No Cover Image

E-Thesis 513 views 601 downloads

Modelling Damage, Fragmentation and Progressive Collapse of Structures Using Gausian Springs Based Applied Element Method / Mai A. Latif

DOI (Published version): 10.23889/Suthesis.48975

Abstract

Modelling the progressive collapse of structures is necessary for planning con-trolled demolitions, studying the effect of natural disasters on structures, and determining the weakest locations of a structure for further reinforcement and enhancement. Computational mechanics served an important contr...

Full description

Published: 2018
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa48975
Tags: Add Tag
No Tags, Be the first to tag this record!
first_indexed 2019-02-25T19:55:35Z
last_indexed 2019-10-21T16:54:06Z
id cronfa48975
recordtype RisThesis
fullrecord <?xml version="1.0"?><rfc1807><datestamp>2019-02-26T09:36:36.9642515</datestamp><bib-version>v2</bib-version><id>48975</id><entry>2019-02-25</entry><title>Modelling Damage, Fragmentation and Progressive Collapse of Structures Using Gausian Springs Based Applied Element Method</title><swanseaauthors/><date>2019-02-25</date><abstract>Modelling the progressive collapse of structures is necessary for planning con-trolled demolitions, studying the e&#xFB00;ect of natural disasters on structures, and determining the weakest locations of a structure for further reinforcement and enhancement. Computational mechanics served an important contribution to modelling the progressive collapse of structures, since it is very expensive to model collapse in an experimental evaluation for large scales.Existing developments of computational methods for the scope of collapse of structures are extensively reviewed &#xFB01;rst. It is concluded that the Applied Element Method (AEM) is one of the simplest schemes for modelling the progressive col-lapse with su&#xFB03;cient accuracy. The AEM is represented as pairs of rigid elements connected by shear and normal springs, along the edges of the elements. The material properties are represented in the sti&#xFB00;ness of the springs. The stresses and de&#xFB02;ection between elements are based on the de&#xFB02;ection of the springs.The de&#xFB02;ection and internal stresses of several structural beams are assessed using the conventional AEM and it is evident that the computational e&#xFB03;ciency of the method is inadequate since a sizable amount of elements and springs per element is required to achieve a speci&#xFB01;c level of accuracy. Hence, a modi&#xFB01;cation to the AEM is necessary to reduce the computational cost of the method. This thesis is focused on the development of the AEM for linear and nonlinear ma-terial behaviour, the development of a damage material model for representing damage and fragmentation, and an application of collapse of structures subject to earthquake and extreme wind loading.The AEM is enhanced using the Gaussian quadrature to &#xFB01;nd the exact loca-tion of springs. Using a Gaussian distribution it is concluded that only 2 springs per element are required for elastic elements, while a total of 6 springs are required for elasto-plastic elements. In conjunction with the Gaussian springs modi&#xFB01;ca-tion, a further modi&#xFB01;cation is implemented that utilises an adaptive technique for selecting the number of springs per element based on elasticity and elasto-plasticity of the springs. In nonlinear material analysis the Newton-Raphson integration scheme is adapted.To model damage in materials a softening material behaviour is employed. The developed softening algorithm is a return mapping method that is based on the predictor-corrector hardening plasticity algorithm. To represent the failure of a spring in the AEM, the sti&#xFB00;ness of the spring is set to zero. This results in a singular global sti&#xFB00;ness matrix that can not be solved directly. Using a dynamic model for the analysis eliminates the need of inverting the sti&#xFB00;ness matrix, so the explicit Central Di&#xFB00;erence Method is used for linear and nonlinear dynamic analysis.The &#xFB01;ndings in this thesis are (1) the conventional AEM is modi&#xFB01;ed by changing the distribution of the springs using the Gaussian quadrature allowing for ex-act calculation of optimal spring locations (2) only 2 and 6 linear and nonlinear springs are needed, respectively between a pair of elements, reducing the overall computational cost of the structure and increasing the accuracy (3) an adaptive transition springs technique is implemented and allowed for an overall reduced computational cost (4) a softening return mapping algorithm is developed for representing material damage (5) a time integrating technique is required when element separation occurs to avoid a singular matrix (6) application of the Gaus-sian AEM is performed on 2D frames subject to earthquake loads and extreme wind loads.</abstract><type>E-Thesis</type><journal/><publisher/><keywords>progressive collapse, damage, applied element method, elastoplastic</keywords><publishedDay>31</publishedDay><publishedMonth>12</publishedMonth><publishedYear>2018</publishedYear><publishedDate>2018-12-31</publishedDate><doi>10.23889/Suthesis.48975</doi><url/><notes>A selection of third party content is redacted or is partially redacted from this thesis.