scholarly journals Numerical Simulation on Dynamic Behavior of Slab–Column Connections Subjected to Blast Loads

2021 ◽  
Vol 11 (16) ◽  
pp. 7573
Author(s):  
Kwang Mo Lim ◽  
Taek Hee Han ◽  
Joo Ha Lee
Keyword(s):  
Numerical Analysis ◽  
Blast Resistance ◽  
Mesh Size ◽  
Material Model ◽  
Simulation Method ◽  
Blast Load ◽  
Blast Loads ◽  
Element Analysis ◽  
Model And Simulation ◽  
Resistance Performance

Although many studies on the blast-resistant performance of structures have focused mainly on single members such as beams and columns, there is little research on the behavior of joints that are subjected to blast loads. In this study, the structural behavior of a slab–column connection subjected to blast load was investigated using a numerical analysis method. LS-DYNA was used as a finite element analysis program, and in order to improve the accuracy of numerical analysis, mesh size, material model, and simulation method of blast load were determined through preliminary analysis. The effect of different restraints of the joints, depending on the position of the columns in the slab, on the blast resistance performance was investigated. As a result, the highly confined slab-interior column connection showed better behavior than other edge and corner columns. The drop panel installed between the lower column and the slab was effective in improving the blast-resistance performance of the slab–column connection. For a more accurate evaluation of blast resistance performance, it was suggested that various evaluation factors such as ductility ratio, reinforcing stress, and concrete fracture area can be considered along with the support rotation, which is an important evaluation factor suggested by many standards.

scholarly journals Prediction of Damage Level of Slab-Column Joints under Blast Load

2020 ◽  
Vol 10 (17) ◽  
pp. 5837
Author(s):  
Kwang Mo Lim ◽  
Do Guen Yoo ◽  
Bo Yeon Lee ◽  
Joo Ha Lee
Keyword(s):  
Numerical Analysis ◽  
Prediction Equation ◽  
General Purpose ◽  
Blast Loads ◽  
Joint Region ◽  
Element Analysis ◽  
Scaled Distance ◽  
Damage Level ◽  
Disturbed Zone ◽  
Column Joint

The behavior of a slab-column joint subjected to blast loads was studied by numerical analysis using a general-purpose finite element analysis program, LS-DYNA. Under the explosive load, the joint region known as the stress disturbed zone was defined as a region with a scaled distance of 0.1 m/kg1/3 or less through comparison with ConWep’s empirical formula. Displacement and support rotation according to Trinitrotoluene (TNT) weight and scaled distance were investigated by dividing in and out of the joint region. In addition, fracture volume was newly proposed as an evaluation factor for blast-resistant performance, and it was confirmed that the degree of damage to a member due to blast loads was well represented by the fracture volume. Finally, a prediction equation for the blast-resistant performance of the slab-column joint was proposed, and the reliability and accuracy of the equation were verified through additional numerical analysis.

scholarly journals Numerical Analysis-Based Blast Resistance Performance Assessment of Cable-Stayed Bridge Components Subjected to Blast Loads

2020 ◽  
Vol 10 (23) ◽  
pp. 8511
Author(s):  
Jungwhee Lee ◽  
Keunki Choi ◽  
Chulhun Chung
Keyword(s):  
Numerical Analysis ◽  
Blast Resistance ◽  
Assessment Process ◽  
Public Nature ◽  
Bridge Structures ◽  
Set Up ◽  
Existing Bridges ◽  
Resistance Performance ◽  
Selection Of ◽  
Cable Stayed Bridges

Cable-stayed bridges are infrastructure facilities of a highly public nature; therefore, it is essential to ensure operational safety and prompt response in the event of a collapse or damage, which are caused by natural and social disasters. Among social disasters, blast accidents can occur in cable-stayed bridges as a result of explosions produced by vehicle collisions or terrorist attacks; this can lead to the degradation in their structural performances and subsequent collapse. In this research, a procedure to assess structural blast-resistance performance is suggested based on a numerical analysis approach, and the feasibility of the procedure is demonstrated by performing an example assessment. The suggested procedure includes (1) selection of major structural components that severely affect the global structural behavior, (2) set-up blast hazard scenarios consisting of various blast levels and locations, and (3) assessment of the components using numerical blast simulation. By performing an example assessment, the critical blast level for each component could be determined and the blast location that affects the considering components the most severely could be found as well. The scenario-based assessment process employed in this study is expected to facilitate the evaluation of bridge structures under blasts in both existing bridges and future designs.

