bluuebunny/crossref_metadata_2025 huggingface dataset:
Can Huawei sue the US government for defamation?
Authors: Kwan Martin
Published: March 2020

This article studies the law of foreign state immunity from a comparative perspective and uses the facts of Huawei-US controversy as a test case to illustrate the differences in the laws of various jurisdictions. The US government has made a number of allegations against Huawei regarding its 5G products and services. The US has also called for the imposition of a ban on Huawei from competing for 5G contracts in a number of common law countries. As a result, Huawei’s business and its reputation are inevitably damaged. Certain allegations against Huawei’s business ethics may be difficult to support due to lack of evidence to support it. This article evaluates the threshold question of foreign state immunity to see if Huawei can sue the US government for defamation. It is concluded that state immunity would block such a claim in most common law jurisdictions, though it may be possible to sue in Canada. It would mean (1) Huawei does not have sufficient legal protection, and (2) it would imply a country may be able to use defamation as an innovative and strategic tool to interfere with commercial competition whilst it may not have any legal consequence. The position on foreign state immunity in China will be discussed for academic comparison.
Dynamics of body weight and comorbidities in obese patients after sleeve gastrectomy vs. gastric bypass
Authors: Volkova Anna R. , Fishman Michael B. , Semikova Galina V.
Published: March 2020

Background: Bariatric surgery methods have proven to be most effective in treating obesity. Weight regain (WR) is often found after various types of bariatric surgery. The clinical significance of WR is not clearly defined.
Aims: to assess the dynamics of body weight and determine the amount of clinically significant WR based on the study of carbohydrate metabolism and blood pressure in patients with obesity after performing sleeve gastrectomy (SG) and gastric bypass (GB).
Materials and methods: 68 patients with obesity after SG (40) and GB (28) were observed for 3 years. Body mass index (BMI), percentage of excess BMI lost (% EBMIL), WR, glycated hemoglobin, blood pressure were evaluated.
Results: A comparable efficiency (EBMIL more than 50%) of the SG and the GB was at the nadir point. %EBMIL over 50% was achieved in 78.8% of patients after SG and 80.0% of patients after GB. WR more than 15% was associated with a significant increase in systolic blood pressure. Clinically significant WR in the SG group was detected in 32.5% of patients, in the GB group in 17.2% of patients (p 0.05).
Conclusion: WR of more than 15% was associated with a significant increase in systolic blood pressure in patients with obesity after SG and GB, which makes it possible to consider WR of more than 15% clinically significant. A clinically significant WR 36 months after surgery was detected in 32.5% of patients after SG and 17.2% of patients after GB.
A case report of severe hypoaldosteronism following unilateral adrenalectomy for aldosteronoma
Authors: Egshatyan Lilit
Published: March 2020

Primary aldosteronism is characterized by hypertension and accounts for about 10% of hypertensive patients. Hyperkalemia and renal disease post adrenalectomy has been described in the literature. We present а case of primary aldosteronism with long standing hypertension (more than 10 years) with severe hypokalemia (1.9 mmol/l). Post unilateral adrenalectomy he had reduction in the blood pressure and became eukalemic. However, after 8 weeks of adrenalectomy patient developed hyperkalemia and increased serum creatinine, which resolved with fludrocortisone and attempt to discontinue fludrocortisone resulted in hyperkalemia and rising creatinine.
Screening of developing post-operative hyperkalemia should be actively considered in high-risk patients: older age, longer duration of hypertension, higher levels of aldosterone and severe hypokalemia before surgery, impaired estimated glomerular filtration rate and long-term treatment with spironolactone.
Constelações de uma práxis pedagógica: o sensível, a linguagem, as infâncias e a memória (presenças de Walter Benjamin) na formação docente
Authors: Miklos Dilson
Published: March 2020

Linguagem, arte, infância e memória são alguns dos conceitos que o ensaio apresenta a partir do olhar de Walter Benjamin que nos acompanha na escrita a fim de extrair enunciados de um contexto voltado à formação de professores. Nesse percurso são apresentados dois conceitos que emergem da pesquisa docente, a saber: práxis poética e narrativimagem. O campo do sensível é o lócus onde aflora esse conjunto de saberes que se comunica poeticamente e que objetiva refletir sobre o currículo e práticas pedagógicas outras. Ainda, há o esforço, na companhia do  filósofo  berlinense, de compreender o processo da formação a partir de uma perspectiva menos totalizante e definitiva.
Jovens doutores em início da carreira docente
Authors: Feldkercher Nadiane
Published: March 2020

