This paper deals with the cyclic elastoplastic large displacement analysis and stability evaluation of steel tubular braces subjected to axial tension and compression. The inelastic cyclic performance of cold-formed steel braces made of circular hollow sections is examined through finite element analysis using the commercial computer program ABAQUS. First some of the most important parameters considered in the practical design and ductility evaluation of steel braces of tubular sections 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 inelastic behavior of steel tubular braces are discussed and evaluated.
we select cantilever beam having I,C,T section and we select material cast iron, stainless steel, steel and analyze base upon modal and static analysis.we see here deformation,stress ,strain and based upon it we conclude.
Influence line diagram for model arch bridgekunalsahu9883
It mainly deals with the graphical representation of the influence line daigram of the reaction forces, Bending moment and displacement. The material and section properties are used as mention in design and modeling of the bridge. The modeling and analysis was of the “Lupu bridge” in the MIDAS Civil2014 software. This presentation provides a critical analysis of The Lupu Bridge in Shanghai.
OUTLINE
introduction
classification
loads
materials used
Type of reinforcement
RCC
construction methods in RCC
Analysis and design
Detailing
Basic Rules
Site visit
video
we select cantilever beam having I,C,T section and we select material cast iron, stainless steel, steel and analyze base upon modal and static analysis.we see here deformation,stress ,strain and based upon it we conclude.
Influence line diagram for model arch bridgekunalsahu9883
It mainly deals with the graphical representation of the influence line daigram of the reaction forces, Bending moment and displacement. The material and section properties are used as mention in design and modeling of the bridge. The modeling and analysis was of the “Lupu bridge” in the MIDAS Civil2014 software. This presentation provides a critical analysis of The Lupu Bridge in Shanghai.
OUTLINE
introduction
classification
loads
materials used
Type of reinforcement
RCC
construction methods in RCC
Analysis and design
Detailing
Basic Rules
Site visit
video
What Is A Beam? And What Are The Different Types Of Beam? (https://civiltech-...PoojaGurnule
The article or blog is related to the beam and different types of beam depending on different conditions. Based on Support Conditions, Based on Construction Materials, Based on Cross-Section Shapes, Based on Geometry, Based on Equilibrium Conditions, Based on Method Of Construction
Effect of masonry walls in the progressive collapse of a ten storied rc buildingkunalsahu9883
In this project, a progressive collapse assessment was carried out for a typical ten-story reinforced concrete framed structure, with and
without a masonry infill wall, designed according to codes for minimum design loads for buildings and other structures.
Three different types of analysis were carried out namely linear static analysis, nonlinear static analysis and nonlinear dynamic analysis
using SAP2000.
It was found for the studied case that, the infilled masonry walls have a valuable contribution in mitigating progressive collapse of the
reinforced concrete framed structures.
simple supported beams with shear force and bending moments diagrams, different types of loading conditions, everyday scenarios of simply supported beams, advantages and disadvantages of simple supported beams
SEISMIC BEHAVIOR OF STEEL RIGID FRAME WITH IMPERFECT BRACE MEMBERSIAEME Publication
Model of a steel rigid frame made of thin-walled box section with existence of I-section brace member with initial overall and local imperfection adopted to investigate buckling effects on steel structural behavior as it was subjected to earthquake excitation. In order to take into account of the influence of local deflections on structural response, shell elements were employed to model brace member as well as base columns. Cross sections components with relatively high amplitude of
buckling parameters were considered in different case studies to make it susceptible to develop local deflection. Beam elements were also utilized to develop models with the same specification. FEM method applied to conduct nonlinear time history analysis using earthquake record in in-plane and
out-of-plane direction
What Is A Beam? And What Are The Different Types Of Beam? (https://civiltech-...PoojaGurnule
The article or blog is related to the beam and different types of beam depending on different conditions. Based on Support Conditions, Based on Construction Materials, Based on Cross-Section Shapes, Based on Geometry, Based on Equilibrium Conditions, Based on Method Of Construction
Effect of masonry walls in the progressive collapse of a ten storied rc buildingkunalsahu9883
In this project, a progressive collapse assessment was carried out for a typical ten-story reinforced concrete framed structure, with and
without a masonry infill wall, designed according to codes for minimum design loads for buildings and other structures.
Three different types of analysis were carried out namely linear static analysis, nonlinear static analysis and nonlinear dynamic analysis
using SAP2000.