Methods for Theoretical Assessment of Delamination Risks in Electronic Packaging

2017 ◽  
Author(s):  
Torsten Hauck ◽  
Ilko Schmadlak ◽  
Nishant Lakhera ◽  
Sandeep Shantaram ◽  
David Samet ◽  
...  
Keyword(s):  
Fracture Mechanics ◽  
Electronic Packaging ◽  
Bulk Material ◽  
Material Model ◽  
Simulation Method ◽  
Critical Energy ◽  
Failure Criteria ◽  
Electronic Packages ◽  
Element Analysis ◽  
Advantages And Disadvantages

Fracture mechanics is an essential field of study towards the improvement and development of electronic packages. In combination with modern simulation method such as finite element analysis (FEA), fracture mechanics is widely used and appreciated in the industry. Many different approaches have been developed to calculate the fracture parameters for interfaces or bulk material under given loads in order to compare them against previously measured failure criteria. While many publications are available that have described the different simulation approaches in detail or compare the different fracture test methods, there have been few comparisons of these simulation approaches with respect to their use in research and development of electronic packages. The objective of this work is to compare different delamination modeling methodologies and their applications for electronic packaging. The work highlights the differences in theory behind each approach as well as the differences in their practical use to predict delamination or asses a fracture risk in electronic packages. The intention was to use commercially available FE-codes in conjunction with a well-defined set of adhesion strength tests. During this work, energy based fracture criteria were applied by means of the virtual crack closure technique (VCCT), the J-integral and the cohesive zone material model (CZM) methods. These methodologies are most commonly used but can differ significantly from each other as will be shown in this comparison. To demonstrate the use of these techniques, copper lead frame to epoxy mold compound (EMC) delamination was assessed, representing a very common packaging failure mode. Critical energy release rates were measured on multiple Copper-EMC test specimens under varying load phase angles. ANSYS was used to build mechanical simulation models of a selected device. Existing post processing procedures were applied to assess delamination risk based on above mentioned techniques. The simulation study considers realistic monotonic loading conditions and results will also be compared to existing failure analysis images for demonstration and validation purpose. As an outcome, the paper will include a ranking of the approaches as well as a summary of advantages and disadvantages, based method and accuracy. An outlook on future developments such as fatigue or aging phenomena will finish the work.

An Influence of the Mesh Size on the Results of Finite Element Analysis of Z-Purlins Supported by Sandwich Panels

2013 ◽  
Vol 475-476 ◽  
pp. 1483-1486 ◽  
Author(s):  
Olga Tusnina
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Numerical Analysis ◽  
Sandwich Panels ◽  
Mesh Size ◽  
Numerical Analyses ◽  
Element Analysis ◽  
Thin Walled

In this paper the questions of numerical analysis of thin-walled Z-purlins in the coverings of buildings made of sandwich panels are considered. Numerical analyses are done in the program MSC.NASTRAN. An influence of the mesh of elements on the results of calculations is studied. The results of carried out numerical analyses allowed developing the method for determining the stiffness of connection purlin with sandwich panels.

scholarly journals The Finite Element Analysis for Concrete Filled Steel Columns under Blast Load

2016 ◽  
Author(s):  
Fereydoon Omidinasab ◽  
Peyman Beiranvand ◽  
Saeideh Sadeghi Golmakani ◽  
Mohammad Zarei
Keyword(s):  
Blast Resistance ◽  
Fire Behavior ◽  
Steel Tube ◽  
Absorption Capacity ◽  
Blast Load ◽  
Energy Absorption Capacity ◽  
Element Analysis ◽  
Steel Columns ◽  
Concrete Confinement ◽  
The Finite Element Analysis

Concrete-filled steel columns have been extensively used in the world due to having all suitable characteristics of concrete and steel, more ductility, increasing concrete confinement using steel wall, large energy-absorption capacity and appropriate fire behavior. In present paper, concrete-filled steel square columns have been simulated under the influence of blast load using ABAQUS software. These responses will be compared for scaled distances based on the distance to source and weight of explosive material. As result, it can be seen that although concrete deformation has been restricted using steel tube, but inner layer of concrete has been seriously damaged and column displacement will be decreased by increasing scaled distance. We also concluded that concrete-filled steel columns have high ductility and blast resistance.

scholarly journals Effect of Blast Loading on Seismically Detailed RC Columns and Buildings

2021 ◽  
Vol 7 (8) ◽  
pp. 1406-1425
Author(s):  
Marco Fouad ◽  
Mohamed N. Fayed ◽  
Gehan A. Hamdy ◽  
Amr Abdelrahman
Keyword(s):  
Blast Resistance ◽  
Near Field ◽  
Mesh Size ◽  
Experimental Results ◽  
Structural Elements ◽  
Blast Loads ◽  
Structural Element ◽  
Rc Columns ◽  
Damage Pattern ◽  
Multistory Building

