Search results for: collapse

Authors: A. Al-Rifaie, Z. W. Guan, S. W. Jones

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Beam to column connection can be considered as the most important structural part that affects the response of buildings to progressive collapse. However, many studies were conducted to investigate the beam to column connection under accidental loads such as fire, blast and impact load to investigate the connection response. The study is a part of a PhD plan to investigate different types of connections under lateral impact load. The conventional test setups, such as cruciform setup, were designed to apply shear forces and bending moment on the connection, whilst, in the lateral impact case, the connection is subjected to combined tension and moment. Hence, a review is presented to introduce the previous test setup that is used to investigate the connection behaviour. Then, the design and fabrication of the novel test setup is presented. Finally, some trial test results to investigate the efficiency of the proposed setup are discussed. The final results indicate that the setup was efficient in terms of the simplicity and strength.

Keywords: connections, impact load, drop hammer, testing methods

Procedia PDF Downloads 261

Authors: Ying Zhang

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In ASME Boiler and Pressure Vessel Code, the plastic load is defined by applying the twice elastic slope (TES) criterion of plastic collapse to a characteristic load-deformation curve for the vessel. Several other plastic criterion such as tangent intersection (TI) criterion, plastic work (PW) criterion have been proposed in the literature, but all exhibit a practical limitation: difficult to define the load parameter for vessels subject to several combined loads. An alternative criterion: plastic work-tangent (PWT) criterion for evaluating plastic load in pressure vessel design by analysis is presented in this paper. According to the plastic work-load curve, when the tangent variation is less than a given value in the plastic phase, the corresponding load is the plastic load. Application of the proposed criterion is illustrated by considering the elastic-plastic response of the lower head of reactor pressure vessel (RPV) and nozzle intersection of (RPV). It is proposed that this is because the PWT criterion more fully represents the constraining effect of material strain hardening on the spread of plastic deformation and more efficiently ton evaluating the plastic load.

Keywords: plastic load, plastic work, strain hardening, plastic work-tangent criterion

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Authors: N. Chérif, T. Allaoui, M. Benasla, H. Chaib

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Industrialization and population growth are the prime factors for which the consumption of electricity is steadily increasing. Thus, to have a balance between production and consumption, it is necessary at first to increase the number of power plants, lines and transformers, which implies an increase in cost and environmental degradation. As a result, it is now important to have mesh networks and working close to the limits of stability in order to meet these new requirements. The transient stability studies involve large disturbances such as short circuits, loss of work or production group. The consequence of these defects can be very serious, and can even lead to the complete collapse of the network. This work focuses on the regulation means that networks can help to keep their stability when submitted to strong disturbances. The magnetic energy storage-based superconductor (SMES) comprises a superconducting coil short-circuited on it self. When such a system is connected to a power grid is able to inject or absorb the active and reactive power. This system can be used to improve the stability of power systems.

Keywords: short-circuit, power oscillations, multiband PSS, power system, SMES, transient stability

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Authors: Ebru Aktepe Erkoç, Atilla Uluğ

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In this research which has been prepared to show the relationship between Gökova Bay’s morphotectonic structure and seismicity, it is clear that there are many active faults in the region. The existence of a thick sedimentary accumulation since Late Quaternary times is obvious as a result of the geophysical workings in the region and the interpretation of seismic data which has been planning to be taken from the Bay. In the regions which have been tectonically active according to the interpretation of the taken data, the existence of the successive earthquakes in the last few years is remarkable. By analyzing large earthquakes affecting the areas remaining inside the sediments in West Anatolian Collapse System, this paper aims to reveal the fault systems constituting earthquakes with the information obtained from this study and to determine seismicity of the present residential areas right next to them. It is also aimed to anticipate the measures to be taken against possible earthquake hazards, to identify these areas posing a risk in terms of residential and urban planning and to determine at least partly the characteristics of the basin.

Keywords: Gökova Bay, sedimentation, seismic, West Anatolian

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Authors: Junkyeong Kim, Seunghee Park, Ju-Won Kim, Myung-Sug Cho

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Recently, demands for the construction of Nuclear Power Plants (NPP) using high strength concrete (HSC) has been increased. However, HSC might be susceptible to brittle fracture if the curing process is inadequate. To prevent unexpected collapse during and after the construction of HSC structures, it is essential to confirm the strength development of HSC during the curing process. However, several traditional strength-measuring methods are not effective and practical. In this study, a novel method to estimate the strength development of HSC based on electromechanical impedance (EMI) measurements using an embedded piezoelectric sensor is proposed. The EMI of NPP concrete specimen was tracked to monitor the strength development. In addition, cross-correlation coefficient was applied in sequence to examine the trend of the impedance variations more quantitatively. The results confirmed that the proposed technique can be applied successfully monitoring of the strength development during the curing process of HSC structures.