It was found for the studied case that, the infilled masonry walls have a valuable contribution in mitigating progressive collapse of the
reinforced concrete framed structures.
simple supported beams with shear force and bending moments diagrams, different types of loading conditions, everyday scenarios of simply supported beams, advantages and disadvantages of simple supported beams
SEISMIC BEHAVIOR OF STEEL RIGID FRAME WITH IMPERFECT BRACE MEMBERSIAEME Publication
Model of a steel rigid frame made of thin-walled box section with existence of I-section brace member with initial overall and local imperfection adopted to investigate buckling effects on steel structural behavior as it was subjected to earthquake excitation. In order to take into account of the influence of local deflections on structural response, shell elements were employed to model brace member as well as base columns. Cross sections components with relatively high amplitude of
buckling parameters were considered in different case studies to make it susceptible to develop local deflection. Beam elements were also utilized to develop models with the same specification. FEM method applied to conduct nonlinear time history analysis using earthquake record in in-plane and
out-of-plane direction
International Journal of Engineering and Science Invention (IJESI) inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
SENSITIVITY ANALYSIS ABOUT INFLUENCE OF OUT-OF-PLANE DEFLECTIVE DEFORMATION ...IAEME Publication
In this study, it is aimed at verifying the relationship between amount of the initial deflective deformation of simply supported steel plates and ultimate compressive strength of them through elasto-plastic finite deformation analysis. When initial deflection has been controlled smaller unitl now or out-of plane deformation has become large after an earthquake, the current compressive strength curve of steel plates in Japan cannot be applied. Therefore, more accurate prediction method have been required in near future, on behalf of rational design of steel structures. In other words, it is needed to make clear the relationship between the initial imperfection and the strength of simply supported steel plate. For this purpose, the parametric study on compressive strength of steel plates taking the initial deflection and a width-thickness ratio parameter into account was carried out.
The purpose of the experimental work presented in this study is to study the effect
of concrete compressive strength and steel reinforcement ratio on capacity and
deflection of reinforced concrete two-way slabs. Three steel reinforcement ratios are
considered which are minimum, maximum and average of them in addition to two
concrete compressive strength
values of 20 and 30 MPa. The results from
experimental work show that increasing the reinforcing steel ratio leads to increase the
ultimate capacity of the slab in addition to decrease the maximum deflection. For slabs
with
= 20 MPa, increasing the reinforcing steel ratio from the minimum to the
maximum, i.e. 600 %, leads to increase ultimate capacity by about 156 % and decrease
maximum deflection by about 52 %. Wheras, For slabs with
= 30 MPa, increasing
the reinforcing steel ratio from the minimum to the maximum, i.e. 900 %, leads to
increase ultimate capacity by about 155 % and decrease maximum central deflection
by about 27 %. In addition, matmatical expresions for load-deflection relationships are
presented in the current study
SUGGESTING DEFLECTION EXPRESSIONS FOR RC 2-WAY SLABSIAEME Publication
The purpose of the experimental work presented in this study is to study the effect
of concrete compressive strength and steel reinforcement ratio on capacity and
deflection of reinforced concrete two-way slabs. Three steel reinforcement ratios are
considered which are minimum, maximum and average of them in addition to two
concrete compressive strength
values of 20 and 30 MPa. The results from
experimental work show that increasing the reinforcing steel ratio leads to increase the
ultimate capacity of the slab in addition to decrease the maximum deflection. For slabs
with
= 20 MPa, increasing the reinforcing steel ratio from the minimum to the
maximum, i.e. 600 %, leads to increase ultimate capacity by about 156 % and decrease
maximum deflection by about 52 %. Wheras, For slabs with
= 30 MPa, increasing
the reinforcing steel ratio from the minimum to the maximum, i.e. 900 %, leads to
increase ultimate capacity by about 155 % and decrease maximum central deflection
by about 27 %. In addition, matmatical expresions for load-deflection relationships are
presented in the current study.
Seismic Capacity Comparisons of Reinforced Concrete Buildings Between Standar...drboon
Earthquakes are cause of serious damage through the building. Therefore, moment resistant frame buildings are widely used as lateral resisting system. Generally three types of moment resisting frames are designed namely Special ductile frames (SDF), Intermediate ductile frames (IDF) and Gravity load designed (GLD) frames, each of which has a certain level of ductility. Comparative studies on the seismic performance of three different ductility of building are performed in this study. The analytical models are considered about failure mode of column (i.e. shear failure, flexural to shear failure and flexural failure); beam-column joint connection, infill wall and flexural foundation. Concepts of incremental dynamic analysis are practiced to assess the required data for performance based evaluations. This study found that the lateral load capacity of GLD, IDF, and SDF building was 19.25, 27.87, and 25.92 %W respectively. The average response spectrum at the collapse state for GLD, IDF, and SDF are 0.75 g, 1.19 g, and 1.33 g, respectively. The results show that SDF is more ductile than IDF and the initial strength of SDF is close to IDF. The results indicate that all of frames are able to resistant a design earthquake.
