La fisuración discreta: una alternativa a los modelos análisis no-lineal de estructuras de hormigón

En este trabajo se presenta un modelo de elementos finitos con fisuración discreta para el análisis no lineal de estructuras planas de hormigón cargadas en su plano. Mediante la utilización de cinco tipos de elementos finitos diferentes se incluyen en el análisis, no sólo el comportamiento no lineal del acero y el hormigón, sino también los efectos de la adherencia, encajamiento de áridos y pasador de las armaduras que cruzan una fisura. Se ha desarrollado un algoritmo que resuelve de manera automática los problemas derivados de la regeneración de la m d a propios de la técnica de la fisuración discreta. Por último, algunos de los resultados obtenidos con el modelo son comparados con los obtenidos experimentalmente en vigas con roturas por cortante y flexión.This paper presents a discrete-crack finite element model for the nonlinear analysis of concrete structures under plane-stress conditions. The model incorporates five types of finite elements in order to take into account the different mechanisms of stress transmission in concrete structures: concrete and steel finite elements, and special finite elements for the modelling of bond, aggregate interlock and dowel-action. The modifications of the finite element mesh, typical of the discret-crack approach, are carried out using a fully automatic strategy. Finally, the model is applied to the analysis of beams failing in flexure and in shear and the analytical predictions compared with the experimental data.Peer Reviewe

La fisuración discreta: una alternativa a los modelos análisis no-lineal de estructuras de hormigón

En este trabajo se presenta un modelo de elementos finitos con fisuración discreta para el análisis no lineal de estructuras planas de hormigón cargadas en su plano. Mediante la utilización de cinco tipos de elementos finitos diferentes se incluyen en el análisis, no sólo el comportamiento no lineal del acero y el hormigón, sino también los efectos de la adherencia, encajamiento de áridos y pasador de las armaduras que cruzan una fisura. Se ha desarrollado un algoritmo que resuelve de manera automática los problemas derivados de la regeneración de la m d a propios de la técnica de la fisuración discreta. Por último, algunos de los resultados obtenidos con el modelo son comparados con los obtenidos experimentalmente en vigas con roturas por cortante y flexión.This paper presents a discrete-crack finite element model for the nonlinear analysis of concrete structures under plane-stress conditions. The model incorporates five types of finite elements in order to take into account the different mechanisms of stress transmission in concrete structures: concrete and steel finite elements, and special finite elements for the modelling of bond, aggregate interlock and dowel-action. The modifications of the finite element mesh, typical of the discret-crack approach, are carried out using a fully automatic strategy. Finally, the model is applied to the analysis of beams failing in flexure and in shear and the analytical predictions compared with the experimental data.Peer Reviewe

Shear strength assessment of RC members: influence of shear reinforcement and yielding of the flexural reinforcement

[EN] An extensive experimental programme consisting of 15 shear tests on continuous reinforced concrete beams was carried out to assess the shear strength of beams with and without shear reinforcement. The influence of large flexural strains in the shear strength was analysed as the tests were designed to fail in shear after yielding of the flexural reinforcement. The assessment of the shear strength was investigated based on the contribution of the various potential shear-transfer actions following the possibilities offered by Digital Image Correlation (DIC). In this field, several approaches accounting for the role of the various shear-transfer actions have recently been proposed, such as the Critical Shear Crack Theory or the Compression Chord Capacity Model, and significant advances on the analysis of the activation of these shear-transfer actions have been performed by the use of DIC. In this work, detailed surface displacement measurements were performed by means of DIC, allowing to track the development and kinematics of the critical shear crack leading to failure. Based on this information, together with suitable constitutive models, the amount of shear transferred by each shear-transfer action was estimated at different load levels and at failure. The calculated shear strength of the specimens was obtained as the sum of the contribution of the various shear-transfer actions at failure and its comparison with the experimental results showed consistent agreement for the different cases. Based on the results, different conclusions and implications about the contribution of the various shear-transfer actions at shear failure are presented. In general, the contribution of each shear-transfer action is strongly influenced by cracking patterns and by the location, shape and kinematics of the critical shear crack.This research was funded through grants from the Ministerio de Economía y Competitividad of Spain with the research project BIA2015-64672-C4-4-R. The experimental program was developed in the Laboratory of Concrete of the Institute of Concrete Science and Technology (ICITECH) of the Universitat Politècnica de València (UPV). Andrea Monserrat has been particularly supported by the Conselleria d¿Educació, Investigació, Cultura i Esport of Generalitat Valenciana (Orden 6/2015, DOCV n. 7615 15.09.2015) with the European Regional Development Fund (ERDF) allocated by the EU. VIC2D software was employed during the research stay of Andrea Monserrat at the EPFL (Lausanne, Switzerland).Monserrat López, A.; Miguel Sosa, P. (2021). Shear strength assessment of RC members: influence of shear reinforcement and yielding of the flexural reinforcement. Fédération Internationale du Béton (fib) - International Federation for Structural Concrete. 1-10. http://hdl.handle.net/10251/182385S11

