Design of post‐installed and cast‐in‐place anchors according to the newEN 1992‐4 andACI 318‐19
Abstract: Post-installed and cast-in-place anchors are widely used to connect structural or nonstructural elements using a steel baseplate at the concrete structure. Generally, concrete anchors must be qualified if their failure would compromise the safety or result in substantial economic damage. Concrete anchor qualification results in technical approvals forming the basis for a code-compliant design. In Europe, anchor design is governed by the new standard EN 1992-4, and in the United States by ACI 318. Qualification… Show more
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Cited by 6 publications
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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). Esta tesis desarrolla una nueva técnica de refuerzo estructural: convirtiendo estructuras existentes de hormigón armado o pretensado a secciones mixtas, mediante la inserción de conectadores previa demolición controlada con agua a alta presión. El punto clave de la investigación, de carácter tecnológico, es la técnica de hidrodemolición, muy poco habitual en realizaciones de refuerzo. Esta técnica posibilita nuevas técnicas de refuerzo, gracias a la apertura de huecos y la no afectación del armado existente. Es en estas zonas demolidas dónde resulta simple el rearmado con nueva armadura, o la inserción de conectores (para convertir a sección mixta), previo a la inyección con morteros de reparación fluidos. La creciente robotización de los terminales de hidrodemolición ya permiten un avance autónomo y programado de varios parámetros de la demolición, incluso en estruturas sumergidas. Las interfases resultantes son muy sólidas, libres de fisuración y con rendimentos de avance elevados. Gracias a ello se garantiza una gran solidez de la conexión, al no existir taladros con holguras y al poder insertar los conectores en zonas armadas. De esta forma se consiguen refuerzos de gran potencia, al trasmitirse rasantes elevados. Para aprovechar el rápido avance de la hidrodemolición, se descarta el uso de hormigones tradicionales y se investiga la adaptación y empleo de morteros de altas prestaciones (endurecimiento en pocas horas). Para mejorar el comportamiento en post-rotura, a nivel local en la zona de la cabeza del perno, y para reducir la fisuración, se incorporan fibras poliméricas estructurales al mortero de interfase. Este trabajo explora una nueva técnica de refuerzo estructural, y para su desarrollo se limita a elementos tipo viga, aunque el concepto de forma genérica es extensible a otras tipologías estructurales (muros, regiones D, etc.). El trabajo da continuidad a investigaciones y realizaciones previas realizadas en USA y Suecia, dónde se ¿post-conectan¿ puentes de vigas metálicas antiguas a losas de tablero, originalmente no colaborantes. Asimismo, esta tesis se focaliza en sobrearmar a tracción vigas ya existentes. Será esta nueva disposición geométrica, la que exigirá nuevos procedimientos constructivos y conceptos de diseño, distintos a los investigados previamente. La fase experimental evalúa aspectos tecnológicos y resistentes. Ésta se divide en tres fases, que cubren los puntos clave de la tecnología: validación en campo y laboratorio de las técnicas involucradas, validación conjunta del sistema de refuerzo y modelización numérica y analítica de los resultados . La técnica se ejecuta y valida en una serie de vigas ensayadas a flexión a 3 puntos, con dos variantes de conectores. Para definir criterios y recomendaciones de diseño se comparan los resultados con modelos analíticos simplificados. Complementariamente se comparan con modelos numéricos para visualizar el comportamiento ante variaciones en la zona de apoyos. La investigación valida la constructibilidad y respuesta estructural de la técnica (en ductilidad y capacidad última). Finalmente se proponen futuras líneas de investigación al tratarse de una técnica nueva: validación en fatiga, secciones a cortante, inclusión de sensores y uso de otros materiales (UHPC, FRP, AMF)
