Excavation-induced deformations of earth-retaining walls(ERWs)can critically affect the safety of surrounding structures,highlighting the need for reliable prediction models to support timely decision-making during co...Excavation-induced deformations of earth-retaining walls(ERWs)can critically affect the safety of surrounding structures,highlighting the need for reliable prediction models to support timely decision-making during construction.This study utilizes traditional statistical ARIMA(Auto-Regressive Integrated Moving Average)and deep learning-based LSTM(Long Short-Term Memory)models to predict earth-retaining walls deformation using inclinometer data from excavation sites and compares the predictive performance of both models.The ARIMA model demonstrates strengths in analyzing linear patterns in time-series data as it progresses over time,whereas LSTM exhibits superior capabilities in capturing complex non-linear patterns and long-term dependencies within the time series data.This research includes preprocessing of measurement data for inclinometer,performance evaluation based on various time series data lengths and input variable conditions,and demonstrates that the LSTM model offers statistically significant improvements in predictive performance over the ARIMA model.In addition,by combining LSTM with attention mechanism,attention-based LSTM(ATLSTM)is proposed to improve the short-and long-term prediction performance and solve the problem of excavation site domain change.This study presents the advantages and disadvantages of major time series analysis models for the stability evaluation of mud walls using geotechnical inclinometer data from excavation sites,and suggests that time series analysis models can be used effectively through comparative experiments.展开更多
The widespread adoption of tunnel boring machines(TBMs)has led to an increased focus on disc cutter wear,including both normal and abnormal types,for efficient and safe TBM excavation.However,abnormal wear has yet to ...The widespread adoption of tunnel boring machines(TBMs)has led to an increased focus on disc cutter wear,including both normal and abnormal types,for efficient and safe TBM excavation.However,abnormal wear has yet to be thoroughly investigated,primarily due to the complexity of considering mixed ground conditions and the imbalance in the number of instances between the two types of wear.This study developed a prediction model for abnormal TBM disc cutter wear,considering mixed ground conditions,by employing interpretable machine learning with data augmentation.An equivalent elastic modulus was used to consider the characteristics of mixed ground conditions,and wear data was obtained from 65 cutterhead intervention(CHI)reports covering both mixed ground and hard rock sections.With a balanced training dataset obtained by data augmentation,an extreme gradient boosting(XGB)model delivered acceptable results with an accuracy of 0.94,an F1-score of 0.808,and a recall of 0.8.In addition,the accuracy for each individual disc cutter exhibited low variability.When employing data augmentation,a significant improvement in recall was observed compared to when it was not used,although the difference in accuracy and F1-score was marginal.The subsequent model interpretation revealed the chamber pressure,cutter installation radius,and torque as significant contributors.Specifically,a threshold in chamber pressure was observed,which could induce abnormal wear.The study also explored how elevated values of these influential contributors correlate with abnormal wear.The proposed model offers a valuable tool for planning the replacement of abnormally worn disc cutters,enhancing the safety and efficiency of TBM operations.展开更多
Amidst the recent development in the usage of curtain walls for office buildings, high utilization of energy and poor thermal comfort issues have become paramount. This paper assesses thermal comfort in multi storey (...Amidst the recent development in the usage of curtain walls for office buildings, high utilization of energy and poor thermal comfort issues have become paramount. This paper assesses thermal comfort in multi storey (naturally and mechanically ventilated) office buildings in Accra, the Capital city of Ghana using Fanger’s Predicted Mean Votes (PMV) and Predicted Percentage of Dissatisfied persons (PPD) model. The model relates to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 55 (which gives an acceptable temperature range of 23℃ - 26℃) and the International Standards Organization (ISO) 7730. Indoor environmental parameters (temperature and relative humidity) of 4 multi storey office buildings were recorded over a 10 month period. The environmental parameters were analyzed using PMVcalc_v2 software which resulted in the generation of PMV-PPD values. The findings reveal high PMV-PPD values in the Naturally Ventilated Building (NVB) whiles the Mechanically Ventilated Buildings (MVB) fall within the comfort zone. Meanwhile, the Actual Mean Votes (AMV) by the occupants suggest all four buildings are relatively comfortable with the mechanically ventilated offices being more comfortable. Additionally, it is recommended that buildings are orientated with their longer sides facing north-south, with enough shading in order to improve the thermal comfort conditions of work spaces.展开更多
There is a growing concern of the integration of bamboo as a material into the building construction industry even though its potential is underscored. Certain factors serve as barriers to the use of bamboo in buildin...There is a growing concern of the integration of bamboo as a material into the building construction industry even though its potential is underscored. Certain factors serve as barriers to the use of bamboo in building construction. This study employed a questionnaire survey which sought to investigate the perceptions of 84 Architects and 100 Senior Managers of small and medium scale Building construction firms on the factors that influence the use of bamboo in building construction. Relative Importance Index and Chi-squared tests were performed to identify the significant factors that influence the use of bamboo in building construction. The results showed that the building contractors considered nonspecification of bamboo for building projects by Architects, inadequate bamboo processing companies in Ghana and insufficient cooperation from government to be the key factors which influence the use of bamboo for building construction. The results further showed that the Architects considered lack of knowledge in bamboo detailing, limited knowledge of bamboo and lack of expertise to use it, and inadequate bamboo processing companies to be the key influential factors inhibiting the use of bamboo in building construction. The results are of value to the construction industry as it identifies significant factors which influence the usage of bamboo in building construction. Promotion of bamboo usage in building construction should be given the needed publicity to create the awareness of its potential as a building material.展开更多
