Pub Date : 2022-09-09DOI: 10.1590/s1983-41952023000200007
I. Metwally
abstract: Under contact explosions, the reinforced concrete structures can behave in a brittle manner with highly localized damage like concrete cratering, spalling, and reinforcement rupturing. High-speed fragmentation resulting from concrete spall may cause severe casualties and injuries. It is therefore important to restrained concrete fragments and improve collapse resistance of the slab. A new retrofitting technique is proposed in this paper which completely prevents fragmentation. To mitigate blast effects on civil structures, a new kind of concrete material named Ultra-High-Performance-Concrete (UHPC) is now widely studied and applied. UHPC material is known for its high compressive and tensile strength, large energy absorption capacity as well as good workability and anti-abrasion ability compared to normal strength concrete(NRC). All of recent experimental published work concerning blast performance of UHPC slabs under far or near explosion effect, on the other side, the contact explosion tests are relatively limited experimentally and nearly impossible because of security restrictions and costly in terms of both preparation and measurements. So, the real and accurate finite element models are needed to address this gap and understanding the real contact-explosion behavior of both NRC and UHPC slabs. The numerical analyses allow gaining insight into the complex failure mechanisms occurring in the slab and not directly observable. In this study, coupled smoothed particle hydrodynamics (SPH) method and finite element method is utilized to simulate the contact blast tests. Numerical results are compared with the experimental observations, and the feasibility and accuracy of the numerical model are validated. The validated numerical model provided a useful tool for designing potential blast-retrofitting solutions which can prevent the local material damage and fragmentations in both NRC & UHPC slabs subjected to contact explosion. This study introduced adequate and very efficient protection solution for both NRC & UHPC slabs exposed to contact explosion (1 kg of TNT) by utilizing the composite action generated between slabs & bonded steel plates. The 2 mm and 1 mm bonded steel plates at both faces of the NRC and UHPC slabs respectively attained a superior resistance to contact explosion.
{"title":"Damage assessment & innovation of efficient retrofitting solution of RC slabs exposed to contact explosion","authors":"I. Metwally","doi":"10.1590/s1983-41952023000200007","DOIUrl":"https://doi.org/10.1590/s1983-41952023000200007","url":null,"abstract":"abstract: Under contact explosions, the reinforced concrete structures can behave in a brittle manner with highly localized damage like concrete cratering, spalling, and reinforcement rupturing. High-speed fragmentation resulting from concrete spall may cause severe casualties and injuries. It is therefore important to restrained concrete fragments and improve collapse resistance of the slab. A new retrofitting technique is proposed in this paper which completely prevents fragmentation. To mitigate blast effects on civil structures, a new kind of concrete material named Ultra-High-Performance-Concrete (UHPC) is now widely studied and applied. UHPC material is known for its high compressive and tensile strength, large energy absorption capacity as well as good workability and anti-abrasion ability compared to normal strength concrete(NRC). All of recent experimental published work concerning blast performance of UHPC slabs under far or near explosion effect, on the other side, the contact explosion tests are relatively limited experimentally and nearly impossible because of security restrictions and costly in terms of both preparation and measurements. So, the real and accurate finite element models are needed to address this gap and understanding the real contact-explosion behavior of both NRC and UHPC slabs. The numerical analyses allow gaining insight into the complex failure mechanisms occurring in the slab and not directly observable. In this study, coupled smoothed particle hydrodynamics (SPH) method and finite element method is utilized to simulate the contact blast tests. Numerical results are compared with the experimental observations, and the feasibility and accuracy of the numerical model are validated. The validated numerical model provided a useful tool for designing potential blast-retrofitting solutions which can prevent the local material damage and fragmentations in both NRC & UHPC slabs subjected to contact explosion. This study introduced adequate and very efficient protection solution for both NRC & UHPC slabs exposed to contact explosion (1 kg of TNT) by utilizing the composite action generated between slabs & bonded steel plates. The 2 mm and 1 mm bonded steel plates at both faces of the NRC and UHPC slabs respectively attained a superior resistance to contact explosion.","PeriodicalId":262995,"journal":{"name":"Revista IBRACON de Estruturas e Materiais","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128618654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-28DOI: 10.1590/s1983-41952021000600003
J. F. Natalli, E. Thomaz, J. C. Mendes, R. A. F. Peixoto
abstract: Over the years, Portland cement concretes have undergone increasing demands for constructability, cost, quality, and environmental impact. These demands were met, mainly, through changes in the cement composition and the introduction of chemical admixtures. In this sense, through a literature review, the authors sought to create a collection of information on the evolution of these materials and their standards from 1937 to 2020 in Brazil . This work is part of a research project that aims to elaborate a dating protocol for Brazilian concretes. From the review conducted, the authors observed that the absence of systematic records in the Brazilian civil construction sector hinders the attempt to create a chronology of the development of concrete in the country. In addition, we concluded that the knowledge of the evolution of Portland cement and chemical admixtures is relevant information that can assist in concrete dating processes. The reliable comparison data, posteriorly combined with microstructural characterisation techniques, may lay the basis for an effective dating methodology.
