Innovative technologies, advanced design methodologies, and an increasing demand for improved building performance prompted by widespread concern for degradation of the natural environment have provoked a reconsideration of architecture’s traditional relationship to the ground. In the past, building construction was adjusted as necessary to accommodate challenging terrain, but using advanced modelling technology, contemporary architects now design landform buildings, or landscrapers, which simulate naturally occurring topographic features, including artificial mountains, dramatic geological formations, excavations deep into the earth, vegetated roofs, and landscaped promenades at high elevations walked upon or over. By merging the ground plane and built fabric, new construction can be better integrated with environmentally sensitive sites and reduce resource consumption. Rather than merely follow topographic contours or occupy a given site, landform buildings can provide its replacement. This paper will examine how landform buildings utilize properties usually associated with the natural environment such as continuity with surrounding topography, weathering, contextual integration above and below ground, and programmatic indeterminacy to achieve unique expressions of local, regional, or national identity, improving their surroundings, enhancing their experiential potential and advancing architectural practice.
{"title":"LANDFORM BUILDINGS AND THE FUTURE OF CONSTRUCTED TOPOGRAPHIES","authors":"René Davids","doi":"10.2495/arc220161","DOIUrl":"https://doi.org/10.2495/arc220161","url":null,"abstract":"Innovative technologies, advanced design methodologies, and an increasing demand for improved building performance prompted by widespread concern for degradation of the natural environment have provoked a reconsideration of architecture’s traditional relationship to the ground. In the past, building construction was adjusted as necessary to accommodate challenging terrain, but using advanced modelling technology, contemporary architects now design landform buildings, or landscrapers, which simulate naturally occurring topographic features, including artificial mountains, dramatic geological formations, excavations deep into the earth, vegetated roofs, and landscaped promenades at high elevations walked upon or over. By merging the ground plane and built fabric, new construction can be better integrated with environmentally sensitive sites and reduce resource consumption. Rather than merely follow topographic contours or occupy a given site, landform buildings can provide its replacement. This paper will examine how landform buildings utilize properties usually associated with the natural environment such as continuity with surrounding topography, weathering, contextual integration above and below ground, and programmatic indeterminacy to achieve unique expressions of local, regional, or national identity, improving their surroundings, enhancing their experiential potential and advancing architectural practice.","PeriodicalId":23773,"journal":{"name":"WIT Transactions on the Built Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81108612","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}
Climate change is one of the most significant challenges currently. Reducing greenhouse gas emissions and global energy demand has become an important research topic. These challenges have increased interest in retrofitting the existing building stock. Energy retrofitting, i.e., energy savings and optimal energy use, is necessary to close the gap between limited resources and increasing energy demand. Applying an energy-efficient insulation system can significantly decrease the energy consumed via a building’s air-conditioning system during the summer. Hence, building insulation has become a promising research topic, especially insulation based on nanomaterials due to their low U-values. This research paper examines the energy retrofitting effectiveness of an old educational building in Egypt using Nanogel ® Aerogel insulating material by integrating it with the building envelope, while walls are insulated with vacuum insulation panels (VIPs). The energy simulation was performed by DesignBuilder software (version 6.1.0.006). The results indicate that integrating VIP and aerogel in the building envelope can increase the thermal performance of a building in a hot climate like Egypt, which especially needs cooling loads during the summer months. It also shows a significant reduction in annual energy consumption, saving up to 36.5% compared to the base case.