O objetivo deste estudo foi compreender a condição jovem dos professores em fase de iniciação à docência universitária. Consideramos iniciante os professores com até 3 anos de experiência e jovem aqueles com até 32 anos, que realizaram, sequencialmente, graduação, mestrado e doutorado e, em seguida, ingressaram na docência. Na pesquisa, de abordagem qualitativa, coletamos os dados por meio de entrevistas com 6 jovens professores iniciantes vinculados à Universidade Federal de Pelotas e por observações de aulas de graduação desses docentes. Os dados, trabalhados através da análise de conteúdo, foram interpretados a partir de teorias sobre a formação docente e a iniciação à docência. Para os professores, a condição jovem não é um fator de padronização ou de causalidade nas formas de ser, de atuar ou de se relacionar com os alunos. Porém, essa condição produz no professor vivências tanto motivadoras quanto limitações que são vividas em paralelos, enquanto constroem suas identidades docentes.
Imagens e Identidades da Docência: ser, tornar-se e fazer-se professor, professora
Authors: Campos Vanessa T. Bueno , Gaspar Maria de Lourdes Ribeiro , Morais Sarah Juvencino de Oliveira
Published: March 2020

A identidade profissional docente não é inerente ou fixa; é complexa e construída a partir da significação social que atribuímos ao tornar-se e o fazer-se professor, professora. Essa premissa nos orientou, nesse artigo, tecermos reflexões sobre os conceitos em torno da constituição da identidade profissional docente decorrentes da produção de desenhos elaborados por estudantes da educação básica e superior. O questionamento que nos orientou foi: quais imagens são comumente relacionadas a docência e como é constituída a identidade profissional dos/as professores/as na percepção de estudantes? Optamos pela pesquisa exploratória com abordagem qualitativa, tendo como parâmetro no plano teórico e empírico, a revisão bibliográfica e a análise de conteúdo dos discursos expresso nos desenhos. A análise das produções dos discentes revelaram que a identidade profissional docente é compreendida por eles/elas na relação que estabelecem em sala de aula, marcada pela afetividade, pelo acesso ao conhecimento, pelas tradições sociais e culturais.
STABILITY EVALUATION OF STEEL BRACED FRAMES UNDER INELASTIC CYCLIC LOADING
Authors: Mamaghani Iraj H. P.
Published: March 2020

This paper deals with the inelastic cyclic analysis and stability (strength and ductility) evaluation of steel braced frames. The inelastic cyclic performance of steel braced frames is examined through finite element analysis using the commercial computer program ANSYS. First some of the most important parameters considered in the practical design and ductility evaluation of steel braces are presented. Then the details of finite element modeling and numerical analysis are described. Later the accuracy of the analytical model employed in the analysis is substantiated by comparing the analytical results with the available test data in the literature. Finally, the effects of some important structural and material parameters on cyclic elastoplastic behavior of steel braced frames are discussed and evaluated. It is concluded that the numerical method and finite-element modeling employed in the numerical analysis can predict with a reasonable degree of accuracy the experimentally observed cyclic behavior of steel-braced frames.
BEHAVIORS OF SLIP-CRITICAL BOLTS IN COMBINATION WITH FILLET WELDS
Authors: Chang Heui-Yung , Yeh Ching-Yu , Chen Chia-Yu
Published: March 2020

According to the Specification for Structural Steel Buildings (AISC 2010), slip-critical bolts can only share load with longitudinal welds in a joint. Moreover, the bolt available strength shall not be taken greater than 50% of the bearing-type. This paper presents the result of a series of joint tests verifying the specification. The joints were tested in a manner similar to previous work (e.g. Manuel and Kulak 2000). The slip strength values of JIS F10T and F14T bolts were tested and compared. Transverse and longitudinal fillet welds with a leg size of 12 mm and the same amount of weld material were adopted and tested respectively. The strength ratio between bolts and welds changes from 5/8 to 6/9 in the combination joints. The result shows that in the combination with longitudinal welds, the bolts tend to slip and contact the plates, developing greater bearing strength. In the combination with transverse welds, the bolts slip and the pretension decreases greatly. But the combination also causes the fracture surfaces of transverse welds to change, providing additional strength to compensate the decrease in bolt slip strength. The combination joints therefore can develop strength greater than the sum of slip strength and fracture strength.
EXPERIMENTAL STUDY ON CONCRETE PERMEABILITY AFFECTED BY ENVIRONMENTAL VIBRATION
Authors: Ma Xue-Feng , Bu Jian-Qing
Published: March 2020

This study investigates the effect of environmental vibrations on concrete permeability. Based on published field measurement data and relevant references, two different sinusoidal vibration parameters (5 Hz/4 mm and 20 Hz/2 mm) are selected and applied to a newly constructed concrete by a vertical vibrating table and AC impedance technique. The concrete permeability is examined, and the influence of some factors including different vibration time (before initial curdle, between initial curdle and finial curdle, and after final curdle) and different vibration energy are discussed. From the experimental results, the following conclusions can be drawn. Irrespective of whether or not the concrete is vibrated, the uniformity inside the concrete along the direction of concrete pouring is more discrete in the upper and lower part of the concrete. Furthermore, the permeability at both ends of the concrete is larger than that in the middle portion. The newly constructed concrete's permeability is increased when the vibration energy is lowered, and decreased when the vibration energy is increased, and the new constructed concrete permeability affected by environment vibration obviously before initial curdle time.
AN EXPLORATION OF TEAM INTEGRATION IN DESIGN-BID-BUILD PROJECTS
Authors: Sanz Amalia , Franz Bryan , Molenaar Keith , Esmaeili Behzad , Pellicer Eugenio
Published: March 2020

