Nonlinear Dynamic Finite Analysis of BFRP-Strengthened Masonry Structure Based on ABAQUS

2014 ◽  
Vol 936 ◽  
pp. 1331-1335
Author(s):  
Zhen Lei ◽  
Yong Wang ◽  
Jun Tong Qu
Keyword(s):  
Nonlinear Dynamic ◽  
Structural Damage ◽  
Failure Process ◽  
Dynamical Analysis ◽  
Base Shear ◽  
Confined Masonry ◽  
Damage And Failure ◽  
Before And After ◽  
Concrete Damage ◽  
Strengthening Technique

The externally bonded FRP is an effective strengthening technique, which is mainly verified through laboratory tests. In this paper, numerical analysis models were established in ABAQUS respectively based on an experimental scaled three-story confined masonry structures before and after strengthened with BFRP. Then dynamical analysis considering material nonlinearity, geometric nonlinearity and contact nonlinearity was carried out on these two models. Here, representative volume element method was used to simplify the simulation of masonry. Besides, concrete damage plasticity model was adopted to simulate the structural damage and failure process. The reliability and accuracy of nonlinear dynamic finite analysis were validated by comparing the numerical simulation results and experimental results in terms of dynamic property, displacement and acceleration response and the maximum base shear.

Damage Observation and Analysis of a Rock Brazilian Disc Using High-Speed DIC Method

2011 ◽  
Vol 70 ◽  
pp. 87-92 ◽  
Author(s):  
Shao Peng Ma ◽  
Dong Yan ◽  
Xian Wang ◽  
Yan Yan Cao
Keyword(s):  
Strain Field ◽  
Damage Evolution ◽  
High Speed ◽  
Failure Process ◽  
Tensile Load ◽  
Brazilian Test ◽  
Elastic Model ◽  
Strain Fields ◽  
Brazilian Disc ◽  
Damage And Failure

Observation of damage evolution is of great importance to the understanding of the failure process of rock materials. High-speed DIC system is constructed and used to observe the strain field evolution of the granodiorite disc in Brazilian test. The strain fields at different load levels are analyzed based on the stain abnormality indicator (SAI) which is the ratio of the strain measured in experiment to the strain from theoretical solution in an isotropy and elastic model. SAI could be used to indicate the damage in the specimen. The process of damage and failure of the specimen in Brazilian disc test is quantitatively analyzed and deeply discussed according to the strain fields and the statistics of SAI. Experimental results in this paper show that the failure process of the disc specimen in Brazilian test is not simple crack propagation under tensile load, but a complicated damage evolution procedure.

Nonlinear Structural Damage Detection Based on Adaptive Volterra Filter Model

2018 ◽  
Vol 18 (02) ◽  
pp. 1871003 ◽  
Author(s):  
J. Prawin ◽  
A. Rama Mohan Rao
Keyword(s):  
Damage Detection ◽  
Structural Damage ◽  
Linear Models ◽  
Time History ◽  
Diagnostic Techniques ◽  
Filter Model ◽  
Volterra Filter ◽  
Damage Indices ◽  
Before And After ◽  
Nonlinear Time History

The majority of the existing damage diagnostic techniques are based on linear models. Changes in the state of the dynamics of these models, before and after damage in the structure based on the vibration measurements, are popularly used as damage indicators. However, the system may initially behave linearly and subsequently exhibit nonlinearity due to the incipience of damage. Breathing cracks that exhibit bilinear behavior are one such example of the damage induced due to nonlinearity. Further many real world structures even in their undamaged state are nonlinear. Hence, in this paper, we present a nonlinear damage detection technique based on the adaptive Volterra filter using the nonlinear time history response. Three damage indices based on the adaptive Volterra filter are proposed and their sensitiveness to damage and noise is assessed through two numerically simulated examples. Numerical investigations demonstrate the effectiveness of the adaptive Volterra filter model to detect damage in nonlinear structures even with measurement noise.

Research on Corner Structure Under Explosive Loading for War-Ship Cabin

2010 ◽  
Author(s):  
Xiangshao Kong ◽  
Shuangxi Xu ◽  
Weiguo Wu ◽  
Xiaobin Li ◽  
Yuanzhou Zheng
Keyword(s):  
Shock Wave ◽  
Nonlinear Dynamic ◽  
Failure Process ◽  
High Strength ◽  
Explosive Loading ◽  
Inclined Plate ◽  
Explosion Pressure ◽  
Conventional Structure ◽  
Dynamic Software ◽  
Plate Connection

For the warship cabin under explosive loading, the detail structure in cabin corner can easily be torn by the high-strength shock wave converging at the structure corner. In order to avoid that the crevasse occurs at the corner firstly, three strengthening structure forms were designed for the cabin corner: thickening connection, circular connection and inclined plate connection. Failure process of the joint in the two-cabin structure under the explosive loading was simulated by the nonlinear dynamic software DYTRAN. Comparing the response of the corner strengthening structure to that of the conventional structure, it was concluded that three strengthening structure forms changed failure mode of the cabin structure effectively and the crevasse initiated at the explosion pressure release hole on the transverse bulkhead, which reduced the tearing of the cabin corner. To seek more reasonable corner strengthening structure, the pressure and the stress on the bulkhead under the explosive loading of the three corner strengthening structures were compared. The results showed the inclined plate connection can prevent the shock wave from concentrating at the corner, decrease the stress on the longitudinal bulkhead, and resist the shock wave spreading into the inner cabins most effectively in the three strengthening forms.