</notes><college>COLLEGE NANME</college><CollegeCode>COLLEGE CODE</CollegeCode><institution>Swansea University</institution><degreelevel>Doctoral</degreelevel><degreename>Ph.D</degreename><apcterm/><lastEdited>2019-02-26T09:36:36.9642515</lastEdited><Created>2019-02-25T16:19:20.1794841</Created><path><level id="1">Faculty of Science and Engineering</level><level id="2">School of Engineering and Applied Sciences - Uncategorised</level></path><authors><author><firstname>Mai A.</firstname><surname>Latif</surname><order>1</order></author></authors><documents><document><filename>0048975-25022019164328.pdf</filename><originalFilename>Abdul_Latif_Mai_PhD_Thesis_Final_Redacted.pdf</originalFilename><uploaded>2019-02-25T16:43:28.7900000</uploaded><type>Output</type><contentLength>33250152</contentLength><contentType>application/pdf</contentType><version>Redacted version - open access</version><cronfaStatus>true</cronfaStatus><embargoDate>2019-02-24T00:00:00.0000000</embargoDate><copyrightCorrect>true</copyrightCorrect></document></documents><OutputDurs/></rfc1807>
spelling 2019-02-26T09:36:36.9642515 v2 48975 2019-02-25 Modelling Damage, Fragmentation and Progressive Collapse of Structures Using Gausian Springs Based Applied Element Method 2019-02-25 Modelling the progressive collapse of structures is necessary for planning con-trolled demolitions, studying the effect of natural disasters on structures, and determining the weakest locations of a structure for further reinforcement and enhancement. Computational mechanics served an important contribution to modelling the progressive collapse of structures, since it is very expensive to model collapse in an experimental evaluation for large scales.Existing developments of computational methods for the scope of collapse of structures are extensively reviewed first. It is concluded that the Applied Element Method (AEM) is one of the simplest schemes for modelling the progressive col-lapse with sufficient accuracy. The AEM is represented as pairs of rigid elements connected by shear and normal springs, along the edges of the elements. The material properties are represented in the stiffness of the springs. The stresses and deflection between elements are based on the deflection of the springs.The deflection and internal stresses of several structural beams are assessed using the conventional AEM and it is evident that the computational efficiency of the method is inadequate since a sizable amount of elements and springs per element is required to achieve a specific level of accuracy. Hence, a modification to the AEM is necessary to reduce the computational cost of the method. This thesis is focused on the development of the AEM for linear and nonlinear ma-terial behaviour, the development of a damage material model for representing damage and fragmentation, and an application of collapse of structures subject to earthquake and extreme wind loading.The AEM is enhanced using the Gaussian quadrature to find the exact loca-tion of springs. Using a Gaussian distribution it is concluded that only 2 springs per element are required for elastic elements, while a total of 6 springs are required for elasto-plastic elements. In conjunction with the Gaussian springs modifica-tion, a further modification is implemented that utilises an adaptive technique for selecting the number of springs per element based on elasticity and elasto-plasticity of the springs. In nonlinear material analysis the Newton-Raphson integration scheme is adapted.To model damage in materials a softening material behaviour is employed. The developed softening algorithm is a return mapping method that is based on the predictor-corrector hardening plasticity algorithm. To represent the failure of a spring in the AEM, the stiffness of the spring is set to zero. This results in a singular global stiffness matrix that can not be solved directly. Using a dynamic model for the analysis eliminates the need of inverting the stiffness matrix, so the explicit Central Difference Method is used for linear and nonlinear dynamic analysis.The findings in this thesis are (1) the conventional AEM is modified by changing the distribution of the springs using the Gaussian quadrature allowing for ex-act calculation of optimal spring locations (2) only 2 and 6 linear and nonlinear springs are needed, respectively between a pair of elements, reducing the overall computational cost of the structure and increasing the accuracy (3) an adaptive transition springs technique is implemented and allowed for an overall reduced computational cost (4) a softening return mapping algorithm is developed for representing material damage (5) a time integrating technique is required when element separation occurs to avoid a singular matrix (6) application of the Gaus-sian AEM is performed on 2D frames subject to earthquake loads and extreme wind loads. E-Thesis progressive collapse, damage, applied element method, elastoplastic 31 12 2018 2018-12-31 10.23889/Suthesis.48975 A selection of third party content is redacted or is partially redacted from this thesis. COLLEGE NANME COLLEGE CODE Swansea University Doctoral Ph.D 2019-02-26T09:36:36.9642515 2019-02-25T16:19:20.1794841 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised Mai A. Latif 1 0048975-25022019164328.pdf Abdul_Latif_Mai_PhD_Thesis_Final_Redacted.pdf 2019-02-25T16:43:28.7900000 Output 33250152 application/pdf Redacted version - open access true 2019-02-24T00:00:00.0000000 true