Keywords: concrete curing, embedded piezoelectric sensor, high strength concrete, nuclear power plant, self-sensing impedance

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Authors: M. R. Aziz, W. Kuntjoro, N. V. David

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This paper presents the ballistic terminal study of the non-filled and water-filled aluminum tank. The objective was to determine the failure stages for both cases. The tank was impacted by fragment simulating projectile (FSP) with 260 m/s for non-filled and 972 m/s for water-filled. The aluminum tank was 3 mm thick, 150 mm wide and 750 mm long. The ends of the tank were closed with two polymethyl methacrylate (PMMA) windows. The test was conducted at the Science and Technology Research Institute for Defense (STRIDE) Batu Arang, Selangor, Malaysia. The results showed four main stages for non-filled tank, which were first contact between FSP and the tank, partially perforated, fully perforated with FSP and plug still intact and lastly fully perforated with FSP and plug separated. Meanwhile, for the water-filled tank, there were seven main stages, which were first contact between FSP and the tank, partial perforation, full perforation, drag phase, cavity phase, bounce wave event and the collapse of the cavity.

Keywords: fragment simulating projectile, high speed camera, tensile test, terminal ballistic

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Authors: Kahil Amar, Meziani Faroudja, Khelil Nacim

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The principal objective of this study is the evaluation of the seismic performance of reinforced concrete frame structures, taking into account of the behavior laws, reflecting the real behavior of materials, using CASTEM2000 software. A finite element model used is based in modified Takeda model with Timoshenko elements for columns and beams. This model is validated on a Vecchio experimental reinforced concrete (RC) frame model. Then, a study focused on the behavior of a RC frame with three-level and three-story in order to visualize the positioning the plastic hinge (plastic rotation), determined from the curvature distribution along the elements. The results obtained show that the beams of the 1^st and 2^nd level developed a very large plastic rotations, or these rotations exceed the values corresponding to CP (Collapse prevention with cp q_CP = 0.02 rad), against those developed at the 3^rd level, are between IO and LS (Immediate occupancy and life Safety with q_IO = 0.005 rad and rad q_LS = 0.01 respectively), so the beams of first and second levels submit a very significant damage.

Keywords: seismic performance, performance level, pushover analysis, plastic rotation, plastic hinge

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Authors: Xiyue Wen

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With the rapid development of the city, old communities in the city are facing a series of problems. On one hand, aging facilities, obsolete spatial patterns, aging populations arouse in the aging of the community. On the other hand, public space is reduced and is taking up by cars parking or facilities setting, which lead to the collapse of traditional life in the old communities. That is to say, modern amenities haven’t helped to reform the old community, but have leading to tedious and inefficient, when it is not accommodated in the traditional space. Exploring a way is imminent to the east the contradiction between modern living facilities and spatial patterns of traditional. We select a typical site-GeDa Community in Xi’an, built in 70-80s，and carry out a concept calling 'Raising Landscape', which enables a convenient and efficient space for parking, as well as a high-quality yard for activities. In addition, the design implements low cost, simple construction, resident participation, so that it can be spread in the same texture of urban space.

Keywords: old communities, renewal strategy, raising landscape, public space, parking space

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Authors: Shivan Sirdy

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In this study, we discuss the properties of absolute void space or the universe at zero seconds, and how these properties play a vital role in creating a mechanism in which the very first particle gets created simultaneously everywhere. We find the limit in which when the absolute void volume reaches will lead to the collapse that leads to the creation of the first particle. This discussion is made following the elementary dimensions theory study that was peer-reviewed at the end of 2020; everything in the universe is made from four elementary dimensions, these dimensions are the three spatial dimensions (X, Y, and Z) and the Void resistance as the factor of change among the four. Time itself was not considered as the fourth dimension. Rather time corresponds to a factor of change, and during the research, it was found out that the Void resistance is the factor of change in the absolute Void space, where time is a hypothetical concept that represents changes during certain events compared to a constant change rate event. Therefore, time does exist, but as a factor of change as the Void resistance: Time= factor of change= Void resistance.

Keywords: elementary dimensions, absolute void, time alternative, early universe, universe at zero second, Void resistant, Hydrogen atom, Hadron field, Lepton field

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Authors: Christopher Oyediran, Nicola Ubayasiri, Christopher Gough

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Splenic artery aneurysms are often clinically occult, occasionally identified incidentally with imaging. The pathogenesis of aneurysms is complex, but certain factors are thought to contribute to their development. Given the potential fatal complications of rupture, a high index of suspicion is required to make an early diagnosis. We present a case of a 36-year-old female with a history of endometriosis and multiple sclerosis who presented to the Emergency Department with sudden onset epigastric pain and collapse. On arrival, she was pale and clammy with profound tachycardia and hypotension. An ultrasound done in the resuscitation department revealed abdominal free fluid. She was resuscitated with blood and transferred for emergent laparotomy. Laparotomy revealed massive haemoperitoneum from the spleen. She underwent emergency splenectomy and inspection of the spleen revealed a splenic artery aneurysm. She received our massive transfusion protocol followed by a short stay on ITU, making a good post-operative recovery and was discharged home a week later.