Academia and industry research enables researchers to conduct research projects that are more relevant to current business practices and context. Although, several construction research works have been done by the aca...Academia and industry research enables researchers to conduct research projects that are more relevant to current business practices and context. Although, several construction research works have been done by the academics in the tertiary institutions in Ghana, it is sad to know that, a large number of these research works have not moved from the pure stage to the applied stage. This study seeks to establish the imperative of academia and industry collaboration in building research in Ghana. A total of 116 construction practising professionals consisting of Ghana Institute of Construction (GIOC) corporate members (QS, Architects, Engineers and so on) from the industry, and academics from tertiary academic institutions (That’s, Lecturers from KNUST and UEW) that run postgraduate construction programmes in Ghana as at February 2016 constituted the respondents for this study. Census and systematic sampling techniques were used for the sampled population. Descriptive statistics was employed in the data analysis for the mean and standard deviation (SD) score values of variables. The most imperatives for academia and industry collaboration were found to be: ensuring research findings solve socio-economic and development problems, the intermittent collapse of buildings, support for the local industries to produce quality materials locally to feed the construction industry, proper contract documentations and administration. This research would bring to light the urgent issues in the construction industry that calls for greater collaboration between the academia and industry in Ghana. It reveals a deeper understanding on the need for collaborative research in the Ghanaian construction industry, by providing the most imperatives to academia-industry collaborative research in Ghana.展开更多
The pressurization smoke control system has been commonly used as a smoke control system at the emergency stairs of high-rise buildings. However, a higher possibility of overpressure between the lobby and the accommod...The pressurization smoke control system has been commonly used as a smoke control system at the emergency stairs of high-rise buildings. However, a higher possibility of overpressure between the lobby and the accommodation or pressure drop in the lobby could lead to failure in achievement of the purpose of pressurization system, particularly when supplying the leakage and supplementary air flow through one air-supply path at a time. To improve this particular issue, the devise configurations, as well as the different ways to supply the leakage and supplementary air flow through the different flow passages have been proposed. The performance of the trial product was evaluated on the test bed, ultimately providing a safe evacuation environment if high-rise buildings fired.展开更多
The act of unauthorized siting of buildings has persisted in most developing countries. Despite numerous efforts at local levels to address this problem, its existence and effects keep on rising in various metropolise...The act of unauthorized siting of buildings has persisted in most developing countries. Despite numerous efforts at local levels to address this problem, its existence and effects keep on rising in various metropolises in Ghana. This research explores the causes of unauthorized siting of buildings in Asakae, a suburb of the Sekondi-Takoradi Metropolis, and suggests measures to curb them. In view of this, a sample size of 182 house-owners was chosen for the study. Accordingly, the sample size was determined using Fisher et al. formula and questionnaire survey approach was adopted for the study. More so, data generated from the survey were further analyzed, using Relative Importance Index. The findings of the survey indicated that ignorance on planning and building regulations, inadequate housing schemes, unrealistic zonings and the location of land are critical variables which influence unauthorized siting of buildings. It is recommended that the populace should be given regular public education on land-use planning and the building regulations of Ghana. More so, the Assemblies should automate their systems, with respect to monitoring and detection of buildings under construction;so that buildings that were being located at unapproved places could be quickly detected, and appropriate measures could be taken before their completion.展开更多
BIM （building information modeling） is a technological innovation, not only during the design process, but also during the planning and preparation stages of a construction project, as it also supports making invest...BIM （building information modeling） is a technological innovation, not only during the design process, but also during the planning and preparation stages of a construction project, as it also supports making investment decisions. An innovation which is comparable, if only slightly less significant, was the transition from using 2D systems to the 3D structural model design. The article outlines the advantages of using BIM in the preparatory stages of a construction project. It also presents benefits which relate to the employment of the BIM system in cost estimation process. The article describes the Zuzia BIM system which uses the BIM model, as this system has just been created in Poland for the purpose of construction cost estimation. The preparation of the bill of quantities is automated in this system and this has been achieved on the basis of data directly obtained from virtual models of buildings, which were carried out thanks to the collaboration of various design sectors. The article authors, using their own experience, present difficulties which can be encountered by cost estimators in Poland when calculating the value of a building with the help of the BIM concept. The article shows the design errors that prevent or hinder takeoff automatic calculation based on BIM model. Design errors shown in the article are for example reinforcement bars have been defined by a designer as elements hollow in the middle or as one element for the whole building, one type of elements assigned as few different or incorrect defining of elements in relation to the type of works.展开更多
Today,to describe the thermal performance of the building envelope and its components we use a variation of metrics;such as,R-value,ACH(air exchange rate per hour),SHGC(solar heat gain coefficient)of windows,U-factor ...Today,to describe the thermal performance of the building envelope and its components we use a variation of metrics;such as,R-value,ACH(air exchange rate per hour),SHGC(solar heat gain coefficient)of windows,U-factor etc.None of these performance indicators is meant to represent the overall thermal performance.In this paper,such a metric is introduced,the BEP(building envelope performance)value.Unlike the thermal resistance,typically expressed as an R-value,the BEP-value considers additional elements of heat transfer that affect the energy demand of the building because of exterior and interior(solar)thermal loads:conductive and radiant heat transfer,and air infiltration.To demonstrate BEP’s utility,validation studies were carried out by comparing the BEP-value to theoretical results using whole building energy simulation tools such as EnergyPlus and WUFI Plus.Results show that BEP calculations are comparable to calculations made using these simulation tools and that unlike other similar metrics,the BEP-value accounts for all heat transfer mechanisms that are relevant for the overall energy performance of the building envelope.The BEP-value thus allows comparing envelopes of buildings with different use types in a fair and realistic manner.展开更多
This paper mainly discusses the problems existing in the traditional design process of the refrigeration station and tries to solve them with BIM technology. Considering the characteristics of BIM technology, BIM desi...This paper mainly discusses the problems existing in the traditional design process of the refrigeration station and tries to solve them with BIM technology. Considering the characteristics of BIM technology, BIM design process is presented based on the traditional design process to achieve the goal of improving design quality and efficiency.展开更多
