Capítols de llibre
http://hdl.handle.net/2117/83720
2024-03-28T21:25:45ZCarbonation resistance of recycled aggregate concrete using different cement types
http://hdl.handle.net/2117/390626
Carbonation resistance of recycled aggregate concrete using different cement types
Etxeberria Larrañaga, Miren
This paper describes the influence of the cement type and the use of 50% coarse RCA on the carbonation resistance of concrete. Twelve concrete mixtures were produced using four types of cement (CEM I, CEM IIAL, CEM IIAS and CEM IV of 42.5 MPa) and three different types of coarse aggregates (natural, RCA and carbonated-RCA [C-RCA]). All the concretes used 300 kg of cement and an effective water/cement (w/c) ratio of 0.49. The compressive strength at 28 and 56 days and the carbonation rate (at the accelerated and natural carbonation test) were determined and analysed. In both carbonation processes, it was concluded that while the concretes produced with CEM IV achieved the highest carbonation rate, the IIAS concretes achieved the lowest, regardless of the types of aggregates employed. On the other hand, the concretes produced with RCA and C-RCA achieved similar carbonation rate properties. Moreover, the natural carbonation coefficient, knat, determined experimentally, was 1.6–1.8 times higher than the carbonation rate estimated by the accelerated test. According to knat and following the structural code, all the concretes produced with CEM IV and the concrete produced with IIAL cement and C-RCA aggregates would not be allowed to be used in reinforced concrete exposure to a XC4 environment.
2023-07-11T15:15:14ZEtxeberria Larrañaga, MirenThis paper describes the influence of the cement type and the use of 50% coarse RCA on the carbonation resistance of concrete. Twelve concrete mixtures were produced using four types of cement (CEM I, CEM IIAL, CEM IIAS and CEM IV of 42.5 MPa) and three different types of coarse aggregates (natural, RCA and carbonated-RCA [C-RCA]). All the concretes used 300 kg of cement and an effective water/cement (w/c) ratio of 0.49. The compressive strength at 28 and 56 days and the carbonation rate (at the accelerated and natural carbonation test) were determined and analysed. In both carbonation processes, it was concluded that while the concretes produced with CEM IV achieved the highest carbonation rate, the IIAS concretes achieved the lowest, regardless of the types of aggregates employed. On the other hand, the concretes produced with RCA and C-RCA achieved similar carbonation rate properties. Moreover, the natural carbonation coefficient, knat, determined experimentally, was 1.6–1.8 times higher than the carbonation rate estimated by the accelerated test. According to knat and following the structural code, all the concretes produced with CEM IV and the concrete produced with IIAL cement and C-RCA aggregates would not be allowed to be used in reinforced concrete exposure to a XC4 environment.SP-357—8: Punching-shear strength of reinforced concrete slabs subjected to concentric transverse loads and in-plane tensile forces
http://hdl.handle.net/2117/386188
SP-357—8: Punching-shear strength of reinforced concrete slabs subjected to concentric transverse loads and in-plane tensile forces
Marí Bernat, Antonio Ricardo; Fernández Sánchez, Pablo Gonzalo; Oller Ibars, Eva; Cladera Bohigas, Antoni
Reinforced concrete slabs can be subjected simultaneously to transverse loads and in-plane tensile forces, as it occurs in top slabs of continuous box girder bridges at intermediate supports, or in flat slabs supported on columns, subjected to horizontal loads. To study the effects of in-plane forces in the slab punching-shear strength, an experimental and theoretical investigation was carried out, which is described in this paper. Five square slabs of 1650 mm (42”) side and 120 mm (4.7”) thickness were tested under a centered transverse point load and different degrees of uniaxial in-plane tensile force. Numerical predictions using non-linear finite element analyses were performed to help in the experiments design. Furthermore, the punching-shear mechanical model, Compression Chord Capacity Model (CCCM), was extended to incorporate the effects of in-plane tensile forces. The experimental results showed that the punching strength linearly decreases with the level of applied tensile force and, if cracking in the slabs is produced by the tensile force, yielding of the reinforcement and further reduction may take place. Excellent agreement was found between theoretical predictions and tests results. Furthermore, the CCCM was verified with available results of punching tests with uniaxial and biaxial tensile forces, obtaining very good results.
