The purpose of this research is to optimize several variables, including fiber length, volumetric fiber percentage, and sodium hydroxide (NaOH) solution concentration, which influence the bending and compression behavior of cementitious composites reinforced with plant-based fibers from Agave americana. Samples of composites based on fibers extracted from Agave americana and a cement matrix were manufactured and prepared according to a reference mortar. Box-Behnken Design (BBD) of Response Surface Methodology (RSM) was employed to build an experimental design to explore their mechanical behavior and to construct a set of mathematical models predictive of their behavior. The first stage of the work includes the extraction and processing of Agave americana fibers and the preparation of cement and Agave americana mortar specimens. The second phase aims to establish mathematical models to forecast the workability of the cement mortar and its strength at 28 days while emphasizing the correlations and interactions between the different components through the Design Expert software.
{"title":"Optimization of Bending and Compressive Strength Behavior of Agave americana Fiber Reinforced Cementitious Composite Using Response Surface Methodology","authors":"Samir Deghboudj, Wafia Boukhedena, H. Satha","doi":"10.3311/ppci.21696","DOIUrl":"https://doi.org/10.3311/ppci.21696","url":null,"abstract":"The purpose of this research is to optimize several variables, including fiber length, volumetric fiber percentage, and sodium hydroxide (NaOH) solution concentration, which influence the bending and compression behavior of cementitious composites reinforced with plant-based fibers from Agave americana. Samples of composites based on fibers extracted from Agave americana and a cement matrix were manufactured and prepared according to a reference mortar. Box-Behnken Design (BBD) of Response Surface Methodology (RSM) was employed to build an experimental design to explore their mechanical behavior and to construct a set of mathematical models predictive of their behavior. The first stage of the work includes the extraction and processing of Agave americana fibers and the preparation of cement and Agave americana mortar specimens. The second phase aims to establish mathematical models to forecast the workability of the cement mortar and its strength at 28 days while emphasizing the correlations and interactions between the different components through the Design Expert software.","PeriodicalId":49705,"journal":{"name":"Periodica Polytechnica-Civil Engineering","volume":"242 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90779727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study provides a semi-probabilistic approach to durability design of reinforced concrete structures, subjected to carbonation-induced corrosion. The method was developed from an existing approach and using comprehensive data collated from the literature. A statistical model for predicting accelerated carbonation coefficient, using as input variables mix proportions and test conditions was also generated. The performance of the proposed method was assessed and proved appropriate. Besides delivering a more consistent semi-probabilistic method to design for the avoidance of unforeseen carbonation-induced corrosion problems, the developed statistical model to estimate the accelerated carbonation coefficient is a useful tool on the mix design, from the standpoint of conforming with the accelerated carbonation coefficients obtained through the semi-probabilistic method.
{"title":"Reinforced Concrete Durability Design Through a Semi-probabilistic Approach","authors":"Murali Kannan Sundhar Paulpandian, Rui Neves","doi":"10.3311/ppci.21350","DOIUrl":"https://doi.org/10.3311/ppci.21350","url":null,"abstract":"This study provides a semi-probabilistic approach to durability design of reinforced concrete structures, subjected to carbonation-induced corrosion. The method was developed from an existing approach and using comprehensive data collated from the literature. A statistical model for predicting accelerated carbonation coefficient, using as input variables mix proportions and test conditions was also generated. The performance of the proposed method was assessed and proved appropriate. Besides delivering a more consistent semi-probabilistic method to design for the avoidance of unforeseen carbonation-induced corrosion problems, the developed statistical model to estimate the accelerated carbonation coefficient is a useful tool on the mix design, from the standpoint of conforming with the accelerated carbonation coefficients obtained through the semi-probabilistic method.","PeriodicalId":49705,"journal":{"name":"Periodica Polytechnica-Civil Engineering","volume":"67 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80633138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study was dedicated to evaluating the durability of the carbonatic stones of Crac des Chevaliers castle against salt crystallization. Crac des Chevaliers castle is a UNESCO world heritage site located in Syria and is considered one of the most important crusader castles built in the 12th century. Salt efflorescence is a common decay type detected on the stone blocks of this building, so six dolomite stone lithotypes with various structures tested under salt aging in three different salt solutions; sodium chloride, magnesium sulfate, and sodium sulfate. Among those lithotypes were two microbioclastic wackstone and four microcrystalline dolomite. The microbioclastic wackstone had low open porosity (18 and 11 v/v%) compared to the microcrystalline dolomites of about 28v/v% open porosity. Two of the microcrystalline dolomite lithotypes had bimodal pore networks and around 4 v/v% closed pores, however, the other two exhibited very small closed porosity (around 0.35 v/v%). The results revealed that even though the great effect of the open porosity on the durability of the specimens, the closed porosity also had a major role and the weathering form depended on the salt composition and the stone porosity properties. The primary decay type of the specimens in sodium sulfate solution was granular disintegration while pitted surfaces formed in sodium chloride solution, and the exfoliation of the stone surface into thin layers was observable after the aging with magnesium sulfate solution. The effect of NaCl crystallization on the specimen was not as aggressive as that of the sulfates.