{"title":"IMPACT OF NANO INSULATING MATERIALS ON ENERGY RETROFIT OF BUILDINGS","authors":"Hatem F. Salem, M. Ibrahim, Zeyad El-sayad","doi":"10.2495/arc220051","DOIUrl":"https://doi.org/10.2495/arc220051","url":null,"abstract":"Climate change is one of the most significant challenges currently. Reducing greenhouse gas emissions and global energy demand has become an important research topic. These challenges have increased interest in retrofitting the existing building stock. Energy retrofitting, i.e., energy savings and optimal energy use, is necessary to close the gap between limited resources and increasing energy demand. Applying an energy-efficient insulation system can significantly decrease the energy consumed via a building’s air-conditioning system during the summer. Hence, building insulation has become a promising research topic, especially insulation based on nanomaterials due to their low U-values. This research paper examines the energy retrofitting effectiveness of an old educational building in Egypt using Nanogel ® Aerogel insulating material by integrating it with the building envelope, while walls are insulated with vacuum insulation panels (VIPs). The energy simulation was performed by DesignBuilder software (version 6.1.0.006). The results indicate that integrating VIP and aerogel in the building envelope can increase the thermal performance of a building in a hot climate like Egypt, which especially needs cooling loads during the summer months. It also shows a significant reduction in annual energy consumption, saving up to 36.5% compared to the base case.","PeriodicalId":23773,"journal":{"name":"WIT Transactions on the Built Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88466186","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}
Alberto M. B. Martins, L. Simões, J. Negrão, F. Ferreira
Cable-stayed bridges optimization consists of finding the stiffness and mass arrangement of the load-bearing members (deck, towers and cable-stays) and the cable forces distribution, aiming to minimize cost and to achieve an adequate structural behaviour under static and dynamic loading. The first works on this topic were reported over 40 years ago but it is attracting growing interest with more than half of the publications in the last decade. The main goal of this paper is to share the perspective of this research groups 30 years’ experience in this domain. This paper starts with an overview of the optimum design of cable-stayed bridges followed by a presentation of previous research works by the authors. Current research and future developments envisaged are also referred to. The first works consisted of the optimization of steel bridges considering three-dimensional modelling, box-girder decks, seismic action and uncertainty-based optimization. The optimum design of concrete bridges and the simultaneous optimization of structure and control devices in steel footbridges subjected to pedestrian-induced vibrations and steel bridges under seismic action followed. The optimization of bridges with complex geometries and other cable-supported concrete bridges, like extradosed bridges and under-deck cable-stayed bridges, are subjects of recent research. The optimization of long-span and multi-span bridges, including novel cable arrangements, and the optimum design considering robustness are of major relevance in future developments. Although with limited scope at present, given the problem size, it is expected an increasing use of metaheuristic algorithms, artificial neural networks and surrogate models.
{"title":"30 YEARS’ EXPERIENCE ON THE OPTIMIZATION OF CABLE-STAYED BRIDGES","authors":"Alberto M. B. Martins, L. Simões, J. Negrão, F. Ferreira","doi":"10.2495/hpsu220061","DOIUrl":"https://doi.org/10.2495/hpsu220061","url":null,"abstract":"Cable-stayed bridges optimization consists of finding the stiffness and mass arrangement of the load-bearing members (deck, towers and cable-stays) and the cable forces distribution, aiming to minimize cost and to achieve an adequate structural behaviour under static and dynamic loading. The first works on this topic were reported over 40 years ago but it is attracting growing interest with more than half of the publications in the last decade. The main goal of this paper is to share the perspective of this research groups 30 years’ experience in this domain. This paper starts with an overview of the optimum design of cable-stayed bridges followed by a presentation of previous research works by the authors. Current research and future developments envisaged are also referred to. The first works consisted of the optimization of steel bridges considering three-dimensional modelling, box-girder decks, seismic action and uncertainty-based optimization. The optimum design of concrete bridges and the simultaneous optimization of structure and control devices in steel footbridges subjected to pedestrian-induced vibrations and steel bridges under seismic action followed. The optimization of bridges with complex geometries and other cable-supported concrete bridges, like extradosed bridges and under-deck cable-stayed bridges, are subjects of recent research. The optimization of long-span and multi-span bridges, including novel cable arrangements, and the optimum design considering robustness are of major relevance in future developments. Although with limited scope at present, given the problem size, it is expected an increasing use of metaheuristic algorithms, artificial neural networks and surrogate models.","PeriodicalId":23773,"journal":{"name":"WIT Transactions on the Built Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84456343","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}
The paper deals with the optimization of single-storey hall structures consisting of the same main frames to which steel purlins, façade rails and façade columns are connected. The frames can be steel or timber portal frames. While the steel frames are made of steel I-sections, the timber frames are made of glulam with rectangular cross-sections. The hall structure is optimized using mixed-integer nonlinear programming (MINLP), a combined continuous-discrete optimization technique. MINLP optimization is performed in three steps. It starts with defining the hall superstructure, modelling the optimization model of the structure, and solving the defined optimization problem. The superstructure includes all discrete alternatives of topologies, standard dimensions and material qualities competing for a feasible and optimal result. The optimization model includes continuous and discrete binary variables. The continuous variables represent dimensions, cross-sections, material grades, loads, etc., while the binary variables are used to optimize the topology of the structure and to select standard dimensions/profiles and material grades. The objective function of the material cost of the structure is subject to a system of (in)equality constraints of structural analysis and dimensioning. The dimensioning constraints are defined according to the Eurocode regulations. In order to solve the defined optimization problem, the modified outer-approximation/equality-relaxation (OA/ER) algorithm was used. A numerical example of MINLP optimization of a steel and timber frame hall structure is presented at the end of the article. nonlinear The frames may be made of steel profiles or glulam. The optimization of the hall structure is performed using mixed-integer non-linear programming, MINLP. The objective function of the material cost of the structure is subject to a system of (in)equality constraints of statics and dimensioning. The modified outer-approximation/equality-relaxation algorithm (OA/ER) is applied to solve the optimization problem. The computer program MYPSIN is used. In addition to the determined minimal material cost of the structure, the optimal topology of the hall structure, the strength classes of the materials used, the standard steel profiles, and the discrete/rounded cross-sections of the glulam frames and of the concrete foundations are calculated.