{"title":"A review on the evolution of Portland cement and chemical admixtures in Brazil","authors":"J. F. Natalli, E. Thomaz, J. C. Mendes, R. A. F. Peixoto","doi":"10.1590/s1983-41952021000600003","DOIUrl":"https://doi.org/10.1590/s1983-41952021000600003","url":null,"abstract":"abstract: Over the years, Portland cement concretes have undergone increasing demands for constructability, cost, quality, and environmental impact. These demands were met, mainly, through changes in the cement composition and the introduction of chemical admixtures. In this sense, through a literature review, the authors sought to create a collection of information on the evolution of these materials and their standards from 1937 to 2020 in Brazil . This work is part of a research project that aims to elaborate a dating protocol for Brazilian concretes. From the review conducted, the authors observed that the absence of systematic records in the Brazilian civil construction sector hinders the attempt to create a chronology of the development of concrete in the country. In addition, we concluded that the knowledge of the evolution of Portland cement and chemical admixtures is relevant information that can assist in concrete dating processes. The reliable comparison data, posteriorly combined with microstructural characterisation techniques, may lay the basis for an effective dating methodology.","PeriodicalId":262995,"journal":{"name":"Revista IBRACON de Estruturas e Materiais","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117163139","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-28DOI: 10.1590/s1983-41952021000600008
Letícia Andreolli Dias, Fernanda Boll Birck, Lucas Kaefer, Daiana Cristina Metz Arnold, A. S. de Vargas
ABSTRACT: The present study evaluated the use of red ceramic residues (RCR) as pigments in matrices based on White Portland cement. Five mortars were prepared for the present study: control mortar (M0), at 1:2,3 ratio (cement: sand) and water/cement ratio of 0.60, other four mortars were prepared containing RCR in 10% (M10), 20% (M20), 50% (M50), 100% (M100) of volume in replace to the sand. Colorimetric tests indicated a significant increase in the coloring, due to the increase of the RCR used. Tests of resistance to compression strength indicated a significant increase in the results as there was an increase in the substitution content of the sand by RCR. In the flexural tensile strength was no significant influence for contents of up to 50%. Therefore, the RCR showed potential as a pigmentation product and can contribute to the increase in compressive strength in Portland cement-based matrices.