Strength of pile caps under eccentric loads: Experimental study and review of code provisions

[EN] Pile caps are rigid reinforced concrete structures that transfer column loads, generally consisting of a combination of an axial load and bending moments in one or two directions, to the piles. The design formulations of pile caps for more than two piles were derived from the results of experimental tests under a centered load. The practice of checking both punching and shear failure modes is common as described in the literature review, even though these formulations were developed for more slender elements. Currently, Codes ACI 318-14 and EC2 allow designing pile caps with strut-and-tie models or sectional approaches (shear, punching and flexural designs). In this study, 21 full-scale pile caps with different shear span-depth ratios and reinforcement layouts were studied to investigate the effect of eccentric loading on the strength and accuracy of the code formulations. The results show that in eccentrically loaded pile caps, the ultimate load is reduced but the maximum pile reaction increases and the secondary reinforcement proves effective to enhance the pile cap strength. Although the strut-and-tie models (STM) allow eccentric loads to be taken into consideration, they predict a much lower peak load than that observed at the experimental results and do not adequately reflect either the influence of slenderness or the failure mode. In general the sectional approach provided by Codes ACI-318-14, EC2 and MC-2010 (Level I of Approximation) lead to safe predictions of the peak load but do not always correctly predict the failure mode. The ultimate load predicted by EC-2 formulation comes closest to the experimental peak load, accurately reflects the influence of slenderness and the effect of secondary reinforcement, however, additional assumptions need to be made for its application. The ACI formulation complemented by the CRSI-2008 Special Investigation for deep pile caps is the safest but does not adequately capture the effect of horizontal and vertical secondary reinforcement. The MC2010 LoAI formulation is also conservative but does not detect the influence of slenderness or the contribution of secondary reinforcement.The authors wish to express their gratitude for the financial support (BIA2012-32300 and BIA2015-64672-C4-4-R) received from the Spanish Ministry of Economy and Competitiveness, which enabled the experimental campaign to be carried out, also for the PhD fellowship (BES-2013-063409).Miguel-Tortola, L.; Miguel Sosa, P.; Pallarés Rubio, L. (2019). Strength of pile caps under eccentric loads: Experimental study and review of code provisions. Engineering Structures. 182:251-267. https://doi.org/10.1016/j.engstruct.2018.12.064S25126718

The influence of transverse reinforcement and yielding of flexural reinforcement on the shear-transfer actions of RC members

[EN] The assessment of the shear strength of reinforced concrete beams with and without shear reinforcement is investigated in this paper on the basis of the contribution of the various potential shear-transfer actions. To that aim, a comprehensive experimental programme is presented, aimed at representing realistic conditions in reinforced concrete members. The programme comprised 15 cantilevers and 15 continuous beams with and without stirrups. In addition, some of the tests were designed to fail in shear after yielding of the flexural reinforcement, allowing to investigate on the structural implications of this phenomenon. The tests were instrumented by means of surface measurements using Digital Image Correlation (DIC), tracking in a detailed manner the development and kinematics of the critical shear crack leading to failure. Based on these mea-surements, and by accounting for suitable constitutive models, the contribution of the shear-transfer actions is estimated at different levels of load. The comparison of the experimental results with the calculated shear strength (sum of the contribution of the various shear-transfer actions at failure) shows consistent agreement for the various cases investigated. On this basis, several conclusions about the dominant shear-transfer actions at shear failure are presented, particularly on the role of the shear reinforcement and on the implications of the flexural reinforcement yielding on the overall response.This research was funded by grants from the Spanish Ministry of Economy and Competitiveness to Research Project BIA2015-64672-C4-4-R. The experimental programme was developed in the Laboratory of Concrete at the Institute of Concrete Science and Technology (ICITECH) of the Universitat Politecnica de Valencia (UPV), with concrete supplied by Caplansa. Andrea Monserrat was supported by the Conselleria d'Educacio, Investigacio, Cultura i Esport of the Generalitat Valenciana (Order 6/2015, DOGV no. 7615 15.09.2015) with European Regional Development Funds (ERDF) allocated by the EU. VIC2D software was employed during the research stay of Andrea Monserrat at the EPFL (Lausanne, Switzerland).Monserrat López, A.; Fernánez Ruiz, M.; Miguel Sosa, P. (2021). The influence of transverse reinforcement and yielding of flexural reinforcement on the shear-transfer actions of RC members. Engineering Structures. 234:1-17. https://doi.org/10.1016/j.engstruct.2021.111949S11723