A recent large sample study of project delivery in the United States (U.S.) concluded that more integrated teams led both directly and indirectly to more successful construction projects. Concurrent with this U.S. study, construction projects in Spain were surveyed using the same data collection questionnaire. While the sample size of participating projects in Spain was not as large as the U.S. and targeted only design-bid-build (DBB) deliveries, there were notable differences in the levels of team integration between the two data sets. Comparable DBB projects in Spain had significantly fewer team members participating in high-quality, multidisciplinary interactions than their U.S. counterparts. However, they relied on greater use of qualifications and experience in selection. DBB projects from the U.S. and Spain data sets are compared, with respect to their use, and proportion, of the team participating in: design charrettes, joint goal-setting, building information modeling (BIM) and construction phase co-location. To further explore these differences, we also examine how DBB delivery is implemented in the U.S. and Spain. While it was discovered that Spanish DBB projects did use some tools to increase team integration, the findings of this comparison suggest that the Spanish industry could improve team integration by: (1) incorporating earlier construction team involvement; (2) promoting cost transparency with open book construction contracts that transition to a lump sum near the completion of the project, and (3) encouraging the designer and contractors to use BIM throughout the project.
FACTORS AFFECTING THE SELECTION OF CONTRACTORS IN GREEN BUILDING PROJECTS
Authors: Gurgun Asli , Ozbek Mehmet
Published: March 2020

The growing interest in sustainable design and construction introduces new set of risks specific to green building projects. One of the challenges in green building projects that require special consideration is the selection of the appropriate contractors to ensure that the targeted sustainability goals of the projects will be achieved. Rapid growth of green building movement requires that contractors that are willing to be active in sustainable construction learn green building rating systems, application processes, green products, and related laws and regulations. This study investigates major factors affecting the selection of contractors that will be responsible for the construction of projects aiming certification through green building certification systems. An extensive literature survey was completed to identify the significant factors in the selection process, which are important for the successful completion of the projects. It is found that experience in green building projects and certification system procedures, managerial approach, technical approach, price, past performance, and qualifications are important in the selection of contractors in green buildings.
EXPERIMENTAL STUDY OF ULTRA-HIGH PERFORMANCE FIBER REINFORCED CONCRETE DOSAGES WITH ULTRA FAST SETTING TIME
Authors: Gimenez-Carbo Ester , Torres Raquel , Serna Pedro
Published: March 2020

The overall objective of the work is the development of ultra high performance fiber reinforced concrete (UHPFRC) dosages that can be used for shotcrete. In this study, a number of UHPFRC mixtures with different amount of admixtures (plasticizers and accelerating) and different mixing time were tested, to increase either the rate of stiffening or setting of the concrete or the rate of hardening and early-strength development. Workability, consistency and mechanical properties of UHPFRC including compressive and flexural strengths at different ages were assessed. Results showed mixtures than begin their first setting in less than 1 minute, with very good mechanical properties in 24 hours, and without reducing the compressive strength at 28 days. From the results obtained, various uses of these mixtures are proposed taking into account, the new context of the Construction field, with the appearance of new placing concrete techniques.
A REVIEW OF CORPORATE SOCIAL RESPONSIBILITY PRACTICES IN DEVELOPING COUNTRIES
Authors: Alotaibi Ali , Edum-Fotwe Francis , Price Andrew
Published: March 2020

The construction industry plays a vital role in every economy by contributing substantially to the national gross domestic product (GDP). Despite the significance of the industry, construction is often criticized for adversely impacting society and the environment through the nature of its work. Managing societal and environmental impacts are at the heart of corporate social responsibility (CSR) which is a critical factor for achieving long-term competitiveness. CSR has been adopted by many industries to address the negative impacts that result from their operations. Research in CSR within the construction industry is limited and still in its infancy, especially in the Kingdom of Saudi Arabia (KSA) where there is a negligible uptake of CSR activities and a lack of strategies and guidelines. The key question here is why the construction industry in KSA has not fully embraced the concept of CSR. This article presents the results of a literature study undertaken to develop an understanding of the reasons that militate against the implementation of CSR in general, and specifically in construction within KSA. The paper adopts a structured approach to analyze materials published on CSR, in general, and how it has been applied in the construction sector, including KSA. The analysis indicates that there are critical factors that have hampered the fulfillment of CSR requirements in construction. A lack of awareness and knowledge is ranked as the greatest barrier, and the lack of a practical and theoretical framework to examine the level of CSR implementation closely follows in tow. The analysis suggests that CSR within KSA is currently at a basic level and focused on philanthropic activities. It also indicates that there is a need to go beyond this basic level by developing an appropriate framework to assist KSA construction companies in integrating CSR fully into their business practice.
ASSESSING THE BEHAVIOR OF COLUMN-SPLICE CONNECTIONS BETWEEN CFSTS IN AXIAL TENSION
Authors: Saha Avik , Saha Swapan , Uy Brian , Li Dongxu
Published: March 2020