{"title":"Study of red ceramic residues as pigments in matrices based on white Portland cement","authors":"Letícia Andreolli Dias, Fernanda Boll Birck, Lucas Kaefer, Daiana Cristina Metz Arnold, A. S. de Vargas","doi":"10.1590/s1983-41952021000600008","DOIUrl":"https://doi.org/10.1590/s1983-41952021000600008","url":null,"abstract":"ABSTRACT: The present study evaluated the use of red ceramic residues (RCR) as pigments in matrices based on White Portland cement. Five mortars were prepared for the present study: control mortar (M0), at 1:2,3 ratio (cement: sand) and water/cement ratio of 0.60, other four mortars were prepared containing RCR in 10% (M10), 20% (M20), 50% (M50), 100% (M100) of volume in replace to the sand. Colorimetric tests indicated a significant increase in the coloring, due to the increase of the RCR used. Tests of resistance to compression strength indicated a significant increase in the results as there was an increase in the substitution content of the sand by RCR. In the flexural tensile strength was no significant influence for contents of up to 50%. Therefore, the RCR showed potential as a pigmentation product and can contribute to the increase in compressive strength in Portland cement-based matrices.","PeriodicalId":262995,"journal":{"name":"Revista IBRACON de Estruturas e Materiais","volume":"10872 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134027426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-12DOI: 10.1590/s1983-41952021000600007
Anna Christinna Secundo Lopes, Joel Araújo do Nascimento Neto, Rodrigo Barros
abstract: The present study assesses conventionally used design standards, analyzing the effects caused by the construction loads, that is, a gradual increase in load and stiffness during construction, and soil-structure interaction (SSI), with soil represented by linear springs, in a structural masonry building over a support structure of reinforced concrete. The equivalent frame model, developed by Nascimento Neto, was used to simulate the support structure and the first masonry floor, and a specific three-dimensional frame model to simulate the other floors. Four analysis models were applied to assess stress distribution at the base of the walls, and the stresses and displacements of the support structure. The results show that introducing SSI and the construction loads causes relief or the possible need to reinforce elements designed in Ultimate Limit State (ULS) and Serviceability Limit State (SLS), as well as uniform settlement.
{"title":"Analysis of structural masonry buildings taking into account the construction sequence loads and soil-structure interaction","authors":"Anna Christinna Secundo Lopes, Joel Araújo do Nascimento Neto, Rodrigo Barros","doi":"10.1590/s1983-41952021000600007","DOIUrl":"https://doi.org/10.1590/s1983-41952021000600007","url":null,"abstract":"abstract: The present study assesses conventionally used design standards, analyzing the effects caused by the construction loads, that is, a gradual increase in load and stiffness during construction, and soil-structure interaction (SSI), with soil represented by linear springs, in a structural masonry building over a support structure of reinforced concrete. The equivalent frame model, developed by Nascimento Neto, was used to simulate the support structure and the first masonry floor, and a specific three-dimensional frame model to simulate the other floors. Four analysis models were applied to assess stress distribution at the base of the walls, and the stresses and displacements of the support structure. The results show that introducing SSI and the construction loads causes relief or the possible need to reinforce elements designed in Ultimate Limit State (ULS) and Serviceability Limit State (SLS), as well as uniform settlement.","PeriodicalId":262995,"journal":{"name":"Revista IBRACON de Estruturas e Materiais","volume":"34 1-6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116857347","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-05DOI: 10.1590/s1983-41952021000600009
Náyra Louise Alonso Marque, C. Nogueira
abstract: Reinforced concrete flat slabs are structural systems in which slabs are directly supported by columns, without the use of beams. A structural phenomenon that deserves attention in these systems is the punching shear, characterized by the occurrence of shear stresses close to the slab-column interface, which can produce fragile rupture in those regions. This study presents some results of reliability index β obtained for slab-column connections based on FORM, according to the Brazilian standard’s model, considering the model error. The critical contours C and C’ without shear reinforcement are analyzed. The results showed that failure in the C contour is very unlikely, while the probabilities of rupture in the C' contour when considering the influence of the model error are greater than the target values recommended in the literature for the ULS.
{"title":"Probabilistic analysis of slab-column connections subjected to punching shear according to the ABNT NBR 6118 (2014) recommendations considering the model error measure","authors":"Náyra Louise Alonso Marque, C. Nogueira","doi":"10.1590/s1983-41952021000600009","DOIUrl":"https://doi.org/10.1590/s1983-41952021000600009","url":null,"abstract":"abstract: Reinforced concrete flat slabs are structural systems in which slabs are directly supported by columns, without the use of beams. A structural phenomenon that deserves attention in these systems is the punching shear, characterized by the occurrence of shear stresses close to the slab-column interface, which can produce fragile rupture in those regions. This study presents some results of reliability index β obtained for slab-column connections based on FORM, according to the Brazilian standard’s model, considering the model error. The critical contours C and C’ without shear reinforcement are analyzed. The results showed that failure in the C contour is very unlikely, while the probabilities of rupture in the C' contour when considering the influence of the model error are greater than the target values recommended in the literature for the ULS.","PeriodicalId":262995,"journal":{"name":"Revista IBRACON de Estruturas e Materiais","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132473733","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-05DOI: 10.1590/s1983-41952021000600005
F. Salgado, F. Silva
abstract: As a solution to the high depletion of natural resources and huge waste generated by the construction industry, the use of coarse recycled aggregate has become a trend in many countries. The construction and demolition waste is heterogeneous and mostly composed of concrete and masonry debris. The recycling process usually involves not only crushing and screening but also advanced techniques to separate these two fractions. These processes are costly and most frequently ineffective. Although most studies and international standards focused only on recycled concrete aggregate for structural use, it is possible to achieve similar characteristics with mixed recycled aggregates that have a ceramic fraction of up to 20%. This initiative can decrease recycling costs and make it more feasible. Therefore, this work presents an experimental investigation of a Brazilian recycled aggregate, which was separated into three fractions: mixed, concrete, and masonry aggregates. The analyses showed that the mixed recycled aggregate displayed geometric, physical, and mechanical properties similar to the recycled concrete aggregate. In addition, concrete made with 20% of mixed recycled aggregate presented a reduction of only 0.6% in maximum compressive strength and 36.8% in the modulus of elasticity compared with concrete made with the same amount of recycled concrete aggregate.