Buckling behavior of straight slot tubesunder oblique loading – A comparative...IJAEMSJORNAL
Hollow tubes are the most important or crucial parts of the rapidly growing automobile and construction industry. The tube is subjected to pure buckling. In theanalysis, one end is fixed and the force is applied to theother end and by application of different angles of inclinations ranging from 0˚ to 20˚ with different thicknessof the range of 0.5 to 2.0. Linear buckling code was used forfinding the critical buckling load. This research paper is about the effects of buckling under oblique loading. It is the process in which the tube is subjected to compressive oblique loading and the tube fails by the first increase in crossectional area and then bulging on any of the sides but in the case, oblique loading in hollow tube shell bulges internally or inside the perimeter of the tube.
Finite Element Simulation of Steel Plate Concrete Beams subjected to ShearIJERA Editor
In a test series ofSteel plate Concrete (SC) beams conducted by the authorsto determine the minimum shear
reinforcement ratio, complex structural behavior of the tested beams was observed, including shear cracking
occurred within the concrete in the web and bond-slip failure of the bottom steel plate of the beam due to
insufficient shear reinforcement ratio (Qin et al. 2015).This paper focuses on finite element simulation (FEM) of
the SC beams withemphasis on shear and bond-slip behavior. A new constitutive model is proposed to account for
the bond-slip behavior of steel plates. Also, the Cyclic Softened Membrane Model proposed by Hsu and Mo
(2010)is utilized to simulate the shear behavior of concrete with embedded shear reinforcement. Both constitutive
models areimplemented into a finite element analysis program based on the framework of OpenSees (2013).The
proposed FEM is able to capturethe behavior of the tested SC beams.
Finite Element Simulation of Steel Plate Concrete Beams subjected to ShearIJERA Editor
In a test series ofSteel plate Concrete (SC) beams conducted by the authorsto determine the minimum shear
reinforcement ratio, complex structural behavior of the tested beams was observed, including shear cracking
occurred within the concrete in the web and bond-slip failure of the bottom steel plate of the beam due to
insufficient shear reinforcement ratio (Qin et al. 2015).This paper focuses on finite element simulation (FEM) of
the SC beams withemphasis on shear and bond-slip behavior. A new constitutive model is proposed to account for
the bond-slip behavior of steel plates. Also, the Cyclic Softened Membrane Model proposed by Hsu and Mo
(2010)is utilized to simulate the shear behavior of concrete with embedded shear reinforcement. Both constitutive
models areimplemented into a finite element analysis program based on the framework of OpenSees (2013).The
proposed FEM is able to capturethe behavior of the tested SC beams.
Analysis and Optimum Design for Steel Moment Resisting Frames to Seismic Exci...IJCMESJOURNAL
The essential purpose of this wander is to develop an Interior Penalty Function (IPF) based estimation to multi-storey steel traces for slightest weight of frames. The frames are proposed for contradicting even impact in view of seismic stacking close by gravity forces. Various structural stems are used for restricting seismic (lateral) forces; however steel moment resisting frames (MRFs) are considered for the present work. The framework solidifies codal courses of action of IS 800-2007, as needs be gets the edges with perfect weight for in-plane moments with lateral support of beam element. Strength and buckling criteria are considered as direct goals close by side constraints in formulating optimization problem. A Software program is made that uses an interior penalty function (IPF) for weight minimization of two-dimensional moment restricting steel encompassed structures. The program uses MATLAB, performs one dimensional interest, and structural design in an iterative technique. The design cases have exhibited that the proposed estimation gives a beneficial instrument to the practicing fundamental algorithm. The program is associated with 6 and 9 storey (4 bays) moment resisting frames (MRFs). The program showed its capacity of optimizing the largeness of two medium size frames. To get part obliges in frames an examination technique must be associated. In the present work Equivalent Lateral Force framework (ELF) and material nonlinear time history analysis (NTH) are associated and perfect qualities gained from both the examinations are contemplated.
Analysis and Optimum Design for Steel Moment Resisting Frames to Seismic Exci...IJCMESJOURNAL
The essential purpose of this wander is to develop an Interior Penalty Function (IPF) based estimation to multi-storey steel traces for slightest weight of frames. The frames are proposed for contradicting even impact in view of seismic stacking close by gravity forces. Various structural stems are used for restricting seismic (lateral) forces; however steel moment resisting frames (MRFs) are considered for the present work. The framework solidifies codal courses of action of IS 800-2007, as needs be gets the edges with perfect weight for in-plane moments with lateral support of beam element. Strength and buckling criteria are considered as direct goals close by side constraints in formulating optimization problem. A Software program is made that uses an interior penalty function (IPF) for weight minimization of two-dimensional moment restricting steel encompassed structures. The program uses MATLAB, performs one dimensional interest, and structural design in an iterative technique. The design cases have exhibited that the proposed estimation gives a beneficial instrument to the practicing fundamental algorithm. The program is associated with 6 and 9 storey (4 bays) moment resisting frames (MRFs). The program showed its capacity of optimizing the largeness of two medium size frames. To get part obliges in frames an examination technique must be associated. In the present work Equivalent Lateral Force framework (ELF) and material nonlinear time history analysis (NTH) are associated and perfect qualities gained from both the examinations are contemplated.
