scholarly journals The Sacred Mountain of Varallo in Italy: Seismic Risk Assessment by Acoustic Emission and Structural Numerical Models

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Alberto Carpinteri ◽  
Giuseppe Lacidogna ◽  
Stefano Invernizzi ◽  
Federico Accornero
Keyword(s):  
Finite Element ◽  
Acoustic Emission ◽  
Seismic Risk ◽  
Numerical Models ◽  
Element Model ◽  
Structural Condition ◽  
Structural Behavior ◽  
Italian Renaissance ◽  
Regional Seismicity ◽  
Sacred Mountain

We examine an application of Acoustic Emission (AE) technique for a probabilistic analysis in time and space of earthquakes, in order to preserve the valuable Italian Renaissance Architectural Complex named “The Sacred Mountain of Varallo.” Among the forty-five chapels of the Renaissance Complex, the structure of the Chapel XVII is of particular concern due to its uncertain structural condition and due to the level of stress caused by the regional seismicity. Therefore, lifetime assessment, taking into account the evolution of damage phenomena, is necessary to preserve the reliability and safety of this masterpiece of cultural heritage. A continuous AE monitoring was performed to assess the structural behavior of the Chapel. During the monitoring period, a correlation between peaks of AE activity in the masonry of the “Sacred Mountain of Varallo” and regional seismicity was found. Although the two phenomena take place on very different scales, the AE in materials and the earthquakes in Earth’s crust, belong to the same class of invariance. In addition, an accurate finite element model, performed with DIANA finite element code, is presented to describe the dynamic behavior of Chapel XVII structure, confirming visual and instrumental inspections of regional seismic effects.

scholarly journals Measurements of bridges' vibration characteristics using a mobile phone

2015 ◽  
Vol 8 (5) ◽  
pp. 721-743 ◽  
Author(s):  
Z. M. C. Pravia ◽  
J. D. Braido
Keyword(s):  
Finite Element ◽  
Fourier Transform ◽  
Mobile Phone ◽  
Natural Frequencies ◽  
Numerical Models ◽  
Element Model ◽  
Concrete Bridges ◽  
Structural Behavior ◽  
Experimental Phase ◽  
Bridge Inspection

ABSTRACTThis research presents an alternative way to perform a bridge inspection, which considers the dynamics parameters from the structure. It shows an experimental phase with use of a mobile phone to extract the accelerations answers from two concrete bridges, from those records is feasible to obtain natural frequencies using the Fast Fourier Transform (FFT).Numerical models with uses finite element model (FEM) allow to determine the natural frequencies from the two concrete bridges and compare with the experimental phase of each one. The final results shows it's possible to use mobiles phones to extract vibration answers from concrete bridges and define the structural behavior of bridges from natural frequencies, this procedure could be used to evaluate bridges with lower costs.

scholarly journals Sensitivity Analysis of the Influence of Structural Parameters on Dynamic Behaviour of Highly Redundant Cable-Stayed Bridges

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
B. Asgari ◽  
S. A. Osman ◽  
A. Adnan
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Structural Parameters ◽  
Element Model ◽  
Structural Behavior ◽  
Model Tuning ◽  
The Finite Element Model ◽  
Cable Stayed Bridges

The model tuning through sensitivity analysis is a prominent procedure to assess the structural behavior and dynamic characteristics of cable-stayed bridges. Most of the previous sensitivity-based model tuning methods are automatic iterative processes; however, the results of recent studies show that the most reasonable results are achievable by applying the manual methods to update the analytical model of cable-stayed bridges. This paper presents a model updating algorithm for highly redundant cable-stayed bridges that can be used as an iterative manual procedure. The updating parameters are selected through the sensitivity analysis which helps to better understand the structural behavior of the bridge. The finite element model of Tatara Bridge is considered for the numerical studies. The results of the simulations indicate the efficiency and applicability of the presented manual tuning method for updating the finite element model of cable-stayed bridges. The new aspects regarding effective material and structural parameters and model tuning procedure presented in this paper will be useful for analyzing and model updating of cable-stayed bridges.