{"title":"Properties of recycled aggregates from different composition and its influence on concrete strength","authors":"F. Salgado, F. Silva","doi":"10.1590/s1983-41952021000600005","DOIUrl":"https://doi.org/10.1590/s1983-41952021000600005","url":null,"abstract":"abstract: As a solution to the high depletion of natural resources and huge waste generated by the construction industry, the use of coarse recycled aggregate has become a trend in many countries. The construction and demolition waste is heterogeneous and mostly composed of concrete and masonry debris. The recycling process usually involves not only crushing and screening but also advanced techniques to separate these two fractions. These processes are costly and most frequently ineffective. Although most studies and international standards focused only on recycled concrete aggregate for structural use, it is possible to achieve similar characteristics with mixed recycled aggregates that have a ceramic fraction of up to 20%. This initiative can decrease recycling costs and make it more feasible. Therefore, this work presents an experimental investigation of a Brazilian recycled aggregate, which was separated into three fractions: mixed, concrete, and masonry aggregates. The analyses showed that the mixed recycled aggregate displayed geometric, physical, and mechanical properties similar to the recycled concrete aggregate. In addition, concrete made with 20% of mixed recycled aggregate presented a reduction of only 0.6% in maximum compressive strength and 36.8% in the modulus of elasticity compared with concrete made with the same amount of recycled concrete aggregate.","PeriodicalId":262995,"journal":{"name":"Revista IBRACON de Estruturas e Materiais","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128935467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-02DOI: 10.1590/s1983-41952021000600002
A. T. Souza, Catharina de Almeida Carvalhais, W. J. Santos
abstract: Water retaining agents are the main admixtures used to retain water against evaporation and substrate suction, and there are several chemical compounds for this purpose. To deepen the knowledge of mortar admixtures, several concentrations (0%, 1.5%, 5%, 10% and 15%) of three different types of admixtures were studied: an acrylic polymer, a cellulosic and ethylene vinyl acetate. Fresh properties (consistency, water retention, density and incorporated air), physical indexes (density and porosity) and compressive strength at 28 days were analyzed. It has been found that admixtures can act in different ways on mortars depending on the type of chemical agent used and can significantly affect the mechanical and durability characteristics in the fresh and hardened state. With this work it was verified the importance of searching references about the influence of chemical compounds before using it.
