Pub Date : 2023-04-30DOI: 10.14311/cej.2023.01.0001
D. Zahradník, Jakub Vynikal
Spherical cameras are being used more frequently in surveying because of their low cost and possibility to process spherical images with conventional SfM methods. Fish-eye lenses are now frequently found on modern 360° cameras, allowing for the capture of the entire scene and subsequent model reconstitution by a non-photogrammetrist specialist. Gyrospherics are a feature of cameras that ensure image stabilization to reduce blur when the camera is moving. This feature allows it to capture moving scenes in time-lapse mode. However, two main factors - hardware parameters and software algorithms - affect the quality of the images that are captured. The 360° camera design allows for a variety of data processing methods by SfM. These images were created using multiple image sensors and lenses from each 360° camera. These images can be processed individually or by applying rules to define relationships between images. Also, images from cameras can be stitched and processed with a spherical camera model. In this paper is proposed processing methods of data from 360° cameras and estimated accuracy of each method.
{"title":"Possible approaches for processing of spherical images using SfM","authors":"D. Zahradník, Jakub Vynikal","doi":"10.14311/cej.2023.01.0001","DOIUrl":"https://doi.org/10.14311/cej.2023.01.0001","url":null,"abstract":"Spherical cameras are being used more frequently in surveying because of their low cost and possibility to process spherical images with conventional SfM methods. Fish-eye lenses are now frequently found on modern 360° cameras, allowing for the capture of the entire scene and subsequent model reconstitution by a non-photogrammetrist specialist. Gyrospherics are a feature of cameras that ensure image stabilization to reduce blur when the camera is moving. This feature allows it to capture moving scenes in time-lapse mode. However, two main factors - hardware parameters and software algorithms - affect the quality of the images that are captured. The 360° camera design allows for a variety of data processing methods by SfM. These images were created using multiple image sensors and lenses from each 360° camera. These images can be processed individually or by applying rules to define relationships between images. Also, images from cameras can be stitched and processed with a spherical camera model. In this paper is proposed processing methods of data from 360° cameras and estimated accuracy of each method.","PeriodicalId":21974,"journal":{"name":"Stavební obzor - Civil Engineering Journal","volume":"56 2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91317841","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 : 2022-12-31DOI: 10.14311/cej.2022.04.0049
Kexin Zhang
In recent years, there have been cases of strengthening bridge structures with polyurethane cement mortar. To further explore the properties of polyurethane materials, the effects of emery, lime, quartz sand and cement on the mechanical properties of polyurethane powder composites are studied by three-point flexural test. In the flexural test, the polyurethane cement composite formed a control group by changing the content of polyester polyol. The flexural strength and ductility are improved to a certain extent due to the addition of polyester polyol.The average flexural strength of other polyurethane powder composites such as polyurethane emery test block is 45.1 MPa and the corresponding strain is 6203 με, the average flexural strength of polyurethane lime test block is 33.4 MPa and the corresponding strain is 6470 με, the average flexural strength of polyurethane quartz sand test block is 49.23 MPa and the corresponding strain is 7521 με. The results show that the flexural strength of polyurethane emery material and polyurethane quartz sand material is higher than that of polyurethane cement, which can be used to replace cement to a certain extent to reduce the cost of polyurethane composite material.