Explosions caused by standoff charges near buildings have drastic effects on the internal and external structural elements which can cause loss of life and fatal injuries in case of failure or collapse of the structural element. Providing structural elements with blast resistance is therefore gaining increasing importance. This paper presents numerical investigation of RC columns with different reinforcement detailing subjected to near-field explosions. Detailed finite element models are made using LS-DYNA software package for several columns having seismic and conventional reinforcement detailing which were previously tested under blast loads. The numerical results show agreement with the published experimental results regarding displacements and damage pattern. Seismic detailing of columns enhances the failure shape of the column and decrease the displacement values compared to columns with conventional reinforcement detailing. Further, the effect of several modeling parameters are studied such as mesh sensitivity analysis, inclusion of air medium and erosion values on the displacements and damage pattern. The results show that decreasing the mesh size, increasing erosion value and inclusion of air region provide results that are very close to experimental results. Additionally, application is made on a slab-column multistory building provided with protective walls having different connection details subjected to blast loads. The results of this study are presented and discussed. Use of a top and bottom floor slab connection of protective RC walls are better than using the full connection at the four sides to the adjacent columns and slabs. This leads to minimizing the distortion and failure of column, and therefore it increases the chance of saving the building from collapse and saving human lives. Doi: 10.28991/cej-2021-03091733 Full Text: PDF

Lifetime Prediction of Tires with Regard to Oxidative Aging5

2008 ◽  
Vol 36 (1) ◽  
pp. 63-79 ◽  
Author(s):  
L. Nasdala ◽  
Y. Wei ◽  
H. Rothert ◽  
M. Kaliske
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Superposition Principle ◽  
Accelerated Aging ◽  
Material Model ◽  
Aging Behavior ◽  
Element Analysis ◽  
Material Parameters ◽  
Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

scholarly journals Optimization Study of Post-Weld Heat Treatment for 12Cr1MoV Pipe Welded Joint

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 127
Author(s):  
Zichen Liu ◽  
Xiaodong Hu ◽  
Zhiwei Yang ◽  
Bin Yang ◽  
Jingkai Chen ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Stress Reduction ◽  
Simulation Method ◽  
Post Weld Heat Treatment ◽  
Residual Stress Field ◽  
Element Analysis ◽  
Tempering Treatment ◽  
Temper Heat Treatment ◽  
Weld Heat

In order to clarify the role of different post-weld heat treatment processes in the manufacturing process, welding tests, post-weld heat treatment tests, and finite element analysis (FEA) are carried out for 12C1MoV steel pipes. The simulated temperature field and residual stress field agree well with the measured results, which indicates that the simulation method is available. The influence of post-weld heat treatment process parameters on residual stress reduction results is further analyzed. It is found that the post weld dehydrogenation treatment could not release residual stress obviously. However, the residual stress can be relieved by 65% with tempering treatment. The stress relief effect of “post weld dehydrogenation treatment + temper heat treatment” is same with that of “temper heat treatment”. The higher the temperature, the greater the residual stress reduction, when the peak temperature is at 650–750 °C, especially for the stress concentration area. The longer holding time has no obvious positive effect on the reduction of residual stress.

scholarly journals Effect of blast loading and resulting progressive failure of a cable-stayed bridge

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Ravi Mudragada ◽  
S. S. Mishra
Keyword(s):  
Progressive Failure ◽  
Blast Resistance ◽  
Progressive Collapse ◽  
Building Structures ◽  
Structural Elements ◽  
Blast Loads ◽  
Cable Stayed Bridge ◽  
Bridge Performance ◽  
Cable Stayed Bridges

AbstractMany researchers have carried out experimental and numerical investigations to examine building structures’ response to explosive loads. Studies of bridges subjected to blast loads are limited. Hence, in this study, we present a case study on a cable-stayed bridge, namely, Charles River Cable-Stayed Bridge-Boston, to assess its robustness and resistance against the progressive collapse resulting from localized failure due to blast loads. Three different blast scenarios are considered to interpret the bridge performance to blast loads. To monitor the progressive failure mechanisms of the structural elements due to blast, pre-defined plastic hinges are assigned to the bridge deck. The results conclude that the bridge is too weak to sustain the blast loads near the tower location, and the progressive collapse is inevitable. Hence, to preserve this cable-stayed bridge from local and global failure, structural components should be more reinforced near the tower location. This case study helps the designer better understand the need for blast resistance design of cable-stayed bridges.

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