2023-04-13T11:58:36ZMarí Bernat, Antonio RicardoFernández Sánchez, Pablo GonzaloOller Ibars, EvaCladera Bohigas, AntoniReinforced concrete slabs can be subjected simultaneously to transverse loads and in-plane tensile forces, as it occurs in top slabs of continuous box girder bridges at intermediate supports, or in flat slabs supported on columns, subjected to horizontal loads. To study the effects of in-plane forces in the slab punching-shear strength, an experimental and theoretical investigation was carried out, which is described in this paper. Five square slabs of 1650 mm (42”) side and 120 mm (4.7”) thickness were tested under a centered transverse point load and different degrees of uniaxial in-plane tensile force. Numerical predictions using non-linear finite element analyses were performed to help in the experiments design. Furthermore, the punching-shear mechanical model, Compression Chord Capacity Model (CCCM), was extended to incorporate the effects of in-plane tensile forces. The experimental results showed that the punching strength linearly decreases with the level of applied tensile force and, if cracking in the slabs is produced by the tensile force, yielding of the reinforcement and further reduction may take place. Excellent agreement was found between theoretical predictions and tests results. Furthermore, the CCCM was verified with available results of punching tests with uniaxial and biaxial tensile forces, obtaining very good results.Influence of treated mixed recycled aggregates in concrete properties
http://hdl.handle.net/2117/385397
Influence of treated mixed recycled aggregates in concrete properties
Etxeberria Larrañaga, Miren; Vintimilla Molina, Carla Teresa
Extensive construction and demolition waste (CDW) is generated during the construction process. That waste is currently deposited in landfills. It is necessary to produce and employ mixed recycled aggregates (MRA) in low strength (up to 30 MPa) concrete elements. This study aimed to describe the properties (physical, mechanical and durability) of concrete made with treated (employing water glass, WG5, and silane admixture, Si6) MRA aggregate compared to untreated recycled concrete. Two types of MRA aggregates (with different amounts of ceramic particles) were employed. The concretes used 100% coarse and fine recycled aggregates with 300 kg of cement and an effective water/cement ratio of 0.50. These concrete mixes were suitable for use as 25 MPa concrete. The concrete produced with MRA aggregates with the WG5 surface treatment achieved the desired strength for reinforced concrete of 30–35 MPa. However, all the concretes obtained a low value of the elastic modulus. Although all the concretes manufactured with 100% recycled aggregate met the EHE requirements (Spanish Standard of Structural Concrete, EHE) regarding the depth of water penetration under pressure and relatively low carbonation coefficient, the drying shrinkage was high. However, the surface treatments of aggregate reduced recycled concrete shrinkage considerably.
2023-03-23T18:42:46ZEtxeberria Larrañaga, MirenVintimilla Molina, Carla TeresaExtensive construction and demolition waste (CDW) is generated during the construction process. That waste is currently deposited in landfills. It is necessary to produce and employ mixed recycled aggregates (MRA) in low strength (up to 30 MPa) concrete elements. This study aimed to describe the properties (physical, mechanical and durability) of concrete made with treated (employing water glass, WG5, and silane admixture, Si6) MRA aggregate compared to untreated recycled concrete. Two types of MRA aggregates (with different amounts of ceramic particles) were employed. The concretes used 100% coarse and fine recycled aggregates with 300 kg of cement and an effective water/cement ratio of 0.50. These concrete mixes were suitable for use as 25 MPa concrete. The concrete produced with MRA aggregates with the WG5 surface treatment achieved the desired strength for reinforced concrete of 30–35 MPa. However, all the concretes obtained a low value of the elastic modulus. Although all the concretes manufactured with 100% recycled aggregate met the EHE requirements (Spanish Standard of Structural Concrete, EHE) regarding the depth of water penetration under pressure and relatively low carbonation coefficient, the drying shrinkage was high. However, the surface treatments of aggregate reduced recycled concrete shrinkage considerably.Reliability of shear strength models for fibre reinforced concrete members without shear reinforcement
http://hdl.handle.net/2117/382057
Reliability of shear strength models for fibre reinforced concrete members without shear reinforcement
Tošić, Nikola; Bairán García, Jesús Miguel; Fuente Antequera, Albert de la
The scope and amount of fibre reinforced concrete (FRC) structural applications have seen significant increases. This means that safe and reliable ultimate limit state (ULS) models are necessary for FRC structural members. Among these, shear strength of FRC members without shear reinforcement is highly important due to the brittleness of shear failure. Because of this, the fib Model Code 2010 introduced two shear strength models: an empirical model based on Eurocode 2 and a physical model based on the Modified Compression Field Theory. However, a comprehensive reliability assessment of these models has been lacking. Therefore, in this study, the safety format of these models is assessed and the partial safety factors for FRC in shear, ¿c and ¿F are updated. As a first step, a large database of experimental results on FRC beams is used to determine model uncertainties. Following this, a comprehensive parametric probabilistic analysis is performed using the First Order Reliability Method to determine the adequate values of ¿c for different target reliability indices ß. The results of this study show that in order to reach typical reliability indices used in ULS design, ¿c and ¿F values need to be increased for FRC members without shear reinforcement for both models proposed by the fib Model Code 2010.