Keywords: aneurysm, human chorionic gonadotrophin (hCG), resuscitation, laparotomy

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Authors: Oleg Kabantsev, Karomatullo Umarov

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The engineering analysis of earthquake consequences demonstrates a significantly different level of damage to load-bearing systems of different types. Buildings with reinforced concrete columns and separate shear-walls receive the highest level of damage. Traditional methods for predicting damage under earthquake excitations do not provide an answer to the question about the reasons for the increased vulnerability of reinforced concrete frames with shear-walls bearing systems. Thus, the study of the problem of formation and accumulation of damages in the structures reinforced concrete frame with shear-walls requires the use of new methods of assessment of the stress-strain state, as well as new approaches to the calculation of the distribution of forces and stresses in the load-bearing system based on account of various mechanisms of elastic-plastic deformation of reinforced concrete columns and walls. The results of research into the processes of non-linear deformation of structures with a transition to destruction (collapse) will allow to substantiate the characteristics of limit states of various structures forming an earthquake-resistant load-bearing system. The research of elastic-plastic deformation processes of reinforced concrete structures of frames with shear-walls is carried out on the basis of experimentally established parameters of limit deformations of concrete and reinforcement under dynamic excitations. Limit values of deformations are defined for conditions under which local damages of the maximum permissible level are formed in constructions. The research is performed by numerical methods using ETABS software. The research results indicate that under earthquake excitations, plastic deformations of various levels are formed in various groups of elements of the frame with the shear-wall load-bearing system. During the main period of seismic effects in the shear-wall elements of the load-bearing system, there are insignificant volumes of plastic deformations, which are significantly lower than the permissible level. At the same time, plastic deformations are formed in the columns and do not exceed the permissible value. At the final stage of seismic excitations in shear-walls, the level of plastic deformations reaches values corresponding to the plasticity coefficient of concrete , which is less than the maximum permissible value. Such volume of plastic deformations leads to an increase in general deformations of the bearing system. With the specified parameters of the deformation of the shear-walls in concrete columns, plastic deformations exceeding the limiting values develop, which leads to the collapse of such columns. Based on the results presented in this study, it can be concluded that the application seismic-force-reduction factor, common for the all load-bearing system, does not correspond to the real conditions of formation and accumulation of damages in elements of the load-bearing system. Using a single coefficient of seismic-force-reduction factor leads to errors in predicting the seismic resistance of reinforced concrete load-bearing systems. In order to provide the required level of seismic resistance buildings with reinforced concrete columns and separate shear-walls, it is necessary to use values of the coefficient of seismic-force-reduction factor differentiated by types of structural groups.1

Keywords: reinforced concrete structures, earthquake excitation, plasticity coefficients, seismic-force-reduction factor, nonlinear dynamic analysis

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Authors: Luis F. Caballero-castro, Dirsa Feliciano, Daniela Novoa, Orlando Arroyo, Jesús D. Villalba-morales

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Colombia faces a critical challenge in seismic resilience due to the prevalence of informal housing, which constitutes approximately 70% of residential structures. More than 10 million Colombians (20% of the population), live in homes susceptible to collapse in the event of an earthquake. This, combined with the fact that 83% of the population is in intermediate and high seismic hazard areas, has brought serious consequences to the country. These consequences became evident during the 1999 Armenia earthquake, which affected nearly 100,000 properties and represented economic losses equivalent to 1.88% of that year's Gross Domestic Product (GDP). Despite previous efforts to reinforce informal housing through methods like externally reinforced masonry walls, alternatives related to seismic protection systems (SPDs), such as Buckling-Restrained Braces (BRB), have not yet been explored in the country. BRBs are reinforcement elements capable of withstanding both compression and tension, making them effective in enhancing the lateral stiffness of structures. In this study, the use of low-cost and easily installable BRBs for the retrofit of informal housing in Colombia was evaluated, considering the economic limitations of the communities. For this purpose, a case study was selected involving an informally constructed dwelling in the country, from which field information on its structural characteristics and construction materials was collected. Based on the gathered information, nonlinear models with and without BRBs were created, and their seismic performance was analyzed and compared through incremental static (pushover) and nonlinear dynamic analyses. In the first analysis, the capacity curve was identified, showcasing the sequence of failure events occurring from initial yielding to structural collapse. In the second case, the model underwent nonlinear dynamic analyses using a set of seismic records consistent with the country's seismic hazard. Based on the results, fragility curves were calculated to evaluate the probability of failure of the informal housings before and after the intervention with BRBs, providing essential information about their effectiveness in reducing seismic vulnerability. The results indicate that low-cost BRBs can significantly increase the capacity of informal housing to withstand earthquakes. The dynamic analysis revealed that retrofit structures experienced lower displacements and deformations, enhancing the safety of residents and the seismic performance of informally constructed houses. In other words, the use of low-cost BRBs in the retrofit of informal housing in Colombia is a promising strategy for improving structural safety in seismic-prone areas. This study emphasizes the importance of seeking affordable and practical solutions to address seismic risk in vulnerable communities in earthquake-prone regions in Colombia and serves as a model for addressing similar challenges of informal housing worldwide.