This study aims to determine the key and underlying Leadership and Top Management (LTM) factors that have a significant impact on sustaining the implementation of Total Quality Management (TQM) within the construction...This study aims to determine the key and underlying Leadership and Top Management (LTM) factors that have a significant impact on sustaining the implementation of Total Quality Management (TQM) within the construction industry in Ghana. The research methodology employed in this study was a quantitative technique. Questionnaires were distributed to 641 participants within construction industry in Ghana. Questionnaires retrieved for the analysis were 536. Three steps approached were used for the data analysis. These include Exploratory Factor Analysis (EFA), Confirmatory Factor Analysis (CFA), and Structural Equation Modeling (SEM) analysis. After conducting the EFA and CFA, SEM was also used to analyze the construct validity. The SEM analysis helps to determine four key indicator variables for the leadership and top management construct. These include Leadership/Top Management approach to employees’ management, Leadership/Top Management understanding of TQM, Leadership/Top Management empowerment of employees to resolve quality issues, and Leadership/Top Management endorsement of TQM. All the four indicator variables were found to be good of fit and closely associated with the dependent variable. The study adds to the body of knowledge by using EFA, CFA and SEM techniques to establish key leadership and top management factors affecting TQM implementation in Ghana’s construction industry. The findings in general suggested that leadership and top Management factors identified have a direct positive impact on sustaining TQM implementation in the Ghanaian construction industry. Consequently, the leadership and top management factors identified in this study can help improve TQM in the Ghanaian construction industry.展开更多
Natural minerals,such as kaolinite,halloysite,montmorillonite,attapulgite,bentonite,sepiolite,forsterite,and wollastonite,have considerable potential for use in CO_(2) capture and mineralization due to their abundant ...Natural minerals,such as kaolinite,halloysite,montmorillonite,attapulgite,bentonite,sepiolite,forsterite,and wollastonite,have considerable potential for use in CO_(2) capture and mineralization due to their abundant reserves,low cost,excellent mechanical prop-erties,and chemical stability.Over the past decades,various methods,such as those involving heat,acid,alkali,organic amine,amino sil-ane,and ionic liquid,have been employed to enhance the CO_(2) capture performance of natural minerals to attain high specific surface area,a large number of pore structures,and rich active sites.Future research on CO_(2) capture by natural minerals will focus on the full utiliza-tion of the properties of natural minerals,adoption of suitable modification methods,and preparation of composite materials with high specific surface area and rich active sites.In addition,we provide a summary of the principle and technical route of direct and indirect mineralization of CO_(2) by natural minerals.This process uses minerals with high calcium and magnesium contents,such as forsterite(Mg_(2)SiO_(4)),serpentine[Mg_(3)Si_(2)O(OH)_(4)],and wollastonite(CaSiO_(3)).The research status of indirect mineralization of CO_(2) using hydro-chloric acid,acetic acid,molten salt,and ammonium salt as media is also introduced in detail.The recovery of additives and high-value-added products during the mineralization process to increase economic benefits is another focus of future research on CO_(2) mineralization by natural minerals.展开更多
The construction industry, known for its low productivity, is increasingly utilising software and mobile apps to enhance efficiency. However, more comprehensive research is needed to understand the effectiveness of th...The construction industry, known for its low productivity, is increasingly utilising software and mobile apps to enhance efficiency. However, more comprehensive research is needed to understand the effectiveness of these technology applications. The PRISMA principles utilised a scoping review methodology to ascertain pertinent studies and extract significant findings. From 2013 onwards, articles containing data on mobile applications or software designed to enhance productivity in the construction sector were obtained from multiple databases, including Emerald Insight, Science Direct, IEEE Xplore, and Google Scholar. After evaluating 2604 articles, 30 were determined to be pertinent to the study and were subsequently analysed for the review. The review identified five key themes: effectiveness, benefits, successful implementation examples, obstacles and limitations, and a comprehensive list of software and mobile apps. In addition, 71 software and mobile apps have shown potentially how these technologies can improve communication, collaboration, project management, real-time collaboration, document management, and on-the-go project information and estimating processes in the construction industry, increasing efficiency and productivity. The findings highlight the potential of these technologies such as Automation, Radio-Frequency Identification (RFID), Building Information Modeling (BIM), Augmented Reality (AR), Virtual Reality (VR), and Internet of Things (IoT) to improve efficiency and communication in the construction industry. Despite challenges such as cost, lack of awareness, resistance to change, compatibility concerns, human resources, technological and security concerns and licensing issues, the study identifies specific mobile applications and software with the potential to enhance efficiency significantly, improve productivity and streamline workflows. The broader societal impacts of construction software and mobile app development include increased efficiency, job creation, and sustainability.展开更多
Electrifying end uses is a key strategy to reducing GHG emissions in buildings.However,it may increase peak electricity demand that triggers the need to upgrade the existing power distribution system,leading to delays...Electrifying end uses is a key strategy to reducing GHG emissions in buildings.However,it may increase peak electricity demand that triggers the need to upgrade the existing power distribution system,leading to delays in electrification and needs of significant investment.There is also concern that building electrification may cause an increase of energy costs,leading to further energy burden for low-income communities.This study uses the urban scale building modeling tool CityBES to assess the electrification impacts of more than 43,000 residential buildings in a neighborhood of Portland,Oregon,USA.Energy efficiency upgrades were investigated on their potential to mitigate the increase of peak electricity demand and energy burden.Simulation results from the calibrated EnergyPlus models show that electrification with heat pumps for space heating and cooling as well as for domestic water heating can reduce CO_(2)e emissions by 38%,but increase peak electricity demand by about 9%from the baseline building stock.Combining electrification measures and energy efficiency upgrades can reduce CO_(2)e emissions by 48%while reducing peak electricity demand by 6%and saving the median household energy costs by 28%.City and utility decision makers should consider integrating energy efficiency upgrades with electrification measures as an effective residential building electrification strategy,which significantly reduces carbon emissions,caps or even decreases peak demand while reducing energy burden of residents.展开更多
