A new approach for displacement and stress monitoring of tunnel based on iFEM methodology

2021 ◽  
Author(s):  
Pierclaudio Savino ◽  
Francesco Tondolo
Keyword(s):  
Input Data ◽  
Structural Response ◽  
Fem Analysis ◽  
Computational Procedure ◽  
Loading Conditions ◽  
Underground Structures ◽  
Stress Monitoring ◽  
Load Pattern ◽  
Structural Configurations ◽  
Structural Loading

Abstract Structural monitoring plays a key role for underground structures such as tunnels. Strain readings are expected to report structural conditions during construction and at the final delivery of the works. Furthermore, it is increasingly requested an extension to long-term monitoring from contractors with possible use of the same system in service during construction. A robust and efficient monitoring methodology from discrete strain measurements is the inverse Finite Element Method (iFEM), which allows to reconstruct the structural response without input data on the load pattern applied to the structure as well as material and inertial properties of the elements and therefore it is interesting for structural configurations affected by uncertain loading conditions, such as the tunnel. The formulation presented in this paper, based on the iFEM theory, is improved from the previous work available in literature for both the shape functions used and the computational procedure. Indeed, the approach allows to overcome inconsistencies related to structural loading conditions and a pseudo-inverse matrix preserve all the rigid body modes without imposing specific constraints which is typical for tunnels. Numerical validation of the iFEM procedure is performed by simulating the input data coming from a tunnel working in a heterogeneous soil under different loading conditions with direct FEM analysis.

Mapping of crack edges by seismic methods

1982 ◽  
Vol 72 (3) ◽  
pp. 779-792
Author(s):  
J. D. Achenbach ◽  
A. Norris ◽  
K. Viswanathan
Keyword(s):  
Input Data ◽  
A Priori ◽  
Signal Propagation ◽  
Computational Procedure ◽  
Crack Edge ◽  
Inverse Mapping ◽  
Arrival Times ◽  
Ultrasonic Signals ◽  
Geometrical Theory Of Diffraction ◽  
Local Edge

abstract The inverse problem of diffraction of elastic waves by the edge of a large crack has been investigated on the basis of elastodynamic ray theory and the geometrical theory of diffraction. Two methods are discussed for the mapping of the edge of a crack-like flaw in an elastic medium. The methods require as input data the arrival times of diffracted ultrasonic signals. The first method maps flash points on the crack edge by a process of triangulation with the source and receiver as given vertices of the triangle. By the use of arrival times at neighboring positions of the source and/or the receiver, the directions of signal propagation, which determine the triangle, can be computed. This inverse mapping is global in the sense that no a priori knowledge of the location of the crack edge is necessary. The second method is a local edge mapping which determines planes relative to a known point close to the crack edge. Each plane contains a flash point. The envelope of the planes maps an approximation to the crack edge. The errors due to inaccuracies in the input data and in the computational procedure have been illustrated by specific examples.

scholarly journals Modelling of Friction Coefficient for Shoes Type LL By Means of Polynomial Fitting

2018 ◽  
Vol 12 (1) ◽  
pp. 114-127 ◽  
Author(s):  
L. Cantone ◽  
A. Ottati
Keyword(s):  
Experimental Data ◽  
Friction Coefficient ◽  
Input Data ◽  
Normal Force ◽  
Loading Conditions ◽  
Polynomial Fitting ◽  
Maximum Acceleration ◽  
Stopping Distance ◽  
Freight Traffic ◽  
Brake Cylinder

Introduction: The paper describes the automatic procedure, implemented in UIC software TrainDy, for the simulation of friction coefficient of new LL shoes, used to avoid noise from freight traffic. Method: This procedure uses certified experimental data obtained at dynamometer bench as input data and computes a series of polynomials laws that describe the evolution of friction coefficient with speed, for different values of normal force between brake blocks and wheel and for different initial braking speeds. Result: Numerical results are compared against two series of experimental slip tests, carried on Trenitalia freight wagons, in terms of both stopping distances (for different starting speeds and loading conditions) and pressure in brake cylinder, speed and acceleration. Errors in terms of stopping distance are always below 5% whereas errors in terms of maximum acceleration are up to 20%.

