Seismic design of reinforced concrete frames for minimum embodied CO2 emissions

Optimum structural design of reinforced concrete (RC) frames has been the focus of extensive research. Typically, previous studies set economic cost as the main design objective despite the fact that RC structures are major contributors of CO2 emissions. The limited number of studies examining optimum design of RC frames for minimum CO2 emissions do not address seismic design considerations. However, in many countries around the world, including most of the top-10 countries in CO2 emissions from cement production, RC structures must be designed against earthquake threat. To bridge this gap, the present study develops optimum seismic designs of RC frames for minimum cradle to gate embodied CO2 emissions and compares them with optimum designs based on construction cost. The aim is to identify efficient design practices that minimize the environmental impact of earthquake-resistant RC frames and examine the trade-offs between their cost and CO2 footprint. To serve this goal, an RC frame is optimally designed according to all ductility classes of Eurocode 8 and for various design peak ground accelerations (PGAs), concrete classes and materials embodied CO2 footprint scenarios. It is found that the minimum feasible CO2 emissions of RC frames strongly depend on the adopted ductility class in regions of high seismicity, where low ductility seismic design can generate up to 60% more CO2 emissions than designs for medium and high ductility. The differences reduce, however, as the level of seismicity decreases. Furthermore, CO2 emissions increase significantly with the design PGA. On the other hand, they are less sensitive to the applied concrete class. It is also concluded that, for medium to high values of the ratio of the unit environmental impact of reinforcing steel to the respective impact of concrete, the minimum CO2 seismic designs are very closely related to the minimum cost designs. However, for low values of the same ratio, the minimum cost design solutions can generate up to 13% more emissions than the minimum CO2 designs

A roadmap for China to peak carbon dioxide emissions and achieve a 20% share of non-fossil fuels in primary energy by 2030

As part of its Paris Agreement commitment, China pledged to peak carbon dioxide (CO2) emissions around 2030, striving to peak earlier, and to increase the non-fossil share of primary energy to 20% by 2030. Yet by the end of 2017, China emitted 28% of the world's energy-related CO2 emissions, 76% of which were from coal use. How China can reinvent its energy economy cost-effectively while still achieving its commitments was the focus of a three-year joint research project completed in September 2016. Overall, this analysis found that if China follows a pathway in which it aggressively adopts all cost-effective energy efficiency and CO2 emission reduction technologies while also aggressively moving away from fossil fuels to renewable and other non-fossil resources, it is possible to not only meet its Paris Agreement Nationally Determined Contribution (NDC) commitments, but also to reduce its 2050 CO2 emissions to a level that is 42% below the country's 2010 CO2 emissions. While numerous barriers exist that will need to be addressed through effective policies and programs in order to realize these potential energy use and emissions reductions, there are also significant local environmental (e.g., air quality), national and global environmental (e.g., mitigation of climate change), human health, and other unquantified benefits that will be realized if this pathway is pursued in China

Capturing industrial CO2 emissions in Spain: Infrastructures, costs and break-even prices

This paper examines the conditions for the deployment of large-scale pipeline and storage infrastructure needed for the capture of CO2 in Spain by 2040. It details a modeling framework that allows us to determine the optimal infrastructure needed to connect a geographically disaggregated set of emitting and storage clusters, along with the threshold CO2 values necessary to ensure that the considered emitters will make the necessary investment decisions. This framework is used to assess the relevance of various policy scenarios, including (i) the perimeter of the targeted emitters for a CCS uptake, and (ii) the relevance of constructing several regional networks instead of a single grid to account for the spatial characteristics of the Spanish peninsula. We find that three networks naturally emerge in the north, center and south of Spain. Moreover, the necessary CO2 break-even price critically depends on the presence of power stations in the capture perimeter. Policy implications of these findings concern the elaboration of relevant, pragmatic recommendations to envisage CCS deployment locally, focusing on emitters with lower substitution options toward low-carbon alternatives

Extrusion-based additive manufacturing of concrete products. Revolutionizing and remodeling the construction industry

Additive manufacturing is one of the main topics of the fourth industrial revolution; defined as Industry 4.0. This technology offers several advantages related to the construction and architectural sectors; such as economic; environmental; social; and engineering benefits. The usage of concrete in additive technologies allows the development of innovative applications and complexity design in the world of construction such as buildings; housing modules; bridges; and urban and domestic furniture elements. The aim of this review was to show in detail a general panoramic of extrusion-based additive processes in the construction sector; the main advantages of using additive manufacturing with the respect to traditional manufacturing; the fundamental requirements of 3D printable material (fresh and hardened properties), and state-of-the-art aesthetic and architectural projects with functional properties