Increasing the sustainability of construction materials is a key goal in the construction industry. As the demand for high-rise residential structures grows, new more efficient methods of achieving sustainability are required. Rendering larger structures demountable to enable the re-use of steel structural members is one solution. The aim of this study was to investigate and assess the behavior of blind bolted column-column connections between concrete filled steel tubes in axial tension. The investigation aimed to address the need for accurate design guidelines for tensile members in the composite design standards such as Eurocode 4 and encourage the use of column-column connections in large-scale demountable structures. A numerical investigation of the blind bolted column-column connection has been performed using ABAQUS. The model consisted of two concrete filled square hollow steel sections connected using sleeve plates welded to the top tube only, as well as 16 M20 Lindapter Hollo-bolts connecting the tubes. The numerical investigation revealed that the sections tested conformed with AS1170.1 regarding columns in tension. Results of the numerical investigation have been compared against experimental results for a continuous CFST and it was found that the connections performed better in tension. The parametric analysis revealed no dependence of the shape of force-displacement relationships on diameter to thickness ratio, concrete compressive strength or yield stress.
VULNERABILITY REDUCTION OF STEEL MOMENT RESISTING FRAMES BY MEANS OF REDUCED BEAM SECTION
Authors: Montuori Rosario
Published: March 2020

The idea and the developed example of this work are based on the attainment of seismic performance improvement by simply trimming the flanges of the beam-ends. This strategy is to be applied by considering both the results of the theory of plastic mechanism control and the rules assuring the yielding of reduced beam sections (RBS) when seismic loads are applied to the structure. The results of such strategy are not always effective. In fact, there are several conditions that are to be satisfied in order to obtain an actual seismic improvement. Notwithstanding, when these conditions are satisfied, the cost of intervention can be considered as negligible. For this reason, this strategy can be very interesting and the rules applied in this work can clarify which is the effect of RBS taking into account all the parameters playing a role in the final design, i.e. existing column sections, resistance and ductility of existing connections, vertical loads acting in seismic load combination, amount of the reduction of beam section and its distance from the connection.
REINFORCED CONCRETE CRACK MODEL BASED ON STIFFNESS ANALYSIS OF TENSION MEMBERS
Authors: Murray Angus , Gilbert Raymond Ian , Castel Arnaud
Published: March 2020

The average spacing of primary cracks in a reinforced concrete (RC) member greatly influences its in-service behavior, especially with regard to stiffness and average crack width. Accurate predictions of the average crack spacing are therefore crucial for satisfying serviceability requirements in RC structures. This is particularly the case when relying on analytical models that treat cracks discretely rather than in a smeared fashion. Popular code-based models for primary crack spacing are often wildly inaccurate and may lead to poor predictions of in-service behavior. In this paper, the problem or primary crack formation is approached from a stiffness perspective. The proposed model is based on the results of several experimental tension stiffening studies in the literature, as well as a previous numerical study dealing with the effect on stiffness of non-plane deformation in the neighborhood of primary cracks. The proposed model is compared to some popular code-based models and is shown to better predict average crack spacing for a wide variety of beams, slabs, and tension members.
SHRINKAGE AND CREEP EFFECT ANALYSES OF DOUBLE COMPOSITE CONTINUOUS BOX-GIRDER BRIDGE CONSTRUCTED BY PRE-JACKING METHOD
Authors: Duan Shujin , Wang Bin , Wang Yuanyuan , Niu Runming
Published: March 2020

Continuous double steel and concrete composite beam is a new structural system developed on the basis of common steel and concrete composite beam. Controlling concrete slab crack width in a continuous double composite beam is a significant content in the bridge construction process. Jacking-up and landing bearing supports method is applied to a double composite girder bridge construction and its structural mechanical behaviors in the whole process will be simulated. By using of User Programmable Features and ANSYS Parametric Design Language, the commercial FEM software ANSYS was further developed. The exponential model of concrete creep and the implicit solution of concrete creep equation under the action of variable stress were introduced into ANSYS, to realize the concrete shrinkage and creep effect analysis of double composite continuous box-girder bridges constructed by pre-jacking method. The results show that it is improved that the stress state of the top concrete slab in the negative moment regions by pre-jacking method. Due to the effect of concrete creep, the concrete creep will cause tensile stress in the negative moment regions of the composite beam, which will reduce the compressive stress in the top concrete slab. The effect of prestressing is greatly affected by pre-jacking value, and the creep of the concrete also causes the stress redistribution of the concrete and the steel beam.
ANALYSIS OF SPACE FRAMES WITH GENERALIZED SEMI-RIGID CONNECTIONS
Authors: Duan Shujin , Li Zhiyue , Liu Meixiang , Xie Xiaofeng
Published: March 2020

A mechanical model and analytic method are proposed, in which, the axial, the shearing and the bending semi-rigid characteristics of space frames are taken into account. An independent zero-length connection element comprising six translational and rotational springs is used to simulate the beam-to-column connection. The model, namely six-spring mechanical model, has an advantage that the element number of structure does not increase. The matrix displacement method is used to analyze mechanism of the model, including element analysis and structural analysis. The stiffness matrix of the element is derived. Some reaction forces at the end of the element are obtained when it is subjected to two kinds of different loads respectively. The obtained stiffness matrix gets the characteristics of symmetry and singularity and that makes the size of total stiffness matrix for semi-rigid frame the same as that for frame with rigid joints.
INFLUENCE OF TIE BEAMS ON THE SEISMIC PERFORMANCE OF TWO-COLUMNED HIGH PIERS
Authors: Li Yong , Li Yafeng , Duan Shujin
Published: March 2020