11(4) 2020 ITJEMAST Multidisciplinary Research Articlesdrboon
Research papers 2020 Behavioral finance; Personality traits; Behavioral factors; Overconfidence bias; Locus of control; Decision-making; Biased behavior Carbon (CO2) emissions; Economic Growth; Energy consumption; Trade; ARDL Approach; Granger Causality; Energy use Pedestrian start-up time; Street crosswalk, Pedestrian traffic signals; Pedestrians traffic lights; zebra crossings; Intersection crossings Service Attributes; Relationship quality; Relationship outcomes; Banking services; Electronic Customer Relationship Management; Virtual relationships; eBanking; eCRM College town landscape; College town character; Campus community; Urban identity; College town space; Sense of a place; Public Space; University gardens; Cultural identity; Campus identity; Businesses in college towns Emotional quotient; Self-emotional appraisal; Workplace Advice Network (WAN) Centrality; Service Sector Organizations; Sociometric matrix; Interconnectivity of nodes
11(3) 2020 ITJEMAST Multidisciplinary Research Articles drboon
Non-destructive testing method Heat loss Thermal conductivity Specific heat Know-how Psychological contract breach Employees' Workplace behaviour Workplace spirituality Human resource management (HRM) Power sector Positive classroom Male teachers Classroom management system Public primary schools Private primary school Positive motivation students Quality primary education Grout rheology Construction workings High-precision lining Tunneling complex Cement slurry Reinforcement solutions Smart building systems Green architecture Green roof Green design Sustainable environmental architecture Smart energy management Architecture technology Neo-Functionalism Trade integration CPEC agreement Economic integration Regional cooperation Pak-China relations Pak-Iran relations Central Asia Republics Sino-Pakistan Agreement
11(2)2020 International Transaction Journal of Engineering, Management, & Ap...drboon
Multidisciplinary Management, Journalism and Mass Communication Science (Information and Media Sciences), Political Sciences (International Affairs), Global Studies), Animal Sciences, Feeding Technology, Healthcare Management.
V8(3) 2017:: International Transaction Journal of Engineering, Management, & ...drboon
Research articles published in V8(3) 2017:: International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies ==>
Awareness of Passive Design on Apartment Façade Designs in Putrajaya, Malaysia
127
Comparative Analysis of Low-Cost Housing Policies in Malaysia and Nigeria
139
A Study on Kevin Lynch’s Urban Design Elements: Precinct 9 East Putrajaya
153
Investigating Urban Design Elements of Bandar Baru Sentul, Kuala Lumpur
169
A Study on Sharing Home Ownership Schemes in Malaysia
183
The Impact of Window to Wall Ratio (WWR) and Glazing Type on Energy Consumption in Air-Conditioned Office Buildings
197
Competitiveness Factors of Thai Construction Industry within the AEC Context: A Qualitative Approach
209
Application of Confirmatory Factor Analysis in Government Construction Procurement Problems in Thailand
221
In a world of rapidly increasing urbanization, striving to develop more livable cities, the city’s streets designing and planning should be high on the agenda for policymakers, city planners and other practitioners, as well as researchers. Designing streets is not as easy as it might originally seem, however, done correctly it means that one third of the city was designed successfully with an immense impact on the rest of the city. The key challenge in developing sustainable and fulfilling streets is to develop an integrated approach in planning them, where it is necessary to consider all aspects involved. Meanwhile, efforts devoted to this topic vary considerably from place to place. Thus, this paper aims at discussing the main elements involved in designing streets for a livable city, in a comprehensive approach including pedestrians, vehicles, and parking areas.
Impact of Building Envelope Modification on Energy Performance of High-Rise A...drboon
In residential buildings, providing comfortable living environment for building occupants is a major challenge for architects, engineers and those who involved in the building industry. It is reported that considerable energy is consumed to provide and maintain acceptable indoor conditions for thermal comfort in residential buildings in hot-humid climate. The observable increase in energy consumption is chiefly resulting from the growing use of air conditioning system. There are various energy conservation measures which can be applied to reduce energy consumption and among these measures are passive envelope design measures. This paper addresses the energy performance of selected high-rise apartments in Kuala Lumpur. Energy Plus software is utilized in measuring the performance because of its availability, validity and accuracy. Possible energy savings due to passive envelope design measures integration are investigated. This includes investigating the effect of thermal insulation and glazing type on potential energy savings.
Enhancement of Space Environment Via Healing Gardendrboon
Green nature, sunlight and fresh air have been known as important component of healing in healthcare facilities. This paper presents the finding of an exploratory study on healing garden elements in healthcare facilities. The purpose of the paper is to find the elements of healing gardens and its healing factors in the existing garden design. In conducting this research study, site observation and informal interview at selected healthcare facilities have been performed. The study reveals the elements of existing garden design, the interactivity and the end users expectation on a garden. The finding shows that lacking some of the elements of garden design lead to less user friendliness and interactivity in the garden. It also shows that the visibility, accessibility, quietness and comfortable condition in the garden give impact to the utilization of the garden.
