Stovner Tower Accessible Pedestrian Walkway to the Fiord Viewpoint

2021 ◽  
Author(s):  
Birger Opgård ◽  
Gaute Mo ◽  
Fernando Ibáñez Climent ◽  
Altea Cámara Aguilera
Keyword(s):  
Modal Analysis ◽  
Corrosion Protection ◽  
Steel Tube ◽  
Maximum Height ◽  
Fe Model ◽  
Change Of Direction ◽  
Steel Connections ◽  
Central Tube ◽  
Abrupt Changes ◽  
Straight Segments

<p>The Stovner Tower forms part of an activity park in the Stovner district of Oslo. The tower, providing a serpentine walkway through the treetops with a maximum height of 15m, is designed to be universally accessible. The route is based on a series of straight lengths connected with abrupt changes of direction. The 2m wide walkway has an overall length of 270m with a constant 1:15 slope. There are four intermediate horizontal platforms intended as relaxation and viewing areas, each one with different sizes. The principal deck structure is steel, formed from a central tube with a diameter of 762mm. The tube is made up of a series of 2m long straight segments which form the walkway change of direction. Steel cantilever ribs are located at 1.5m centres to support both the solid timber decking and the 1.3m high guardrail. The central steel tube is supported at multiple locations by tripod columns formed from GL32c glulam timber sections varying from 200x200mm to 350x350mm. The timber columns are anchored to the bedrock located close to the surface in this area. Steel walkway sections were shop welded in transportable lengths with bolted on- site connections. Timber to steel connections were also bolted. Steel is painted for corrosion protection. All timber, both solid C24 for decking and glulam columns, is treated for external use. A 3D SAP2000 FE model was used for verifications including a buckling analysis for the slender timber columns and a modal analysis to check for frequencies that would make the structure susceptible to pedestrian-induced vibrations.</p>

scholarly journals Condensation method in practical modal analysis of hull vibration with application of 3D FE model

2019 ◽  
pp. 162-169
Author(s):  
Valeriy Sutyrin
Keyword(s):  
Modal Analysis ◽  
Three Dimensional ◽  
Element Model ◽  
Fe Model ◽  
Structural Elements ◽  
Natural Vibrations ◽  
Condensation Method ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element ◽  
Analytical Approaches

This paper gives modal analysis results for mid-body of a refrigerator carrier ship by means of combined three-dimensional finite-element model with 1.5 million DOF. The study estimates the error of modal analysis for the ship structure if its boundary conditions are specified in advance, i.e. approximately, as well as analyses the gain in time offered by structuring the analytical model as per reduction (condensation) method. Analytical approaches thus transformed can be successfully applied in filtering lower frequencies and modes of natural vibrations for structural elements and joints of hull in the direct vicinity of exciting force application points.

Application of Unifuse Overlay Tubes in the Convection Section of Waste-to-Energy Boilers

2003 ◽  
Author(s):  
Pedro Amador ◽  
George Lai
Keyword(s):  
Carbon Steel ◽  
Corrosion Protection ◽  
Steel Substrate ◽  
Gas Metal Arc Welding ◽  
Steel Tube ◽  
Waste To Energy ◽  
Stainless Steel Tube ◽  
Weld Overlay ◽  
Alloy 625 ◽  
Gtaw Process

The modern weld overlay applied by automatic gas-metal-arc welding (GMAW) process using Ni-Cr-Mo-Nb alloy 625 has been extremely successful in providing corrosion and erosion/corrosion protection for the waterwalls of waste-to-energy (WTE) boilers for over a decade. Without alloy 625 weld overlay protection, the carbon steel waterwall of a waste-to-energy boiler would be corroded through in a matter of months. The overlaid waterwalls for numerous WTE boilers have shown excellent performance results with services up to 10 years or more. Welding Services Inc. has developed a patented process for manufacturing weld overlay bimetallic tubes involving GMAW/GTAW process. Unifuse® 625 overlay tubing with carbon steel substrate has been successfully used as screen tubes, superheater tubes and generating banks in the convection section. The overlay tubes have successfully replaced such corrosion protection methods as stainless steel tube shields and refractories.

scholarly journals Test and Numerical Study on Monotonic Behavior of Complex CFT Column Joints

2019 ◽  
Vol 2019 ◽  
pp. 1-20
Author(s):  
Zeliang Yu ◽  
Bin Yang ◽  
Bin Jia ◽  
Yuhong Yan ◽  
Shaowen Xiao ◽  
...  
Keyword(s):  
Failure Modes ◽  
Numerical Study ◽  
Local Buckling ◽  
Steel Tube ◽  
Load Test ◽  
Fe Model ◽  
Beam Design ◽  
Overlap Joint ◽  
Cft Column ◽  
Steel Trusses