Two-columned high piers are widely used to continuous rigid frame bridges. The longitudinal flexural stiffness of high piers with height of over 40 m is generally smaller, so tie beams are usually set between two columns to decrease the calculating height of piers to improve the stability behavior. In addition, under the seismic action, tie beams generally yield before columns, forming the plastic hinge and dissipating seismic energy, which decreases the damage of piers. To study the seismic performance of two-columned high piers with tie beams, nonlinear static and quasi-static analysis of a typical two-columned high piers with height 45 m was conducted by two and three-dimensional finite element modeling techniques respectively. Factors of the longitudinal reinforcements and stirrups ratio of tie beams, the stiffness ratio of tie beams to columns and the number of tie beams on the seismic performance of high piers are all discussed. Analysis results show that the seismic performance two-columned high piers is effectively improved with increasing the number of tie beams and setting the stiffness ratio of tie beams to columns in a certain range, while there is little influence of the reinforcement ratio of tie beams. As a result, setting a reasonable number of tie beams is an effective way to improve the seismic performance of two-columned high piers.
DYNAMIC ANALYSIS OF FIBER-REINFORCED POLYMER COMPOSITE ELECTRIC POLES
Authors: Mohamadi Sara , Urgessa Girum
Published: March 2020

This paper presents finite element modeling of tapered fiber-reinforced polymer (FRP) poles in ABAQUS for dynamic analysis. Modal analysis and transient dynamic analysis are presented in order to evaluate the effect of fiber orientation, taper ratio, number of layers and lamina thickness on the dynamic properties of tapered poles. Trends observed from the parametric studies on the analyses of the FRP poles are enumerated. In addition, the effect of rectangular dynamic excitations on the overall response of the FRP poles is presented encapsulating impulsive loadings that may occur due to wind gusts or loss of cable tension supported by the FRP poles. Result shows that the fundamental frequency of the poles decreased as the fiber-orientation increased up to 60 degrees. In addition, the fundamental frequency of the poles increased as the number of layers increased. No significant difference was observed in natural frequency of the poles when varying the lamina thickness without changing the overall laminate thickness. The fundamental frequency of the FRP poles decreased by 10% as the taper ratio increased from 0.4 to 1. Transient dynamic analysis showed that FRP poles with higher fiber orientation angle had the larger maximum tip deflection. However, only small differences were observed when the deflections are normalized as the ratio of the maximum dynamic deformation to the maximum static deformation.
FAILURE LITERACY IN STRUCTURAL ENGINEERING
Authors: Delatte Norbert
Published: March 2020

The history of the development of practice in many engineering disciplines is, in large part, the story of failures, both imminent and actual, and of the changes to designs, standards and procedures made as the result of timely interventions or forensic analyses. All engineers, and more particularly structural engineers, should be failure literate. Failure literacy means knowing about the critical historical failure cases that have shaped the profession, not merely the surface technical details, but the environment, the communications difficulties and the procedural issues. In the U.S., an intensive effort has been under way for nearly a decade to promote failure literacy in engineering education and practice. A number of educational resources have been developed by the Education Committee of the American Society of Civil Engineers Forensic Engineering Division (ASCE FED) to make it easier for engineering students and practicing engineers to learn from failures. Some landmark failures include the Tacoma Narrows bridge collapse, 1940, the Point Pleasant/ Silver Bridge collapse, 1967, the Ronan Point building collapse, 1968 (U.K.), the 2000 Commonwealth avenue building collapse, 1971, the Bailey’s Crossroads building collapse, 1973, the Hartford Civic Center building collapse, 1978, and others. This list, unfortunately, is a living document that will expand as more failures occur. Thorough forensic investigations are vital to capture the lessons from the unfortunate occurrences.
ANALYZING REINFORCED CONCRETE BEAMS BY USING THE UPF FEATURES OF ANSYS
Authors: Lazzari Paula Manica , Campos Filho Américo , Lazarri Bruna Manica , Pacheco Alexandre Rodrigues
Published: March 2020

In this paper, the implementation of an elastoplastic constitutive model with cracking is presented for analyzing reinforced concrete structures using The Finite Element Method (FEM). This implementation was made through the UPF (User Programmable Features), a customization tool available in ANSYS (version 14.5). By using the UPF features, a new constitutive model for concrete was created (in USERMAT3D), adding new subroutines in FORTRAN language to the main program. The main advantage of the implementation of this model is the possibility of using quadratic twenty-node three-dimensional elements (SOLID186) with the element-embedded rebar model (REINF264), making the solution considerably faster and more effective, when compared to typically available options. In order to validate the subroutines added to the system, the beams tested by Leonhardt and Walther (1962) were simulated, covering a wide variety of behaviors, including bending and shear failures. Analyses of the stresses in the concrete and in the reinforcement are made and load-displacement diagrams are presented. The comparisons that are done between numerical and experimental results demonstrate the validity of the results found.
IMPACT OF PREDICTING BRITTLE FAILURE MODES ON SELECTION OF LIMIT STATES OF VERTICALLY-IRREGULAR TALL BUILDINGS
Authors: Mwafy Aman , Khalifa Sayed , El-Ariss Bilal
Published: March 2020