Design of Quadruped Walking Robot with Spherical Shelldrboon
We propose a new quadruped walking robot with a spherical shell, called "QRoSS." QRoSS is a transformable robot that can store its legs in the spherical shell. The shell not only absorbs external forces from all directions, but also improves mobile performance because of its round shape. In rescue operations at a disaster site, carrying robots into a site is dangerous for operators because doing so may result in a second accident. If QRoSS is used, instead of carrying robots in, they are thrown in, making the operation safe and easy. This paper reports details of the design concept and development of the prototype model. Basic experiments were conducted to verify performance, which includes landing, rising and walking through a series of movements.
Motion Analysis of Pitch Rotation Mechanism for Posture Control of Butterfly-...drboon
We developed a small flapping robot on the basis of movements made by a butterfly with a low flapping frequency of approximately 10 Hz, a few degrees of freedom of the wings, and a large flapping angle. In this study, we clarify the pitch rotation mechanism that is used to control its posture during takeoff for different initial pitch and flapping angles by the experiments of both manufactured robots and simulation models. The results indicate that the pitch angle can be controlled by altering the initial pitch angle at takeoff and the flapping angles. Furthermore, it is suggested that the initial pitch angle generates a proportional increase in the pitch angle during takeoff, and that certain flapping angles are conducive to increasing the tendency for pitch angle transition. Thus, it is shown that the direction of the flight led by periodic changing in the pitch angle can be controlled by optimizing control parameters such as initial pitch and flapping angles.
Analysis of Roll Rotation Mechanism of a Butterfly for Development of a Small...drboon
In this paper, we investigated the aerodynamic characteristics during roll rotation of a butterfly based on computational fluid dynamics using a three-dimensional high-speed camera information. This method allows to create a numerical model of a butterfly from the camera images and to analyze the flow field corresponding to the captured behavior. We photographed two behaviors different in rotational axis and analyzed the roll rotational mechanism. In a typical pitch rotational flight, the differential pressure was concentrated on the tip of fore wings. The magnitudes of reaction forces on left and right wings were roughly matched each other. On the other hands, the differential pressure of the roll rotational flight was distributed in the whole of wings. The magnitude of the right reaction force was twice greater than that of left at the first down stroke. The roll angle changed largely at the same time. These results show that a butterfly rotates about roll by changing the reaction forces on each side.
Effect of Oryzalin on Growth of Anthurium andraeanum In Vitrodrboon
Apical shoots and lateral buds of Anthurium andraeanum about 0.5 cm grew very well when cultured on MS medium supplemented with NAA, kinetin, sucrose and gelrite. When brought young plantlets (the same sized) of A. andraeanum soaked in various concentrations of oryzalin with different duration times. The A. andraeanum plantlets were subcultured into the same medium every 4 weeks for 3 times. It was found that 5.0 mg/l oryzalin with 24 and 72 hours gave the best average number of leaves per bunch, plant height and diameter of bunch. These parameters were reverse proportion, when increased concentration of oryzalin, the growth rate in each parameter was decreased with thick and pale green leaves.
Role of 2,4-D on Callus Induction and Shoot Formation to Increase Number of S...drboon
Stem node of Miniature Rose with axillary bud were used as explants. These explants cultured on MS medium supplemented with different concentrations of 2,4-D. It was found that MS medium supplemented with 0.5 mg/l 2,4-D gave the highest number of green callus. The callus cultured on MS medium supplemented with different combinations of NAA and BA to form new shoot and root. From the result, we are able to find the highest number of young shoots that were induced from callus when cultured callus on MS medium supplemented with NAA and BA. When subcultured all new shoots with the same size to MS medium supplemented with different concentrations of NAA and BA, and 2,4- D for six weeks. The result was significant difference (P≤0.5) when compared the average height of plant and percentage of root formation, but their duration time for flowering were not significant different.