title Modelling Damage, Fragmentation and Progressive Collapse of Structures Using Gausian Springs Based Applied Element Method
spellingShingle Modelling Damage, Fragmentation and Progressive Collapse of Structures Using Gausian Springs Based Applied Element Method
,
title_short Modelling Damage, Fragmentation and Progressive Collapse of Structures Using Gausian Springs Based Applied Element Method
title_full Modelling Damage, Fragmentation and Progressive Collapse of Structures Using Gausian Springs Based Applied Element Method
title_fullStr Modelling Damage, Fragmentation and Progressive Collapse of Structures Using Gausian Springs Based Applied Element Method
title_full_unstemmed Modelling Damage, Fragmentation and Progressive Collapse of Structures Using Gausian Springs Based Applied Element Method
title_sort Modelling Damage, Fragmentation and Progressive Collapse of Structures Using Gausian Springs Based Applied Element Method
author ,
author2 Mai A. Latif
format E-Thesis
publishDate 2018
institution Swansea University
doi_str_mv 10.23889/Suthesis.48975
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 1
active_str 0
description Modelling the progressive collapse of structures is necessary for planning con-trolled demolitions, studying the effect of natural disasters on structures, and determining the weakest locations of a structure for further reinforcement and enhancement. Computational mechanics served an important contribution to modelling the progressive collapse of structures, since it is very expensive to model collapse in an experimental evaluation for large scales.Existing developments of computational methods for the scope of collapse of structures are extensively reviewed first. It is concluded that the Applied Element Method (AEM) is one of the simplest schemes for modelling the progressive col-lapse with sufficient accuracy. The AEM is represented as pairs of rigid elements connected by shear and normal springs, along the edges of the elements. The material properties are represented in the stiffness of the springs. The stresses and deflection between elements are based on the deflection of the springs.The deflection and internal stresses of several structural beams are assessed using the conventional AEM and it is evident that the computational efficiency of the method is inadequate since a sizable amount of elements and springs per element is required to achieve a specific level of accuracy. Hence, a modification to the AEM is necessary to reduce the computational cost of the method. This thesis is focused on the development of the AEM for linear and nonlinear ma-terial behaviour, the development of a damage material model for representing damage and fragmentation, and an application of collapse of structures subject to earthquake and extreme wind loading.The AEM is enhanced using the Gaussian quadrature to find the exact loca-tion of springs. Using a Gaussian distribution it is concluded that only 2 springs per element are required for elastic elements, while a total of 6 springs are required for elasto-plastic elements. In conjunction with the Gaussian springs modifica-tion, a further modification is implemented that utilises an adaptive technique for selecting the number of springs per element based on elasticity and elasto-plasticity of the springs. In nonlinear material analysis the Newton-Raphson integration scheme is adapted.To model damage in materials a softening material behaviour is employed. The developed softening algorithm is a return mapping method that is based on the predictor-corrector hardening plasticity algorithm. To represent the failure of a spring in the AEM, the stiffness of the spring is set to zero. This results in a singular global stiffness matrix that can not be solved directly. Using a dynamic model for the analysis eliminates the need of inverting the stiffness matrix, so the explicit Central Difference Method is used for linear and nonlinear dynamic analysis.The findings in this thesis are (1) the conventional AEM is modified by changing the distribution of the springs using the Gaussian quadrature allowing for ex-act calculation of optimal spring locations (2) only 2 and 6 linear and nonlinear springs are needed, respectively between a pair of elements, reducing the overall computational cost of the structure and increasing the accuracy (3) an adaptive transition springs technique is implemented and allowed for an overall reduced computational cost (4) a softening return mapping algorithm is developed for representing material damage (5) a time integrating technique is required when element separation occurs to avoid a singular matrix (6) application of the Gaus-sian AEM is performed on 2D frames subject to earthquake loads and extreme wind loads.
published_date 2018-12-31T03:59:41Z
_version_ 1763753047036526592
score 11.012924

Similar Items