{"title":"INFLUENCE ANALYSIS OF NATURAL VIBRATION CHARACTERISTICS OF STEEL BOX GIRDER WITH SINGLE CABLE FACE AND LARGE CANTILEVER","authors":"Kexin Zhang","doi":"10.14311/cej.2022.04.0049","DOIUrl":"https://doi.org/10.14311/cej.2022.04.0049","url":null,"abstract":"In recent years, there have been cases of strengthening bridge structures with polyurethane cement mortar. To further explore the properties of polyurethane materials, the effects of emery, lime, quartz sand and cement on the mechanical properties of polyurethane powder composites are studied by three-point flexural test. In the flexural test, the polyurethane cement composite formed a control group by changing the content of polyester polyol. The flexural strength and ductility are improved to a certain extent due to the addition of polyester polyol.The average flexural strength of other polyurethane powder composites such as polyurethane emery test block is 45.1 MPa and the corresponding strain is 6203 με, the average flexural strength of polyurethane lime test block is 33.4 MPa and the corresponding strain is 6470 με, the average flexural strength of polyurethane quartz sand test block is 49.23 MPa and the corresponding strain is 7521 με. The results show that the flexural strength of polyurethane emery material and polyurethane quartz sand material is higher than that of polyurethane cement, which can be used to replace cement to a certain extent to reduce the cost of polyurethane composite material.","PeriodicalId":21974,"journal":{"name":"Stavební obzor - Civil Engineering Journal","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74843744","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 : 2022-12-31DOI: 10.14311/cej.2022.04.0043
Ashok Karki, S. Bhattarai, Pradhumna Joshi, M. Kafle, Rajesh Bhattarai
A dam break is a low-probability, high risk catastrophe event that is extremely destructive and has a substantial negative socio-economic impact on downstream and nearby areas. Simulating dam breach and analyzing flood propagation downstream from those events is vital for identifying and minimizing the risks associated downstream of dam location. This study is intended to anlayse the effect of overtopping failure of dam for two scenario (a) base-case scenario (scenario with average value of dam breach parameters from their range) and (b) worst case scenario (the breach with largest geometry, shortest formation time and highest peak outflow magnitude). Further, a hydrodyanmic modelling is perfomed to investigate the sensitivity analysis (local and global) of five dam breach parameters (dam breach elevation, dam breach width, breach formation time, weir coefficient, trigger failure elevation) on breach outflow in a proposed hydropower project located in Nepal. Aeronautical Reconnaissance Coverage Geographic Information System (ArcGIS), Hydraulic Engineering Center River Analysis System (HEC-RAS) and OriginPro 2022b are utilized to analyse the effect of dam breach and parameter sensitivity. Generation of outflow hydrograph shows that worst case scenario has devasting effect downstream with innudation of 1047 of househols and 50.83 kilometers of roads. The breach velocty was recorded as 15.16 m/s and 20.85 m/s for base and worst case respectively. The minimum depth and maximum depth of flooding downstream from dam location was found to be 24.51 m and 73.6 m for base case and 47.43 m and 106.75 m for worst case. Due to backwater effect at Bheri river, peak flow at 14 km downstream from dam reduces significantly to 124852.57 m3/s and 244204.41 m3/s for base and worst case respectively. From local sensitivty analysis it has been found that, dam breach elevation is more sensitive and triggering failure elevation is less sensitive for peak outflow hydrograph. Whereas, dam breach width seems more sensitive and TFE seems least sensitive for peak outflow using Monte Carlo Simulation for gloal sensitivity.
{"title":"DAM BREACH ANALYSIS AND PARAMETER SENSITIVITY ANALYSIS ALONG A RIVER REACH USING HECRAS","authors":"Ashok Karki, S. Bhattarai, Pradhumna Joshi, M. Kafle, Rajesh Bhattarai","doi":"10.14311/cej.2022.04.0043","DOIUrl":"https://doi.org/10.14311/cej.2022.04.0043","url":null,"abstract":"A dam break is a low-probability, high risk catastrophe event that is extremely destructive and has a substantial negative socio-economic impact on downstream and nearby areas. Simulating dam breach and analyzing flood propagation downstream from those events is vital for identifying and minimizing the risks associated downstream of dam location. This study is intended to anlayse the effect of overtopping failure of dam for two scenario (a) base-case scenario (scenario with average value of dam breach parameters from their range) and (b) worst case scenario (the breach with largest geometry, shortest formation time and highest peak outflow magnitude). Further, a hydrodyanmic modelling is perfomed to investigate the sensitivity analysis (local and global) of five dam breach parameters (dam breach elevation, dam breach width, breach formation time, weir coefficient, trigger failure elevation) on breach outflow in a proposed hydropower project located in Nepal. Aeronautical Reconnaissance Coverage Geographic Information System (ArcGIS), Hydraulic Engineering Center River Analysis System (HEC-RAS) and OriginPro 2022b are utilized to analyse the effect of dam breach and parameter sensitivity. \u0000Generation of outflow hydrograph shows that worst case scenario has devasting effect downstream with innudation of 1047 of househols and 50.83 kilometers of roads. The breach velocty was recorded as 15.16 m/s and 20.85 m/s for base and worst case respectively. The minimum depth and maximum depth of flooding downstream from dam location was found to be 24.51 m and 73.6 m for base case and 47.43 m and 106.75 m for worst case. Due to backwater effect at Bheri river, peak flow at 14 km downstream from dam reduces significantly to 124852.57 m3/s and 244204.41 m3/s for base and worst case respectively. From local sensitivty analysis it has been found that, dam breach elevation is more sensitive and triggering failure elevation is less sensitive for peak outflow hydrograph. Whereas, dam breach width seems more sensitive and TFE seems least sensitive for peak outflow using Monte Carlo Simulation for gloal sensitivity.","PeriodicalId":21974,"journal":{"name":"Stavební obzor - Civil Engineering Journal","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87646837","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 : 2022-12-31DOI: 10.14311/cej.2022.04.0040