ITJEMAST5(2): Latest Research from International Transaction Journal of Engin...drboon
An After-Stay Satisfaction Survey of Residents Living in Prefabricated Concrete Structures in Thailand
Hydrothermal Assisted Microwave Pyrolysis of Water Hyacinth for Electrochemical Capacitors Electrodes
Group Technology Paves the Road for Automation
Effect of Laser Priming on accumulation of Free Proline in Spring Durum Wheat (Triticum turgidum L.) under Salinity Stress
Livable Public Open Space for Citizen’s Quality of Life in Medan, Indonesia
ITJEMAST5(1): Latest Research from International Transaction Journal of Engin...drboon
Latest Research from International Transaction Journal of Engineering, Management, & Applied Sciences & Technologies ITJEMAST5(1):
Effects of Calcination Treatment of Diatomite on Dimethyl Ether Synthesis from Methanol
Effect of Blend Ratio on Cure Characteristics, Mechanical Properties, and Aging Resistance of Silica-filled ENR/SBR Blends
An Efficient Formulation of Off-line Model Predictive Control for Nonlinear Systems Using Polyhedral Invariant Sets
Effect of Modeling Parameters on System Hydrodynamics of Air Reactor in Chemical Looping Combustion Using CFD Simulation
Flow Behavior of Geldart A and Geldart C Particles in a Co-current Downflow Circulating Fluidized Bed Reactor
Optimization of Enzymatic Clarification from Corncob
Synthesis of Alkali Metal/CaO Sorbent for CO2 Capture at Low Temperature
Effect of Exchangeable Cations on Bentonite Swelling Characteristics of Geosy...drboon
Geosynthetic clay liners (GCLs) are thin hydraulic barriers which contain the bentonite sandwiched between geotextiles or geomembrane. Bentonite swelling is a very common phenomenon observed in GCLs. It is one of the major causes for permeability reduction in hydraulic barriers. The aim of this study is to characterize the swelling behavior of bentonite in GCLs by exchangeable cations. X-ray diffraction test and scanning electron microscopy were used to quantify the swelling characteristics of this bentonite under contact with salt solutions, as in the hydraulic barriers. The results from X-ray diffraction test showed that the presence of clay minerals was swelling montmorillonite. The swell volume of bentonite decreases with increasing valence of cations. In the case of the same valence the free swell volume of bentonite increased with decreasing concentration of permeant liquids. From another test, the scanning electron microscopy, it can be seen that the bentonite appears as corn flake like crystals for air-dried bentonite. However, specimen permeated with salt solutions, the clay has become more porous and fluffy and porous size seemed to be diminished.
City Space and Social Values: A Lesson from the Past of Historical City of Tu...drboon
Theory that emerges and tends to impose a new urbanity and liveability is that of Ecopolis of the future - ecologically clean city-which focuses on the concept of sustainable development while giving priority to the relationship between economic, social development and quality of life in the built environment. Traditionally cultural aspect of urbanism contains components with an appropriate sacred cosmic symbolism and an urbanism of social consensus between residents, government and professionals in the creation of the Ecopolis. The empirical focus of this paper is the city within the Islamic cultural tradition. This paper is an attempt to grasp the cultural conception of the Medina of Tunis, Tunisia and the traditional urban regulations by a study of classical religio-architectural treatises of Islam. This article will discuss the approach and the lesson we can learn from the traditional modele in a time of ecological crisis and high urbanization.
Slack (or Teams) Automation for Bonterra Impact Management (fka Social Soluti...Jeffrey Haguewood
Sidekick Solutions uses Bonterra Impact Management (fka Social Solutions Apricot) and automation solutions to integrate data for business workflows.
We believe integration and automation are essential to user experience and the promise of efficient work through technology. Automation is the critical ingredient to realizing that full vision. We develop integration products and services for Bonterra Case Management software to support the deployment of automations for a variety of use cases.
This video focuses on the notifications, alerts, and approval requests using Slack for Bonterra Impact Management. The solutions covered in this webinar can also be deployed for Microsoft Teams.
Interested in deploying notification automations for Bonterra Impact Management? Contact us at sales@sidekicksolutionsllc.com to discuss next steps.
Key Trends Shaping the Future of Infrastructure.pdfCheryl Hung
Keynote at DIGIT West Expo, Glasgow on 29 May 2024.
Cheryl Hung, ochery.com
Sr Director, Infrastructure Ecosystem, Arm.
The key trends across hardware, cloud and open-source; exploring how these areas are likely to mature and develop over the short and long-term, and then considering how organisations can position themselves to adapt and thrive.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Kubernetes & AI - Beauty and the Beast !?! @KCD Istanbul 2024Tobias Schneck
As AI technology is pushing into IT I was wondering myself, as an “infrastructure container kubernetes guy”, how get this fancy AI technology get managed from an infrastructure operational view? Is it possible to apply our lovely cloud native principals as well? What benefit’s both technologies could bring to each other?
Let me take this questions and provide you a short journey through existing deployment models and use cases for AI software. On practical examples, we discuss what cloud/on-premise strategy we may need for applying it to our own infrastructure to get it to work from an enterprise perspective. I want to give an overview about infrastructure requirements and technologies, what could be beneficial or limiting your AI use cases in an enterprise environment. An interactive Demo will give you some insides, what approaches I got already working for real.