2023-02-02T20:20:30ZTošić, NikolaBairán García, Jesús MiguelFuente Antequera, Albert de laThe scope and amount of fibre reinforced concrete (FRC) structural applications have seen significant increases. This means that safe and reliable ultimate limit state (ULS) models are necessary for FRC structural members. Among these, shear strength of FRC members without shear reinforcement is highly important due to the brittleness of shear failure. Because of this, the fib Model Code 2010 introduced two shear strength models: an empirical model based on Eurocode 2 and a physical model based on the Modified Compression Field Theory. However, a comprehensive reliability assessment of these models has been lacking. Therefore, in this study, the safety format of these models is assessed and the partial safety factors for FRC in shear, ¿c and ¿F are updated. As a first step, a large database of experimental results on FRC beams is used to determine model uncertainties. Following this, a comprehensive parametric probabilistic analysis is performed using the First Order Reliability Method to determine the adequate values of ¿c for different target reliability indices ß. The results of this study show that in order to reach typical reliability indices used in ULS design, ¿c and ¿F values need to be increased for FRC members without shear reinforcement for both models proposed by the fib Model Code 2010.Water-washed fine and coarse recycled aggregates for real scale concretes production in Barcelona
http://hdl.handle.net/2117/375171
Water-washed fine and coarse recycled aggregates for real scale concretes production in Barcelona
Etxeberria Larrañaga, Miren; Konoiko, Mikhail; García, Carles; Perez Peñalta, Miguel Ángel
The use of recycled aggregate to reduce the over-exploitation of raw aggregates is necessary. This study analysed and categorised the properties of water-washed, fine and coarse, recycled aggre-gates following European Normalization (EN) specification. Because of their adequate properties, zero impurities and chemical soluble salts, plain recycled concrete was produced using 100% recycled concrete aggregates. Two experimental phases were conducted. Firstly, a laboratory phase, and secondly, an on-site work consisting of a real-scale pavement-base layer. The workability of the produced concretes was validated using two types of admixtures. In addition, the compressive and flexural strength, physical properties, drying shrinkage and depth of penetration of water under pressure validated the concrete design. The authors concluded that the worksite-produced concrete properties were similar to those obtained in the laboratory. Consequently, the laboratory results could be validated for large-scale production. An extended slump value was achieved using 2.5–3% of a multifunctional admixture plus 1–1.2% of superplasticiser in concrete production. In addition, all the produced concretes obtained the required a strength of 20 MPa. Although the pavement-base was produced using 300 kg of cement, the concrete made with 270 kg of cement per m3 and water/cement ratio of 0.53 achieved the best properties with the lowest environmental impact.
2022-10-27T13:22:25ZEtxeberria Larrañaga, MirenKonoiko, MikhailGarcía, CarlesPerez Peñalta, Miguel ÁngelThe use of recycled aggregate to reduce the over-exploitation of raw aggregates is necessary. This study analysed and categorised the properties of water-washed, fine and coarse, recycled aggre-gates following European Normalization (EN) specification. Because of their adequate properties, zero impurities and chemical soluble salts, plain recycled concrete was produced using 100% recycled concrete aggregates. Two experimental phases were conducted. Firstly, a laboratory phase, and secondly, an on-site work consisting of a real-scale pavement-base layer. The workability of the produced concretes was validated using two types of admixtures. In addition, the compressive and flexural strength, physical properties, drying shrinkage and depth of penetration of water under pressure validated the concrete design. The authors concluded that the worksite-produced concrete properties were similar to those obtained in the laboratory. Consequently, the laboratory results could be validated for large-scale production. An extended slump value was achieved using 2.5–3% of a multifunctional admixture plus 1–1.2% of superplasticiser in concrete production. In addition, all the produced concretes obtained the required a strength of 20 MPa. Although the pavement-base was produced using 300 kg of cement, the concrete made with 270 kg of cement per m3 and water/cement ratio of 0.53 achieved the best properties with the lowest environmental impact.Dynamic investigation of cultural heritage buildings for seismic safety asssessment
http://hdl.handle.net/2117/372272
Dynamic investigation of cultural heritage buildings for seismic safety asssessment
Elyamani Ali Mohamed, Ahmed; Roca Fabregat, Pedro; Caselles Magallón, Josep Oriol; Clapés Boixader, Jaime
Cultural heritage buildings are prone to failures when subjected to seismic events, and recent earthquakes worldwide resulted in many losses of these buildings. Therefore, there is a need for methodologies for assessing their seismic safety that should be based on enough knowledge of the building. Here, dynamic investigation by dynamic identification testing and dynamic monitoring increase significantly the level of knowledge about the assessed building. The dynamic identification tests give global information about the dynamic properties like natural frequencies that are useful in calibrating and updating a numerical model of the building that could be used in the seismic safety evaluation. Dynamic monitoring gives the dynamic properties’ evolution in time and may be used as an early warning tool able to send alarms when meaningful changes in dynamic properties are observed. This chapter gives some considerations on the different investigation activities of dynamic identification, dynamic monitoring, numerical model updating, and seismic safety assessment of cultural heritage buildings. As an application, the case study of the historic Mallorca cathedral is discussed.