Advancements in sensor technology,data analytics,affordable compute,and communication infrastructure have paved the way for Digital Twin technology in optimizing building operations and controls.This study presents th...Advancements in sensor technology,data analytics,affordable compute,and communication infrastructure have paved the way for Digital Twin technology in optimizing building operations and controls.This study presents the development of an open and interoperable web-based Digital Twin platform for integrating diverse data streams and facilitating effective user interactions.The platform utilizes modern technologies for the web framework and time-series data management,ensuring scalability and responsiveness.The backend supports seamless integration of diverse data sources and emulators,incorporating data from building sensors and meters,external weather Application Programming Interfaces,and advanced EnergyPlus simulation models of the building and its energy systems including the Distributed Energy Resources that are formulated in Functional Mockup Units.A simulation case study was conducted with FlexLab,a test facility on Lawrence Berkeley National Laboratory campus.The case study includes normal operations,Distributed Energy Resource integration,and power outage scenarios,to illustrate the Digital Twin’s ability to provide critical insights into energy performance and thermal resilience.The results demonstrated the platform’s potential as a decision-support tool for optimizing building energy performance and enhancing resilience against extreme weather events.Future work will focus on deploying the Digital Twin platform to a real building for field validation,extending its capabilities to cover more scenarios such as bidirectional Electric Vehicle interactions,and enhancing user engagement.展开更多
The initiation mechanism of debris flow is regarded as the key step in understanding the debrisflow processes of occurrence, development and damage. Moreover, migration, accumulation and blocking effects of fine parti...The initiation mechanism of debris flow is regarded as the key step in understanding the debrisflow processes of occurrence, development and damage. Moreover, migration, accumulation and blocking effects of fine particles in soil will lead to soil failure and then develop into debris flow. Based on this hypothesis and considering the three factors of slope gradient, rainfall duration and rainfall intensity, 16 flume experiments were designed using the method of orthogonal design and completed in a laboratory. Particle composition changes in slope toe, volumetric water content, fine particle movement characteristics and soil failure mechanism were analyzed and understood as follows: the soil has complex, random and unstable structures, which causes remarkable pore characteristics of poor connectivity, non-uniformity and easy variation. The major factors that influence fine particle migration are rainfall intensity and slope. Rainfall intensity dominates particle movement, whereby high intensity rainfall induces a large number of mass movement and sharp fluctuation, causing more fine particles to accumulate at the steep slope toe. The slope toe plays an important role in water collection and fine particleaccumulation. Both fine particle migration and coarse particle movement appears similar fluctuation. Fine particle migration is interrupted in unconnected pores, causing pore blockage and fine particle accumulation, which then leads to the formation of a weak layer and further soil failure or collapses. Fine particle movement also causes debris flow formation in two ways: movement on the soil surface and migration inside the soil. The results verify the hypothesis that the function of fine particle migration in soil failure process is conducive for further understanding the formation mechanism of soil failure and debris flow initiation.展开更多
The success of a tunnel-boring machine （TBM） in a given project depends on the functionality of all components of the system, from the cutters to the backup system, and on the entire rolling stock. However, no part ...The success of a tunnel-boring machine （TBM） in a given project depends on the functionality of all components of the system, from the cutters to the backup system, and on the entire rolling stock. However, no part of the machine plays a more crucial role in the efficient operation of the machine than its cutterhead. The design of the cutterhead impacts the efficiency of cutting, the balance of the head, the life of the cutters, the maintenance of the main bearing/gearbox, and the effectiveness of the mucking along with its effects on the wear of the face and gage cutters/muck buckets. Overall, cutterhead design heavily impacts the rate of penetration （ROP）, rate of machine utilization （U）, and daffy advance rate （AR）. Although there has been some discussion in commonly available publications regarding disk cutters, cutting forces, and some design features of the head, there is limited literature on this subject because the design of cutter- heads is mainly handled by machine manufacturers. Most of the design process involves proprietary algorithms by the manufacturers, and despite recent attention on the subject, the design of rock TBMs has been somewhat of a mystery to most end-users. This paper is an attempt to demystify the basic concepts in design. Although it may not be sufficient for a full-fledged design by the readers, this paper allows engineers and contractors to understand the thought process in the design steps, what to Look for in a proper design, and the implications of the head design on machine operation and life cycle.展开更多
This study proposes an innovative precast shear wall system, called an EVE precast hollow shear wall structure (EVE-PHSW). Precast panels in EVE-PHSW are simultaneously precast with vertical and horizontal holes. Nonc...This study proposes an innovative precast shear wall system, called an EVE precast hollow shear wall structure (EVE-PHSW). Precast panels in EVE-PHSW are simultaneously precast with vertical and horizontal holes. Noncontact lap splices of rebars are used in vertical joints connecting adjacent precast panels for automated prefabrication and easy in situ erection. The seismic behavior of EVE walls was examined through a series of tests on six wall specimens with aspect ratios of 1.0~1.3. Test results showed that EVE wall specimens with inside cast-in situ concrete achieved the desired “strong bending and weak shear” and failed in shear mode. Common main diagonal cracks and brittle shear failure in squat cast-in situ walls were prevented. Inside cast-in situ concrete could signifi cantly improve the shear strength and stiff ness of EVE walls. The details of boundary elements (cast-in situ or prefabricated) and vertical joints (contiguous or spaced) had little eff ect on the global behavior of EVE walls. Noncontact lap splices in vertical joints could enable EVE walls to exhibit stable load-carrying capacity through extensive deformations. Evaluation on design codes revealed that both JGJ 3-2010 and ACI 318-14 provide conservative estimation of shear strength of EVE walls, and EVE walls achieved shear strength reserves comparative to cast-in situ walls. The recommended eff ective stiff ness for cast-in situ walls in ASCE 41-17 appeared to be appropriate for EVE walls.展开更多
基金carried out under the KICT Research Program(Project No.20250285-001,Development of Infrastructure Disaster Prevention Technology Based on Satellites SAR)funded by the Ministry of Science and ICT.