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
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What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Epistemic Interaction - tuning interfaces to provide information for AI supportAlan Dix
Paper presented at SYNERGY workshop at AVI 2024, Genoa, Italy. 3rd June 2024
https://alandix.com/academic/papers/synergy2024-epistemic/
As machine learning integrates deeper into human-computer interactions, the concept of epistemic interaction emerges, aiming to refine these interactions to enhance system adaptability. This approach encourages minor, intentional adjustments in user behaviour to enrich the data available for system learning. This paper introduces epistemic interaction within the context of human-system communication, illustrating how deliberate interaction design can improve system understanding and adaptation. Through concrete examples, we demonstrate the potential of epistemic interaction to significantly advance human-computer interaction by leveraging intuitive human communication strategies to inform system design and functionality, offering a novel pathway for enriching user-system engagements.
AI for Every Business: Unlocking Your Product's Universal Potential by VP of ...
Cyclic Elastoplastic Large Displacement Analysis and Stability Evaluation of Steel Tubular Braces
1. 2012 American Transactions on Engineering & Applied Sciences
American Transactions on
Engineering & Applied Sciences
http://TuEngr.com/ATEAS, http://Get.to/Research
Cyclic Elastoplastic Large Displacement Analysis and
Stability Evaluation of Steel Tubular Braces
a*
Iraj H. P. Mamaghani
a
Department of Civil Engineering, School of Engineering and Mines, University of North Dakota, USA.
ARTICLEINFO A B S T RA C T
Article history: This paper deals with the cyclic elastoplastic large
Received 23 August 2011
Accepted 9 January 2012 displacement analysis and stability evaluation of steel tubular braces
Available online subjected to axial tension and compression. The inelastic cyclic
18 January 2012 performance of cold-formed steel braces made of circular hollow
Keywords: sections is examined through finite element analysis using the
Cyclic, commercial computer program ABAQUS. First some of the most
Elastoplastic, important parameters considered in the practical design and ductility
Large displacement,
evaluation of steel braces of tubular sections are presented. Then the
Analysis,
Stability, details of finite element modeling and numerical analysis are
Steel, described. Later the accuracy of the analytical model employed in the
Tubular, analysis is substantiated by comparing the analytical results with the
Brace, available test data in the literature. Finally the effects of some
Finite-Element. important structural and material parameters on cyclic inelastic
behavior of steel tubular braces are discussed and evaluated.
2012 American Transactions on Engineering & Applied Sciences.
1. Introduction
Steel braced frames are one of the most commonly used structural systems because of their
structural efficiency in providing significant lateral strength and stiffness. The steel braces
*Corresponding author (Iraj H.P. Mamaghani). Tel: +1-701-777 3563, Fax: +1-701-777
3782. E-mail address: iraj.mamaghani@engr.und.edu. 2012. American Transactions on
Engineering & Applied Sciences. Volume 1 No.1 ISSN 2229-1652 eISSN 2229-1660
75
Online Available at http://TUENGR.COM/ATEAS/V01/75-90.pdf
2. contribute to seismic energy dissipation by deforming inelastically during an earthquake. The use
of this type of construction indeed avoids the brittle fractures found in beam-to-column
connections in moment-resisting steel frames that occurred in the Northridge earthquake in 1994
and the Kobe earthquake in 1995 (ASCE, 2000; IGNTSDSS , 1996). However, careful design of
steel braced frames is necessary to avoid possible catastrophic failure by brace rupture in the event
of severe seismic loading. The current capacity design procedure adopted in most seismic design
steel specifications (AISC, 1997; CAN-CSA S16.1, 1989), for concentrically braced frames
requires yielding in the braces as primary members, whereas the secondary members of the frame
should remain elastic and hence carry forces induced by the yielding members. The transition from
current perspective seismic codes to performance-based design specifications requires accurate
predictions of inelastic limit states up to structural collapse.
The cyclic behavior of steel brace members is complex due to the influence of various
parameters such as material nonlinearity, structural nonlinearity, boundary condition, and loading
history. The material nonlinearity includes structural steel characteristics such as residual stresses,
yield plateau, strain hardening and Bauschinger effect. The structural nonlinearity includes
parameters such as brace slenderness, cross-section slenderness, width-to-thickness ratio of the
cross-section’s component elements (or radius-to-thickness ratio of circular hollow sections), and
initial out-of-straightness of the brace. This complex behavior results in various physical
phenomena, such as yielding in tension, buckling in compression, postbuckling deterioration of
compressive load capacity, deterioration of axial stiffness with cycling, and low- cycle fatigue
fractures at plastic regions.
Steel braces can be designed to resist only tensile forces, or to resist both tensile and
compressive axial forces. Recent earthquakes and experiments have shown that the
tension-compression braces provide better performance under cyclic loading (during an
earthquake) as compared with the tension-only braces having almost no compressive strength
(IGNTSDSS, 1996). Under severe earthquakes, the braces are subjected to cyclic axial forces and
they are allowed to undergo compression buckling or tensile yield to dissipate the imposed energy
while columns and collector beams respond elastically. Therefore, understanding the behavior of
the bracing members under idealized cyclic loading is an important step in the careful design of
steel braced frames.