Punching shear failure in three-pile caps: Influence of the shear span-depth ratio and secondary reinforcement

[EN] The strut-and-tie model (STM) is currently established as the best approach for pile cap design. This model leads to efficient estimations of the main reinforcement placed in strips between piles. However, good practices and some international Concrete Design Standards recommend some secondary distributed reinforcement, and even vertical stirrups that are not considered by the STM. An experimental campaign with nine three-pile caps tested by a centered load is presented to show the influence of both secondary reinforcement and the shear span-depth ratio on pile cap strength. The experimental results show a potential redistribution of internal forces in pile caps after yielding of main reinforcement, finally collapsed due to punching. Secondary reinforcement proves efficient to enhance pile cap strength since it takes part in complementary resistance mechanisms. As expected, the failure load increases with shear span-depth ratio reduction. The STM neither captures the effect of this ratio nor considers punching failure. Checking this failure mode is also required for pile caps. The punching formulation of Eurocode 2 allows considering the influence of this ratio, but some interpretation is required whether one deals with pile caps, regarding the effective width of the shear enhancement factor and the definition of the basic control perimeter. A proper definition would prevent unsafe or very conservative results. Therefore, some recommendations for the verification of deep pile caps following the Eurocode 2 are presented. The contribution of vertical stirrups as punching reinforcement is also investigated. The proposed approach is applied to the existing experimental database of three- and four-pile caps to check formulation validity, and conservative predictions with low coefficient of variation are reached.The authors would like to acknowledge the funding received from the Spanish Ministry of Economy and Competitiveness for basic non oriented research projects (BIA2012-32300), which also included a PhD fellowship (BES-2013-063409).Miguel-Tortola, L.; Pallarés Rubio, L.; Miguel Sosa, P. (2018). Punching shear failure in three-pile caps: Influence of the shear span-depth ratio and secondary reinforcement. Engineering Structures. 155:127-142. https://doi.org/10.1016/j.engstruct.2017.10.077S12714215