Over-the-row harvester damage evaluation in super-high-density olive orchard by on-board sensing techniques

2017 ◽  
Vol 8 (2) ◽  
pp. 487-491 ◽  
Author(s):  
J. Martinez-Guanter ◽  
M. Garrido-Izard ◽  
J. Agüera ◽  
C. Valero ◽  
M. Pérez-Ruiz
Keyword(s):  
Structural Damage ◽  
Image Data ◽  
High Density ◽  
Tree Structure ◽  
Light Detection And Ranging ◽  
Olive Grove ◽  
Damage Evaluation ◽  
Olive Fruit ◽  
Before And After ◽  
Extra Stress

New Super-High-Density (SHD) olive orchards designed for mechanical harvesting are increasing very rapidly in Spain. Most studies have focused in effectively removing the olive fruit, however the machine needs to put significant amount of energy on the canopy that could result in structural damage or extra stress on the trees. During harvest, a series of 3-axis accelerometers were installed on the tree structure in order to register vibration patterns. A LiDAR (Light Detection and Ranging) and a camera sensing device were also mounted on a tractor. Before and after harvest measurements showed significant differences in the LiDAR and image data. A fast estimate of the damage produced by an over-the-row harvester with contactless sensing could be useful information for adjusting the machine parameters in each olive grove automatically in the future.

Composite Material of Concrete Meso-Failure Test

2010 ◽  
Vol 160-162 ◽  
pp. 135-139
Author(s):  
Ji Kun Zhao
Keyword(s):  
Dynamic Load ◽  
Main Crack ◽  
Failure Process ◽  
Strain Curve ◽  
Static Modulus ◽  
Starting Point ◽  
Beam Shear ◽  
Concrete Damage ◽  
Extension Direction ◽  
Static Modulus Of Elasticity

With static and dynamic load for the research background, this paper conducted a four-phase composite model for concrete damage test simulation of micro-mechanics. The two kinds of three-point bending beam load ware studied in case of failure process. The study found that the location of the main crack in the most disadvantaged section of beam shear in the vicinity. Crack is always along the aggregate and the mortar bond zone be extended. The main crack extension direction is always toward the load point. The main crack is showing a tortuous shape. Dynamic load and static load the stress - strain curve is basically similar shape, but basically the same as the starting point of the initial fracture. Stress wave in the sample after multiple visits, is the main reason leading to the breakdown of the sample. Dynamic load cases, the concrete elastic modulus higher than the static modulus of elasticity, numerical simulation results agree well with the experimental results.

Performance of a Post-Byzantine Triple-Domed Basilica under Near and Far Fault Seismic Loads

2015 ◽  
pp. 831-867 ◽  
Author(s):  
Constantine C. Spyrakos ◽  
Charilaos A. Maniatakis ◽  
Panagiotis Kiriakopoulos ◽  
Alessio Francioso ◽  
Ioannis M. Taflampas
Keyword(s):  
Structural Damage ◽  
New Technology ◽  
Element Model ◽  
Seismic Loads ◽  
Regional Seismicity ◽  
Near Fault ◽  
Collapse Mechanisms ◽  
Before And After ◽  
Out Of Plane ◽  
Structural Parts

In this Chapter a triple-domed basilica constructed at the end of the 19th century is selected as a case study to present a methodology for the selection of the appropriate intervention techniques in monumental structures. The methodology includes in-situ and laboratory testing, application of analytical methods, consideration of geotechnical parameters and regional seismicity. Seismic loads are estimated according to contemporary and older concepts for seismic design. Since the impact of near-fault phenomena on masonry structures has not been thoroughly studied, although considered as responsible for extensive structural damage during major seismic events, a procedure is presented in order to account for the special characteristics of strong ground motion, in the so-called near-fault region. The seismic performance of the structure before and after interventions, using traditional and new technology, is assessed by applying a validated finite element model. Also, the out-of-plane behavior of structural parts is evaluated through kinematic analysis of selective collapse mechanisms.

scholarly journals Acoustic emission description from a damage and failure scenario of rotomoulded polyolefin sandwich structure subjected to internal pressure for storage applications