文摘Excavation-induced deformations of earth-retaining walls(ERWs)can critically affect the safety of surrounding structures,highlighting the need for reliable prediction models to support timely decision-making during construction.This study utilizes traditional statistical ARIMA(Auto-Regressive Integrated Moving Average)and deep learning-based LSTM(Long Short-Term Memory)models to predict earth-retaining walls deformation using inclinometer data from excavation sites and compares the predictive performance of both models.The ARIMA model demonstrates strengths in analyzing linear patterns in time-series data as it progresses over time,whereas LSTM exhibits superior capabilities in capturing complex non-linear patterns and long-term dependencies within the time series data.This research includes preprocessing of measurement data for inclinometer,performance evaluation based on various time series data lengths and input variable conditions,and demonstrates that the LSTM model offers statistically significant improvements in predictive performance over the ARIMA model.In addition,by combining LSTM with attention mechanism,attention-based LSTM(ATLSTM)is proposed to improve the short-and long-term prediction performance and solve the problem of excavation site domain change.This study presents the advantages and disadvantages of major time series analysis models for the stability evaluation of mud walls using geotechnical inclinometer data from excavation sites,and suggests that time series analysis models can be used effectively through comparative experiments.
基金support of the“National R&D Project for Smart Construction Technology (Grant No.RS-2020-KA157074)”funded by the Korea Agency for Infrastructure Technology Advancement under the Ministry of Land,Infrastructure and Transport,and managed by the Korea Expressway Corporation.
文摘The widespread adoption of tunnel boring machines(TBMs)has led to an increased focus on disc cutter wear,including both normal and abnormal types,for efficient and safe TBM excavation.However,abnormal wear has yet to be thoroughly investigated,primarily due to the complexity of considering mixed ground conditions and the imbalance in the number of instances between the two types of wear.This study developed a prediction model for abnormal TBM disc cutter wear,considering mixed ground conditions,by employing interpretable machine learning with data augmentation.An equivalent elastic modulus was used to consider the characteristics of mixed ground conditions,and wear data was obtained from 65 cutterhead intervention(CHI)reports covering both mixed ground and hard rock sections.With a balanced training dataset obtained by data augmentation,an extreme gradient boosting(XGB)model delivered acceptable results with an accuracy of 0.94,an F1-score of 0.808,and a recall of 0.8.In addition,the accuracy for each individual disc cutter exhibited low variability.When employing data augmentation,a significant improvement in recall was observed compared to when it was not used,although the difference in accuracy and F1-score was marginal.The subsequent model interpretation revealed the chamber pressure,cutter installation radius,and torque as significant contributors.Specifically,a threshold in chamber pressure was observed,which could induce abnormal wear.The study also explored how elevated values of these influential contributors correlate with abnormal wear.The proposed model offers a valuable tool for planning the replacement of abnormally worn disc cutters,enhancing the safety and efficiency of TBM operations.
文摘Amidst the recent development in the usage of curtain walls for office buildings, high utilization of energy and poor thermal comfort issues have become paramount. This paper assesses thermal comfort in multi storey (naturally and mechanically ventilated) office buildings in Accra, the Capital city of Ghana using Fanger’s Predicted Mean Votes (PMV) and Predicted Percentage of Dissatisfied persons (PPD) model. The model relates to the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 55 (which gives an acceptable temperature range of 23℃ - 26℃) and the International Standards Organization (ISO) 7730. Indoor environmental parameters (temperature and relative humidity) of 4 multi storey office buildings were recorded over a 10 month period. The environmental parameters were analyzed using PMVcalc_v2 software which resulted in the generation of PMV-PPD values. The findings reveal high PMV-PPD values in the Naturally Ventilated Building (NVB) whiles the Mechanically Ventilated Buildings (MVB) fall within the comfort zone. Meanwhile, the Actual Mean Votes (AMV) by the occupants suggest all four buildings are relatively comfortable with the mechanically ventilated offices being more comfortable. Additionally, it is recommended that buildings are orientated with their longer sides facing north-south, with enough shading in order to improve the thermal comfort conditions of work spaces.
文摘There is a growing concern of the integration of bamboo as a material into the building construction industry even though its potential is underscored. Certain factors serve as barriers to the use of bamboo in building construction. This study employed a questionnaire survey which sought to investigate the perceptions of 84 Architects and 100 Senior Managers of small and medium scale Building construction firms on the factors that influence the use of bamboo in building construction. Relative Importance Index and Chi-squared tests were performed to identify the significant factors that influence the use of bamboo in building construction. The results showed that the building contractors considered nonspecification of bamboo for building projects by Architects, inadequate bamboo processing companies in Ghana and insufficient cooperation from government to be the key factors which influence the use of bamboo for building construction. The results further showed that the Architects considered lack of knowledge in bamboo detailing, limited knowledge of bamboo and lack of expertise to use it, and inadequate bamboo processing companies to be the key influential factors inhibiting the use of bamboo in building construction. The results are of value to the construction industry as it identifies significant factors which influence the usage of bamboo in building construction. Promotion of bamboo usage in building construction should be given the needed publicity to create the awareness of its potential as a building material.