The proper definition of structural failure of irregular structures is a critical element in building vulnerability assessment. Shear force demands may be the main cause of failure under earthquake loading. This increases the uncertainty related to the definition of the limit states of irregular buildings. The present study thus focuses on the assessment of brittle shear failure on the performance criteria of vertically irregular tall buildings. Five 50-story structures are designed using international standards to represent code-conforming tall buildings with main vertical irregularities. Detailed simulation models are used to assess the failure modes of the buildings under the effect of far-field and near-source earthquake records. Experimentally verified shear strength models are adopted to monitor the shear supply-demand response of the reference structures. Based on the comprehensive results obtained from incremental dynamic analyses, it is concluded that shear modeling is essential for the reliable assessment of vertically irregular buildings. The characteristics of earthquake records and the irregularity type significantly influence the limit states of the reference buildings. Unlike the behavior of the buildings under the far-field earthquake scenario, which is controlled by flexure, the collapse prevention limit state is significantly influenced by the member shear response under the effect of near-field earthquakes. Accordingly, improved limit state criteria are proposed, which supports the reliable earthquake loss estimation of tall buildings with different vertical irregularities.
LOCAL CORROSION ENVIRONMENT AROUND CROSS SECTION OF A PLATE GIRDER BRIDGE
Authors: Maruyama Kazuto , Kamasaki Seiya , Tajima Keiji , Aso Toshihiko
Published: March 2020

Corrosion is one of important factor for securing the safety of steel bridges. In general cases, the corrosive environment of the steel bridge is evaluated as a site environment. However, even in one bridge, the corrosive environment greatly varies from part to part. This research aims to clarify the difference of corrosion environment for each part of plate-girder-bridge which has three main girders. At this bridge, anti-freezing agent is sprayed in winter. On site measurements were performed on five points on each girder, which are both sides of web, both sides of upper/lower part of bottom flange. These measurements points include two points where water leakage is scattered. Temperature, humidity, amount of airborne salt and amount of adhering salt have been measured. In order to comprehensively assess corrosive condition, exposure test was also performed. Observations were carried out for one year. From measurement results, it became clear that temperature and humidity were not uniform at all observation points. These were differed at the inside and outside of girder and upper part and lower part of web. Amount of airborne salt to each girder is strongly influenced by anti-freezing agent. On the upper surface of the lower flange of each girder, there are places where corrosion markedly progresses due to deposits and water leakage.
USING THE ELEMENT-EMBEDDED REBAR MODEL IN ANSYS TO ANALYZE REINFORCED CONCRETE BEAMS
Authors: Lazzari Bruna Manica , Campos Filho Américo , Lazzari Paula Manica , Pacheco Alexandre
Published: March 2020

ANSYS is software well acknowledged by professionals and academics, due to its large range of usage options, offering a number of finite element types, good possibilities of constitutive models and linear and nonlinear analysis of structures in general. For the concrete material, the software uses an elastoplastic model with the Willam-Warnke surface of rupture (1975). However, this model is only available for finite elements that do not offer the possibility of use of the element-embedded model for rebars, demanding a much larger amount of elements to discretize structures. This study is about the development of a computational model using the FEM via ANSYS platform for nonlinear analysis of reinforced concrete beams under plane stress states. The most significant advantage of this implementation is the possibility of using the element-embedded rebar model in ANSYS with its 2D quadratic element PLANE183 for discretization of the concrete together with element REINF263 for discretization of rebars and stirrups, making the solutions more efficient. For representation of the constitutive equations of the steel and the concrete, a proposed model was implemented with the help of the UPF customization tool of ANSYS, where new subroutines were attached to the main program. The numerical results are compared with experimental values for 4 reinforced concrete beams originally tested by Bresler and Scordelis (1963) to validate the proposed model, showing satisfactory results.
FRCM SHEAR STRENGTHENING FOR CONCRETE BEAMS
Authors: Younis Adel , Ebead Usama , Shrestha Kshitij C.
Published: March 2020