scholarly journals Structural Stress Monitoring and FEM Analysis of the Cutting Operation of the Main Bracket of A Semi-Submersible Platform

2019 ◽  
Vol 33 (6) ◽  
pp. 649-659
Author(s):  
Yu-feng Kou ◽  
Jian-min Yang ◽  
Sheng-wen Xu ◽  
Tao Peng ◽  
Jun Liu ◽  
...  
Keyword(s):  
Fem Analysis ◽  
Structural Stress ◽  
Stress Monitoring ◽  
Cutting Operation

Dynamic Response of Underground Structures in Sand: Experimental Data

2017 ◽  
Vol 33 (1) ◽  
pp. 347-372 ◽  
Author(s):  
Anne Lemnitzer ◽  
Lohrasb Keykhosropour ◽  
Yohsuke Kawamata ◽  
Ikuo Towhata
Keyword(s):  
Large Scale ◽  
Research Collaboration ◽  
Pressure Sensors ◽  
Structural Response ◽  
Silica Sand ◽  
Underground Structures ◽  
Bender Elements ◽  
Data Set ◽  
Displacement Transducers ◽  
Ground Motion Records

A densely instrumented system of large-scale underground structures consisting of two vertical shafts connected through a cut-and-cover tunnel and two independent shield tunnels was installed in an 8 m-diameter laminar soil box at the E-Defense shake table in Miki, Japan. The system was subjected to step-sine sweeps and scaled ground motion records of the Kobe (1995) earthquake. The underground structures were embedded in Albany Silica Sand with an average relative density of 54%. System instrumentation consisted of over 800 sensors, including strain gauges, accelerometers, displacement transducers, bender elements and pressure sensors. A U.S.-Japanese research collaboration was established to instrument the vertical shaft elements and record seismic soil pressures. Data records are archived at the NHERI DesignSafe Data Depot_and can be used to analyze the structural response, soil-structure interaction and other response parameters of individual subsurface components as well as the entire system. The DOI for the data set is 10.17603/DS21C78.

Hydrodynamic loadings on a floating guard wall at a navigation lock

2007 ◽  
Vol 34 (9) ◽  
pp. 1069-1074
Author(s):  
Cristhian A. Mancilla Alarcon ◽  
William H McAnally ◽  
Richard L Stockstill
Keyword(s):  
Numerical Modeling ◽  
Structural Analysis ◽  
Interaction Design ◽  
Structural Response ◽  
Ohio River ◽  
Fluid Loading ◽  
Structure Interaction ◽  
Fluid Load ◽  
Load Pattern ◽  
Navigation Lock

New float-in technology is being applied to construction of floating guard walls in navigation projects such as Olmsted lock and dam on the Ohio River. Guard wall fluid-structure interaction design can be decoupled if the effects of the structural response on the fluid load pattern are negligible. The assumption that the hydrodynamic pressures acting on a floating guard wall can be decoupled from the structural response of the wall is tested. The effects of the flow and pressure distribution in the presence of a typical guard wall were modeled and used as boundary conditions for structural analysis of the guard wall. The deformation of the guard wall was then used to recompute the fluid loads. Because the fluid loading did not change significantly, decoupling is considered to be valid.Key words: hydrodynamic forces, lock guard walls, navigation locks, numerical modeling.

Fibreglass Reinforced Polymer Structure Response under Different Impact Scenarios

2019 ◽  
Vol 827 ◽  
pp. 13-18
Author(s):  
Giuseppe Lamanna ◽  
Alessandro Greco ◽  
M. Manzo ◽  
Enrico Armentani ◽  
Constantin Gheorghe Opran
Keyword(s):  
Volume Fraction ◽  
Critical Role ◽  
Structural Response ◽  
Loading Conditions ◽  
Specific Strength ◽  
Reinforced Polymer ◽  
Drop Mass ◽  
Critical Issues ◽  
Polyester Matrix ◽  
Dynamic Loading Conditions

Composite materials are increasingly used in those fields where it is necessary to achieve the requirements of lightweight and high mechanical properties. Even though their high specific strength which get these materials very attractive, especially for the transport field, there are several critical issues that still limit their application in primary structures. Among these, dynamic loading conditions play a critical role because they can significantly lower their residual strength. This paper aims to investigate experimentally the structural response of a 25 mm thick Omega composite structure under different impact loading conditions. The investigated test article consists of E-glass fibres (40% volume fraction) reinforced polyester matrix. The structure is covered by a HELIOPOL 1401 M AGC W 11 gelcoat layer and it has been impacted through a drop mass of 3.94 kg, dropped from heights of 50 mm, 75 mm, 100 mm, 150 mm, 200 mm, 250 mm, 350 mm and 500 mm.