文摘Academia and industry research enables researchers to conduct research projects that are more relevant to current business practices and context. Although, several construction research works have been done by the academics in the tertiary institutions in Ghana, it is sad to know that, a large number of these research works have not moved from the pure stage to the applied stage. This study seeks to establish the imperative of academia and industry collaboration in building research in Ghana. A total of 116 construction practising professionals consisting of Ghana Institute of Construction (GIOC) corporate members (QS, Architects, Engineers and so on) from the industry, and academics from tertiary academic institutions (That’s, Lecturers from KNUST and UEW) that run postgraduate construction programmes in Ghana as at February 2016 constituted the respondents for this study. Census and systematic sampling techniques were used for the sampled population. Descriptive statistics was employed in the data analysis for the mean and standard deviation (SD) score values of variables. The most imperatives for academia and industry collaboration were found to be: ensuring research findings solve socio-economic and development problems, the intermittent collapse of buildings, support for the local industries to produce quality materials locally to feed the construction industry, proper contract documentations and administration. This research would bring to light the urgent issues in the construction industry that calls for greater collaboration between the academia and industry in Ghana. It reveals a deeper understanding on the need for collaborative research in the Ghanaian construction industry, by providing the most imperatives to academia-industry collaborative research in Ghana.
文摘The pressurization smoke control system has been commonly used as a smoke control system at the emergency stairs of high-rise buildings. However, a higher possibility of overpressure between the lobby and the accommodation or pressure drop in the lobby could lead to failure in achievement of the purpose of pressurization system, particularly when supplying the leakage and supplementary air flow through one air-supply path at a time. To improve this particular issue, the devise configurations, as well as the different ways to supply the leakage and supplementary air flow through the different flow passages have been proposed. The performance of the trial product was evaluated on the test bed, ultimately providing a safe evacuation environment if high-rise buildings fired.
文摘The act of unauthorized siting of buildings has persisted in most developing countries. Despite numerous efforts at local levels to address this problem, its existence and effects keep on rising in various metropolises in Ghana. This research explores the causes of unauthorized siting of buildings in Asakae, a suburb of the Sekondi-Takoradi Metropolis, and suggests measures to curb them. In view of this, a sample size of 182 house-owners was chosen for the study. Accordingly, the sample size was determined using Fisher et al. formula and questionnaire survey approach was adopted for the study. More so, data generated from the survey were further analyzed, using Relative Importance Index. The findings of the survey indicated that ignorance on planning and building regulations, inadequate housing schemes, unrealistic zonings and the location of land are critical variables which influence unauthorized siting of buildings. It is recommended that the populace should be given regular public education on land-use planning and the building regulations of Ghana. More so, the Assemblies should automate their systems, with respect to monitoring and detection of buildings under construction;so that buildings that were being located at unapproved places could be quickly detected, and appropriate measures could be taken before their completion.
文摘BIM （building information modeling） is a technological innovation, not only during the design process, but also during the planning and preparation stages of a construction project, as it also supports making investment decisions. An innovation which is comparable, if only slightly less significant, was the transition from using 2D systems to the 3D structural model design. The article outlines the advantages of using BIM in the preparatory stages of a construction project. It also presents benefits which relate to the employment of the BIM system in cost estimation process. The article describes the Zuzia BIM system which uses the BIM model, as this system has just been created in Poland for the purpose of construction cost estimation. The preparation of the bill of quantities is automated in this system and this has been achieved on the basis of data directly obtained from virtual models of buildings, which were carried out thanks to the collaboration of various design sectors. The article authors, using their own experience, present difficulties which can be encountered by cost estimators in Poland when calculating the value of a building with the help of the BIM concept. The article shows the design errors that prevent or hinder takeoff automatic calculation based on BIM model. Design errors shown in the article are for example reinforcement bars have been defined by a designer as elements hollow in the middle or as one element for the whole building, one type of elements assigned as few different or incorrect defining of elements in relation to the type of works.
基金This manuscript has been authored by UT-Battelle LLC under contract DE-AC05-00OR22725 with the US DOE(Department of Energy).
文摘Today,to describe the thermal performance of the building envelope and its components we use a variation of metrics;such as,R-value,ACH(air exchange rate per hour),SHGC(solar heat gain coefficient)of windows,U-factor etc.None of these performance indicators is meant to represent the overall thermal performance.In this paper,such a metric is introduced,the BEP(building envelope performance)value.Unlike the thermal resistance,typically expressed as an R-value,the BEP-value considers additional elements of heat transfer that affect the energy demand of the building because of exterior and interior(solar)thermal loads:conductive and radiant heat transfer,and air infiltration.To demonstrate BEP’s utility,validation studies were carried out by comparing the BEP-value to theoretical results using whole building energy simulation tools such as EnergyPlus and WUFI Plus.Results show that BEP calculations are comparable to calculations made using these simulation tools and that unlike other similar metrics,the BEP-value accounts for all heat transfer mechanisms that are relevant for the overall energy performance of the building envelope.The BEP-value thus allows comparing envelopes of buildings with different use types in a fair and realistic manner.