This paper presents a test and numerical investigation into the monotonic behavior of three different complex steel trusses to concrete-filled tubular (CFT) column joints. Based on an engineering structure, 1 : 4 reduced-scale specimens are manufactured and the three-dimensional subassembly testing system is designed to apply the monotonic load. Test phenomena and load-stress curves show that all three types of joints have a considerable load-carrying capacity and joint rigidity. Finite element (FE) analysis is adopted, and the stress distribution shows good agreement with test data. Both test and FE results show that local buckling and yielding in the root region of steel truss are the main failure modes of test joints and the core area of the CFT column remains intact which are in accordance with the design conception of “strong column and weak beam.” Design conception of proposed overlap joint form is then investigated based on the FE model, and results show that the optimized overlap joint can effectively reduce the stress concentration in the adjacent steel tube and beam member when compared to the traditional N-type overlap joint. Finally, the influence of the outer diaphragm on the stiffness of joint is analyzed. By comparing the end-displacement of the beam member, conclusion can be obtained that the beam flange thickness is suggested to be chosen as the outer diaphragm thickness. The forms of three different proposed joints and their design conceptions can provide good guidance for designers and engineers.

Simulation of Bus Ride Comfort under the Excitation of Road Irregularity

2012 ◽  
Vol 510 ◽  
pp. 249-254 ◽  
Author(s):  
Jin Feng ◽  
Yuan Hua Chen
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Ride Comfort ◽  
Temporal Frequency ◽  
Vertical Vibration ◽  
Fe Model ◽  
Analysis Method ◽  
The Road ◽  
Power Spectral ◽  
Bus Structure

Bus vibration is studied by the finite element method (FEM) base on bus structure model. The bus mathematical model of vertical vibration is established and the vibration response variables were deduced with the modal analysis method. The finite element (FE) model is established and decoupled. The transformational relation between spatial frequency displacement power spectral density (PSD) and temporal frequency displacement PSD and the sampling characteristics of the road irregularity PSD in numerical computation are discussed. Road irregularity load is modeled in software. The FE model is solved using modal analysis method and the acceleration PSD of each keypoint can be gained. Finally, a road test experiment is carried on to verify the simulation results. The example indicated that study on vehicle ride comford by FEM has instructive meaning.

Dynamic Analysis of Indian Railway Integral Coach Factory Bogie

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Srihari Palli ◽  
Ramji Koona ◽  
Rakesh Chandmal Sharma ◽  
Venkatesh Muddada
Keyword(s):  
Dynamic Response ◽  
Modal Analysis ◽  
Fe Model ◽  
Fe Method ◽  
Harmonic Response ◽  
Natural Modes ◽  
Modes Of Vibration ◽  
Indian Railway ◽  
Secondary Suspension ◽  
Railway Sleeper

Dynamic response of railway coach is a key aspect in the design of coach. Indian railway sleeper and 3 tier AC coaches consist of two railway bogies, where the central distance of the center of gravity between the bogies is 14.9 m. Analysis of railway bogie forms a basis for investigating the behaviour of the coach as a whole. The current work carried out is, vehicle dynamic response in terms of Eigen frequency modal analysis and harmonic analysis of a Indian railway 6 Ton Integral Coach Factory (ICF) bogie using finite element (FE) method. The entire bogie model is discretized using solid92 tetrahedral elements. The primary and secondary suspension systems are modelled as COMBIN14 elements in the FE model of the bogie. Modal analysis of the bogie model using Block Lanczos method in ANSYS is carried out to extract first few natural modes of vibration of the bogie. The roll mode frequency attained in Modal analysis is in good agreement with the fundamental frequency calculated analytically. Sinusoidal excitation is fed as input to bottom wheel points to analyse the harmonic response of the bogie in terms of displacement at different salient locations. Harmonic response results reveal that the bogie left and right locations are more vulnerable than the locations near the centre of gravity of the bogie.

FE Modeling of Elliptical Concrete-Filled Steel Tubular Members Subjected to Pure Bending

2013 ◽  
Vol 859 ◽  
pp. 105-108
Author(s):  
Xiong Zhao ◽  
Xu Kuan Li ◽  
Qing Xin Ren ◽  
Tai Cheng ◽  
Xiao Lian Long
Keyword(s):  
Failure Modes ◽  
Steel Tube ◽  
Fe Model ◽  
Stress Distributions ◽  
Fe Modeling ◽  
Pure Bending ◽  
Element Analysis ◽  
Elliptical Section ◽  
As Stress ◽  
Good Agreement

This paper reports a finite element analysis of the flexural behaviour of concrete-filled steel tubular members with elliptical section. A set of test data were used to verify the FE modeling. generally, good agreement was achieved. Typical curves of moment (M) versus deflection at mid-span (um), as well as stress distributions of steel tube and concrete of the composite members were compared and discussed. The results clearly show that the FE model is available for predicting the load-bearing capacities and the failure modes of the specimens.