Keywords: buckling-restrained braces, fragility curves, informal housing, incremental dynamic analysis, seismic retrofit

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Authors: Mergleda Hodo

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All national governments aim to achieve economic equilibrium to build sustainable welfare, political stability, and economic equilibrium. There are various instruments to stimulate economic development and growth and achieve macroeconomic objectives. After the collapse of the political and economic system in the 1990s, some countries faced the complex challenge of economic development. This study aims to determine, based on empirical research, whether and to what extent tax revenue has an impact on the economic development of Albania. Furthermore, it gives an overview of the ways in which high tax burdens on the western Balkan countries have negatively affected foreign investment and reduced economic growth. This analysis is important for these selected countries, as the financial system has changed significantly over the years and has been affected significantly by a period of economic transition. The analysis is performed based on secondary data possessed by the World Bank and the central bank of each participating country between 2005 and 2018. The research findings indicate that tax policy affects, to a significant extent, the economic development of Albania. An efficient tax system is when individuals are willing to pay tax liability which will help in improving the economic well-being of a country.

Keywords: tax, development, economic growth, tax revenue

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Authors: Tory Erickson

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The "Bidirectional Spacetime with Spatial Covariance and Wave-Particle Duality in Spacetime Flow" (BST-SCWPDF) Model introduces a framework aimed at unifying general relativity (GR) and quantum mechanics (QM). By proposing a concept of bidirectional spacetime, this model suggests that time can flow in more than one direction, thus offering a perspective on temporal dynamics. Integrated with spatial covariance and wave-particle duality in spacetime flow, the BST-SCWPDF Model resolves long-standing discrepancies between GR and QM. This unified theory has profound implications for quantum gravity, potentially offering insights into quantum entanglement, the collapse of the wave function, and the fabric of spacetime itself. The Bidirectional Spacetime with Spatial Covariance and Wave-Particle Duality in Spacetime Flow" (BST-SCWPDF) Model offers researchers a framework for a better understanding of theoretical physics.

Keywords: astrophysics, quantum mechanics, general relativity, unification theory, theoretical physics

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Authors: Ana Luísa Mouro

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When the financial crisis exploded in 2008 in the United States, unleashed by the collapse of Lehman Brothers, and contaminated the economies of the European periphery, Germany appeared as the anchor of the stability of all European institutions and countries in difficulty. The solutions provided by the German government have triggered a deep political debate about the key position Germany has conquered at the heart of Europe - a new “German question” has been created. Some say Germany has achieved by peaceful means what was not able to get through military conquest - the domination of Europe – and many fear Germany’s economic power. This debate about the new role of Germany in Europe has received special attention in the European media and Portugal has not been the exception. The present study has been based on the survey, selection and critical analysis of news reporting, opinion articles, interviews and editorials, published in the weekly Expresso and in the daily Público, between 2008 and 2015 (year of the 25th anniversary of Germany’s unification). The findings of this study will show the paradox of German power and its relevance for Europe’s future.

Keywords: Euro crises, German Europe, intercultural hermeneutics, Portuguese quality press

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Authors: Elmamy Ahmedsalem

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The world has witnessed the collapse of many corporate giants as a result of unethical behavior in recent decades. This has induced a series of questions by the global community on why such occurrences could happen, even with corporate governance in place. This paper attempts to propose a philosophical approach from an Islamic perspective to be consolidated with current corporate governance in order to confront contemporary dilemmas. In this paper, ethical theories are presented as a discussion followed by their applications to modern cases of financial collapses. Virtue ethics by Aristotle, justice and fairness by John Rawls, deontology by Immanuel Kant, and utilitarianism by John Stuart Mill, are the four theories which can then be contrasted with the paradigm of Muslim scholars. Despite the differences between the fundamental principles of Islamic and Western worldviews, their ethical theories are aimed at making right decisions and solving ethical dilemmas based on what is good for society. Therefore, Islamic principles should be synthesized with Western philosophy to form a more coherent framework. The integration of Islamic and western ethical theories into business is important for sound corporate governance.

Keywords: business ethics, Islamic philosophy, western philosophy, Western and Islamic worldview of ethics

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Authors: André Furtado, Hugo Rodrigues, António Arêde, Humberto Varum

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Besides characterized as non-structural elements, infill masonry (IM) walls have an important contribute in the structural response of reinforced concrete structures as proved by the damages observed recent earthquakes. In particular, the out-of-plane (OOP) collapse has been one of the most observed failure mechanism. The aim of this research is to contribute to the increase of understanding regarding the OOP behaviour of full-scale infill panels considering different variables such as panel support width and axial load on the top of columns. For this, it was carried out in the Laboratory of Earthquake and Structural Engineering (LESE) an experimental campaign of five full-scale IM walls subjected to OOP distributed cyclic loadings. Specimens with different variables such as previous in-plane damage, support conditions, axial load on the top of the columns were studied. The results will be presented and discussed along the manuscript in terms of force-displacement hysteretic curves, cracking pattern, initial stiffness, stiffness degradation and accumulative energy dissipation.