2022-09-05T15:46:26ZElyamani Ali Mohamed, AhmedRoca Fabregat, PedroCaselles Magallón, Josep OriolClapés Boixader, JaimeCultural heritage buildings are prone to failures when subjected to seismic events, and recent earthquakes worldwide resulted in many losses of these buildings. Therefore, there is a need for methodologies for assessing their seismic safety that should be based on enough knowledge of the building. Here, dynamic investigation by dynamic identification testing and dynamic monitoring increase significantly the level of knowledge about the assessed building. The dynamic identification tests give global information about the dynamic properties like natural frequencies that are useful in calibrating and updating a numerical model of the building that could be used in the seismic safety evaluation. Dynamic monitoring gives the dynamic properties’ evolution in time and may be used as an early warning tool able to send alarms when meaningful changes in dynamic properties are observed. This chapter gives some considerations on the different investigation activities of dynamic identification, dynamic monitoring, numerical model updating, and seismic safety assessment of cultural heritage buildings. As an application, the case study of the historic Mallorca cathedral is discussed.European experience with seawater concrete
http://hdl.handle.net/2117/367752
European experience with seawater concrete
Fukunaga, Takayuki; Amino, Takahiko; Etxeberria Larrañaga, Miren
The use of seawater for concrete production is not common also in Europe now, even for the production of plain concrete exposed to a marine environment. However, in recent decades, certain international and national seawater concrete research projects have been initiated in Europe, including the Roman Maritime Concrete Study (ROMACONS), Sustainable Concrete using Seawater, Salt-contaminated Aggregates, and Non-corrosive Reinforcement (SEACON) and Eco-efficient By-products Suitable for the Market through the Integration of Recycling in Port Environments (SEA MIRENP). Both ROMACONS and SEACON were jointly carried out by European and non-European researchers. In both projects, actual-scale structures were analyzed. The researcher from Universitat Politeècnica de Catalunya (UPC, Barcelona TECH) developed the SEA MIRENP project and carried out actual scale tests at Barcelona Port. This outlines these three projects and describes the actual scale application of concrete produced using seawater for the marine environment as implemented in Europe as part of the projects.
2022-05-26T16:20:28ZFukunaga, TakayukiAmino, TakahikoEtxeberria Larrañaga, MirenThe use of seawater for concrete production is not common also in Europe now, even for the production of plain concrete exposed to a marine environment. However, in recent decades, certain international and national seawater concrete research projects have been initiated in Europe, including the Roman Maritime Concrete Study (ROMACONS), Sustainable Concrete using Seawater, Salt-contaminated Aggregates, and Non-corrosive Reinforcement (SEACON) and Eco-efficient By-products Suitable for the Market through the Integration of Recycling in Port Environments (SEA MIRENP). Both ROMACONS and SEACON were jointly carried out by European and non-European researchers. In both projects, actual-scale structures were analyzed. The researcher from Universitat Politeècnica de Catalunya (UPC, Barcelona TECH) developed the SEA MIRENP project and carried out actual scale tests at Barcelona Port. This outlines these three projects and describes the actual scale application of concrete produced using seawater for the marine environment as implemented in Europe as part of the projects.Stiffening solution of façade frames for reducing the eccentricity in plan-irregular buildings
http://hdl.handle.net/2117/365789
Stiffening solution of façade frames for reducing the eccentricity in plan-irregular buildings
Moyano, Gabriel; Bairán García, Jesús Miguel
Adjusting to architectonic and urbanistic constraints in dense cities frequently require plan irregularities in structures. One recurrent case is the combination of a frame in the façade, to allow parking access, with structural walls in other perimeter axes, for drift control. In long plan buildings, this creates large eccentricities between the mass and stiffness centres. In this paper, we propose one solution that increases the stiffness of the façade frame, without affecting its functionality. The concept consists on creating vertical elements in the inner spans of the intermittent stories, producing a Vierendeel-effect in the frame. The feasibility to improve the seismic performance is investigated through non-linear models. The stiffened frame reduces the distance between the centres of stiffness and mass. The possible variation of the failure mode is discussed, and recommendations for the capacity design of the façade frame are given. It is found that the additional vertical element does not contribute in the gravity load system, so it should not be considered as an intermittent column irregularity. The concept is applied to a 10-storey plan-irregular building, with hypothetical location in Lima (Perú), and its seismic performance is assessed. Compared to the solution with the standard frame, the maximum floor displacement was reduced up to 30%. The dominant period of vibration was reduced up to 15%. The recommended capacity-design condition allowed ductile behaviour without local collapse for demands larger than the MCE.
