Refuerzo de estructuras de hormigón armado y pretensado por conversión a sección mixta mediante hidrodemolición
This thesis develops a new structural strengthening technique: converting existing reinforced concrete structures to composite sections by inserting connectors after controlled demolition with high-pressure water. The key point of the research, of a technological nature, is the technique of hydro de...
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| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2022 |
| País: | España |
| Institución: | CBUC, CESCA |
| Repositorio: | TDR. Tesis Doctorales en Red |
| OAI Identifier: | oai:www.tdx.cat:10803/674341 |
| Acceso en línea: | http://hdl.handle.net/10803/674341 https://dx.doi.org/10.5821/dissertation-2117-367999 |
| Access Level: | acceso abierto |
| Palabra clave: | Àrees temàtiques de la UPC::Enginyeria civil 624 69 |
| Sumario: | This thesis develops a new structural strengthening technique: converting existing reinforced concrete structures to composite sections by inserting connectors after controlled demolition with high-pressure water. The key point of the research, of a technological nature, is the technique of hydro demolition, which is very unusual in strengthening projects. This technique, applied to existing structures (reinforced or prestressed concrete) makes new reinforcement techniques possible, thanks to the opening of voids and the non-affectation of the existing reinforcement. At present, this technique is mostly used for complex demolition or repair work but not for strengthening. It is in these demolished areas where it is easy to re-reinforce with new rebars, or to insert connectors (to convert to composite section), prior to injection with fluid repair mortars. The increasing robotisation of the hydro demolition terminals already allows an autonomous and programmed advancement of various demolition parameters, even underwater. The resulting interfaces are very solid and crack-free and have good production rates. This ensures a high connection strength, as there are no loose bores and the connectors can be inserted in reinforced areas. This results in very strong reinforcements, as high gradients are transmitted. This results in very strong reinforcements, as high shear forces could be transmitted. To take advantage of the rapid progress of hydro demolition, the use of traditional concretes is discarded and the adaptation and use of high performance mortars (hardening in a few hours) is investigated. To improve post-breaking behaviour, locally in the bolt head area, and to reduce cracking, structural polymeric fibres are incorporated into the interface mortar. This work explores a new structural reinforcement technique, and the development is limited to beam-type elements, although the concept is generically extensible to other structural typologies (walls, D-regions, etc.). The work gives continuity to previous research and realisations carried out in the USA and Sweden, where old steel girder bridges are "post-connected" to originally non-collaborative deck slabs. Likewise, this thesis focuses on the steel plating tensioning of existing concrete beams. This new geometric arrangement will require new construction procedures different from those previously investigated. The use of a connector (high-strength bolt) is proposed, although, again, the reinforcement approach admits other types of connectors. The experimental phase evaluates technological and strength aspects. It is divided into three phases, covering the key points of the technology: field and laboratory validation of the techniques involved, validation of the assembly and numerical and analytical modelling of the results. The technique is performed and validated on a series of beams tested in 3-point bending, with two variants of connectors. To define design criteria and recommendations, the results are compared with simplified analytical models. In addition, they are compared with numerical models to visualise the behaviour in the presence of variations in the support zone. The research validates the constructability and structural response of the technique (in ductility and ultimate capacity). Finally, future lines of research are proposed as this is a new technique: validation in fatigue, shear sections, inclusion of sensors and use of other materials (UHPC, FRP, AMF). |
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