Optimum design of composite prestressed concrete girder railway bridges

This paper deals with the formulation of design optimisation of pretsressed concrete bridges. The bridge is of a slab-on-girder type, hence modeled as an equivalent orthotropic plate. The whole bridge system is considered as a simply supported right angle plate. Following linear elastic behaviour, the governing fourth order differential equation of the plate for patch load is solved in order to find out load distribution on the girders forming the bridge as well as the deflections and internal forces at critical sections of the whole bridge. The optimisation problem is formulated for various cross sectional geometries including rectangular, symmetrical I, unsymmetrical I, box, T and inverted T sections. The design variables are the main cross sectional dimensions, prestressing force and tendon eccentricity. The objective function comprises the cost of concrete material, formwork and prestressing steel tendons. The constraint functions are set to satisfy design requirements as per British Standards for bridges (BS 5400). Nonlinear optimisation method based on sequential unconstrained minimisation technique (SUMT) is employed to achieve optimum bridge configuration for specific design parameters of span length, concrete compressive strength and railway loading patterns. A purpose built computer program is set up to carry out the solution of the design optimisation problem efficiently in terms of time and effort. A typical example of unsymmetrical I-section having a small bottom flange as compared to the top flange width with composite deck effect is presented. The results show that the total cost increases as the span increases due to the increase of the initial prestressing force. Furthermore, the total cost decreases as the concrete compressive strength increases in spite of the increasing of the prestressing force. This is due to decrease of the overall depth, top and bottom flange widths, hence leading to a smaller girder size. Such finding will encourage engineers to adopt high strength concrete for bridges as it will help reducing not only the initial cost but also the life cycle cost of the bridge over its entire life

Menentusahkan faktor tekanan kerja guru sekolah menengah Gred A Daerah Batu Pahat

Kajian ini dilaksanakan untuk mengenal pasti faktor-faktor yang mempengaruhi tekanan kerja guru yang mengajar di kawasan bandar dan sekolah tersebut dikategorikan sebagai sekolah gred A. Kajian ini dijalankan di tiga buah sekolah yang terletak di bandar dalam Daerah Batu Pahat iaitu Sekolah Menengah Datin Onn, Sekolah Menengah Dato’ Bentara Luar dan Sekolah Menengah Kebangsaan Munshi Sulaiman. Kajian ini mengesahkan sama ada konstruk yang dihasilkan merupakan faktor tekanan kerja guru sekolah berkenaan. Selain itu, kajian ini juga mengenal pasti apakah faktor paling dominan yang menyebabkan tekanan kerja guru dan , seterusnya melihat impak dimensi terhadap responden berdasarkan faktor yang dikaji. Dalam menentukan konstruk, Classic Theory Test (CTT) dengan menggunakan kaedah kualitatif melalui analisis dokumen dengan membuat kupasan kajian literatur. Analisis faktor model Rasch dengan menggunakan Analisis Komponen Utama pada residual digunakan dalam kajian ini bagi memastikan dan mengesahkan konstruk atau faktor. Berdasarkan dapatan analisis dokumen, konstruk bagi faktor tekanan kerja yang dikenal pasti adalah (i) Beban kerja (ii) Kekangan Masa dan Sumber (iii) Disiplin pelajar (iv) Perhubungan Interpersonel dan (v) Keperluan Penghargaan. Melalui analisis faktor yang dijalankan pula, mendapati kesemua faktor yang dihasilkan telah menepati kriteria yang ditetapkan oleh model Rasch iaitu peratusan varians mentah dijelaskan oleh pengukuran (raw variance explained by measure) melebihi daripada 40%, peratus varians tidak dijelaskan dalam kontras pertama (first contrast unexplained variance) adalah kurang daripada 10%, dan nilai eigen kontras pertama (first contrast eigenvalue) juga kurang daripada 3.0. Hal ini membuktikan dan mengesahkan bahawa keseluruhan konstruk adalah bersifat unidimensi dan mampu mengukur apa yang hendak diukur. Faktor yang paling dominan adalah faktor disiplin pelajar dan terdapat perbezaan persepsi responden dari aspek jantina, umur dan tempoh bekerja terhadap konstruk atau faktor yang dikaji

AI and OR in management of operations: history and trends

The last decade has seen a considerable growth in the use of Artificial Intelligence (AI) for operations management with the aim of finding solutions to problems that are increasing in complexity and scale. This paper begins by setting the context for the survey through a historical perspective of OR and AI. An extensive survey of applications of AI techniques for operations management, covering a total of over 1200 papers published from 1995 to 2004 is then presented. The survey utilizes Elsevier's ScienceDirect database as a source. Hence, the survey may not cover all the relevant journals but includes a sufficiently wide range of publications to make it representative of the research in the field. The papers are categorized into four areas of operations management: (a) design, (b) scheduling, (c) process planning and control and (d) quality, maintenance and fault diagnosis. Each of the four areas is categorized in terms of the AI techniques used: genetic algorithms, case-based reasoning, knowledge-based systems, fuzzy logic and hybrid techniques. The trends over the last decade are identified, discussed with respect to expected trends and directions for future work suggested