Element Model ◽  
Internal Force ◽  
Foundation Pit ◽  
Dimensional Finite Element ◽  
Influence Of Temperature On ◽  
Scale Experiment ◽  
Three Dimensional Finite Element

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.

scholarly journals Experimental and Numerical Investigation on the Perforation Resistance of Double-Layered Metal Shield under High-Velocity Impact of Armor-Piercing Projectiles

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 626
Author(s):  
Riccardo Scazzosi ◽  
Marco Giglio ◽  
Andrea Manes
Keyword(s):  
High Strength Steel ◽  
Steel Plate ◽  
Experimental Studies ◽  
Practical Interest ◽  
High Strength ◽  
Experimental Tests ◽  
Element Model ◽  
Transportation Systems ◽  
Metal Shield ◽  
Softening Parameter

In the case of protection of transportation systems, the optimization of the shield is of practical interest to reduce the weight of such components and thus increase the payload or reduce the fuel consumption. As far as metal shields are concerned, some investigations based on numerical simulations showed that a multi-layered configuration made of layers of different metals could be a promising solution to reduce the weight of the shield. However, only a few experimental studies on this subject are available. The aim of this study is therefore to discuss whether or not a monolithic shield can be substituted by a double-layered configuration manufactured from two different metals and if such a configuration can guarantee the same perforation resistance at a lower weight. In order to answer this question, the performance of a ballistic shield constituted of a layer of high-strength steel and a layer of an aluminum alloy impacted by an armor piercing projectile was investigated in experimental tests. Furthermore, an axisymmetric finite element model was developed. The effect of the strain rate hardening parameter C and the thermal softening parameter m of the Johnson–Cook constitutive model was investigated. The numerical model was used to understand the perforation process and the energy dissipation mechanism inside the target. It was found that if the high-strength steel plate is used as a front layer, the specific ballistic energy increases by 54% with respect to the monolithic high-strength steel plate. On the other hand, the specific ballistic energy decreases if the aluminum plate is used as the front layer.

Reverse Modeling and Topological Optimization for Lightweight Design of Automobile Wheel Hubs with Hollow Ribs

2019 ◽  
Vol 17 (09) ◽  
pp. 1950064
Author(s):  
P. F. Xu ◽  
S. Y. Duan ◽  
F. Wang
Keyword(s):  
Finite Element ◽  
Lightweight Design ◽  
Element Model ◽  
Optimization Method ◽  
Modeling Technique ◽  
Topological Optimization ◽  
Time Interval ◽  
Braking Performance ◽  
Existing Structures ◽  
Physical Conditions

Lightweight of wheel hubs is the linchpin for reducing the unsprung mass and improving the vehicle dynamic and braking performance of vehicles, thus, sustaining stability and comfortability. Current experience-based lightweight designs of wheel hubs have been argued to render uneven distribution of materials. This work develops a novel method to combine the reverse modeling technique with the topological optimization method to derive lightweight wheel hubs based on the principles of mechanics. A reverse modeling technique is first adopted to scan and reproduce the prototype 3D geometry of the wheel hub with solid ribs. The finite element method (FEM) is then applied to perform stress analysis to identify the maximum stress and its location of wheel hub under variable potential physical conditions. The finite element model is then divided into optimization region and nonoptimized region: the former is the interior portion of spoke and the latter is the outer surface of the spoke. A topology optimization is then conducted to remove the optimization region which is interior material of the spokes. The hollow wheel hub is then reconstructed with constant wall thickness about 5[Formula: see text]mm via a reverse modeling technique. The results show that the reconstructed model can reduce the mass of 12.7% compared to the pre-optimized model. The present method of this paper can guarantee the optimal distribution of wheel hub material based on mechanics principle. It can be implemented automatically to shorten the time interval for optimal lightweight designs. It is especially preferable for many existing structures and components as it maintains the structural appearance of optimization object.

Contrastive Study on Finite Element Models of High-Strength Pipelines Crossing Active Faults

2016 ◽  
Vol 850 ◽  
pp. 957-964
Author(s):  
Wei Zheng ◽  
Hong Zhang ◽  
Xiao Ben Liu ◽  
Le Cai Liang ◽  
Yin Shan Han
Keyword(s):  
Finite Element ◽  
Design Method ◽  
Active Faults ◽  
Shell Element ◽  
High Strength ◽  
Element Model ◽  
Beam Element ◽  
Finite Element Models ◽  
Fixed Boundary ◽  
Equivalent Boundary

There is a potential for major damage to the pipelines crossing faults, therefore the strain-based design method is essential for the design of buried pipelines. Finite element models based on soil springs which are able to accurately predict pipelines’ responses to such faulting are recommended by some international guidelines. In this paper, a comparative analysis was carried out among four widely used models (beam element model; shell element model with fixed boundary; shell element model with beam coupled; shell element model with equivalent boundary) in two aspects: differences of results and the efficiency of calculation. The results show that the maximum and minimum strains of models coincided with each other under allowable strain and the calculation efficiency of beam element model was the highest. Besides, the shell element model with beam coupled or equivalent boundary provided the reasonable results and the calculation efficiency of them were higher than the one with fixed boundary. In addition, shell element model with beam coupled had a broader applicability.

Numerical Research on High-Strength Rectangular Section Steel Tube in Rotary-Draw Bending

2014 ◽  
Vol 620 ◽  
pp. 417-423 ◽  
Author(s):  
Zhong Wen Xing ◽  
Zhi Wei Xu ◽  
Hong Liang Yang ◽  
Cheng Xi Lei
Keyword(s):  
High Strength ◽  
Element Model ◽  
Steel Tube ◽  
Rotary Draw Bending ◽  
Rectangular Section ◽  
Control Variate ◽  
Fillet Radius ◽  
Bending Process ◽  
Bending Radius ◽  
Draw Bending

A finite element model of high-strength rectangular section steel tube in rotary-draw bending is established to study the stress and strain in the bending process. Based on control variate method, this paper analyzes the influence laws of three geometric parameters on rotary-draw bending. The results show that bending radius is the most important factor, forming property increases significantly with the increase of bending radius, the trends of cracking and wrinkling are all decreased. The thickness of wall has influence on the strain of inwall, thinner tube may cause crack and wrinkle. Fillet radius has no effect on ektexine, the strain of inwall decreases slightly with the increase of fillet radius.

Use of DNVGL-RP-C203 for Determining the Fatigue Capacity of Connectors

2021 ◽  
Author(s):  
Anthony Muff ◽  
Anders Wormsen ◽  
Torfinn Hørte ◽  
Arne Fjeldstad ◽  
Per Osen ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Testing ◽  
Experimental Testing ◽  
High Strength ◽  
Element Model ◽  
Fatigue Analysis ◽  
Full Scale ◽  
The Finite Element Model

Abstract Guidance for determining a S-N based fatigue capacity (safe life design) for preloaded connectors is included in Section 5.4 of the 2019 edition of DNVGL-RP-C203 (C203-2019). This section includes guidance on the finite element model representation, finite element based fatigue analysis and determination of the connector design fatigue capacity by use of one of the following methods: Method 1 by FEA based fatigue analysis, Method 2 by FEA based fatigue analysis and experimental testing and Method 3 by full-scale connector fatigue testing. The FEA based fatigue analysis makes use of Appendix D.2 in C203-2019 (“S-N curves for high strength steel applications for subsea”). Practical use of Section 5.4 is illustrated with a case study of a fatigue tested wellhead profile connector segment test. Further developments of Section 5.4 of C203-2019 are proposed. This included acceptance criteria for use of a segment test to validate the FEA based fatigue analysis of a full-scale preloaded connector.

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