Luying Li
Unlike the traditional construction mode of rough operation, assembly building construction implements the concept of green development in terms of energy consumption and environmental adaptability. Although assembly construction can effectively reduce construction energy consumption and improve the environmental resilience of building construction work, there is an urgent need for an effective safety assessment model for construction development due to the imperfect operation system and harsh construction environment in the construction industry. Therefore, the study analyzes the relationship of construction safety factors by using Analytic Network Process (ANP) to filter safety evaluation indexes according to the importance ranking. At the same time, the objective weights of safety indicators were determined by the entropy weight method, and the subjective weights determined by the ANP method were combined to construct the safety evaluation model for the construction of assembled buildings. The experiment shows that the maximum similarity between the comprehensive evaluation results of the model in the simulation of safety evaluation of high-rise residential construction and the actual evaluation criteria is 0.772. The experiment proves the reliability of the evaluation of the model, which reduces the safety loopholes and operation hazards for the construction of assembled buildings.
{"title":"Research on safety evaluation of assembly building construction by integrating entropy power method and network analysis model","authors":"Luying Li","doi":"10.14311/cej.2022.04.0040","DOIUrl":"https://doi.org/10.14311/cej.2022.04.0040","url":null,"abstract":"Unlike the traditional construction mode of rough operation, assembly building construction implements the concept of green development in terms of energy consumption and environmental adaptability. Although assembly construction can effectively reduce construction energy consumption and improve the environmental resilience of building construction work, there is an urgent need for an effective safety assessment model for construction development due to the imperfect operation system and harsh construction environment in the construction industry. Therefore, the study analyzes the relationship of construction safety factors by using Analytic Network Process (ANP) to filter safety evaluation indexes according to the importance ranking. At the same time, the objective weights of safety indicators were determined by the entropy weight method, and the subjective weights determined by the ANP method were combined to construct the safety evaluation model for the construction of assembled buildings. The experiment shows that the maximum similarity between the comprehensive evaluation results of the model in the simulation of safety evaluation of high-rise residential construction and the actual evaluation criteria is 0.772. The experiment proves the reliability of the evaluation of the model, which reduces the safety loopholes and operation hazards for the construction of assembled buildings.","PeriodicalId":21974,"journal":{"name":"Stavební obzor - Civil Engineering Journal","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86969535","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 : 2022-12-31DOI: 10.14311/cej.2022.04.0041
Tomáš Bouček, M. Landa, Petr Soukup
Vernacular architecture is an integral part of the national cultural heritage. Today, however, many of these buildings exist only on old plans or photographs and the average citizen has no opportunity to get acquainted with this part of the national identity. Therefore, in our work, we present the development of two web applications with the aim of creating a virtual open-air museum for presenting vernacular architecture in the Czech Republic. The applications were created using open-source technologies, and are implemented with methods that allow easy transfer from one operating system to another. The presented content is a carefully selected sub-sample of more than 10,000 available records representing all regional types of vernacular architecture. The result is one application designed for editors to manage the presented content and one application allowing interactive viewing of the available geo-located records designed for the general public. Individual records can be searched either directly using the map window or by querying the attribute table. These records contain descriptive information about the object, as well as historical photographs and plans and, for some objects, additional information in the form of 3D models, PDF documents and other files. The applications are designed in such a way that their content can be freely expanded in the future and thus contribute to the popularization of vernacular architecture among the general public, which was the main reason for their creation.
