Characterization of the longitudinal shear strength in composite slabs
The concrete-steel composite slabs show a complex structural characterization due to the different behaviours at the two materials. The materials are exposed to different deformations, large deflections and complex stresses with still a limited understanding of their micromechanics. Hence, current b...
| Author: | |
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| Format: | doctoral thesis |
| Publication Date: | 2017 |
| Country: | España |
| Institution: | Universitat Politècnica de Catalunya (UPC) |
| Repository: | UPCommons. Portal del coneixement obert de la UPC |
| Language: | English |
| OAI Identifier: | oai:upcommons.upc.edu:2117/113303 |
| Online Access: | https://hdl.handle.net/2117/113303 https://dx.doi.org/10.5821/dissertation-2117-113303 |
| Access Level: | Open access |
| Keyword: | Micromecànica Lloses de formigó Àrees temàtiques de la UPC::Enginyeria civil |
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Characterization of the longitudinal shear strength in composite slabs |
| title |
Characterization of the longitudinal shear strength in composite slabs |
| spellingShingle |
Characterization of the longitudinal shear strength in composite slabs Plans Pujolràs, Albert Micromecànica Lloses de formigó Àrees temàtiques de la UPC::Enginyeria civil |
| title_short |
Characterization of the longitudinal shear strength in composite slabs |
| title_full |
Characterization of the longitudinal shear strength in composite slabs |
| title_fullStr |
Characterization of the longitudinal shear strength in composite slabs |
| title_full_unstemmed |
Characterization of the longitudinal shear strength in composite slabs |
| title_sort |
Characterization of the longitudinal shear strength in composite slabs |
| dc.creator.none.fl_str_mv |
Plans Pujolràs, Albert |
| author |
Plans Pujolràs, Albert |
| author_facet |
Plans Pujolràs, Albert |
| author_role |
author |
| dc.contributor.none.fl_str_mv |
Marimón Carvajal, Federico Ferrer Ballester, Miquel |
| dc.subject.none.fl_str_mv |
Micromecànica Lloses de formigó Àrees temàtiques de la UPC::Enginyeria civil |
| topic |
Micromecànica Lloses de formigó Àrees temàtiques de la UPC::Enginyeria civil |
| description |
The concrete-steel composite slabs show a complex structural characterization due to the different behaviours at the two materials. The materials are exposed to different deformations, large deflections and complex stresses with still a limited understanding of their micromechanics. Hence, current building codes rely on expensive and tedious laboratory tests that characterize the composite slab failure and the ultimate resistance. The Finite Element (FE) numerical simulations were introduced more than 25 years ago in composite slab studies as a mechanism to validate new design methods and also as an alternative to reduce laboratory tests requirements. However, the simulations historically observed a significant number of simplifications such as reduced scale models or simplified geometries. This dissertation introduces initially a novel modeling and simulation methodology that enables new insights in the steel deck and concrete slab response for bending. Distinct full-scale finite element models were generated for four commercial steel deck profiles to simulate the laboratory tests. An intense and systematic optimization process was carried out as the computational costs and the simulation files size associated with the initial FE models were significant. The three-dimensional composite models detailed embossment depth and slope, steel thickness, or tilting angle, among several others. Common limitations and simplifications related to steel-concrete contact, adhesion, and cohesion factors in previous research efforts were addressed. Newton-Raphson was the simulation method and enabled the consideration of geometrical and materials nonlinearities. The proposed methodology was validated by comparison of the results from the bending simulations with the actual maximum loads, midspan deflection and end slip values obtained from laboratory bending tests. Based on the robustness of the bending simulations, parametric and boundary conditions analyses were performed through pull-out simulations. Micromechanics phenomena that could not be observed during laboratory tests were investigated at the full-scale bending simulations. First, the neutral axes and vertical disconnection representations for the steel deck and concrete slab were characterized and subsequently they proved the existence of partial connection between the materials. Second, a new normal vertical tension parameter sshear was introduced to describe the vertical stresses at the steel deck and the concrete slab. Third, the longitudinal shear strength Zu was computed for different midspan deflections, loads and friction coefficients. The longitudinal shear failure is the most common failure phenomenon among open rib steel deck profiles and thus multiple studies were performed. The observation of a constant Zu value at the shear span of the bending test was novel and indicated that the Eurocode 4 Partial Connection Method was not capable to describe the complex longitudinal shear strength behaviour observed from the simulations. The dissertation concludes with the introduction of a new characterization parameter tu,mechanical to assess the composite slab design efficiency. The parameter is defined as the longitudinal shear strength tu computed from the simulations for a null friction coefficient. The new parameter proved to accurately characterize the performance of the different composite slabs studied in this dissertation when compared with the maximum loads from the laboratory tests. The combiation of the novel modeling and simulation methodology with the tu,mechanical computation enabled a new design process for steel deck profiles. The process developed an iterative computer-focused approach with the goal to reduce the reliance in the costly and tedious laboratory tests. |