Output-Only Modal Analysis of an Internal Unreachable Module Embedded in a Space Electronic Equipment

2012 ◽  
Author(s):  
Lassaad Ben Fekih ◽  
Georges Kouroussis ◽  
David Wattiaux ◽  
Olivier Verlinden ◽  
Christophe De Fruytier
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Degrees Of Freedom ◽  
Transverse Direction ◽  
Mode Shapes ◽  
Fe Model ◽  
Fe Method ◽  
Numeric Model ◽  
Stiffness Matrices ◽  
Output Only

An approach is proposed to identify the modal properties of a subsystem made up of an arbitrary chosen inner module of embedded space equipment. An experimental modal analysis was carried out along the equipment transverse direction with references taken onto its outer housing. In parallel, a numerical model using the finite element (FE) method was developed to correlate with the measured results. A static Guyan reduction has led to a set of master degrees of freedom in which the experimental mode shapes were expanded. An updating technique consisting in minimizing the dynamic residual induced by the FE model and the measurements has been investigated. A last verification has consisted in solving the numeric model composed of the new mass and stiffness matrices obtained by means of a minimization of the error in the constitutive equation method.

scholarly journals Dynamic Axial Crushing of Empty and Foam-Filled Conical Aluminium Tubes: Experimental and Numerical Analysis

2014 ◽  
Vol 566 ◽  
pp. 305-309
Author(s):  
Fauziah Mat ◽  
K.A. Ismail ◽  
Masniezam Ahmad ◽  
Yaacob Sazali ◽  
Inayatullah Othman
Keyword(s):  
Carbon Steel ◽  
Steel Tube ◽  
Nonlinear Finite Element ◽  
Aluminium Foam ◽  
Fe Model ◽  
Steel Tubes ◽  
Foam Filling ◽  
Foam Filled ◽  
Initial Peak ◽  
Selection Of

This paper presents the crushing behaviour of empty and foam-filled conical tubes under axial dynamic loading. A nonlinear finite element (FE) model was developed and validated against experiments. The validated model was subsequently used to assess the beneficial of foam filling with regards to the variation in filler densities and tube materials. The results obtained were further analyzed and compared with straight tubes. We aim to evaluate the critical effective point for different density of fillers in foam-filled tubes based on specific energy absorption (SEA) value. The SEA value was highest for foam-filled conical aluminium tube with aluminium foam filler, followed by straight aluminium tube, straight carbon steel tube and conical carbon steel tube. Moreover, the initial peak force was found lower in aluminium tubes than carbon steel tubes and lower in conical tubes than that in straight tubes. The combination of conical aluminium tube and aluminium foam filler successfully convey the beneficial of foam filling and thus signify that proper combination and selection of tube and filler is vital in assessing the effectiveness of foam-filled tubes.

Constitutive Properties Determination of Human Cranium by an Experimental–Computational Modal Analysis

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Ashkan Eslaminejad ◽  
Mohamad Hosseini-Farid ◽  
Mariusz Ziejewski ◽  
Ghodrat Karami
Keyword(s):  
Tensile Test ◽  
Modal Analysis ◽  
Constitutive Models ◽  
Elastic Model ◽  
Fe Model ◽  
Strain Rates ◽  
Test Results ◽  
Human Skull ◽  
Linear Elastic ◽  
Constitutive Parameters

Abstract In this paper, we identified the material constitutive parameters of the human skull from reported tensile test results. Initially, we applied both linear-elastic and Mooney–Rivlin nonlinear hyperelastic constitutive models to the available tensile test data at different strain rates of 0.005, 0.10, 10, and 150 1/sec. It was shown that the suggested hyperelastic model fitted the test results with higher accuracy in comparison with the linear-elastic model. In the next step, the experimental modal analysis was carried out through roving hammer-impact tests on a dried human skull. The first four natural frequencies of the skull were measured to be 496, 543, 1250, and 1287 Hz, and these values were verified by the modal assurance criterion. Then, a 3D finite element (FE) model of that human skull was created by a 3D scanner and discretized to carry out a computational modal analysis. The performance of the determined material properties for the human skull from both linear and hyperelastic material models was evaluated using FE modal analysis. The calculated modal frequencies were then compared to the experimentally measured frequencies. It was shown that the material parameters from both the linear and hyperelastic constitutive models obtained at a strain rate of 0.10 1/sec, provided the best performance in computational modal analysis with minimum deviations relative to the experimental results. These results confer a better understanding of the human skull behavior among different strain rates, which could increase the accuracy of nonlinearity dynamic simulations on the skull.

Dynamic Properties of a Heliostat Structure Determined by Numerical and Experimental Modal Analysis

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
J. Felipe Vásquez-Arango ◽  
Reiner Buck ◽  
Robert Pitz-Paal
Keyword(s):  
Modal Analysis ◽  
Vortex Shedding ◽  
Natural Frequencies ◽  
Dynamic Properties ◽  
Simple Approach ◽  
Operating Conditions ◽  
Mode Shapes ◽  
Fe Model ◽  
Damping Coefficients ◽  
Operating Points

An experimental and numerical modal analysis was performed on an 8 m2 T-shaped heliostat structure at different elevation angles. The experimental results were used to validate a finite element (FE) model by comparing natural frequencies and mode shapes. The agreement between experiments and simulations is good in all operating points investigated. In addition, damping coefficients were determined experimentally for each mode, in order to provide all necessary information for the development of a dynamic model. Furthermore, potentially critical operating conditions caused by vortex shedding were identified using a simple approach.

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