{"title":"DEVELOPING A VIRTUAL OPEN-AIR MUSEUM OF VERNACULAR ARCHITECTURE","authors":"Tomáš Bouček, M. Landa, Petr Soukup","doi":"10.14311/cej.2022.04.0041","DOIUrl":"https://doi.org/10.14311/cej.2022.04.0041","url":null,"abstract":"Vernacular architecture is an integral part of the national cultural heritage. Today, however, many of these buildings exist only on old plans or photographs and the average citizen has no opportunity to get acquainted with this part of the national identity. Therefore, in our work, we present the development of two web applications with the aim of creating a virtual open-air museum for presenting vernacular architecture in the Czech Republic. The applications were created using open-source technologies, and are implemented with methods that allow easy transfer from one operating system to another. The presented content is a carefully selected sub-sample of more than 10,000 available records representing all regional types of vernacular architecture. The result is one application designed for editors to manage the presented content and one application allowing interactive viewing of the available geo-located records designed for the general public. Individual records can be searched either directly using the map window or by querying the attribute table. These records contain descriptive information about the object, as well as historical photographs and plans and, for some objects, additional information in the form of 3D models, PDF documents and other files. The applications are designed in such a way that their content can be freely expanded in the future and thus contribute to the popularization of vernacular architecture among the general public, which was the main reason for their creation.","PeriodicalId":21974,"journal":{"name":"Stavební obzor - Civil Engineering Journal","volume":"55 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87749361","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 : 2022-12-31DOI: 10.14311/cej.2022.04.0046
Mengjie Li, Zheng Guo
Aiming at the safety problem of the transportation of prefabricated components in prefabricated buildings, set pair analysis (SPA) and Pareto analysis (ABC) are used to propose a transportation safety evaluation model for prefabricated components in prefabricated buildings based on SPA-ABC. Based on the existing research results, the risk factors in the three stages of transportation preparation, transportation work and storage work are sorted out, and the evaluation index system of transportation safety is established. Combining the status quo of transportation operations, SPA is used to determine the index weights. Based on the ABC theory, risk factors are divided into major risk factors (type A), secondary risk factors (type B) and general risk factors (type C), and recommendations are made based on the major risk factors. The results show that ten risk indicators such as transportation operators, transportation plans, and fixing measures for prefabricated components are type A risk factors, which are the focus of prefabricated construction transportation operations.
{"title":"RESEARCH ON TRANSPORTATION SAFETY OF PREFABRICATED BUILDING COMPONENTS","authors":"Mengjie Li, Zheng Guo","doi":"10.14311/cej.2022.04.0046","DOIUrl":"https://doi.org/10.14311/cej.2022.04.0046","url":null,"abstract":"Aiming at the safety problem of the transportation of prefabricated components in prefabricated buildings, set pair analysis (SPA) and Pareto analysis (ABC) are used to propose a transportation safety evaluation model for prefabricated components in prefabricated buildings based on SPA-ABC. Based on the existing research results, the risk factors in the three stages of transportation preparation, transportation work and storage work are sorted out, and the evaluation index system of transportation safety is established. Combining the status quo of transportation operations, SPA is used to determine the index weights. Based on the ABC theory, risk factors are divided into major risk factors (type A), secondary risk factors (type B) and general risk factors (type C), and recommendations are made based on the major risk factors. The results show that ten risk indicators such as transportation operators, transportation plans, and fixing measures for prefabricated components are type A risk factors, which are the focus of prefabricated construction transportation operations.","PeriodicalId":21974,"journal":{"name":"Stavební obzor - Civil Engineering Journal","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81266788","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 : 2022-12-31DOI: 10.14311/cej.2022.04.0044
Zifei Li, Lin Qi, Yongcheng Huai
A kind of lattice-type steel member is presented and a kind of prefabricated connector suitable for the connection between lattice-type steel members are proposed. The mechanical properties of the connectors are analyzed by using the finite element numerical simulation software ABAQUS. The connectors meet the design goals of the stiffness of connection stronger than members. Parameterized analysis is carried out on the prefabricated connector, and the flexural stiffness expression of the connector is obtained. The suggested values of each component of the prefabricated connectors are given based on the size of connected lattice-type steel members.