{"title":"OPTIMIZATION OF STEEL AND TIMBER HALL STRUCTURES","authors":"S. Kravanja, T. Zula","doi":"10.2495/hpsu220041","DOIUrl":"https://doi.org/10.2495/hpsu220041","url":null,"abstract":"The paper deals with the optimization of single-storey hall structures consisting of the same main frames to which steel purlins, façade rails and façade columns are connected. The frames can be steel or timber portal frames. While the steel frames are made of steel I-sections, the timber frames are made of glulam with rectangular cross-sections. The hall structure is optimized using mixed-integer nonlinear programming (MINLP), a combined continuous-discrete optimization technique. MINLP optimization is performed in three steps. It starts with defining the hall superstructure, modelling the optimization model of the structure, and solving the defined optimization problem. The superstructure includes all discrete alternatives of topologies, standard dimensions and material qualities competing for a feasible and optimal result. The optimization model includes continuous and discrete binary variables. The continuous variables represent dimensions, cross-sections, material grades, loads, etc., while the binary variables are used to optimize the topology of the structure and to select standard dimensions/profiles and material grades. The objective function of the material cost of the structure is subject to a system of (in)equality constraints of structural analysis and dimensioning. The dimensioning constraints are defined according to the Eurocode regulations. In order to solve the defined optimization problem, the modified outer-approximation/equality-relaxation (OA/ER) algorithm was used. A numerical example of MINLP optimization of a steel and timber frame hall structure is presented at the end of the article. nonlinear The frames may be made of steel profiles or glulam. The optimization of the hall structure is performed using mixed-integer non-linear programming, MINLP. The objective function of the material cost of the structure is subject to a system of (in)equality constraints of statics and dimensioning. The modified outer-approximation/equality-relaxation algorithm (OA/ER) is applied to solve the optimization problem. The computer program MYPSIN is used. In addition to the determined minimal material cost of the structure, the optimal topology of the hall structure, the strength classes of the materials used, the standard steel profiles, and the discrete/rounded cross-sections of the glulam frames and of the concrete foundations are calculated.","PeriodicalId":23773,"journal":{"name":"WIT Transactions on the Built Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75641983","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}
Advanced numerical and experimental analysis of complex structural loading conditions is presented within this paper. Major building components reinforced concrete (RC) walls are investigated with regard to their detonation resistance in various pre-stressed states. A multi-step simulation approach using successively both implicit and explicit integration schemes is followed to model the coupled static and dynamic loading. The simulation results underline the validity of the chosen modelling approach. A comparison of experimental and numerical values shows good agreement for deformation behaviour as well as for damage pattern. Beyond these predictive calculations further parameter variations indicate the dependency of highly dynamic structural response on quasi-static pre-load conditions.
{"title":"PRE-STRESSED REINFORCED CONCRETE ELEMENTS UNDER BLAST LOADING: NUMERICAL ANALYSIS AND SHOCK TUBE TESTING","authors":"C. Roller, M. Ramin, A. Stolz","doi":"10.2495/hpsu220151","DOIUrl":"https://doi.org/10.2495/hpsu220151","url":null,"abstract":"Advanced numerical and experimental analysis of complex structural loading conditions is presented within this paper. Major building components reinforced concrete (RC) walls are investigated with regard to their detonation resistance in various pre-stressed states. A multi-step simulation approach using successively both implicit and explicit integration schemes is followed to model the coupled static and dynamic loading. The simulation results underline the validity of the chosen modelling approach. A comparison of experimental and numerical values shows good agreement for deformation behaviour as well as for damage pattern. Beyond these predictive calculations further parameter variations indicate the dependency of highly dynamic structural response on quasi-static pre-load conditions.","PeriodicalId":23773,"journal":{"name":"WIT Transactions on the Built Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82583901","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}
Cell size, foil thickness, and the material of the core, influence the ballistic performance of honeycomb-core sandwich panels (HCSP) in the case of hypervelocity impact (HVI) by orbital debris. Two predictive models that account for this influence have been developed in this study: a dedicated ballistic limit equation (BLE) and an artificial neural network (ANN) trained to predict the outcomes of HVI on HCSP. The BLE is a modified version of the Whipple shield BLE and demonstrated excellent accuracy in predicting the ballistic limits of HCSP, when tested against a new set of simulation data, with the discrepancy ranging from 1.13% to 5.58% only. The ANN was developed using MATLAB’s Deep Learning Toolbox framework and was trained utilizing the same HCSP HVI database as that employed for the BLE fitting and demonstrated a very good predictive accuracy, when tested against a set of simulation data not previously used in the training of the network, with the discrepancy ranging from 0.67% to 7.27%.