{"title":"Assessment of the Resistance of Dolomite Stone from Crac des Chevaliers Against Salt Crystallization","authors":"O. Bilal, N. Rozgonyi-Boissinot","doi":"10.3311/ppci.21606","DOIUrl":"https://doi.org/10.3311/ppci.21606","url":null,"abstract":"This study was dedicated to evaluating the durability of the carbonatic stones of Crac des Chevaliers castle against salt crystallization. Crac des Chevaliers castle is a UNESCO world heritage site located in Syria and is considered one of the most important crusader castles built in the 12th century. Salt efflorescence is a common decay type detected on the stone blocks of this building, so six dolomite stone lithotypes with various structures tested under salt aging in three different salt solutions; sodium chloride, magnesium sulfate, and sodium sulfate. Among those lithotypes were two microbioclastic wackstone and four microcrystalline dolomite. The microbioclastic wackstone had low open porosity (18 and 11 v/v%) compared to the microcrystalline dolomites of about 28v/v% open porosity. Two of the microcrystalline dolomite lithotypes had bimodal pore networks and around 4 v/v% closed pores, however, the other two exhibited very small closed porosity (around 0.35 v/v%). The results revealed that even though the great effect of the open porosity on the durability of the specimens, the closed porosity also had a major role and the weathering form depended on the salt composition and the stone porosity properties. The primary decay type of the specimens in sodium sulfate solution was granular disintegration while pitted surfaces formed in sodium chloride solution, and the exfoliation of the stone surface into thin layers was observable after the aging with magnesium sulfate solution. The effect of NaCl crystallization on the specimen was not as aggressive as that of the sulfates.\u0000 ","PeriodicalId":49705,"journal":{"name":"Periodica Polytechnica-Civil Engineering","volume":"37 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74069279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Method of Fundamental Solutions is applied to the Laplace equation. Instead of using the traditional approach with external source points and boundary collocation points, the original domain decomposed into a lot of smaller, overlapping subdomains, and the Method of Fundamental Solutions is used to the individual local subdomains. After eliminating the local source points, local schemes are obtained. Instead of constructing a global scheme, the local subproblems are solved sequentially, in an iterative way. This mimics a multiplicative Schwarz method with overlapping subdomains, which assures the convergence of the method. Combining the iteration with a simple Seidel-type method, the resulting iteration is used as a smoothing procedure of a multi-level method. The points belonging to the coarse and fine levels are defined by a quadtree-generated cell system controlled by the boundary of the original domain. The multi-level character of the obtained method makes it possible to reduce the necessary number of iterations, that is, the overall computational cost can be significantly reduced. Moreover, the solution of large and ill-conditioned systems is completely avoided. The method is illustrated through several numerical test examples.