Finite Element Analysis on the Structure Strength of Air Cushion Vehicle

2014 ◽  
Vol 918 ◽  
pp. 95-100 ◽  
Author(s):  
Ning Liu ◽  
Hui Long Ren ◽  
Jian Zhang Li ◽  
Lian Hui Jia
Keyword(s):  
High Speed ◽  
Normal Load ◽  
Structural Response ◽  
Fem Analysis ◽  
Direct Calculation ◽  
Wave Loads ◽  
Loading Test ◽  
Element Analysis ◽  
Air Cushion ◽  
Air Cushion Vehicle

Air Cushion Vehicle is widely used in the field of military and civil ship in recent years for its characteristic high speed and amphibian. Since the yield strength of aluminum sheet with stiffeners is relative low after welding, to ensure air cushion vehicle has significant strength under normal load and to avoid severe damage under adverse sea conditions, model loading test and theoretical prediction is used to determines the design values of wave loads, and FEM analysis with direct calculation method under the different load cases including the total longitudinal strength, cross-strength, torsional strength and shear strength, and then getting the structural response results. This essay gives several suggestions for the design according to the calculated results of stress and its deformation characteristics.

INTASK—a program for postelastic dynamic analysis of three-dimensional structures

1987 ◽  
Vol 14 (1) ◽  
pp. 127-130
Author(s):  
Shing-Sham Lai ◽  
George T. Will
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Stiffness ◽  
Three Dimensional ◽  
Structural Response ◽  
Time Deformation ◽  
Inelastic Analysis ◽  
Orthogonal Components ◽  
History Of ◽  
Pertinent Information ◽  
Structural Configurations

An inelastic analysis program for three-dimensional structures subjected to static/gravity loads and (or) dynamic loads in the form of three translational and orthogonal components of base motions is described. Using incremental integration technique, the program computes structural response as a function of time. Deformation history of elements within the structure can be traced and pertinent information obtained via user element subroutines. Each node can possess up to six displacement degrees of freedom and can accommodate user elements with any specified nodes and degrees of freedom per node. The program is very flexible for modelling different structural configurations, and components like beam column elements, shear wall elements, slab elements, semirigid connection elements, and inelastic spring elements can be easily added to the base program. Key words: inelastic analysis, three-dimensional structures, earthquake, computer program, dynamic, stiffness matrix, base accelerations, unbalanced forces, element subroutines.

Blast Resistance of Clamped Cylindrical Sandwich Shells with Metallic Foam Cores

2013 ◽  
Vol 535-536 ◽  
pp. 461-464 ◽  
Author(s):  
Lin Jing ◽  
Zhi Hua Wang ◽  
Long Mao Zhao ◽  
V.P.W. Shim
Keyword(s):  
Dynamic Response ◽  
Failure Modes ◽  
Blast Resistance ◽  
Sheet Thickness ◽  
Structural Response ◽  
Experimental Results ◽  
Metallic Foam ◽  
Pendulum System ◽  
Sandwich Shells ◽  
Structural Configurations

The deformation/failure modes and dynamic response of fully clamped cylindrical sandwich shells with aluminum foam cores subjected to air blast loading were investigated experimentally. A four-cable ballistic pendulum system was employed to measure the impulse imparted to the blast-loaded specimen. The deformation/failure modes of specimens were classified and analyzed, the effects of face-sheet thickness, core relative density, specimen curvature and mass of charge on the structural response of metallic sandwich shells were examined. Experimental results indicate that both the deformation/failure modes and the dynamic response of the sandwich shells are sensitive to the structural configurations and blast impulse. The experimental results are useful for validating theoretical predictions, as well as in engineering applications of cellular metal sandwich structures.

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