{"title":"STUDY ON PREFABRICATED CONNECTOR OF DOUBLE-LAYER RECIPROCAL FRAME","authors":"Zifei Li, Lin Qi, Yongcheng Huai","doi":"10.14311/cej.2022.04.0044","DOIUrl":"https://doi.org/10.14311/cej.2022.04.0044","url":null,"abstract":"A kind of lattice-type steel member is presented and a kind of prefabricated connector suitable for the connection between lattice-type steel members are proposed. The mechanical properties of the connectors are analyzed by using the finite element numerical simulation software ABAQUS. The connectors meet the design goals of the stiffness of connection stronger than members. Parameterized analysis is carried out on the prefabricated connector, and the flexural stiffness expression of the connector is obtained. The suggested values of each component of the prefabricated connectors are given based on the size of connected lattice-type steel members.","PeriodicalId":21974,"journal":{"name":"Stavební obzor - Civil Engineering Journal","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75280644","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 : 2022-12-31DOI: 10.14311/cej.2022.04.0045
Vojtěch Cehák
Working with objects in digital spatial form is gradually becoming a standard in many fields. In addition to the advantage of easier object manipulation, digital representation can also be used for presentation purposes or better cataloging. In the case of objects from museum collections, it can serve as a basis for restoration or for conducting deeper research into detailed structures. The method of photogrammetry allows 3D modelling of real objects without physical contact with them, while at the same time making use of affordable equipment. However, the disadvantage of this method is the size of the output data (even hundreds of megabytes), which can be a barrier to easy web sharing. This paper presents an efficient workflow for the 3D digitization of smaller physical objects and the subsequent process of generalizing the resulting triangular model to reduce the data volume. Finally, the model generalization is utilized when publishing the model in a web environment to make it available to the widest possible range of users. The whole procedure is applied to a physical model of a cottage from the village of Orlová (Karviná district, Czechia) from the collection of the Czech National Museum (scale reduction of a vernacular building at a scale of approximately 1:20).
{"title":"Digitization of Physical Models of Rural Architecture","authors":"Vojtěch Cehák","doi":"10.14311/cej.2022.04.0045","DOIUrl":"https://doi.org/10.14311/cej.2022.04.0045","url":null,"abstract":"Working with objects in digital spatial form is gradually becoming a standard in many fields. In addition to the advantage of easier object manipulation, digital representation can also be used for presentation purposes or better cataloging. In the case of objects from museum collections, it can serve as a basis for restoration or for conducting deeper research into detailed structures. The method of photogrammetry allows 3D modelling of real objects without physical contact with them, while at the same time making use of affordable equipment. However, the disadvantage of this method is the size of the output data (even hundreds of megabytes), which can be a barrier to easy web sharing. This paper presents an efficient workflow for the 3D digitization of smaller physical objects and the subsequent process of generalizing the resulting triangular model to reduce the data volume. Finally, the model generalization is utilized when publishing the model in a web environment to make it available to the widest possible range of users. The whole procedure is applied to a physical model of a cottage from the village of Orlová (Karviná district, Czechia) from the collection of the Czech National Museum (scale reduction of a vernacular building at a scale of approximately 1:20).","PeriodicalId":21974,"journal":{"name":"Stavební obzor - Civil Engineering Journal","volume":"20 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81269420","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 : 2022-12-31DOI: 10.14311/cej.2022.04.0042
Yi Yang, Z. Wu, Qian Zhou, Jiahao Bai, Xinyan Guo
CFRP (Carbon Fiber Reinforced Polymer) are widely used in steel structural reinforcement. For steel structures strengthened with CFRP, except the cases the structures have defects before strengthening, the adhesive interface is the weakest part and CFRP debonding is the most common failure mode. In order to investigate the failure mechanism of CFRP strengthened steel structures, this paper presents an experimental study on shear performance of adhesive interface between steel plate and CFRP by twin shear model. Six steel plates strengthened with CFRP are divided into two groups, one has no damage, another has a gap at the mid. The specimens are tested under tensile loadings. The study results show that, the plates with a gap failed for CFRPs debonding, the cracking loading and breaking loading are 14.85kN, and 17.88kN respectively; the strain-loading curves had long linear stages, two strains decrease and other strains of another side increased rapidly at the cracking loading, then they both rose until the plates failed.