{"title":"NEW PREDICTIVE MODELS FOR THE BALLISTIC LIMIT OF SPACECRAFT SANDWICH PANELS SUBJECTED TO HYPERVELOCITY IMPACT","authors":"A. Cherniaev, R. Carriere","doi":"10.2495/hpsu220091","DOIUrl":"https://doi.org/10.2495/hpsu220091","url":null,"abstract":"Cell size, foil thickness, and the material of the core, influence the ballistic performance of honeycomb-core sandwich panels (HCSP) in the case of hypervelocity impact (HVI) by orbital debris. Two predictive models that account for this influence have been developed in this study: a dedicated ballistic limit equation (BLE) and an artificial neural network (ANN) trained to predict the outcomes of HVI on HCSP. The BLE is a modified version of the Whipple shield BLE and demonstrated excellent accuracy in predicting the ballistic limits of HCSP, when tested against a new set of simulation data, with the discrepancy ranging from 1.13% to 5.58% only. The ANN was developed using MATLAB’s Deep Learning Toolbox framework and was trained utilizing the same HCSP HVI database as that employed for the BLE fitting and demonstrated a very good predictive accuracy, when tested against a set of simulation data not previously used in the training of the network, with the discrepancy ranging from 0.67% to 7.27%.","PeriodicalId":23773,"journal":{"name":"WIT Transactions on the Built Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86737044","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}
H. Draganić, S. Lukić, I. Radić, Goran Gazić, M. Jeleč
Blast wave intensity depends on several parameters, namely: explosive material type, charge weight, shape and orientation, detonation point position, detonation initiator type (primary explosive type), the position (distance) of the explosive charge in relation to the intended target (standoff distance) and ground surface. Environmental conditions, particularly air temperature, humidity and atmospheric pressure, also influence blast pressures. It is difficult to accurately predict the blast wave action on target structures if all of these parameters are considered. This research concentrates on the influence of the shape of the explosive charge on blast pressure measurements. Spherical and hemispherical charge shapes are considered usual and, as such, accurate and reliable analytical expressions for the blast wave pressure approximation are available. The form and propagation of spherical charge blast waves are considered to have been thoroughly studied and known. In today’s urban and guerrilla warfare, speed of action is a crucial factor. Rendering the careful shaping of explosive charges is time consuming and unnecessary, hence the need for investigating different charge shapes, other than spherical. This investigation consisted of field range experimental measurements of the incident (free-field) and reflected pressures caused by detonating differently shaped charges. The shapes considered were: spherical, cylindrical and rectangular. The experiments were numerically validated and verified using ANSYS Autodyn hydrocode software. Numerical simulations utilised a coupled Euler–Lagrange planar solver, using an ideal air environment and PEP500 explosive material. Charge shapes varied, according to the experimental outline, and the measuring points were constant, to allow comparison of the measured data.