{"title":"A Localized Version of the Method of Fundamental Solutions in a Multi-level Context","authors":"C. Gáspár","doi":"10.3311/ppci.21535","DOIUrl":"https://doi.org/10.3311/ppci.21535","url":null,"abstract":"The Method of Fundamental Solutions is applied to the Laplace equation. Instead of using the traditional approach with external source points and boundary collocation points, the original domain decomposed into a lot of smaller, overlapping subdomains, and the Method of Fundamental Solutions is used to the individual local subdomains. After eliminating the local source points, local schemes are obtained. Instead of constructing a global scheme, the local subproblems are solved sequentially, in an iterative way. This mimics a multiplicative Schwarz method with overlapping subdomains, which assures the convergence of the method. Combining the iteration with a simple Seidel-type method, the resulting iteration is used as a smoothing procedure of a multi-level method. The points belonging to the coarse and fine levels are defined by a quadtree-generated cell system controlled by the boundary of the original domain. The multi-level character of the obtained method makes it possible to reduce the necessary number of iterations, that is, the overall computational cost can be significantly reduced. Moreover, the solution of large and ill-conditioned systems is completely avoided. The method is illustrated through several numerical test examples.","PeriodicalId":49705,"journal":{"name":"Periodica Polytechnica-Civil Engineering","volume":"4 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81982297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The rapidly growing world population and the accompanying increase in concrete production to meet building and infrastructure needs have led to significant increase in potable water consumption, which resulted in several environmental problems. This paper investigates the feasibility of replacing potable water with highly mineralized treated wastewater in concrete mixing in order to make concrete production more eco-friendly in an arid region. Concrete specimens were prepared using saline treated wastewater (saline-TWW) as mixing water and compared to those mixed with distilled water (DW) and with the performance requirements given by the mixing water quality standards. The results revealed that the concrete mixes produced using saline-TWW exhibited higher early strength and a similar long-term strength than the control mix produced using DW. It was also found that the use of saline-TWW increased the setting times of cement paste but had no remarkable effect on the workability of fresh concrete mixture. Furthermore, the microstructural characteristics of the hardened concrete were assessed by water-permeability test, SEM image analysis, and X-ray diffraction tests. The results revealed that saline-TWW concrete exhibited a more compact microstructure and smaller pore sizes than their counterparts of DW, which means an improvement in the durability of saline-TWW concrete. Moreover, an electrochemical test was conducted to estimate the extent of corrosion of the steel embedded in reinforced mortar specimens prepared using saline-TWW and DW. The electrochemical test results showed that the use of 100% saline-TWW as mixing water of concrete resulted in a high corrosion rate of the embedded steel.
{"title":"Influence of Saline-treated Wastewater on Properties of Concrete: An Experimental Study","authors":"Sarra Dehane, A. Kriker, A. Salhi","doi":"10.3311/ppci.21841","DOIUrl":"https://doi.org/10.3311/ppci.21841","url":null,"abstract":"The rapidly growing world population and the accompanying increase in concrete production to meet building and infrastructure needs have led to significant increase in potable water consumption, which resulted in several environmental problems. This paper investigates the feasibility of replacing potable water with highly mineralized treated wastewater in concrete mixing in order to make concrete production more eco-friendly in an arid region. Concrete specimens were prepared using saline treated wastewater (saline-TWW) as mixing water and compared to those mixed with distilled water (DW) and with the performance requirements given by the mixing water quality standards. The results revealed that the concrete mixes produced using saline-TWW exhibited higher early strength and a similar long-term strength than the control mix produced using DW. It was also found that the use of saline-TWW increased the setting times of cement paste but had no remarkable effect on the workability of fresh concrete mixture. Furthermore, the microstructural characteristics of the hardened concrete were assessed by water-permeability test, SEM image analysis, and X-ray diffraction tests. The results revealed that saline-TWW concrete exhibited a more compact microstructure and smaller pore sizes than their counterparts of DW, which means an improvement in the durability of saline-TWW concrete. Moreover, an electrochemical test was conducted to estimate the extent of corrosion of the steel embedded in reinforced mortar specimens prepared using saline-TWW and DW. The electrochemical test results showed that the use of 100% saline-TWW as mixing water of concrete resulted in a high corrosion rate of the embedded steel.","PeriodicalId":49705,"journal":{"name":"Periodica Polytechnica-Civil Engineering","volume":"30 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86369979","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the sustainable solutions for cementitious materials could be the inclusion of locally available raw materials with possible lower environmental and/or economic impacts that meet technical requirements. This study focuses on waste perlite and recycled concrete powders, which are wastes from natural or artificial rock. Their effects on hardened and fresh properties were investigated by cement replacement of 15, 30 and 45 m%. The waste perlite powders demonstrated higher reactivity, while the recycled concrete powder would act mainly as a filler material. When using recycled concrete and waste perlite powders, an adverse effect was identified on the examined fresh properties.