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2017 |
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2017 2017-09-26 2018 2018-01-24 |
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doctoral thesis http://purl.org/coar/resource_type/c_db06 VoR http://purl.org/coar/version/c_970fb48d4fbd8a85 |
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info:eu-repo/semantics/doctoralThesis |
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doctoralThesis |
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https://hdl.handle.net/2117/113303 https://dx.doi.org/10.5821/dissertation-2117-113303 |
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https://hdl.handle.net/2117/113303 https://dx.doi.org/10.5821/dissertation-2117-113303 |
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Inglés eng |
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Inglés |
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eng |
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open access http://purl.org/coar/access_right/c_abf2 http://creativecommons.org/licenses/by-nc-sa/4.0/ |
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application/pdf |
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Universitat Politècnica de Catalunya |
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Universitat Politècnica de Catalunya |
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reponame:UPCommons. Portal del coneixement obert de la UPC instname:Universitat Politècnica de Catalunya (UPC) |
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Characterization of the longitudinal shear strength in composite slabsPlans Pujolràs, AlbertMicromecànicaLloses de formigóÀrees temàtiques de la UPC::Enginyeria civilThe concrete-steel composite slabs show a complex structural characterization due to the different behaviours at the two materials. The materials are exposed to different deformations, large deflections and complex stresses with still a limited understanding of their micromechanics. Hence, current building codes rely on expensive and tedious laboratory tests that characterize the composite slab failure and the ultimate resistance. The Finite Element (FE) numerical simulations were introduced more than 25 years ago in composite slab studies as a mechanism to validate new design methods and also as an alternative to reduce laboratory tests requirements. However, the simulations historically observed a significant number of simplifications such as reduced scale models or simplified geometries. This dissertation introduces initially a novel modeling and simulation methodology that enables new insights in the steel deck and concrete slab response for bending. Distinct full-scale finite element models were generated for four commercial steel deck profiles to simulate the laboratory tests. An intense and systematic optimization process was carried out as the computational costs and the simulation files size associated with the initial FE models were significant. The three-dimensional composite models detailed embossment depth and slope, steel thickness, or tilting angle, among several others. Common limitations and simplifications related to steel-concrete contact, adhesion, and cohesion factors in previous research efforts were addressed. Newton-Raphson was the simulation method and enabled the consideration of geometrical and materials nonlinearities. The proposed methodology was validated by comparison of the results from the bending simulations with the actual maximum loads, midspan deflection and end slip values obtained from laboratory bending tests. Based on the robustness of the bending simulations, parametric and boundary conditions analyses were performed through pull-out simulations. Micromechanics phenomena that could not be observed during laboratory tests were investigated at the full-scale bending simulations. First, the neutral axes and vertical disconnection representations for the steel deck and concrete slab were characterized and subsequently they proved the existence of partial connection between the materials. Second, a new normal vertical tension parameter sshear was introduced to describe the vertical stresses at the steel deck and the concrete slab. Third, the longitudinal shear strength Zu was computed for different midspan deflections, loads and friction coefficients. The longitudinal shear failure is the most common failure phenomenon among open rib steel deck profiles and thus multiple studies were performed. The observation of a constant Zu value at the shear span of the bending test was novel and indicated that the Eurocode 4 Partial Connection Method was not capable to describe the complex longitudinal shear strength behaviour observed from the simulations. The