{"title":"ANALYSIS OF CHARGE SHAPE INFLUENCE ON BLAST PRESSURE","authors":"H. Draganić, S. Lukić, I. Radić, Goran Gazić, M. Jeleč","doi":"10.2495/hpsu220081","DOIUrl":"https://doi.org/10.2495/hpsu220081","url":null,"abstract":"Blast wave intensity depends on several parameters, namely: explosive material type, charge weight, shape and orientation, detonation point position, detonation initiator type (primary explosive type), the position (distance) of the explosive charge in relation to the intended target (standoff distance) and ground surface. Environmental conditions, particularly air temperature, humidity and atmospheric pressure, also influence blast pressures. It is difficult to accurately predict the blast wave action on target structures if all of these parameters are considered. This research concentrates on the influence of the shape of the explosive charge on blast pressure measurements. Spherical and hemispherical charge shapes are considered usual and, as such, accurate and reliable analytical expressions for the blast wave pressure approximation are available. The form and propagation of spherical charge blast waves are considered to have been thoroughly studied and known. In today’s urban and guerrilla warfare, speed of action is a crucial factor. Rendering the careful shaping of explosive charges is time consuming and unnecessary, hence the need for investigating different charge shapes, other than spherical. This investigation consisted of field range experimental measurements of the incident (free-field) and reflected pressures caused by detonating differently shaped charges. The shapes considered were: spherical, cylindrical and rectangular. The experiments were numerically validated and verified using ANSYS Autodyn hydrocode software. Numerical simulations utilised a coupled Euler–Lagrange planar solver, using an ideal air environment and PEP500 explosive material. Charge shapes varied, according to the experimental outline, and the measuring points were constant, to allow comparison of the measured data.","PeriodicalId":23773,"journal":{"name":"WIT Transactions on the Built Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89847625","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}
Koki Matsumoto, Masaya Itabashi, A. Kawasumi, K. Takemura, Tatsuya Tanaka
An injection overmolding process enables molding and welding at the same time: a discontinuous fiberreinforced thermoplastic is injected onto the thermoformed continuous fiber-reinforced thermoplastic composites for the fabrication of complex shape parts, namely, ribs and bosses. Since the joining strength is significantly influenced by process parameters, such as resin temperature and molding pressure during the overmolding process, achieving reliable joining strength is important for increasing the load bearing capacity. The nanofibers have great potential to increase the toughness of fiber reinforced composites as secondary reinforcement. Furthermore, selective reinforcement is allowed by nanofiber addition in the matrix onto the fiber surface or interlaminar region of laminated composites. Thus, we previously proposed the selective addition of nanofillers at the joining interfaces to increase the joining strength. In this study, we attempt to reveal the effect of cellulose nanofiber (CNF) addition on creep properties for long-term use under constant load. The shear creep test was conducted under various loads and various temperatures using a self-designed fixture. Furthermore, the debonded surface of a single lap joint was observed by optical microscopy and scanning electron microscopy. We discovered that 1.0 wt% CNF addition increased the creep failure time and decreased the creep strain at the same load. Furthermore, the creep rate was significantly decreased by CNF addition regardless of temperature.
{"title":"SELECTIVE REINFORCEMENT OF JOINING INTERFACE USING NANOFIBERS IN SINGLE-LAP JOINTS OF THERMOPLASTIC COMPOSITES FABRICATED BY THE INJECTION OVERMOLDING PROCESS: CREEP DEFORMATION BEHAVIOUR","authors":"Koki Matsumoto, Masaya Itabashi, A. Kawasumi, K. Takemura, Tatsuya Tanaka","doi":"10.2495/hpsu220011","DOIUrl":"https://doi.org/10.2495/hpsu220011","url":null,"abstract":"An injection overmolding process enables molding and welding at the same time: a discontinuous fiberreinforced thermoplastic is injected onto the thermoformed continuous fiber-reinforced thermoplastic composites for the fabrication of complex shape parts, namely, ribs and bosses. Since the joining strength is significantly influenced by process parameters, such as resin temperature and molding pressure during the overmolding process, achieving reliable joining strength is important for increasing the load bearing capacity. The nanofibers have great potential to increase the toughness of fiber reinforced composites as secondary reinforcement. Furthermore, selective reinforcement is allowed by nanofiber addition in the matrix onto the fiber surface or interlaminar region of laminated composites. Thus, we previously proposed the selective addition of nanofillers at the joining interfaces to increase the joining strength. In this study, we attempt to reveal the effect of cellulose nanofiber (CNF) addition on creep properties for long-term use under constant load. The shear creep test was conducted under various loads and various temperatures using a self-designed fixture. Furthermore, the debonded surface of a single lap joint was observed by optical microscopy and scanning electron microscopy. We discovered that 1.0 wt% CNF addition increased the creep failure time and decreased the creep strain at the same load. Furthermore, the creep rate was significantly decreased by CNF addition regardless of temperature.","PeriodicalId":23773,"journal":{"name":"WIT Transactions on the Built Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85584868","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}
Contemporary building regulations intend to define the standards for design and construction while contemplating safety and serviceability for the occupants. Even though these codes safeguard occupants’ lives under severe earthquakes, damage will occur, inducing stiff repairs and in certain cases building demolition. To address this issue, the design of buildings in seismic regions should aim to be more resilient structures that sustain little or no damage when subjected to extreme loading conditions. This study investigates the use of super-elastic shape memory alloys (SSMA) as partial replacement of steel reinforcement in reinforced concrete (RC) structures to enhance their seismic performance. SSMA is considered a particular type of smart alloys that has the ability to undergo large deformations and return to its original shape after the application of a reverse load, and hence can enhance the performance envelope of the structure. A sensitivity analysis is conducted to assess the efficiency of using SSMA at different locations in reinforced concrete frames. Fragility curves evaluating the seismic performance of an eight-story RC frame reinforced with steel and SSMA at different locations are developed. The results reveal the efficient competence of SSMA reinforced structures at different performance levels as they need greater forces to reach their plastic limit, hence increasing the overall performance of the structure.