文摘This paper mainly discusses the problems existing in the traditional design process of the refrigeration station and tries to solve them with BIM technology. Considering the characteristics of BIM technology, BIM design process is presented based on the traditional design process to achieve the goal of improving design quality and efficiency.
文摘This study aims to determine the key and underlying Leadership and Top Management (LTM) factors that have a significant impact on sustaining the implementation of Total Quality Management (TQM) within the construction industry in Ghana. The research methodology employed in this study was a quantitative technique. Questionnaires were distributed to 641 participants within construction industry in Ghana. Questionnaires retrieved for the analysis were 536. Three steps approached were used for the data analysis. These include Exploratory Factor Analysis (EFA), Confirmatory Factor Analysis (CFA), and Structural Equation Modeling (SEM) analysis. After conducting the EFA and CFA, SEM was also used to analyze the construct validity. The SEM analysis helps to determine four key indicator variables for the leadership and top management construct. These include Leadership/Top Management approach to employees’ management, Leadership/Top Management understanding of TQM, Leadership/Top Management empowerment of employees to resolve quality issues, and Leadership/Top Management endorsement of TQM. All the four indicator variables were found to be good of fit and closely associated with the dependent variable. The study adds to the body of knowledge by using EFA, CFA and SEM techniques to establish key leadership and top management factors affecting TQM implementation in Ghana’s construction industry. The findings in general suggested that leadership and top Management factors identified have a direct positive impact on sustaining TQM implementation in the Ghanaian construction industry. Consequently, the leadership and top management factors identified in this study can help improve TQM in the Ghanaian construction industry.
基金supported by the Beijing Natural Science Foundation,China(No.2242055).
文摘Natural minerals,such as kaolinite,halloysite,montmorillonite,attapulgite,bentonite,sepiolite,forsterite,and wollastonite,have considerable potential for use in CO_(2) capture and mineralization due to their abundant reserves,low cost,excellent mechanical prop-erties,and chemical stability.Over the past decades,various methods,such as those involving heat,acid,alkali,organic amine,amino sil-ane,and ionic liquid,have been employed to enhance the CO_(2) capture performance of natural minerals to attain high specific surface area,a large number of pore structures,and rich active sites.Future research on CO_(2) capture by natural minerals will focus on the full utiliza-tion of the properties of natural minerals,adoption of suitable modification methods,and preparation of composite materials with high specific surface area and rich active sites.In addition,we provide a summary of the principle and technical route of direct and indirect mineralization of CO_(2) by natural minerals.This process uses minerals with high calcium and magnesium contents,such as forsterite(Mg_(2)SiO_(4)),serpentine[Mg_(3)Si_(2)O(OH)_(4)],and wollastonite(CaSiO_(3)).The research status of indirect mineralization of CO_(2) using hydro-chloric acid,acetic acid,molten salt,and ammonium salt as media is also introduced in detail.The recovery of additives and high-value-added products during the mineralization process to increase economic benefits is another focus of future research on CO_(2) mineralization by natural minerals.
基金the National Natural Science Foundation of China(Grant Nos.51976155 and 12032010)the Research Fund of State Key Laboratory of Mechanics and Control of Mechanical Structures(Grant No.MCMS-I-0222K01)the Fund of Prospective Layout of Scientific Research for Nanjing University of Aeronautics and Astronautics.
文摘The construction industry, known for its low productivity, is increasingly utilising software and mobile apps to enhance efficiency. However, more comprehensive research is needed to understand the effectiveness of these technology applications. The PRISMA principles utilised a scoping review methodology to ascertain pertinent studies and extract significant findings. From 2013 onwards, articles containing data on mobile applications or software designed to enhance productivity in the construction sector were obtained from multiple databases, including Emerald Insight, Science Direct, IEEE Xplore, and Google Scholar. After evaluating 2604 articles, 30 were determined to be pertinent to the study and were subsequently analysed for the review. The review identified five key themes: effectiveness, benefits, successful implementation examples, obstacles and limitations, and a comprehensive list of software and mobile apps. In addition, 71 software and mobile apps have shown potentially how these technologies can improve communication, collaboration, project management, real-time collaboration, document management, and on-the-go project information and estimating processes in the construction industry, increasing efficiency and productivity. The findings highlight the potential of these technologies such as Automation, Radio-Frequency Identification (RFID), Building Information Modeling (BIM), Augmented Reality (AR), Virtual Reality (VR), and Internet of Things (IoT) to improve efficiency and communication in the construction industry. Despite challenges such as cost, lack of awareness, resistance to change, compatibility concerns, human resources, technological and security concerns and licensing issues, the study identifies specific mobile applications and software with the potential to enhance efficiency significantly, improve productivity and streamline workflows. The broader societal impacts of construction software and mobile app development include increased efficiency, job creation, and sustainability.
文摘Electrifying end uses is a key strategy to reducing GHG emissions in buildings.However,it may increase peak electricity demand that triggers the need to upgrade the existing power distribution system,leading to delays in electrification and needs of significant investment.There is also concern that building electrification may cause an increase of energy costs,leading to further energy burden for low-income communities.This study uses the urban scale building modeling tool CityBES to assess the electrification impacts of more than 43,000 residential buildings in a neighborhood of Portland,Oregon,USA.Energy efficiency upgrades were investigated on their potential to mitigate the increase of peak electricity demand and energy burden.Simulation results from the calibrated EnergyPlus models show that electrification with heat pumps for space heating and cooling as well as for domestic water heating can reduce CO_(2)e emissions by 38%,but increase peak electricity demand by about 9%from the baseline building stock.Combining electrification measures and energy efficiency upgrades can reduce CO_(2)e emissions by 48%while reducing peak electricity demand by 6%and saving the median household energy costs by 28%.City and utility decision makers should consider integrating energy efficiency upgrades with electrification measures as an effective residential building electrification strategy,which significantly reduces carbon emissions,caps or even decreases peak demand while reducing energy burden of residents.