The effects of shape memory alloys’ tension–compression asymmetryon NiTi endodontic files’ fatigue life

2018 ◽  
Vol 232 (5) ◽  
pp. 437-445 ◽  
Author(s):  
MR Karamooz-Ravari ◽  
R Dehghani
Keyword(s):  
Finite Element ◽  
Shape Memory ◽  
Numerical Models ◽  
Equivalent Stress ◽  
Element Model ◽  
Niti Shape Memory Alloy ◽  
Element Analysis ◽  
Tension And Compression ◽  
Von Mises Equivalent Stress ◽  
Von Mises

Nowadays, NiTi rotary endodontic files are of great importance due to their flexibility which enables the device to cover all the portions of curved canal of tooth. Although this class of files are flexible, intracanal separation might happen during canal preparation due to bending or torsional loadings of the file. Since fabrication and characterization of such devices is challenging, time-consuming, and expensive, it is preferable to predict this failure before fabrication using numerical models. It is demonstrated that NiTi shape memory alloy shows asymmetric material response in tension and compression which can significantly affect the lifetime of the files fabricated from. In this article, the effects of this material asymmetry on the bending response of rotary files are assessed using finite element analysis. To do so, a constitutive model which takes material asymmetry into account is used in combination with the finite element model of a RaCe file. The results show that the material asymmetry can significantly affect the maximum von Mises equivalent stress as well as the force–displacement response of the tip of this file.

scholarly journals Vibration-based Bayesian model updating of civil engineering structures applying Gaussian process metamodel

2019 ◽  
Vol 22 (16) ◽  
pp. 3487-3502
Author(s):  
Hossein Moravej ◽  
Tommy HT Chan ◽  
Khac-Duy Nguyen ◽  
Andre Jesus
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Bayesian Approach ◽  
Model Updating ◽  
Numerical Models ◽  
Element Model ◽  
The Body ◽  
Structural Safety ◽  
Discrepancy Function ◽  
The Finite Element Model

Structural health monitoring plays a significant role in providing information regarding the performance of structures throughout their life spans. However, information that is directly extracted from monitored data is usually susceptible to uncertainties and not reliable enough to be used for structural investigations. Finite element model updating is an accredited framework that reliably identifies structural behavior. Recently, the modular Bayesian approach has emerged as a probabilistic technique in calibrating the finite element model of structures and comprehensively addressing uncertainties. However, few studies have investigated its performance on real structures. In this article, modular Bayesian approach is applied to calibrate the finite element model of a lab-scaled concrete box girder bridge. This study is the first to use the modular Bayesian approach to update the initial finite element model of a real structure for two states—undamaged and damaged conditions—in which the damaged state represents changes in structural parameters as a result of aging or overloading. The application of the modular Bayesian approach in the two states provides an opportunity to examine the performance of the approach with observed evidence. A discrepancy function is used to identify the deviation between the outputs of the experimental and numerical models. To alleviate computational burden, the numerical model and the model discrepancy function are replaced by Gaussian processes. Results indicate a significant reduction in the stiffness of concrete in the damaged state, which is identical to cracks observed on the body of the structure. The discrepancy function reaches satisfying ranges in both states, which implies that the properties of the structure are predicted accurately. Consequently, the proposed methodology contributes to a more reliable judgment about structural safety.

scholarly journals Finite Element Modeling and Parametric Study on Floor Steel Beam Concrete Slab System in Non-Composite Action.

2018 ◽  
Vol 24 (7) ◽  
pp. 95
Author(s):  
Salah R. Al-Zaidee ◽  
Ehab Ghazi Al-Hasany
Keyword(s):  
Finite Element ◽  
Friction Force ◽  
Parametric Study ◽  
Numerical Models ◽  
Concrete Slab ◽  
Linear Regression Analysis ◽  
Element Model ◽  
Steel Beam ◽  
Composite Action ◽  
Shear Connectors

This study aims to show, the strength of steel beam-concrete slab system without using shear connectors (known as a non-composite action), where the effect of the friction force between the concrete slab and the steel beam has been investigated, by using finite element simulation. The proposed finite element model has been verified based on comparison with an experimental work. Then, the model was adopted to study the system strength with a different steel beam and concrete slab profile. ABAQUS has been adopted in the preparation of all numerical models for this study. After validation of the numerical models, a parametric study was conducted, with linear and non-linear Regression analysis. An equation regarding the concrete slab-steel beam system strength in non-composite action has been pointed out. Where the actual strength of the beam without using shear connectors has been located in between the full composite action and non-composite action. However, partial-composite action has been noted, due to the effectiveness of friction force which makes the beam behave as composite before the slip occurs.  

scholarly journals A musculoskeletal finite element model of rat knee joint for evaluating cartilage biomechanics during gait

2021 ◽  
Author(s):  
Gustavo A. Orozco ◽  
Kalle Karjalainen ◽  
Eng Kuan Moo ◽  
Lauri Stenroth ◽  
Petri Tanska ◽  
...  
Keyword(s):  
Finite Element ◽  
Animal Models ◽  
Knee Joint ◽  
Gait Cycle ◽  
Numerical Models ◽  
Small Animal ◽  
Element Model ◽  
Lateral Compartment ◽  
Fe Model ◽  
Joint Injury