dissertation concludes with the introduction of a new characterization parameter tu,mechanical to assess the composite slab design efficiency. The parameter is defined as the longitudinal shear strength tu computed from the simulations for a null friction coefficient. The new parameter proved to accurately characterize the performance of the different composite slabs studied in this dissertation when compared with the maximum loads from the laboratory tests. The combiation of the novel modeling and simulation methodology with the tu,mechanical computation enabled a new design process for steel deck profiles. The process developed an iterative computer-focused approach with the goal to reduce the reliance in the costly and tedious laboratory tests.Les lloses mixtes formades per acer i formigó presenten una caracterització estructural complexa degut al comportament diferent dels seus dos materials constituents. Aquests materials pateixen diferents nivells de deformacions, grans desplaçaments i distribucions d'esforços complexes, i avui en dia encara es desconeixen molts dels aspectes fonamentals de la seva micro-mecànica. En conseqüència, les normatives actuals requereixen la realització d'assajos de laboratori per a cada llosa mixta a través d'un procés costós i llarg. La utilització de les simulacions numèriques basades en elements finits per l'estudi de les lloses mixtes es va introduir fa més de 25 anys com a un mecanisme per validar nous processos de disseny i per reduir els exigents requeriments dels assajos normatius de laboratori. Malgrat això, històricament i fins a dia d'avui les simulacions numèriques han patit simplificacions importants, com la realització de models a escala reduïda o amb geometries simples. La recerca introdueix inicialment una nova metodologia de modelat i simulació en lloses mixtes que aporta noves dades en el comportament del perfil de xapa nervada i de la llosa de formigó. Es van desenvolupar diferents models d'elements finits per a quatre perfils de xapa comercials per replicar els assajos de laboratori de flexió. Inicialment, es va implementar un procés d'optimització sistemàtic en els models d'elements finits, ja que tant els costos computacionals com la mida de les simulacions eren elevats. Els models tridimensionals van incloure la profunditat i pendent de les emboticions, el gruix de la xapa d'acer i l'angle del nervi, entre molts altres paràmetres geomètrics. Es van millorar simplificacions i limitacions habituals observades en recerca publicada anteriorment sobre la interfície formigó-acer, el factor d'adhesió i els factors de cohesió. Es va implementar el mètode de simulació de Newton-Raphson, que va permetre la consideració de no-linealitats en geometries i materials. La metodologia proposada va ser validada comparant-la amb els resultats experimentals dels assajos de flexió. A partir de la solidesa observada en les simulacions de flexió, es van desenvolupar nous models d'elements finits de l'assaig de pull-out per realitzar un estudi paramètric i de condicions de contorn. A partir de les simulacions, es van analitzar multitud de fenòmens micro-mecànics que no s'havien pogut detectar directament en el laboratori. Primer, es van caracteritzar les representacions dels eixos neutres i la desconnexió vertical entre el formigó i l'acer, i posteriorment es va demostrar l'existència de connexió parcial entre ambdós materials. Segon, es va definir una nova tensió vertical normal σshear per descriure les tensions verticals observades entre la xapa d'acer i la llosa de formigó. Tercer, es va calcular l'esforç longitudinal a rasant tu per a tota la longitud del nervi i per a diferents càrregues. L'observació d'un segment amb valor constant va validar una de les hipòtesis del Mètode de la Connexió Parcial de l'Eurocodi 4. Així mateix, també va posar de manifest que el model mecànic d'aquest mètode no era capaç de capturar la complexitat observada en les simulacions per l'esforç "τu". La recerca conclou amb la introducció d'un nou paràmetre de caracterització de l'eficiència de la llosa mixta anomenat "τu,mechanical". Aquest paràmetre es defineix com l'esforç longitudinal a rasant tu obtingut de les simulacions amb fricció nul.la. El nou paràmetre va caracteritzar correctament els diferents perfils comercials modelats quan van ser comparats amb la seva resistència última obtinguda en els assajos de laboratori. La combinació de "τu,mechanical" i la nova metodologia de modelat i simulació genera un nou procés de disseny per lloses mixtes. A través d'un procés iteratiu centrat en simulacions que optimitzen "τu,mechanical", el procés genera una proposta de disseny final de la xapa d'acer, sense la necessitat de realitzar cap assaig al laboratori.Universitat Politècnica de CatalunyaMarimón Carvajal, FedericoFerrer Ballester, Miquel20172017-09-2620182018-01-24doctoral thesishttp://purl.org/coar/resource_type/c_db06VoRhttp://purl.org/coar/version/c_970fb48d4fbd8a85info:eu-repo/semantics/doctoralThesisapplication/pdfhttps://hdl.handle.net/2117/113303https://dx.doi.org/10.5821/dissertation-2117-113303reponame:UPCommons. Portal del coneixement obert de la UPCinstname:Universitat Politècnica de Catalunya (UPC)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2http://creativecommons.org/licenses/by-nc-sa/4.0/info:eu-repo/semantics/openAccessoai:upcommons.upc.edu:2117/1133032026-05-27T15:37:01Z |
| score |
15.300719 |