{"title":"Investigation of Waste Perlite and Recycled Concrete Powders as Supplementary Cementitious Materials","authors":"Amina Dacić, Olivér Fenyvesi, Katalin Kopecskó","doi":"10.3311/ppci.21593","DOIUrl":"https://doi.org/10.3311/ppci.21593","url":null,"abstract":"One of the sustainable solutions for cementitious materials could be the inclusion of locally available raw materials with possible lower environmental and/or economic impacts that meet technical requirements. This study focuses on waste perlite and recycled concrete powders, which are wastes from natural or artificial rock. Their effects on hardened and fresh properties were investigated by cement replacement of 15, 30 and 45 m%. The waste perlite powders demonstrated higher reactivity, while the recycled concrete powder would act mainly as a filler material. When using recycled concrete and waste perlite powders, an adverse effect was identified on the examined fresh properties.","PeriodicalId":49705,"journal":{"name":"Periodica Polytechnica-Civil Engineering","volume":"123 9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135628906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Montayev, B. Omarov, R. Ristavletov, K. Dosov, Nurgul Montayeva, Kanat Dosaliev
The article presents the results of research on application of sintering and crystallization initiators based on a composition of blast-furnace granulated slag and glass wastes in the ceramic masses for production of ceramic paving blocks by vibro-pressing. The leading role of sintering and crystallization initiators in assuring the strong and dense structure of ceramic pieces was updated. The main laws of changes in physical and mechanical properties of ceramic paving stone samples depending on the amount of sintering and crystallization initiators in the burning temperature range 950–1000 °C have been established. It was determined that the availability of finely dispersed glass powder (fraction less than 0.1 mm) as a component of crystallization sintering initiators contributes to early emergence of liquid phase in the ceramic mass, as softening temperature of glass powder begins already at 720–750 °C. According to the results of X-ray phase and electron microscopic analysis it was determined that crystallization of low-temperature form of ß-wollastonite (CaSiO3) is observed in the samples burnt at the temperature range of 950–1000 °C. It was proved that the availability of ß-wollastonite in the ceramic mass serves as a reinforcing component. It has been established that high strength values are achieved in those compositions where ß-wollastonite crystallization in the burning products is the highest. As a result of scientific and experimental work the feasibility of producing the ceramic paving stones by vibropressing containing sintering and crystallization initiators that meet the requirements of quality, aesthetics, environmental friendliness, resource- and energy-saving was proved.