{"title":"Analysis of mortar coating with different types and proportions of chemical admixtures that have water retentivity properties","authors":"A. T. Souza, Catharina de Almeida Carvalhais, W. J. Santos","doi":"10.1590/s1983-41952021000600002","DOIUrl":"https://doi.org/10.1590/s1983-41952021000600002","url":null,"abstract":"abstract: Water retaining agents are the main admixtures used to retain water against evaporation and substrate suction, and there are several chemical compounds for this purpose. To deepen the knowledge of mortar admixtures, several concentrations (0%, 1.5%, 5%, 10% and 15%) of three different types of admixtures were studied: an acrylic polymer, a cellulosic and ethylene vinyl acetate. Fresh properties (consistency, water retention, density and incorporated air), physical indexes (density and porosity) and compressive strength at 28 days were analyzed. It has been found that admixtures can act in different ways on mortars depending on the type of chemical agent used and can significantly affect the mechanical and durability characteristics in the fresh and hardened state. With this work it was verified the importance of searching references about the influence of chemical compounds before using it.","PeriodicalId":262995,"journal":{"name":"Revista IBRACON de Estruturas e Materiais","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127767354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-02DOI: 10.1590/s1983-41952021000600012
A. Sousa, Y. D. Costa, Luiz Augusto da Silva Florêncio, C. M. Costa
abstract: This study evaluates load variations in instrumented prestressed ground anchors installed in a bored pile retaining wall system in sandy soil. Data were collected from instrumentation assembled in the bonded length of three anchors, which were monitored during pullout tests and during different construction phases of the retaining wall system. Instrumentation consisted of electrical resistance strain gauges positioned in five different sections along the bonded length. Skin friction distributions were obtained from the field load measurements. Results showed that the skin friction followed a non-uniform distribution along the anchor bonded length. The mobilized skin friction concentrated more intensely on the bonded length half closest to the unbonded length, while the other half of the bonded length developed very small skin friction. The contribution of the unbonded length skin friction to the overall anchor capacity was significant and this should be accounted for in the interpretation of routine anchor testing results. Displacements applied to the anchor head were sufficient to mobilize the ultimate skin friction on the unbonded length, but not on the bonded length. Performance of loading-unloading stages on the ground anchor intensified the transfer of load from the unbonded length to the bonded length. Long-term monitoring of the anchor after lock-off revealed that the load at the anchor bonded length followed a tendency to reduce with time and was not significantly influenced by the retaining wall construction phases.
{"title":"Load transfer on instrumented prestressed ground anchors in sandy soil","authors":"A. Sousa, Y. D. Costa, Luiz Augusto da Silva Florêncio, C. M. Costa","doi":"10.1590/s1983-41952021000600012","DOIUrl":"https://doi.org/10.1590/s1983-41952021000600012","url":null,"abstract":"abstract: This study evaluates load variations in instrumented prestressed ground anchors installed in a bored pile retaining wall system in sandy soil. Data were collected from instrumentation assembled in the bonded length of three anchors, which were monitored during pullout tests and during different construction phases of the retaining wall system. Instrumentation consisted of electrical resistance strain gauges positioned in five different sections along the bonded length. Skin friction distributions were obtained from the field load measurements. Results showed that the skin friction followed a non-uniform distribution along the anchor bonded length. The mobilized skin friction concentrated more intensely on the bonded length half closest to the unbonded length, while the other half of the bonded length developed very small skin friction. The contribution of the unbonded length skin friction to the overall anchor capacity was significant and this should be accounted for in the interpretation of routine anchor testing results. Displacements applied to the anchor head were sufficient to mobilize the ultimate skin friction on the unbonded length, but not on the bonded length. Performance of loading-unloading stages on the ground anchor intensified the transfer of load from the unbonded length to the bonded length. Long-term monitoring of the anchor after lock-off revealed that the load at the anchor bonded length followed a tendency to reduce with time and was not significantly influenced by the retaining wall construction phases.","PeriodicalId":262995,"journal":{"name":"Revista IBRACON de Estruturas e Materiais","volume":"111 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133184540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-02DOI: 10.1590/s1983-41952021000600011
O. S. Izquierdo, M. Corrêa, I. S. Izquierdo, I. G. Araujo
abstract: The Brazilian Standard Structural Masonry considers for the maximum tensile stress (fs) of the reinforcements embedded in the grout in clay blocks with smooth surfaces several limits of the yield stress for the reinforcement (fyk). This work aims to analyze the limits of the yield stress of reinforcement bars in clay block masonry structures by numerical and parametric analysis in push-out and pull-out tests, varying the type of grout and reinforcement diameter. A numerical study was performed using a 3D-model with the DIANA® software based on the Finite Element Method. The parametric study confirmed that the limits obtained in this research for reinforcement diameter of 8 mm, 10 mm, 12.5 mm and 16 mm are in agreement with the limits specified by the Brazilian Standard, with exception of the 20 mm diameter, which limit was lower than indicated by the Standard. The tensile stress limits of the embedded reinforcement progressively reduce with increasing rebar diameter, being the failure is dominated by the bond strength of the block/grout interface.