2022-04-12T15:36:50ZMoyano, GabrielBairán García, Jesús MiguelAdjusting to architectonic and urbanistic constraints in dense cities frequently require plan irregularities in structures. One recurrent case is the combination of a frame in the façade, to allow parking access, with structural walls in other perimeter axes, for drift control. In long plan buildings, this creates large eccentricities between the mass and stiffness centres. In this paper, we propose one solution that increases the stiffness of the façade frame, without affecting its functionality. The concept consists on creating vertical elements in the inner spans of the intermittent stories, producing a Vierendeel-effect in the frame. The feasibility to improve the seismic performance is investigated through non-linear models. The stiffened frame reduces the distance between the centres of stiffness and mass. The possible variation of the failure mode is discussed, and recommendations for the capacity design of the façade frame are given. It is found that the additional vertical element does not contribute in the gravity load system, so it should not be considered as an intermittent column irregularity. The concept is applied to a 10-storey plan-irregular building, with hypothetical location in Lima (Perú), and its seismic performance is assessed. Compared to the solution with the standard frame, the maximum floor displacement was reduced up to 30%. The dominant period of vibration was reduced up to 15%. The recommended capacity-design condition allowed ductile behaviour without local collapse for demands larger than the MCE.Enginyeria de la construcció
http://hdl.handle.net/2117/183491
Enginyeria de la construcció
Molins i Borrell, Climent
Els Anuaris de l’Enciclopèdia recullen els fets, les personalitats, els avenços científics i els temes de debat que han estat més presents en l’àmbit públic.
2020-04-15T16:02:22ZMolins i Borrell, ClimentEls Anuaris de l’Enciclopèdia recullen els fets, les personalitats, els avenços científics i els temes de debat que han estat més presents en l’àmbit públic.The suitability of concrete using recycled aggregates (RAs) for high-performance concrete
http://hdl.handle.net/2117/180078
The suitability of concrete using recycled aggregates (RAs) for high-performance concrete
Etxeberria Larrañaga, Miren
The use of recycled construction and demolition waste (CDW) as concrete aggregate has been studied over the recent years, although, there have only been a few attempts to utilize recycled aggregates in the production of high-performance concrete (HPC) due to the limitations imposed by the inherent defects of mentioned aggregates. This chapter describes the influence on the properties of the fresh and hardened state of recycled HPC by different types of recycled aggregates, produced from concrete, ceramic, and mixed waste. It is necessary to employ “high-quality” coarse recycled concrete aggregates in the production of a 100% recycled HPC to obtain similar mechanical and durability properties to those of natural aggregates. It has been determined that the employment of fly ash also improves the durability of recycled HPC. The high water absorption capacity of the ceramic and mixed aggregates, used as fine recycled aggregates caused a beneficial internal curing, reducing shrinkage, and increasing their suitability with respect to those of natural aggregate concrete.
2020-03-16T15:56:20ZEtxeberria Larrañaga, MirenThe use of recycled construction and demolition waste (CDW) as concrete aggregate has been studied over the recent years, although, there have only been a few attempts to utilize recycled aggregates in the production of high-performance concrete (HPC) due to the limitations imposed by the inherent defects of mentioned aggregates. This chapter describes the influence on the properties of the fresh and hardened state of recycled HPC by different types of recycled aggregates, produced from concrete, ceramic, and mixed waste. It is necessary to employ “high-quality” coarse recycled concrete aggregates in the production of a 100% recycled HPC to obtain similar mechanical and durability properties to those of natural aggregates. It has been determined that the employment of fly ash also improves the durability of recycled HPC. The high water absorption capacity of the ceramic and mixed aggregates, used as fine recycled aggregates caused a beneficial internal curing, reducing shrinkage, and increasing their suitability with respect to those of natural aggregate concrete.