Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
The analysis of rigid-viscoplastic plane structures subjected to large impulsive loading
This thesis is concerned with the analysis of plane ductile beams and frames which are subjected to large impulsive loading. The elastic response is ignored, and the material is considered as rigidviscoplastic in order to take rate effects into account. Computational advantage is obtained by modelli...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
Department of Civil Engineering
2023
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614398285086720 |
|---|---|
| access_status_str | Open Access |
| author | Griffin, Paul Dominic |
| author_browse | Griffin, Paul Dominic |
| author_facet | Griffin, Paul Dominic |
| author_sort | Griffin, Paul Dominic |
| collection | Thesis |
| description | This thesis is concerned with the analysis of plane ductile beams and frames which are subjected to large impulsive loading. The elastic response is ignored, and the material is considered as rigidviscoplastic in order to take rate effects into account. Computational advantage is obtained by modelling this behaviour by a homogeneous viscous constitutive relation, as the rigid phase is absent. As opposed to the standard displacement method finite element formulation where interpolation functions describing the velocity field across elements are given, a formulation is used in which nodal velocities, moments and element axial forces are carried as parameters. Three methods of analysis are presented; firstly, the mode approximation technique is described, where the actual behaviour of the structure is approximated in closed form by the product of a mode shape and a function of time. A new algorithm for the determination of the mode shape is presented. The mode technique is then extended to include geometric effects by means of the instantaneous mode solution technique. Secondly, a method is given whereby at each instant the accelerations (by the Tamuzh principle) and the rates of change of moment (by virtual velocities formulation) are found, and velocities and moments are integrated forward independently to obtain a solution. Finally, a direct method of analysis is described, where nodal forces conjugate to a given velocity field are calculated (by the principle of virtual velocities), and hence from the equations of motion, accelerations are determined. An implicit forward integration scheme is employed to advance the solution in time. Illustrative examples are presented which show that these techniques give very good and computationally efficient predictions of the displaced shape of the structures under consideration, even when displacements are in the order of the dimensions of the structure. |
| format | Thesis |
| id | oai:open.uct.ac.za:11427/38875 |
| institution | University of Cape Town (South Africa) |
| language | eng |
| last_indexed | 2026-06-10T12:51:24.594Z |
| license_str | Not specified — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Department of Civil Engineering |
| publisherStr | Department of Civil Engineering |
| record_format | dspace |
| source_str | UCTD — University of Cape Town Open Access Repository |
| spelling | oai:open.uct.ac.za:11427/38875 The analysis of rigid-viscoplastic plane structures subjected to large impulsive loading Griffin, Paul Dominic Civil engineering This thesis is concerned with the analysis of plane ductile beams and frames which are subjected to large impulsive loading. The elastic response is ignored, and the material is considered as rigidviscoplastic in order to take rate effects into account. Computational advantage is obtained by modelling this behaviour by a homogeneous viscous constitutive relation, as the rigid phase is absent. As opposed to the standard displacement method finite element formulation where interpolation functions describing the velocity field across elements are given, a formulation is used in which nodal velocities, moments and element axial forces are carried as parameters. Three methods of analysis are presented; firstly, the mode approximation technique is described, where the actual behaviour of the structure is approximated in closed form by the product of a mode shape and a function of time. A new algorithm for the determination of the mode shape is presented. The mode technique is then extended to include geometric effects by means of the instantaneous mode solution technique. Secondly, a method is given whereby at each instant the accelerations (by the Tamuzh principle) and the rates of change of moment (by virtual velocities formulation) are found, and velocities and moments are integrated forward independently to obtain a solution. Finally, a direct method of analysis is described, where nodal forces conjugate to a given velocity field are calculated (by the principle of virtual velocities), and hence from the equations of motion, accelerations are determined. An implicit forward integration scheme is employed to advance the solution in time. Illustrative examples are presented which show that these techniques give very good and computationally efficient predictions of the displaced shape of the structures under consideration, even when displacements are in the order of the dimensions of the structure. 2023-09-27T08:40:59Z 2023-09-27T08:40:59Z 1982 2023-09-27T08:09:20Z Doctoral Thesis Doctoral PhD http://hdl.handle.net/11427/38875 eng application/pdf Department of Civil Engineering Faculty of Engineering and the Built Environment |
| spellingShingle | Civil engineering Griffin, Paul Dominic The analysis of rigid-viscoplastic plane structures subjected to large impulsive loading |
| thesis_degree_str | Doctoral |
| title | The analysis of rigid-viscoplastic plane structures subjected to large impulsive loading |
| title_full | The analysis of rigid-viscoplastic plane structures subjected to large impulsive loading |
| title_fullStr | The analysis of rigid-viscoplastic plane structures subjected to large impulsive loading |
| title_full_unstemmed | The analysis of rigid-viscoplastic plane structures subjected to large impulsive loading |
| title_short | The analysis of rigid-viscoplastic plane structures subjected to large impulsive loading |
| title_sort | analysis of rigid viscoplastic plane structures subjected to large impulsive loading |
| topic | Civil engineering |
| url | http://hdl.handle.net/11427/38875 |
| work_keys_str_mv | AT griffinpauldominic theanalysisofrigidviscoplasticplanestructuressubjectedtolargeimpulsiveloading AT griffinpauldominic analysisofrigidviscoplasticplanestructuressubjectedtolargeimpulsiveloading |