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). Esta tesis desarrolla una nueva técnica de refuerzo estructural: convirtiendo estructuras existentes de hormigón armado o pretensado a secciones mixtas, mediante la inserción de conectadores previa demolición controlada con agua a alta presión. El punto clave de la investigación, de carácter tecnológico, es la técnica de hidrodemolición, muy poco habitual en realizaciones de refuerzo. Esta técnica posibilita nuevas técnicas de refuerzo, gracias a la apertura de huecos y la no afectación del armado existente. Es en estas zonas demolidas dónde resulta simple el rearmado con nueva armadura, o la inserción de conectores (para convertir a sección mixta), previo a la inyección con morteros de reparación fluidos. La creciente robotización de los terminales de hidrodemolición ya permiten un avance autónomo y programado de varios parámetros de la demolición, incluso en estruturas sumergidas. Las interfases resultantes son muy sólidas, libres de fisuración y con rendimentos de avance elevados. Gracias a ello se garantiza una gran solidez de la conexión, al no existir taladros con holguras y al poder insertar los conectores en zonas armadas. De esta forma se consiguen refuerzos de gran potencia, al trasmitirse rasantes elevados. Para aprovechar el rápido avance de la hidrodemolición, se descarta el uso de hormigones tradicionales y se investiga la adaptación y empleo de morteros de altas prestaciones (endurecimiento en pocas horas). Para mejorar el comportamiento en post-rotura, a nivel local en la zona de la cabeza del perno, y para reducir la fisuración, se incorporan fibras poliméricas estructurales al mortero de interfase. Este trabajo explora una nueva técnica de refuerzo estructural, y para su desarrollo se limita a elementos tipo viga, aunque el concepto de forma genérica es extensible a otras tipologías estructurales (muros, regiones D, etc.). El trabajo da continuidad a investigaciones y realizaciones previas realizadas en USA y Suecia, dónde se ¿post-conectan¿ puentes de vigas metálicas antiguas a losas de tablero, originalmente no colaborantes. Asimismo, esta tesis se focaliza en sobrearmar a tracción vigas ya existentes. Será esta nueva disposición geométrica, la que exigirá nuevos procedimientos constructivos y conceptos de diseño, distintos a los investigados previamente. La fase experimental evalúa aspectos tecnológicos y resistentes. Ésta se divide en tres fases, que cubren los puntos clave de la tecnología: validación en campo y laboratorio de las técnicas involucradas, validación conjunta del sistema de refuerzo y modelización numérica y analítica de los resultados . La técnica se ejecuta y valida en una serie de vigas ensayadas a flexión a 3 puntos, con dos variantes de conectores. Para definir criterios y recomendaciones de diseño se comparan los resultados con modelos analíticos simplificados. Complementariamente se comparan con modelos numéricos para visualizar el comportamiento ante variaciones en la zona de apoyos. La investigación valida la constructibilidad y respuesta estructural de la técnica (en ductilidad y capacidad última). Finalmente se proponen futuras líneas de investigación al tratarse de una técnica nueva: validación en fatiga, secciones a cortante, inclusión de sensores y uso de otros materiales (UHPC, FRP, AMF)
Pull‐out tests of handcrafted studs embedded in concrete with red mud synthetic coarse aggregate
This paper presented the experimental results of the strength capacity of studs embedded centrally in concrete with red mud synthetic coarse aggregates, with the variation of the handcrafted headed stud thickness (3.17, 4.76, 6.35, and 7.9 mm) and no shank bond influence with concrete. The results regarding the compressive strength of concrete showed considerable strength gain with synthetic coarse aggregate, ranging from 27.00 to 43.50 MPa, while in concrete with natural coarse aggregate, the variation was 27.00 to 36.50 MPa. Also, it was observed that the cracking in the concrete matrix of the synthetic coarse aggregate occurred in the aggregate instead of the transition zone, as occurred with the natural coarse aggregate concrete. However, the solid morphological formation of synthetic coarse aggregate provided excellent chemical adhesion to the headed stud, providing a hardening failure behavior after reaching the yield strength value of the steel bar with higher displacements. This can enable the optimized consumption of materials in the dosage of low‐strength structural concrete and the anchoring application of studs with smaller‐headed thicknesses, up to 8% of head diameter, generating economy and sustainability.
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