{"title":"Sintering and Crystallization Intensifiers for Production of Ceramic Paving Blocks by Vibropressing Technology","authors":"S. Montayev, B. Omarov, R. Ristavletov, K. Dosov, Nurgul Montayeva, Kanat Dosaliev","doi":"10.3311/ppci.21818","DOIUrl":"https://doi.org/10.3311/ppci.21818","url":null,"abstract":"The article presents the results of research on application of sintering and crystallization initiators based on a composition of blast-furnace granulated slag and glass wastes in the ceramic masses for production of ceramic paving blocks by vibro-pressing. The leading role of sintering and crystallization initiators in assuring the strong and dense structure of ceramic pieces was updated. The main laws of changes in physical and mechanical properties of ceramic paving stone samples depending on the amount of sintering and crystallization initiators in the burning temperature range 950–1000 °C have been established. It was determined that the availability of finely dispersed glass powder (fraction less than 0.1 mm) as a component of crystallization sintering initiators contributes to early emergence of liquid phase in the ceramic mass, as softening temperature of glass powder begins already at 720–750 °C. According to the results of X-ray phase and electron microscopic analysis it was determined that crystallization of low-temperature form of ß-wollastonite (CaSiO3) is observed in the samples burnt at the temperature range of 950–1000 °C. It was proved that the availability of ß-wollastonite in the ceramic mass serves as a reinforcing component. It has been established that high strength values are achieved in those compositions where ß-wollastonite crystallization in the burning products is the highest. As a result of scientific and experimental work the feasibility of producing the ceramic paving stones by vibropressing containing sintering and crystallization initiators that meet the requirements of quality, aesthetics, environmental friendliness, resource- and energy-saving was proved.","PeriodicalId":49705,"journal":{"name":"Periodica Polytechnica-Civil Engineering","volume":"1 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82984290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper proposes a methodology framework for the reliability assessment of smart steel Moment Resisting Frame structures (MRFs) equipped with Nickle Titanium Shape Memory Alloy (NiTi SMA) connections subjected to blast loading. The reliability assessment framework is formulated based on a two-step approach algorithm. In the 1st Step, the Monte Carlo Latin Hypercube Sampling Strategy simulation (MC-LHS) is adapted to generate the uncertain parameters sample points. Considering the numerical simulations, the 2nd Step employs simplified performance functions and the generated random outcomes from the 1st Step. The proposed reliability approach is verified against direct Monte Carlo Simulation (MCS) and First-Order Reliability Method (FORM). The performance functions are columns’ axial force and bending moments, rotation capacity at the connections, and Inter-Story Drift Ratio (ISDR). Throughout the development of the reliability assessment, the probabilistic models are parametrized on geometrical properties, material properties, vertical loads, model errors, and charge weights. The developed reliability framework is applied to a prototype 4-story smart MRF. The structural safety level is obtained in terms of the Reliability Index (β). The results show that the reliability framework provides an accurate and efficient structural collapse prediction of the MRFs equipped with NiTi SMA-based connections. Finally, sensitivity analysis is performed to indicate the sensitivity of building collapse to blast wave characteristics, material strength, vertical gravity loads, and column profile dimensions. The sensitivity analysis results also confirm the efficiency of the proposed reliability framework in observing the highly sensitive parameters, which is explosive charge weight.
{"title":"Reliability Assessment Methodology of Blast Protective Steel Moment Resisting Frame Using NiTi SMA-based Connection","authors":"Sardasht S. Weli, L. Vigh","doi":"10.3311/ppci.20493","DOIUrl":"https://doi.org/10.3311/ppci.20493","url":null,"abstract":"This paper proposes a methodology framework for the reliability assessment of smart steel Moment Resisting Frame structures (MRFs) equipped with Nickle Titanium Shape Memory Alloy (NiTi SMA) connections subjected to blast loading. The reliability assessment framework is formulated based on a two-step approach algorithm. In the 1st Step, the Monte Carlo Latin Hypercube Sampling Strategy simulation (MC-LHS) is adapted to generate the uncertain parameters sample points. Considering the numerical simulations, the 2nd Step employs simplified performance functions and the generated random outcomes from the 1st Step. The proposed reliability approach is verified against direct Monte Carlo Simulation (MCS) and First-Order Reliability Method (FORM). The performance functions are columns’ axial force and bending moments, rotation capacity at the connections, and Inter-Story Drift Ratio (ISDR). Throughout the development of the reliability assessment, the probabilistic models are parametrized on geometrical properties, material properties, vertical loads, model errors, and charge weights. The developed reliability framework is applied to a prototype 4-story smart MRF. The structural safety level is obtained in terms of the Reliability Index (β). The results show that the reliability framework provides an accurate and efficient structural collapse prediction of the MRFs equipped with NiTi SMA-based connections. Finally, sensitivity analysis is performed to indicate the sensitivity of building collapse to blast wave characteristics, material strength, vertical gravity loads, and column profile dimensions. The sensitivity analysis results also confirm the efficiency of the proposed reliability framework in observing the highly sensitive parameters, which is explosive charge weight.","PeriodicalId":49705,"journal":{"name":"Periodica Polytechnica-Civil Engineering","volume":"462 4","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72586708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The shear behavior is one of the most mysterious physical phenomena of an RC (reinforced concrete) beam. Many shear-transfer actions (such as dowel action, cantilever action, aggregate interlock, tension softening, etc.) affect it. Still, there is no scientific agreement on the number and the role of these phenomena.The paper investigates the historical development of these shear-transfer actions and the calculation models made from them through the glass of experimental research in the last one and half centuries in Hungary, in the context of the current international state of the art. This historical approach gives us an understanding of how the researchers and engineers of the past tried to understand the structure, and it leads us to accept that we are also on the way to understanding the shear behavior. However, the perfect model and understanding are far away from now. But are we on the right way?