Asiakirjojen tiedoksiantomenettelyt kotimaas-sa ja kansainvälisesti

Tässä opinnäytetyössä tarkastelen asiakirjojen tiedoksiantomenetelmien käyttöä kotimaisissa ja kansainvälisissä yhteyksissä. Opinnäytetyöni keskeisenä tutkimuskysymyksenä esittelen tiedoksiannon kehityksen linjaa sekä sen merkityksestä käräjäoikeuksissa. Lisäksi kerron käräjäoikeuksissa käytössä olevista erilaisista tiedoksiantomenetelmistä nyt ja tulevaisuudessa kutsujen ja haasteiden osalta. Työni alku perustuu tiedoksiannon historiaan, jonka jälkeen paneudun nykypäivän tilaan. Työssäni käsiteltävällä tiedoksiannolla oikeudenkäynnissä tarkoitetaan haasteiden, kutsujen ja muiden oikeudellisten asiakirjojen antamista asianosaisen tai muun henkilön tietoon. Tiedoksiannolla on suuri merkitys oikeudenkäynnissä asianomaisen oikeusturvan kannalta unoh-tamatta vähäisten resurssien tehokasta käyttöä. Työni perustuu joiltakin osin kansainväliseen oikeusapuun, jonka olen rajannut Pohjoismaiseen ja EU-maiden väliseen tiedoksiantoon. Kansainvälisestä tiedoksiannosta yritän esittää realistisen kuvan nykytilasta sekä käsityksen huomioon otettavista asioista tiedoksiantoprosessin aikana, kun asianosainen asuu EU-maissa tai Pohjoismaissa. Keskeisempiä lähteistä työssäni olen käyttänyt oikeudenkäymiskaarta (OK 1.1.1734/4), hallituksen esitystä (HE 123/2009) sekä kansainvälisistä tiedoksiannoista tehtyjä sopimuksia. Työni kuluessa olen haastatellut käräjäoikeuksien henkilökuntaa.Service procedures of documents in domestic and internationally In this thesis service procedures of documents, which are used in domestic and international connection, are considered. As the most important research subject, the development line of the service, and its sense in the district court, is presented. Furthermore, different service procedures used in connection with subpoena and summons are explored in detail. In legal proceeding summons, subpoena and other juridical documents informing the parties or other people involved are called service. Servicing plays a significant role in the legal protection of the proper, not to mention effective use of small resources. The thesis is partially based on international legal assistance, of which only servicing between the Nordic and EU countries is focused on. The aim is to create a clear picture of the current state of international service and to provide a general understanding of matters that should be taken into account during declaration processes in situations, in which the party lives, in one of the EU countries or in Scandinavia. As the main source of law I have used code of Judicial Procedure (OK 1.1.1734/4), the Governmental Bill (HE 123/2009) as well as agreements on international service of notice. During the work I have also interviewed district court staff

A Simplified Approach for the Ultimate Limit State Analysis of Three-Dimensional Reinforced Concrete Elements

Several advanced constitutive models of concrete have been developed in recent decades, some of which are able to reproduce the behaviour of concrete structures with a high level of accuracy. Yet given their complex formulation, their application by most practitioners can entail some difficulties. This paper describes the adoption of an alternative, simplified comprehensible constitutive model for the ultimate limit state analysis of 3D reinforced concrete structural elements. The proposed model is described and the undertaken assumptions are justified. Different uniaxial stress strain models can be adopted, particularly neglecting the tensile strength of concrete permits to study the goodness of the stress field method and the strut-and-tie method for 3D elements. This model was implemented into a non-linear finite element-based tool developed by the authors. The results of twelve four-pile caps and three socket base column-to-foundation connections are shown. The proposed approach facilitated the identification of the flow of forces and allowed a better understanding of the structural response.The authors wish to thank the Spanish Ministry of Education for the FPU fellowship FPU12-01459 received by the first author, and the Spanish Ministry of Economy and Competitiveness for funding Project BIA 2012-32300.Meléndez-Gimeno, C.; Miguel Sosa, P.; Pallarés Rubio, L. (2016). A Simplified Approach for the Ultimate Limit State Analysis of Three-Dimensional Reinforced Concrete Elements. Engineering Structures. 123:330-340. https://doi.org/10.1016/j.engstruct.2016.05.039S33034012

Proposal and experimental validation of simplified strut-and-tie models on dapped-end beams

[EN] Dapped-end beams are frequent precast concrete elements. Spalling on the top of the hanger reinforcement has been observed to be often their governing failure mode. This failure hinders the geometric definition of strut-and-tie models for design or assessment purposes. In this work, a simplified procedure for defining the geometry of strut-and-tie models considering spalling failures is proposed. The model is based on the results of a specific experimental programme consisting on twenty-eight tests on fifteen different reinforcement configurations with and without inclined reinforcement. The experimental results show that elements with high amounts of reinforcement and hanger reinforcement concentrated in one layer are more prone to spalling failures, and suggest that the geometry of strut-and-tie models is strongly influenced by the behaviour of the nodal region on top of the hanger reinforcement. The model is verified for tests with and without spalling failures, including elements from the literature, showing sound agreement between the modelling results and experimental observations.The authors wish to thank the Spanish Ministry of Science and Innovation for funding Project BIA2009-11369 and for FPI fellowship BES-2010-030353 received by the first author. This work forms part of the first author's doctoral research awarded by the Business Chair of Sustainable and Advanced Construction at the Universitat Polithcnica de Valencia.Mata-Falcón, J.; Pallarés Rubio, L.; Miguel Sosa, P. (2019). Proposal and experimental validation of simplified strut-and-tie models on dapped-end beams. Engineering Structures. 183:594-609. https://doi.org/10.1016/j.engstruct.2019.01.010S59460918