Keywords: infill masonry walls, experimental testing, out-of-plane, full-scale

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Authors: Muhammad Tariq A. Chaudhary

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The tremendous loss of life that resulted in the aftermath of recent earthquakes in developing countries is mostly due to the collapse of non-engineered and semi-engineered building structures. Such structures are used as houses, schools, primary healthcare centres and government offices. These building are classified structurally into two categories viz. non-engineered and semi-engineered. Non-engineered structures include: adobe, Unreinforced Masonry (URM) and wood buildings. Semi-engineered buildings are mostly low-rise (up to 3 story) light concrete frame structures or masonry bearing walls with reinforced concrete slab. This paper presents an overview of the typical damage observed in non-engineered structures and their most likely causes in the past earthquakes with specific emphasis on the performance of such structures in the 2005 Kashmir earthquake. It is demonstrated that seismic performance of these structures can be improved from life-safety viewpoint by adopting simple low-cost modifications to the existing construction practices. Incorporation of some of these practices in the reconstruction efforts after the 2005 Kashmir earthquake are examined in the last section for mitigating seismic risk hazard.

Keywords: Kashmir earthquake, non-engineered buildings, seismic hazard, structural details, structural strengthening

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Authors: Alexandra Steed

Abstract:

Alexandra Steed URBAN was commissioned to undertake the South Essex Green and Blue Infrastructure Study (SEGBI) on behalf of the Association of South Essex Local Authorities (ASELA): a partnership of seven neighboring councils within the Thames Estuary. Located on London’s doorstep, the 70,000-hectare region is under extraordinary pressure for regeneration, further development, and economic expansion, yet faces extreme challenges: sea-level rise and inadequate flood defenses, stormwater flooding and threatened infrastructure, loss of internationally important habitats, significant existing community deprivation, and lack of connectivity and access to green space. The brief was to embrace these challenges in the creation of a document that would form a key part of ASELA’s Joint Strategic Framework and feed into local plans and master plans. Thus, helping to tackle climate change, ecological collapse, and social inequity at a regional scale whilst creating a relationship and awareness between urban communities and the surrounding landscapes and nature. The SEGBI project applied a ‘land-based’ methodology, combined with a co-design approach involving numerous stakeholders, to explore how living infrastructure can address these significant issues, reshape future planning and development, and create thriving places for the whole community of life. It comprised three key stages, including Baseline Review; Green and Blue Infrastructure Assessment; and the final Green and Blue Infrastructure Report. The resulting proposals frame an ambitious vision for the delivery of a new regional South Essex Estuary (SEE) Park – 24,000 hectares of protected and connected landscapes. This unified parkland system will drive effective place-shaping and “leveling up” for the most deprived communities while providing large-scale nature recovery and biodiversity net gain. Comprehensive analysis and policy recommendations ensure best practices will be embedded within planning documents and decisions guiding future development. Furthermore, a Natural Capital Account was undertaken as part of the strategy showing the tremendous economic value of the natural assets. This strategy sets a pioneering precedent that demonstrates how the prioritisation of living infrastructure has the capacity to address climate change and ecological collapse, while also supporting sustainable housing, healthier communities, and resilient infrastructures. It was only achievable through a collaborative and cross-boundary approach to strategic planning and growth, with a shared vision of place, and a strong commitment to delivery. With joined-up thinking and a joined-up region, a more impactful plan for South Essex was developed that will lead to numerous environmental, social, and economic benefits across the region, and enhancing the landscape and natural environs on the periphery of one of the largest cities in the world.

Keywords: climate change, green and blue infrastructure, landscape architecture, master planning, regional planning, social equity

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Authors: M. Khaled Abduesslam, Mohammed Ali, Basher H. Alsdai, Muhammad Nizam Inayati

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This paper presents the voltage problem location classification using performance of Least Squares Support Vector Machine (LS-SVM) and Learning Vector Quantization (LVQ) in electrical power system for proper voltage problem location implemented by IEEE 39 bus New-England. The data was collected from the time domain simulation by using Power System Analysis Toolbox (PSAT). Outputs from simulation data such as voltage, phase angle, real power and reactive power were taken as input to estimate voltage stability at particular buses based on Power Transfer Stability Index (PTSI).The simulation data was carried out on the IEEE 39 bus test system by considering load bus increased on the system. To verify of the proposed LS-SVM its performance was compared to Learning Vector Quantization (LVQ). The results showed that LS-SVM is faster and better as compared to LVQ. The results also demonstrated that the LS-SVM was estimated by 0% misclassification whereas LVQ had 7.69% misclassification.

Keywords: IEEE 39 bus, least squares support vector machine, learning vector quantization, voltage collapse

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Authors: Mohammad Enayet Hossain, Nur Farhah Mahadi

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The global COVID-19 pandemic has contaminated millions of people at a startling rate. The COVID-19 pandemic came out of mediocre and has since spread all over the world, causing to record 5 million deaths worldwide in just a few months. The economic crisis has triggered a global contraction, leading to an economic collapse expected over 2020-2021. This study examines whether Islamic social finance can effectively mitigate the dangers of humanitarian catastrophes. The study provides a multirange method for maximizing the advantage of Islamic social financings tools such as zakat and waqf. The information, documents, and data for this study are gathered using a qualitative method. The study employed ongoing research, literature review, news stories, reports, and trusted online sources. Eventually, this may add to knowledge by examining the role of Islamic social finance in the current Covid-19 crisis. The findings have consequences for governments and policymakers who want to solve the COVID-19 problem with Islamic social finance ideas and solutions, thereby enhancing people's social well-being and the global economy's development.