{"title":"COLLAPSE FRAGILITY CURVES FOR SEISMIC ASSESSMENT OF SUPERPLASTIC SHAPE MEMORY ALLOY IN REINFORCED CONCRETE STRUCTURES","authors":"Farah Jaafar, G. Saad","doi":"10.2495/hpsu220161","DOIUrl":"https://doi.org/10.2495/hpsu220161","url":null,"abstract":"Contemporary building regulations intend to define the standards for design and construction while contemplating safety and serviceability for the occupants. Even though these codes safeguard occupants’ lives under severe earthquakes, damage will occur, inducing stiff repairs and in certain cases building demolition. To address this issue, the design of buildings in seismic regions should aim to be more resilient structures that sustain little or no damage when subjected to extreme loading conditions. This study investigates the use of super-elastic shape memory alloys (SSMA) as partial replacement of steel reinforcement in reinforced concrete (RC) structures to enhance their seismic performance. SSMA is considered a particular type of smart alloys that has the ability to undergo large deformations and return to its original shape after the application of a reverse load, and hence can enhance the performance envelope of the structure. A sensitivity analysis is conducted to assess the efficiency of using SSMA at different locations in reinforced concrete frames. Fragility curves evaluating the seismic performance of an eight-story RC frame reinforced with steel and SSMA at different locations are developed. The results reveal the efficient competence of SSMA reinforced structures at different performance levels as they need greater forces to reach their plastic limit, hence increasing the overall performance of the structure.","PeriodicalId":23773,"journal":{"name":"WIT Transactions on the Built Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87674761","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}
I. Miličević, Robert Bušić, Kristijan Bebek, David Briševac
Concrete with recycled rubber as a partial replacement of fine natural aggregate, intended for use in load-bearing structural elements, requires specific fresh concrete properties such as a particular slump and flow classes. These specific requirements can be caused by increased water or superplasticizer content. Therefore, concrete mixtures with different percentages of two types of superplasticizers A1 and A2, i.e. 0.2, 0.4 and 0.6% by cement mass, were prepared. Furthermore, the effect of retention of consistency after 15, 30, 45, 60, and 90 minutes, was also studied. Slump and flow table tests were performed at 15-minute intervals to determine the fresh performance of each concrete mixture and retention of consistency. Test results indicate that mixtures with superplasticizer A2 show a more uniform workability range during the measurement period and at the end of the measurement, remain within the same consistency classes, as in the initial measurement.
{"title":"INFLUENCE OF SUPERPLASTICIZER TYPE AND DOSAGE ON RETENTION OF CONSISTENCY OF RUBBERIZED CONCRETE","authors":"I. Miličević, Robert Bušić, Kristijan Bebek, David Briševac","doi":"10.2495/hpsu220031","DOIUrl":"https://doi.org/10.2495/hpsu220031","url":null,"abstract":"Concrete with recycled rubber as a partial replacement of fine natural aggregate, intended for use in load-bearing structural elements, requires specific fresh concrete properties such as a particular slump and flow classes. These specific requirements can be caused by increased water or superplasticizer content. Therefore, concrete mixtures with different percentages of two types of superplasticizers A1 and A2, i.e. 0.2, 0.4 and 0.6% by cement mass, were prepared. Furthermore, the effect of retention of consistency after 15, 30, 45, 60, and 90 minutes, was also studied. Slump and flow table tests were performed at 15-minute intervals to determine the fresh performance of each concrete mixture and retention of consistency. Test results indicate that mixtures with superplasticizer A2 show a more uniform workability range during the measurement period and at the end of the measurement, remain within the same consistency classes, as in the initial measurement.","PeriodicalId":23773,"journal":{"name":"WIT Transactions on the Built Environment","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2022-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81004907","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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