{"title":"An Experimental Study on Shear Performance of Adhesive Interface between Steel Plates and CFRP","authors":"Yi Yang, Z. Wu, Qian Zhou, Jiahao Bai, Xinyan Guo","doi":"10.14311/cej.2022.04.0042","DOIUrl":"https://doi.org/10.14311/cej.2022.04.0042","url":null,"abstract":"CFRP (Carbon Fiber Reinforced Polymer) are widely used in steel structural reinforcement. For steel structures strengthened with CFRP, except the cases the structures have defects before strengthening, the adhesive interface is the weakest part and CFRP debonding is the most common failure mode. In order to investigate the failure mechanism of CFRP strengthened steel structures, this paper presents an experimental study on shear performance of adhesive interface between steel plate and CFRP by twin shear model. Six steel plates strengthened with CFRP are divided into two groups, one has no damage, another has a gap at the mid. The specimens are tested under tensile loadings. The study results show that, the plates with a gap failed for CFRPs debonding, the cracking loading and breaking loading are 14.85kN, and 17.88kN respectively; the strain-loading curves had long linear stages, two strains decrease and other strains of another side increased rapidly at the cracking loading, then they both rose until the plates failed.","PeriodicalId":21974,"journal":{"name":"Stavební obzor - Civil Engineering Journal","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85094034","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 : 2022-12-31DOI: 10.14311/cej.2022.04.0048
Igor Mikolášek
Traffic surveys routinely estimate the profile of traffic demand in a certain road section, showing the expected evolution of the demand over a workday or weekend. However, the actual demand fluctuates around this value. That can lead to brief excess of the capacity at the moment of high demand and consequent congestion due to the capacity drop. This type of traffic demand variability has not yet been properly studied despite the fact it can play significant role in traffic modelling and engineering applications. This paper presents results of analysis of demand variability in five-minute aggregation intervals. The results do not clearly show a single random distribution that would accurately model the demand variability. Normal, lognormal and gamma distributions all show reasonably well fit to the data for individual intervals. Based on count of best fits, the lognormal distribution seems best, but in most cases, the difference between the distributions is not statistically significant. There appears to be a pattern where certain distributions have better fit in different times of day and week. The regularity and magnitude of demand (e.g. morning peak hour) probably play a role in this, as well as the aggregation interval.
{"title":"STOCHASTIC TRAFFIC DEMAND PROFILE","authors":"Igor Mikolášek","doi":"10.14311/cej.2022.04.0048","DOIUrl":"https://doi.org/10.14311/cej.2022.04.0048","url":null,"abstract":"Traffic surveys routinely estimate the profile of traffic demand in a certain road section, showing the expected evolution of the demand over a workday or weekend. However, the actual demand fluctuates around this value. That can lead to brief excess of the capacity at the moment of high demand and consequent congestion due to the capacity drop. This type of traffic demand variability has not yet been properly studied despite the fact it can play significant role in traffic modelling and engineering applications. This paper presents results of analysis of demand variability in five-minute aggregation intervals. The results do not clearly show a single random distribution that would accurately model the demand variability. Normal, lognormal and gamma distributions all show reasonably well fit to the data for individual intervals. Based on count of best fits, the lognormal distribution seems best, but in most cases, the difference between the distributions is not statistically significant. There appears to be a pattern where certain distributions have better fit in different times of day and week. The regularity and magnitude of demand (e.g. morning peak hour) probably play a role in this, as well as the aggregation interval.","PeriodicalId":21974,"journal":{"name":"Stavební obzor - Civil Engineering Journal","volume":"130 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75120448","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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