{"title":"Numerical and parametric study of the yield stress limits of reinforcement bars in clay block masonry structures","authors":"O. S. Izquierdo, M. Corrêa, I. S. Izquierdo, I. G. Araujo","doi":"10.1590/s1983-41952021000600011","DOIUrl":"https://doi.org/10.1590/s1983-41952021000600011","url":null,"abstract":"abstract: The Brazilian Standard Structural Masonry considers for the maximum tensile stress (fs) of the reinforcements embedded in the grout in clay blocks with smooth surfaces several limits of the yield stress for the reinforcement (fyk). This work aims to analyze the limits of the yield stress of reinforcement bars in clay block masonry structures by numerical and parametric analysis in push-out and pull-out tests, varying the type of grout and reinforcement diameter. A numerical study was performed using a 3D-model with the DIANA® software based on the Finite Element Method. The parametric study confirmed that the limits obtained in this research for reinforcement diameter of 8 mm, 10 mm, 12.5 mm and 16 mm are in agreement with the limits specified by the Brazilian Standard, with exception of the 20 mm diameter, which limit was lower than indicated by the Standard. The tensile stress limits of the embedded reinforcement progressively reduce with increasing rebar diameter, being the failure is dominated by the bond strength of the block/grout interface.","PeriodicalId":262995,"journal":{"name":"Revista IBRACON de Estruturas e Materiais","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116579307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2021-07-02DOI: 10.1590/s1983-41952021000600004
R. G. Delalibera, G. F. Sousa
abstract: Pile caps are structural elements used to transfer loads from the superstructure to a group of piles. The design of caps is normally based on analytical formulations, considering the strut and tie method. Through the advance of computational technology, the use of an integrated soil and foundation model may suggest a behavioral trend to obtain a more realistic modeling for the structural element being studied. This work aimed at analyzing, in numerical fashion, the structural behavior of reinforced concrete two-pile caps considering the lateral friction between the piles and the ground through a continuous modeling, as well as to analyze the portion of the load that is transferred to the ground directly by the cap. The lateral friction was modeled considering node coupling and through contact elements. Simulations were performed considering three soil types (sandy, clayish, and soilless), three cap heights, and three pile lengths. Soil parameters were obtained through semi-empirical correlations. Through these analyses, the conclusion was reached that, on average, 4.50% of the force applied to the pillar is transferred directly to the ground by cap. In terms of the principal compression stresses, in the superior nodal region, the strut tends to form beyond the section of the column. Alternatively, increasing cap stiffness provided, on average, an increase in the load carrying capacity of the models.
{"title":"Numerical analyses of two-pile caps considering lateral friction between the piles and soil","authors":"R. G. Delalibera, G. F. Sousa","doi":"10.1590/s1983-41952021000600004","DOIUrl":"https://doi.org/10.1590/s1983-41952021000600004","url":null,"abstract":"abstract: Pile caps are structural elements used to transfer loads from the superstructure to a group of piles. The design of caps is normally based on analytical formulations, considering the strut and tie method. Through the advance of computational technology, the use of an integrated soil and foundation model may suggest a behavioral trend to obtain a more realistic modeling for the structural element being studied. This work aimed at analyzing, in numerical fashion, the structural behavior of reinforced concrete two-pile caps considering the lateral friction between the piles and the ground through a continuous modeling, as well as to analyze the portion of the load that is transferred to the ground directly by the cap. The lateral friction was modeled considering node coupling and through contact elements. Simulations were performed considering three soil types (sandy, clayish, and soilless), three cap heights, and three pile lengths. Soil parameters were obtained through semi-empirical correlations. Through these analyses, the conclusion was reached that, on average, 4.50% of the force applied to the pillar is transferred directly to the ground by cap. In terms of the principal compression stresses, in the superior nodal region, the strut tends to form beyond the section of the column. Alternatively, increasing cap stiffness provided, on average, an increase in the load carrying capacity of the models.","PeriodicalId":262995,"journal":{"name":"Revista IBRACON de Estruturas e Materiais","volume":"34 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123398593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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