This paper presents the results of an experimental study carried out to examine the efficacy of Fabric-Reinforced Cementitious Matrix (FRCM) in strengthening RC beams susceptible to shear failure. In this paper, seven shear-critical RC beams, of 2,500 mm in length, 150 mm in width, and 330 mm in depth, were tested under three-point loading until failure. Two main test variables were considered, which are: a) Strengthening material: carbon, polyparaphenylene benzobisoxazole (PBO), or glass FRCM, and b) Strengthening application pattern: a single full-length FRCM plate or a set of intermittent and spaced FRCM strips were applied along the critical shear zone. The test results confirmed the efficacy of FRCM strengthening in improving the load capacity of shear-critical RC beams. The FRCM-strengthening contributed to increases in the load capacity ranged between 31% and 100% compared to the reference specimen. The full-length strengthened specimens generally showed a better strength enhancement compared to the intermittent counterparts when using the same FRCM material. Such intuitive observation assures the importance of the amount of strengthening material applied in the critical shear zone. Besides, specimens utilizing carbon fibers in its FRCM strengthening material showed the highest strength enhancement among the three systems.
INCREASING ROBUSTNESS OF REINFORCED CONCRETE STRUCTURES UNDER COLUMN LOSS SCENARIO
Authors: Elkholy Said , El-Ariss Bilal
Published: March 2020

This paper presents a simple technique to enhance robustness of reinforced concrete (RC) plane frames to progressive collapse under column loss scenario. The response of the enhanced/mitigated RC frames is analyzed using fiber force-based finite element analysis and applying displacement-controlled nonlinear static pushdown at the location of failed column. The technique involves addition of external unbounded steel cables to the continuous beam in each floor at anchorage and deviator locations. The cables transfer the loads above the failed column to the anchorages and deviators that are assumed to perform as rigid arms, which in turn redistribute the loads to adjacent columns. The numerical model computes the frame progressive collapse robustness using push-down analysis to simulate a column elimination and estimate the effects of cable catenary action on the frame. Two-dimensional RC frame of six stories and four bays was adopted in the study. The numerical results demonstrate the prospect of increasing robustness of RC frames to progressive collapse using presented technique.
EXPERIMENTAL STUDY OF RESTRAINED STEEL-CONCRETE COMPOSITE BEAMS UNDER CYCLIC LOADS
Authors: Yodmunee Sarawut , Kanchanalai Torkul
Published: March 2020

Composite structures are made from steel connected with slab concrete holding together with shear connectors. This facilitates in loading capacity according to AISC and AASHTO standard design. The test on restrained steel-concrete beams under monotonic loading and cyclic loading condition is with the fully composite and the partially composite. The result of this research is that the fully composite is more loading capacity than the partially composite. Moreover, the study also focuses on the deformation capacity ratio between the fully composite and the partially composite under both mentioned conditions. In this aspect, it is found that the deformation capacity of the fully composite is less than the partially composite. From the study, it is suggested that the steel-concrete composite be design for the fully composite because it can hold the highest strength, prevent slipping between steel and slab concrete, and increase the durability.
A COMPUTATIONAL FRAMEWORK FOR HOLISTIC LIFE-CYCLE DESIGN OF BUILDINGS
Authors: Haukaas Terje , Gavrilovic Stevan
Published: March 2020

This paper combines building information modeling with advanced structural modeling to optimize the design of building components using a life-cycle perspective. A new object-oriented software framework that extends an existing program is presented. It creates information-rich finite element models from industry foundation class files that are exported from building information programs. In addition to models for structural responses, the new components contain models for construction cost, repair cost, environmental impact cost, and human health cost. Random variable objects represent uncertainties in material properties, hazards, and cost models. Similarly, design variable objects represent decisions, such as structural dimensions and materials. All costs are summed and the expected value of this sum is employed as a decision criterion. This paper presents the software framework and a demonstration application.
STRUCTURAL CHARACTERISTICS OF TRADITIONAL THATCHED HOUSES IN OLD POST TOWNS
Authors: Takiyama Noriko , Tamaki Ryohei , Chen Xinyan , Yamaguchi Akari , Miyamoto Mitsuhiro
Published: March 2020

We report the progress of our research on seismic performance estimation of a traditional thatched house in Ouchi-Juku, Fukushima prefecture, registered as an IPDGHB in 1981, based on field surveys. First, we carried out a field survey of two existing thatched houses to understand their structural properties and conducted microtremor measurements of these houses and examined their ground to analyze their vibrational characteristics. Based on vibration mode of the house, it was found that the amplitude was large on the front side, which was used as often as a souvenir shop and Japanese restaurant, because the front of the house had less walls. Finally, we calculated the yield base shear coefficient as an indicator of seismic performance and compared it with the regression functions of traditional town houses in Kyoto. It is found that the thatched house in Ouchi-Juku had a higher shear force than a wooden house in Kyoto.
ESTIMATION OF AIRBORNE SALT LEVEL FOR BRIDGE CONSTRUCTION
Authors: Ohya Makoto , Takebe Masamich , Hirose Nozomu , Ajiki Shota , Aso Toshihiko
Published: March 2020

