Bond-slip model of headed bar and its application to component-based model for precast concrete joints under accidental loads
This study focused on investigating bond-slip behaviour of headed bars embedded in well-confined concrete. Test results based on eight pull-out specimens under displacement-controlled incremental loading showed that recommended development lengths from ACI318–19 are conservative in developing ultima...
| Main Authors: | , |
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| Other Authors: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
2024
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| Online Access: | https://hdl.handle.net/10356/175803 |
| _version_ | 1811694774848061440 |
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| author | Nguyen, Van Hung Tan, Kang Hai |
| author2 | School of Civil and Environmental Engineering |
| author_facet | School of Civil and Environmental Engineering Nguyen, Van Hung Tan, Kang Hai |
| author_sort | Nguyen, Van Hung |
| collection | NTU |
| description | This study focused on investigating bond-slip behaviour of headed bars embedded in well-confined concrete. Test results based on eight pull-out specimens under displacement-controlled incremental loading showed that recommended development lengths from ACI318–19 are conservative in developing ultimate strength of headed bars associated with smaller slips than straight bars. Moreover, it was found that different (but sufficiently long) embedment lengths had a significant effect on the free-end slip but negligible effect on the loaded-end slip of headed bars. Additionally, the study highlighted the significance of head bearing in anchorage formation, especially during inelastic stage when bond strength had deteriorated. To address inaccuracy in predicting structural behaviour caused by inadequate anchorage strength of headed bars, a macro bond-slip model was proposed based on correlation in strain distribution obtained from the pull-out tests. Subsequently, the proposed model was incorporated into a component-based model (CBM) and validated against test results of PC joints under seismic loading. A numerical investigation using the validated CBM was conducted to study behaviour of exterior PC joints with headed bars and special detailing. These included Type X joint with X-bent bars and plastic hinge relocation (PHR), and Type A joint with an additional bar layer (ABL) in the beam-joint region, subjected to extreme loads such as seismic action or progressive collapse. The results revealed that seismic behaviour of exterior joints was governed by ductile failure of the beam at the PHR and vertical joint interface in Type X and Type A joints, respectively. Progressive collapse was primarily caused by column failure, with flexural and catenary action effectively preventing collapse. Notably, under both loading conditions, presence of ABL in Type A joint and X-bent bars with PHR in Type X joint improves flexural strength of beams at critical sections and joint shear strength, ultimately enhancing structural performance of joints. Design recommendations include replacing hooked bars with headed bars as well as implementing X-bent bars with PHR and ABL in PC joints. The authors advocate the strong-column-weak-beam design approach as an effective measure to prevent progressive collapse. |
| first_indexed | 2024-10-01T07:12:55Z |
| format | Journal Article |
| id | ntu-10356/175803 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2024-10-01T07:12:55Z |
| publishDate | 2024 |
| record_format | dspace |
| spelling | ntu-10356/1758032024-05-07T01:01:16Z Bond-slip model of headed bar and its application to component-based model for precast concrete joints under accidental loads Nguyen, Van Hung Tan, Kang Hai School of Civil and Environmental Engineering Engineering Headed bar Bond-slip model This study focused on investigating bond-slip behaviour of headed bars embedded in well-confined concrete. Test results based on eight pull-out specimens under displacement-controlled incremental loading showed that recommended development lengths from ACI318–19 are conservative in developing ultimate strength of headed bars associated with smaller slips than straight bars. Moreover, it was found that different (but sufficiently long) embedment lengths had a significant effect on the free-end slip but negligible effect on the loaded-end slip of headed bars. Additionally, the study highlighted the significance of head bearing in anchorage formation, especially during inelastic stage when bond strength had deteriorated. To address inaccuracy in predicting structural behaviour caused by inadequate anchorage strength of headed bars, a macro bond-slip model was proposed based on correlation in strain distribution obtained from the pull-out tests. Subsequently, the proposed model was incorporated into a component-based model (CBM) and validated against test results of PC joints under seismic loading. A numerical investigation using the validated CBM was conducted to study behaviour of exterior PC joints with headed bars and special detailing. These included Type X joint with X-bent bars and plastic hinge relocation (PHR), and Type A joint with an additional bar layer (ABL) in the beam-joint region, subjected to extreme loads such as seismic action or progressive collapse. The results revealed that seismic behaviour of exterior joints was governed by ductile failure of the beam at the PHR and vertical joint interface in Type X and Type A joints, respectively. Progressive collapse was primarily caused by column failure, with flexural and catenary action effectively preventing collapse. Notably, under both loading conditions, presence of ABL in Type A joint and X-bent bars with PHR in Type X joint improves flexural strength of beams at critical sections and joint shear strength, ultimately enhancing structural performance of joints. Design recommendations include replacing hooked bars with headed bars as well as implementing X-bent bars with PHR and ABL in PC joints. The authors advocate the strong-column-weak-beam design approach as an effective measure to prevent progressive collapse. The authors would like to gratefully acknowledge the funding entitled “Precast progressive collapse testing programme” as part of the Changi East development programme, which is provided by Changi Airport Group of Singapore. Award No. NTU Ref: 2018–1451. Any opinions, findings, and conclusions expressed in this paper are those of the authors and do not necessarily reflect the view of Changi Airport Group of Singapore. 2024-05-07T01:01:16Z 2024-05-07T01:01:16Z 2024 Journal Article Nguyen, V. H. & Tan, K. H. (2024). Bond-slip model of headed bar and its application to component-based model for precast concrete joints under accidental loads. Engineering Structures, 307, 117791-. https://dx.doi.org/10.1016/j.engstruct.2024.117791 0141-0296 https://hdl.handle.net/10356/175803 10.1016/j.engstruct.2024.117791 2-s2.0-85188603652 307 117791 en NTU Ref: 2018–1451 Engineering Structures © 2024 Elsevier Ltd. All rights reserved. |
| spellingShingle | Engineering Headed bar Bond-slip model Nguyen, Van Hung Tan, Kang Hai Bond-slip model of headed bar and its application to component-based model for precast concrete joints under accidental loads |
| title | Bond-slip model of headed bar and its application to component-based model for precast concrete joints under accidental loads |
| title_full | Bond-slip model of headed bar and its application to component-based model for precast concrete joints under accidental loads |
| title_fullStr | Bond-slip model of headed bar and its application to component-based model for precast concrete joints under accidental loads |
| title_full_unstemmed | Bond-slip model of headed bar and its application to component-based model for precast concrete joints under accidental loads |
| title_short | Bond-slip model of headed bar and its application to component-based model for precast concrete joints under accidental loads |
| title_sort | bond slip model of headed bar and its application to component based model for precast concrete joints under accidental loads |
| topic | Engineering Headed bar Bond-slip model |
| url | https://hdl.handle.net/10356/175803 |
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