Keywords: covid-19 pandemic, Islamic social finance, zakat, waqf

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Authors: Negar Sartipzadeh

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The historic buildings are generally the ones which have been built by materials like brick, mud, stone, and wood. Some phenomena such as severe earthquakes can be tremendously detrimental to the structures, imposing serious effects and losses on such structures. Hence, it matters a lot to ascertain safety and reliability of the structures under such circumstances. It has been asserted that the major reason for the collapse of Unreinforced Masonry (URM) in various earthquakes is the incapability of resisting the forces and vice versa because such URMs are meant for the gravity load and they fail to withstand the shear forces inside the plate and the bending forces outside the plate. For this reason, restrengthening such structures is a key factor in lowering the seismic loss in developing countries. Seismic reinforcement of the historic buildings with regard to their cultural value on one hand, and exhaustion and damage of many of the structural elements on the other hand, have brought in restricting factors which necessitate the seismic reinforcement methods meant for such buildings to be maximally safe, non-destructive, effective, and non-obvious. Henceforth, it is pinpointed that making use of diverse technologies such as active controlling, Energy dampers, and seismic separators besides the current popular methods would be justifiable for such buildings, notwithstanding their high imposed costs.

Keywords: masonry buildings, seismic reinforcement, Unreinforced Masonry (URM), earthquake

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Authors: Hadj Brahim Mounia, Belhamel Farid, Souici Messoud

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In big cities, construction on sloping land (landslide) is becoming increasingly prevalent due to the unavailability of flat lands. This has created a major challenge for structural engineers with regard to structure design, due to the difficulties encountered during the implementation of projects, both for the structure and the soil. This paper analyses the effect of the number of floors of a building, founded on isolated footing on the stability of the slope using the computer code finite element PLAXIS 2D v. 8.2. The isolated footings of a building in this case were anchored in soil so that the levels of successive isolated footing realize a maximum slope of base of three for two heights, which connects the edges of the nearest footings, according to the Algerian building code DTR-BC 2.331: Shallow foundations. The results show that the embedment of the foundation into the soil reduces the value of the safety factor due to the change of the stress state of the soil by these foundations. The number of floors a building has also influences the safety factor. It has been noticed from this case of study that there is no risk of collapse of slopes for an inclination between 5° and 8°. In the case of slope inclination greater than 10° it has been noticed that the urbanization is prohibited.

Keywords: isolated footings, multi-storeys building, PLAXIS 2D, slope

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Authors: Dagikhudo Dagiev

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This paper is a thorough contribution to the analysis of Russian, Soviet and post-Soviet scholarship on the study of Ismailism in Central Asia. It focuses on the lengthy development of Russian studies on Ismailism from the Russian colonial domination to the entire period of Soviet rule, down to the collapse of the Soviet Union and the last two decades of post-Soviet history. These studies, conducted along the lines of various disciplines in the span of more than one hundred years, have resulted in a large amount of scholarly contributions. This paper aims at probing the virtues and shortcoming of such scholarship. Particularly, our investigation of the specialised fields in the Russian-Soviet Studies has required laborious researches in Russian and Central Asian libraries, which have enabled us to provide a guide through this literature, assessing its ideological leanings and qualities, institutions and level of scholarship. Despite some shortcomings, due to Marxism and the authoritarian rule of the Communist Party over the socio-religious life of the people and religious communities, Soviet studies have produced many positive insights on Ismailis studies. These captured almost every aspects of the life of the Ismaili community from anthropology to archaeology, ethnography, history, philosophy, ritual practice and, most importantly, collection and preservation of Ismaiili manuscripts, which will be examined and assessed in this study.

Keywords: Central Asian Studies, Ismailism, Russian Studies, Soviet Studies

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Authors: Hamid Goharnejad, Milad Sadeghpoor Moalem, Mahmood Zakeri Niri, Leili Sadeghi Khalegh Abadi

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While there are many benefits to using reservoir dams, their break leads to destructive effects. From the viewpoint of International Committee of Large Dams (ICOLD), dam break means the collapse of whole or some parts of a dam; thereby the dam will be unable to hold water. Therefore, studying dam break phenomenon and prediction of its behavior and effects reduces losses and damages of the mentioned phenomenon. One of the most common types of reservoir dams is embankment dam. Overtopping in embankment dams occurs because of flood discharge system inability in release inflows to reservoir. One of the most important issues among managers and engineers to evaluate the performance of the reservoir dam rim when sliding into the storage, creating waves is large and long. In this study, the effects of floods which caused the overtopping of the dam have been investigated. It was assumed that spillway is unable to release the inflow. To determine outflow hydrograph resulting from dam break, numerical model using Flow-3D software and empirical equations was used. Results of numerical models and their comparison with empirical equations show that numerical model and empirical equations can be used to study the flood resulting from dam break.