{"title":"Historical Shear Experiments of RC Beams in Hungary and their Effect on Change of Shear Design","authors":"Péter Pál Ther, I. Sajtos","doi":"10.3311/ppci.21433","DOIUrl":"https://doi.org/10.3311/ppci.21433","url":null,"abstract":"The shear behavior is one of the most mysterious physical phenomena of an RC (reinforced concrete) beam. Many shear-transfer actions (such as dowel action, cantilever action, aggregate interlock, tension softening, etc.) affect it. Still, there is no scientific agreement on the number and the role of these phenomena.The paper investigates the historical development of these shear-transfer actions and the calculation models made from them through the glass of experimental research in the last one and half centuries in Hungary, in the context of the current international state of the art. This historical approach gives us an understanding of how the researchers and engineers of the past tried to understand the structure, and it leads us to accept that we are also on the way to understanding the shear behavior. However, the perfect model and understanding are far away from now. But are we on the right way?\u0000 ","PeriodicalId":49705,"journal":{"name":"Periodica Polytechnica-Civil Engineering","volume":"27 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74629536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, the numerical back analyses of four, typical, monitored deep excavations completed in Budapest are presented. The typical excavation solution in Budapest city center, down to 15–18 m excavation depth, is a diaphragm wall embedded in the clay bedrock and supported by prestressed anchors embedded in the sedimentary soils above the clay. In these case studies this solution is analyzed with traditional Winkler type and more complex PLAXIS 2D and 3D finite element models. The focus of the study was to compare the measured wall deformations with the calculated ones derived by the listed methods. As the clay bedrock is a deterministic layer for the wall behavior, several different FEM models were prepared to analyze the appropriateness of the potential constitutive models for its proper characterization. As a conclusion, practical proposals were made for practitioners for future excavations.
{"title":"Two- and Three-dimensional Numerical Back-analysis of Deep Excavation Case Studies from Budapest, Hungary","authors":"Attila Szepesházi, B. Móczár","doi":"10.3311/ppci.21829","DOIUrl":"https://doi.org/10.3311/ppci.21829","url":null,"abstract":"In this paper, the numerical back analyses of four, typical, monitored deep excavations completed in Budapest are presented. The typical excavation solution in Budapest city center, down to 15–18 m excavation depth, is a diaphragm wall embedded in the clay bedrock and supported by prestressed anchors embedded in the sedimentary soils above the clay. In these case studies this solution is analyzed with traditional Winkler type and more complex PLAXIS 2D and 3D finite element models. The focus of the study was to compare the measured wall deformations with the calculated ones derived by the listed methods. As the clay bedrock is a deterministic layer for the wall behavior, several different FEM models were prepared to analyze the appropriateness of the potential constitutive models for its proper characterization. As a conclusion, practical proposals were made for practitioners for future excavations.","PeriodicalId":49705,"journal":{"name":"Periodica Polytechnica-Civil Engineering","volume":"74 1","pages":""},"PeriodicalIF":1.8,"publicationDate":"2023-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80319195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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