In the construction for steel bridges, it is important to accurately evaluate the environmental characteristics of the local region. It is well-known that the salt accumulation affects the corrosion of steel bridges. In order to evaluate the corrosion durability for a bridge, the airborne salt level is investigated monthly for a year prior to construction of the bridge. It is acknowledged that the airborne salt level varies seasonally, and thus it is possible that the one-year monitoring result does not necessarily represent long-term annual conditions for the airborne salt level. These climate changes make it difficult for the engineer to evaluate the corrosion durability for the steel bridges over a period of 100 years. In this study, the authors invested efforts to develop a procedure of estimating the airborne salt level based on available meteorological information. The estimation results showed reasonable agreement with the measured airborne salt level. It is confirmed that the proposed concise evaluation procedure based on only wind direction and speed information is useful as a method for estimating the airborne salt level.
EXPERIMENTAL STUDY ON H-SHAPED STEEL BEAM WITH CONTINUOUS BRACING SUBJECTED TO END MOMENT
Authors: Kido Masae , Liu Mao , Hoki Kazuaki , Onomiya Yoichi , Tsuda Keigo
Published: March 2020

As for H-shaped beams, concrete floor slab and purlins can be considered as bracing if they have enough stiffness and strength. There are many studies about bracing against lateral torsional buckling. However, the effect of lateral bracing cannot be properly considered in the practical design currently. The purpose of this study is to show the effect of the lateral bracing and vertical stiffener experimentally. The test on the lateral buckling of H-shaped steel beam with a steel plate which is a continuous bracing is carried out. Parameters are the position of bracing and presence or absence of vertical stiffener. The steel plate is welded on the compressive flange or the tensile flange. The vertical stiffener may be considered as the bracing for lateral buckling however the effects of them are not clear. The vertical stiffener is set at the position where the lateral deformation is assumed largest. The lateral buckling and local buckling occurs in the test specimens without bracing and with continuous bracing on the tensile flange. The maximum strength of the test specimen with a vertical stiffener is 5% smaller than that of the test specimen without a vertical stiffener. However, the strength degradation of the test specimen with a vertical stiffener is smaller and the load is 90 % more than the maximum load when the rotation angle is 0.07 rad.
FINITE ELEMENT ANALYSIS OF CONTROLLED LOW STRENGTH MATERIAL PAVEMENT BASES: FREE VIBRATION ANALYSIS
Authors: Huang Li-Jeng , Wang Her-Yung , Huang Wen-Ling , Lin Ming-Chao
Published: March 2020

This paper presents free vibration analysis of pavement bases constructed using sustainable material, a controlled low-strength material (CLSM), using finite element (FE) method. The CLSM concrete is introduced as pavement bases for its special features of easy compaction, high workability and relatively low cost. Rut-resistant stone matrix asphalt is placed on top of CLSM as wearing surface layer. The Young's moduli of CLSM are obtained from laboratory tests for two different binder mixtures, marked as CLSM-B80/30% and CLSM-B130/30%. Two-dimensional planar strain assumption is employed in the FE formulation of steady-state elasto-dynamic analysis of four-layered flexible pavements in which four kinds of different base materials are considered: graded crushed stone, CLSM-B80/30%, CLSM-B130/30% and AC. Comparison study on computed natural frequencies and mode shapes of the flexible pavement using different bases materials will be conducted. Results show that CLSM pavement bases depict higher natural frequencies as compared with graded crushed stone bases and can be suitable sustainable materials employed for pavement design and construction in highway engineering.
STRUCTURAL AND TECHNOLOGICAL INVESTIGATIONS OF BUILDING ENVELOPE
Authors: Miniotaite Ruta
Published: March 2020

The article examines technological and structural solutions for walls, roofs, floors in order to find the most effective barriers for each material and its thickness. Thermal insulation materials are the key factor to be considered in energy efficient buildings. Selected alternative materials are mineral wool, polystyrene and polyurethane foam. Thermal parameters, economic and technological indicators are compared within the envelope. The optimal thickness of the envelope component is found by calculating every envelope option by means of test utility method. The most efficient insulation material is determined by the simple additive weighting (SAW) method. The optimal thickness of insulation materials: 400 mm for the roof, 300 mm for walls and 300 mm for floors. The most effective materials are as follows: polyurethane foam for the roof, polyurethane foam for walls and polystyrene for floors.
FINANCIAL AND ECONOMICAL RISKS IMPACTING COST OF LEED CERTIFIED PROJECTS
Authors: Gurgun Asli Pelin , Polat Gul , Bayhan Hasan Gokberk , Damci Atilla
Published: March 2020

Green buildings have benefits for the environment, which has been acknowledged by the vast majority of building professionals. LEED is one of the most recognized green building certification systems in the world. However, issues related to financial aspects of the entire process and LEED certification may be significant and constitutes new financial burdens to the cost of the projects. After a diligent literature research, main issues related to cost can be identified under four major categories such as; cost of the certification process, scarcity of insurance solutions, rental due to delay related to green construction procedures and conditions, and failure to use of financial incentives (tax/loan discounts, low financing rates) because of delays or lower certification levels than expected throughout the LEED certification. This study focuses on the assessment of professionals’ experiences about the financial and economical risks green buildings and their impacts on cost by identifying the most common drawbacks and evaluate relevant precautions against them. Analysis results show that high cost of certification process is one of the concerns for the majority of the professionals. Rental loss due to delay related to green construction procedures and conditions, costs related to certification, documentation, practices and design are found as the other risk factors in the study. Proper allocation of such risks in contract documents and special insurance products with appropriate endorsements could be used to mitigate related risks.