Abnormal loading of the knee due to injuries or obesity is thought to contribute to the development of osteoarthritis (OA). Small animal models have been used for studying OA progression mechanisms. However, numerical models to study cartilage responses under dynamic loading in preclinical animal models have not been developed. Here we present a musculoskeletal finite element (FE) model of a rat knee joint to evaluate cartilage biomechanical responses during a gait cycle. The rat knee joint geometries were obtained from a 3-D MRI dataset and the boundary conditions regarding loading in the joint were extracted from a musculoskeletal model of the rat hindlimb. The fibril-reinforced poroelastic (FRPE) properties of the rat cartilage were derived from data of mechanical indentation tests. Our numerical results showed the relevance of simulating anatomical and locomotion characteristics in the rat knee joint for estimating tissue responses such as contact pressures, stresses, strains, and fluid pressures. We found that the contact pressure and maximum principal strain were virtually constant in the medial compartment whereas they showed the highest values at the beginning of the gait cycle in the lateral compartment. Furthermore, we found that the maximum principal stress increased during the stance phase of gait, with the greatest values at midstance. We anticipate that our approach serves as a first step towards investigating the effects of gait abnormalities on the adaptation and degeneration of rat knee joint tissues and could be used to evaluate biomechanically-driven mechanisms of the progression of OA as a consequence of joint injury or obesity.

Numerical and Experimental Analysis of Articular Chondrocyte Deformation: Calibration of a Multiscale Finite Element Model

2007 ◽  
Author(s):  
Scott L. Bevill ◽  
Paul L. Briant ◽  
Thomas P. Andriacchi
Keyword(s):  
Finite Element ◽  
Load Transfer ◽  
Numerical Models ◽  
Experimental Studies ◽  
Element Model ◽  
Cartilage Explants ◽  
Fe Model ◽  
Articular Chondrocyte ◽  
Superficial Zone

Mechanical loading of chondrocytes in isolation [1] and of articular cartilage in culture [2] has been reported to be a potent regulator of chondrocyte metabolism. Experimental studies have related tissue-level and cell-level strains in mechanically loaded cartilage explants [3], but cannot be readily extended to address more physiologic loading cases. Numerical models, which might address this need, have primarily been axisymmetric [4, 5] or two-dimensional [6] and have idealized chondrocyte geometry. Given the complexity of the mechanism of the load transfer between the tissue and cell, however, there remains a lack of information regarding the in vivo level of cell stresses and strains. Thus, the purpose of this study was to develop a multiscale experimental/numerical approach to calibrate a three-dimensional finite element (FE) model of a chondrocyte based on experimentally derived chondrocyte morphology and deformation data. The method was than applied to determine the modulus of a chondrocyte located in the superficial zone.

scholarly journals Numerical Investigation on the Role of Mechanical Factors Contributing to Globe Flattening in States of Elevated Intracranial Pressure

Life ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 316
Author(s):  
Jafar A. Mehr ◽  
Heather E. Moss ◽  
Hamed Hatami-Marbini
Keyword(s):  
Finite Element ◽  
Intracranial Pressure ◽  
Finite Element Model ◽  
Material Properties ◽  
Numerical Study ◽  
Numerical Models ◽  
Element Model ◽  
Elevated Intracranial Pressure ◽  
Mr Images ◽  
Mechanical Factors

Flattening of the posterior eye globe in the magnetic resonance (MR) images is a sign associated with elevated intracranial pressure (ICP), often seen in people with idiopathic intracranial hypertension (IIH). The exact underlying mechanisms of globe flattening (GF) are not fully known but mechanical factors are believed to play a role. In the present study, we investigated the effects of material properties and pressure loads on GF. For this purpose, we used a generic finite element model to investigate the deformation of the posterior eyeball. The degree of GF in numerical models and the significance of different mechanical factors on GF were characterized using an automated angle-slope technique and a statistical measure. From the numerical models, we found that ICP had the most important role in GF. We also showed that the angle-slope graphs pertaining to MR images from five people with high ICP can be represented numerically by manipulating the parameters of the finite element model. This numerical study suggests that GF observed in IIH patients can be accounted for by the forces caused by elevation of ICP from its normal level, while material properties of ocular tissues, such as sclera (SC), peripapillary sclera (PSC), and optic nerve (ON), would impact its severity.

Sign in / Sign up

Export Citation Format

Share Document