基金supported by the Laboratory Directed Research and Development(LDRD)Program of Lawrence Berkeley National Laboratory,provided by the Director,Office of Science,of the U.S.Department of Energy under Contract No.DE-AC02-05CH11231.
文摘Advancements in sensor technology,data analytics,affordable compute,and communication infrastructure have paved the way for Digital Twin technology in optimizing building operations and controls.This study presents the development of an open and interoperable web-based Digital Twin platform for integrating diverse data streams and facilitating effective user interactions.The platform utilizes modern technologies for the web framework and time-series data management,ensuring scalability and responsiveness.The backend supports seamless integration of diverse data sources and emulators,incorporating data from building sensors and meters,external weather Application Programming Interfaces,and advanced EnergyPlus simulation models of the building and its energy systems including the Distributed Energy Resources that are formulated in Functional Mockup Units.A simulation case study was conducted with FlexLab,a test facility on Lawrence Berkeley National Laboratory campus.The case study includes normal operations,Distributed Energy Resource integration,and power outage scenarios,to illustrate the Digital Twin’s ability to provide critical insights into energy performance and thermal resilience.The results demonstrated the platform’s potential as a decision-support tool for optimizing building energy performance and enhancing resilience against extreme weather events.Future work will focus on deploying the Digital Twin platform to a real building for field validation,extending its capabilities to cover more scenarios such as bidirectional Electric Vehicle interactions,and enhancing user engagement.
基金supported by the key international collaborative project of Natural Science Foundation of China(No.41520104002)
文摘The initiation mechanism of debris flow is regarded as the key step in understanding the debrisflow processes of occurrence, development and damage. Moreover, migration, accumulation and blocking effects of fine particles in soil will lead to soil failure and then develop into debris flow. Based on this hypothesis and considering the three factors of slope gradient, rainfall duration and rainfall intensity, 16 flume experiments were designed using the method of orthogonal design and completed in a laboratory. Particle composition changes in slope toe, volumetric water content, fine particle movement characteristics and soil failure mechanism were analyzed and understood as follows: the soil has complex, random and unstable structures, which causes remarkable pore characteristics of poor connectivity, non-uniformity and easy variation. The major factors that influence fine particle migration are rainfall intensity and slope. Rainfall intensity dominates particle movement, whereby high intensity rainfall induces a large number of mass movement and sharp fluctuation, causing more fine particles to accumulate at the steep slope toe. The slope toe plays an important role in water collection and fine particleaccumulation. Both fine particle migration and coarse particle movement appears similar fluctuation. Fine particle migration is interrupted in unconnected pores, causing pore blockage and fine particle accumulation, which then leads to the formation of a weak layer and further soil failure or collapses. Fine particle movement also causes debris flow formation in two ways: movement on the soil surface and migration inside the soil. The results verify the hypothesis that the function of fine particle migration in soil failure process is conducive for further understanding the formation mechanism of soil failure and debris flow initiation.
文摘The success of a tunnel-boring machine （TBM） in a given project depends on the functionality of all components of the system, from the cutters to the backup system, and on the entire rolling stock. However, no part of the machine plays a more crucial role in the efficient operation of the machine than its cutterhead. The design of the cutterhead impacts the efficiency of cutting, the balance of the head, the life of the cutters, the maintenance of the main bearing/gearbox, and the effectiveness of the mucking along with its effects on the wear of the face and gage cutters/muck buckets. Overall, cutterhead design heavily impacts the rate of penetration （ROP）, rate of machine utilization （U）, and daffy advance rate （AR）. Although there has been some discussion in commonly available publications regarding disk cutters, cutting forces, and some design features of the head, there is limited literature on this subject because the design of cutter- heads is mainly handled by machine manufacturers. Most of the design process involves proprietary algorithms by the manufacturers, and despite recent attention on the subject, the design of rock TBMs has been somewhat of a mystery to most end-users. This paper is an attempt to demystify the basic concepts in design. Although it may not be sufficient for a full-fledged design by the readers, this paper allows engineers and contractors to understand the thought process in the design steps, what to Look for in a proper design, and the implications of the head design on machine operation and life cycle.
基金Beijing Everest Green Building Technology Ltd. for the funding
文摘This study proposes an innovative precast shear wall system, called an EVE precast hollow shear wall structure (EVE-PHSW). Precast panels in EVE-PHSW are simultaneously precast with vertical and horizontal holes. Noncontact lap splices of rebars are used in vertical joints connecting adjacent precast panels for automated prefabrication and easy in situ erection. The seismic behavior of EVE walls was examined through a series of tests on six wall specimens with aspect ratios of 1.0~1.3. Test results showed that EVE wall specimens with inside cast-in situ concrete achieved the desired “strong bending and weak shear” and failed in shear mode. Common main diagonal cracks and brittle shear failure in squat cast-in situ walls were prevented. Inside cast-in situ concrete could signifi cantly improve the shear strength and stiff ness of EVE walls. The details of boundary elements (cast-in situ or prefabricated) and vertical joints (contiguous or spaced) had little eff ect on the global behavior of EVE walls. Noncontact lap splices in vertical joints could enable EVE walls to exhibit stable load-carrying capacity through extensive deformations. Evaluation on design codes revealed that both JGJ 3-2010 and ACI 318-14 provide conservative estimation of shear strength of EVE walls, and EVE walls achieved shear strength reserves comparative to cast-in situ walls. The recommended eff ective stiff ness for cast-in situ walls in ASCE 41-17 appeared to be appropriate for EVE walls.