2020 ◽  
Vol 21 (1) ◽  
pp. 105 ◽  
Author(s):  
Eric Lainé ◽  
Jean-Claude Grandidier ◽  
Maxime Cruz ◽  
Anne-Laure Gorge ◽  
Claire Bouvy ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Structural Damage ◽  
Sandwich Structure ◽  
Water Pressure ◽  
Average Frequency ◽  
Polymer Structure ◽  
Foam Core ◽  
Damage And Failure ◽  
Failure Scenario ◽  
Polyethylene Sample

The aim of this paper is to study the damage mechanisms in a sandwich polymer structure that contains three layers: two polyolefin skins and the foam core (skin–foam–skin). Specific tests on structure associated with the acoustic emission (AE) technique and tomographic observations (RX) are used to identify the damage. Initially, a conventional tensile test was performed to correlate the acoustic emission with the initiation of plasticity and damage to a polyethylene sample. The results obtained are close to those observed in other studies and it is possible to separate the signal from cavitation and propagation of necking. The technique is then employed to capture the rupture of a polymer skin on a multilayer rotomoulded structure (bottle). Tests were carried out on this bottle under internal water pressure. Three tests are performed with more or less early interruptions in order to identify the first damage and understand their evolution. Different quantities (average frequency, RA value, etc.) are observed in order to quantify and understand the perceived damage. With the AE/RX correlation and mechanical behaviour, a scenario of structural damage is proposed.

scholarly journals P0208DIFFERENTIAL ADAPTATION OF RENAL FUNCTION IN TWO TYPES OF INTENSE PHYSICAL EXERCISE

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Armando Coca ◽  
Pablo Gonzalez ◽  
Maria Jesus Rollan ◽  
Beatriz Toribio ◽  
Hortensia Marcos ◽  
...  
Keyword(s):  
Renal Function ◽  
Uric Acid ◽  
Serum Creatinine ◽  
Structural Damage ◽  
Marathon Running ◽  
Vigorous Exercise ◽  
Castilla Y Leon ◽  
Before And After ◽  
Physical Tests ◽  
Blood And Urine Samples

Abstract Background and Aims Marathon running induces AKI even in adequately prepared and healthy athletes. Heat stress, maintained during more than 2h, has been proposed as one of the leading causes of AKI in marathons runners. Other possible explanations of AKI in this setting could be associated with a reduction of blood supply to the kidneys during the exercise, inadequate hydration or actual structural damage due to microtraumatisms. However, the effect of vigorous exercise of shorter duration on renal function has not been previously described although most risk factors described could also affect kidney function in this type of physical activity. Method 40 volunteer healthy athletes were enrolled in this study. Subjects participated in two physical tests (10km running, 1.5km swimming) which were separated by at least two weeks from each other. These tests were chosen because of their similar oxygen consumption rate and metabolic load. Vitals, blood and urine samples were collected immediately before and after each test. Informed consent was obtained from all participants. The project was funded by Consejería de Sanidad, Junta de Castilla y León (GRS1732/A/18). Results Athletes ranged from 23 to 53 years old. 35% were female. A comparison of hemodynamic and analytical parameters is summarized in Table 1. Running induced a significantly higher rise of serum creatinine and inflammatory markers compared to swimming. Additionally, running caused an increment of serum phosphorus and uric acid levels. Both types of exercise caused a mild increase of urinary albumin/creatinine ratio. Conclusion Compared to swimming, running was associated with a greater rise of serum creatinine, possibly linked to a higher degree of acute inflammation and blood flow redistribution to the muscles. The rise of serum uric acid levels may be associated with increased metabolism and reduced elimination of this molecule while running.

scholarly journals Resistivity and AE Response Characteristics in the Failure Process of CGB under Uniaxial Loading

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Tingye Qi ◽  
Guorui Feng
Keyword(s):  
Failure Process ◽  
Peak Stress ◽  
Uniaxial Loading ◽  
Energy Curve ◽  
Cumulative Energy ◽  
Response Characteristics ◽  
Before And After ◽  
The Difference ◽  
Linear Slope ◽  
The Stability

To understand the characteristics of the acoustic emission (AE) and electrical resistivity of cemented coal gangue backfill (CGB) under uniaxial compression, the variations in these characteristics at 1 day, 3 days, and 7 days are analyzed by means of a stress-strain-resistivity-AE test, and the microperformances are investigated. The research results indicate that the AE can reflect the initiation and propagation of cracks and later explain the variation of the resistivity of the specimens under the uniaxial loading. The cumulative energy curve of AE is approximately two straight lines corresponding to the peak stress, and the difference in the linear slope gradually decreased with the increasing curing time due to the lower pore solution content and the compact pore structure. The relationships between the stress and resistivity and the loading condition before and after the peak stress at different curing times were established. Therefore, it is of great significance to predict the stability of the filling body by monitoring the AE and resistivity variations of the filling body. In addition, it is possible to calculate the roof stress using the relation equation between the resistivity and stress.

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