Keywords: embankment dam break, empirical equations, Taleghan dam, Flow-3D numerical model

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Authors: Gia Lam Le, Dennis T. Bergado, Thi Ngoc Truc Nguyen

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This study focuses on behaviors of improved soft clay using prefabricated vertical drain (PVD) combined with vacuum and electro-osmotic preloading. Large-scale consolidations of reconstituted soft Bangkok clay were conducted for PVD improvement with vacuum (vacuum-PVD), and vacuum combined with heat (vacuum-thermo-PVD). The research revealed that vacuum-thermo-PVD gives high efficiency of the consolidation rate compared to the vacuum-PVD. In addition, the magnitude of settlement of the specimen improved by the vacuum-thermo-PVD is higher than the vacuum-PVD because the assistance of heat causes the collapse of the clay structure. Particularly, to reach 90% degree of consolidation, the thermal-vacuum-PVD reduced about 58% consolidation time compared to the vacuum-PVD. The increase in consolidation rate is resulted from the increase in horizontal coefficient of consolidation, Ch, the reduction of the smear effect expressed by the ratio of the horizontal hydraulic conductivity in the undisturbed zone, kh, and the horizontal hydraulic conductivity in the smeared zone, ks. Furthermore, the shear strength, Su, increased about 100% when compared using the vacuum-thermal-PVD to the vacuum PVD. In addition, numerical simulations gave reasonable results compared to the laboratory data.

Keywords: PVD improvement, vacuum preloading, prefabricated vertical drain, thermal PVD

Procedia PDF Downloads 427

Authors: Andrea Paltrinieri, Alberto Dreassi, Stefano Miani, Alex Sclip

Abstract:

The financial crises caused a collapse in prices of most asset classes, raising the attention on alternative investments such as Sukuk, a smaller, fast growing but often misunderstood market. We study diversification benefits of Sukuk, their correlation with other asset classes and the effects of their inclusion in investment portfolios of institutional and retail investors, through a comprehensive comparison of their risk/return profiles during and after the financial crisis. We find a beneficial performance adjusted for the specific volatility together with a lower correlation especially during the financial crisis. The distribution of Sukuk returns is positively skewed and leptokurtic, with a risk/return profile similarly to high yield bonds. Overall, our results suggest that Sukuk present diversification opportunities, a significant volatility-adjusted performance and lower correlations especially during the financial crisis. Our findings are relevant for a number of institutional investors. Long term investors, such as life insurers would benefit from Sukuk’s protective features during financial crisis yet keeping return and growth opportunities, whereas banks would gain due to their role of placers, advisors, market makers or underwriters.

Keywords: sukuk, zero beta asset, asset allocation, sukuk market

Procedia PDF Downloads 446

Authors: Solomon Huluka, Akrum Abdul-Latif, Rachid Baleh

Abstract:

Metal foams have been developed intensively as a new class of materials for the last two decades due to their unique structural and multifunctional properties. The aim of this experimental work was to characterize the effect of biaxial loading complexity (combined compression-torsion) on the plastic response of highly uniform architecture open-cell aluminum foams of spherical porous with a density of 80%. For foam manufacturing, the Kelvin cells model was used to generate the generally spherical shape with a cell diameter of 11 mm. A patented rig called ACTP (Absorption par Compression-Torsion Plastique), was used to investigate the foam response under quasi-static complex loading paths having different torsional components (i.e. 0°, 45° and 60°). The key mechanical responses to be examined are yield stress, stress plateau, and energy absorption capacity. The collapse mode was also investigated. It was concluded that the higher the loading complexity, the greater the yield strength and the greater energy absorption capacity of the foam. Experimentally, it was also noticed that there were large softening effects that occurred after the first pick stress for both biaxial-45° and biaxial-60° loading.

Keywords: aluminum foam, loading complexity, characterization, biaxial loading

Procedia PDF Downloads 91

Authors: Mohsen Abdelrazek Khorshid Ali Selim

Abstract:

Disadvantages and errors of current concrete reinforcement methodsL: Current concrete reinforcement methods are adopted in most parts of the world in their various doctrines and names. They adopt the so-called concrete slab system, where these slabs are semi-independent and isolated from each other and from the surrounding environment of concrete columns or beams, so that the reinforcing steel does not cross from one slab to another or from one slab to adjacent columns. It or the beams surrounding it and vice versa are only a few centimeters and no more. The same applies exactly to the concrete columns that support the building, where the reinforcing steel does not extend from the slabs or beams to the inside of the columns or vice versa except for a few centimeters and no more, just as the reinforcing steel does not extend from inside the column at the top. The ceiling is only a few centimetres, and the same thing is literally repeated in the concrete beams that connect the columns and separate the slabs, where the reinforcing steel does not cross from one beam to another or from one beam to the slabs or columns adjacent to it and vice versa, except for a few centimeters, which makes the basic building elements of columns, slabs and beams They all work in isolation from each other and from the environment surrounding them from all sides. This traditional method of reinforcement may be valid and lasting in geographical areas that are not exposed to earthquakes and earthquakes, where all the loads and tensile forces in the building are constantly directed vertically downward due to gravity and are borne directly by the vertical reinforcement of the building. However, in the case of earthquakes and earthquakes, the loads and tensile forces in the building shift from the vertical direction to the horizontal direction at an angle of inclination that depends on the strength of the earthquake, and most of them are borne by the horizontal reinforcement extending between the basic elements of the building, such as columns, slabs and beams, and since the crossing of the reinforcement between each of the columns, slabs and beams between them And each other, and vice versa, does not exceed several centimeters. In any case, the tensile strength, cohesion and bonding between the various parts of the building are very weak, which causes the buildings to disintegrate and collapse in the horrific manner that we saw in the earthquake in Turkey and Syria in February 2023, which caused the collapse of tens of thousands of buildings in A few seconds later, it left more than 50,000 dead, hundreds of thousands injured, and millions displaced. Description of the new earthquake-resistant model: The idea of the new model in the reinforcement of concrete buildings and constructions is based on the theory that we have formulated as follows: [The tensile strength, cohesion and bonding between the basic parts of the concrete building (columns, beams and slabs) increases as the lengths of the reinforcing steel bars increase and they extend and branch and the different parts of the building share them with each other.] . In other words, the strength, solidity, and cohesion of concrete buildings increase and they become resistant to earthquakes as the lengths of the reinforcing steel bars increase, extend, branch, and share with the various parts of the building, such as columns, beams, and slabs. That is, the reinforcing skewers of the columns must extend in their lengths without cutting to cross from one floor to another until their end. Likewise, the reinforcing skewers of the beams must extend in their lengths without cutting to cross from one beam to another. The ends of these skewers must rest at the bottom of the columns adjacent to the beams. The same thing applies to the reinforcing skewers of the slabs where they must These skewers should be extended in their lengths without cutting to cross from one tile to another, and the ends of these skewers should rest either under the adjacent columns or inside the beams adjacent to the slabs as follows: First, reinforce the columns: The columns have the lion's share of the reinforcing steel in this model in terms of type and quantity, as the columns contain two types of reinforcing bars. The first type is large-diameter bars that emerge from the base of the building, which are the nerves of the column. These bars must extend over their normal length of 12 meters or more and extend to a height of three floors, if desired. In raising other floors, bars with the same diameter and the same length are added to the top after the second floor. The second type is bars with a smaller diameter, and they are the same ones that are used to reinforce beams and slabs, so that the bars that reinforce the beams and slabs facing each column are bent down inside this column and along the entire length of the column. This requires an order. Most engineers do not prefer it, which is to pour the entire columns and pour the roof at once, but we prefer this method because it enables us to extend the reinforcing bars of both the beams and slabs to the bottom of the columns so that the entire building becomes one concrete block that is cohesive and resistant to earthquakes. Secondly, arming the cameras: The beams' reinforcing skewers must also extend to a full length of 12 meters or more without cutting. The ends of the skewers are bent and dropped inside the column at the beginning of the beam to its bottom. Then the skewers are extended inside the beam so that their other end falls under the facing column at the end of the beam. The skewers may cross over the head of a column. Another passes through another adjacent beam and rests at the bottom of a third column, according to the lengths of each of the skewers and beams. Third, reinforcement of slabs: The slab reinforcing skewers must also extend their entire length, 12 meters or more, without cutting, distinguishing between two cases. The first case is the skewers opposite the columns, and their ends are dropped inside one of the columns. Then the skewers cross inside the adjacent slab and their other end falls below the opposite column. The skewers may cross over The head of the adjacent column passes through another adjacent slab and rests at the bottom of a third column, according to the dimensions of the slabs and the lengths of the skewers. The second case is the skewers opposite the beams, and their ends must be bent in the form of a square or rectangle according to the dimensions of the beam’s width and height, and this square or rectangle is dropped inside the beam at the beginning of the slab, and it serves as The skewers are for the beams, then the skewers are extended along the length of the slab, and at the end of the slab, the skewers are bent down to the bottom of the adjacent beam in the shape of the letter U, after which the skewers are extended inside the adjacent slab, and this is repeated in the same way inside the other adjacent beams until the end of the skewer, then it is bent downward in the form of a square or rectangle inside the beam, as happened. In its beginning.

Keywords: earthquake resistant buildings, earthquake resistant concrete constructions, new technology for reinforcement of concrete buildings, new technology in concrete reinforcement

Procedia PDF Downloads 28

Authors: Muhammad Rizwan, Naveed Ahmad, Akhtar Naeem Khan

Abstract:

Seismic behavior factors are evaluated for the performance assessment of low rise reinforced concrete RC frame structures based on experimental study of unidirectional dynamic shake table testing of two 1/3rd reduced scaled two storey frames, with a code confirming special moment resisting frame (SMRF) model and a noncompliant model of similar characteristics but built in low strength concrete .The models were subjected to a scaled accelerogram record of 1994 Northridge earthquake to deformed the test models to final collapse stage in order to obtain the structural response parameters. The fully compliant model was observed with more stable beam-sway response, experiencing beam flexure yielding and ground-storey column base yielding upon subjecting to 100% of the record. The response modification factor - R factor obtained for the code complaint and deficient prototype structures were 7.5 and 4.5 respectively, which is about 10% and 40% less than the UBC-97 specified value for special moment resisting reinforced concrete frame structures.

Keywords: Northridge 1994 earthquake, reinforced concrete frame, response modification factor, shake table testing

Procedia PDF Downloads 136