76 Iraj H.P. Mamaghani
3. This paper deals with the inelastic cyclic analysis of steel tubular braces. The most important
parameters considered in the practical design and ductility evaluation of steel braces of tubular
sections are presented. The cyclic performance of steel tubular braces is examined through finite
element analysis using the computer program ABAQUS (2005). 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. The effects of some important structural and material
parameters on inelastic cyclic behavior of steel braces are discussed and evaluated.
2. Brace Parameters
Energy absorption through hysteretic damping is one of the great interests in seismic design,
because it can reduce the amplitude of seismic response, and thereby reduce the ductility demand
on the structure. Steel braces are very effective structural members and are widely used as energy
dissipaters in skeletal buildings and offshore structures under extreme loading conditions such as
severe earthquake and wave motion. They also minimize story drift of high-rise buildings for
possible moderate earthquakes during their lifetime.
The most important parameters considered in the practical design and ductility evaluation of
steel braces of tubular sections are section slenderness λ s (Mamaghani, et. al., 1996a, 1996b, 1997;
Mamaghani, 2005, 2008) and slenderness ratio of the member λc (AISC, 1997, 1999). While the
former influences local buckling of the section, the latter controls the overal stability. They are
given by:
1b σy
λs = 3(1 −ν 2 ) ( for box sec tion ) (1)
π t E
d σ
λs = 3(1 −ν 2 ) y ( for circular sec tion ) (2)
2t E
1 KL σ y
λc = (3)
π r E
*Corresponding author (Iraj H.P. Mamaghani). Tel: +1-701-777 3563, Fax: +1-701-777
3782. E-mail address: iraj.mamaghani@engr.und.edu. 2012. American Transactions on
Engineering & Applied Sciences. Volume 1 No.1 ISSN 2229-1652 eISSN 2229-1660
77
Online Available at http://TUENGR.COM/ATEAS/V01/75-90.pdf
4. where, b = flange width of a box section; t = plate thickness of the cross-section elements;
σ y = measured yield stress; E = Young’s modulus; ν = Poisson’s ratio; d = outer diameter of
the circular section; K = effective length factor; L = measured length of the brace; and r= radius
of gyration of the cross section. It is worth noting that the section slenderness, λ s , represents the
width-thickness ratio parameter of the flange plate for a box section and the diameter-thickness
ratio of a circular hollow section for a given material.
The limiting diameter-thickness ratio specified in AISC (1997) for plastic design of circular
hollow sections is d / t = 0.045 E / σ y . This d / t limit can be converted to a limiting slenderness
parameter for a compact element according to Equation 2. The corresponding value of λ s ,
considering υ = 0.3 for structural steels, is:
0.045 E σy
λs = 3(1 − 0.32 ) = 0.037 (4)
2σ y E
This implies that when λs ≤ 0.037 , no local buckling occurs before the cross-section attains
full plastic capacity. The limiting width-thickness ratio specified in AISC (1997) for
non-compact circular hollow sections is d / t = 0.11E / σ y which corresponds to λ s = 0.09 .
The ductility behavior of the circular hollow section braces is significantly sensitive to λ s when it
is less than 0.09. The maximum member slenderness limits specified in AISC (1997) for
special concentrically braced frames (SCBF) and ordinary concentrically braced frames are
λ c = 1.87 ( KL / r ≤ 1000 / σ y ) and λc = 1.35 ( KL / r ≤ 720 / σ y ), respectively. SCBF are
expected to withstand significant inelastic deformation when subjected to the force resulting from
the motion of the design earthquake. SCBF have increased ductility due to lesser strength
degradation when compression braces buckle.
3. Numerical Method
Steel braces are vulnerable to damage caused by local and overall interaction buckling during
a major earthquake. A sound understanding of the inelastic behavior of steel braces is important in
developing a rational seismic design methodology and ductility evaluation of steel braced frame
structures.
78 Iraj H.P. Mamaghani
5. An accurate cyclic analysis of braced frames requires precise methods to predict the cyclic
inelastic large-deflection response of the braces. This has been a subject of intensive research and
a variety of analytical methods have been developed to simulate the hysteretic behavior of braces
over the past few decades. The main research approaches used for the cyclic analysis of braces may
be classified as: (1) empirical models, (2) plastic-hinge models, and (3) elastoplastic finite element
models (Mamaghani et al., 1996a). The more accurate models were based on the finite element
method considering geometric and material nonlinearities. This method is generally applicable to
many types of problems, and it requires only the member geometry and material properties
(constitutive law) to be defined.
3.1 Finite Element Method
The finite element analysis is carried out by using the commercial computer program
ABAQUS. The shell element S4R is used in modeling the brace member (ABAQUS, 2005). The
S4R element is a three-dimensional, double-curved, four-node shell element with six degrees of
freedom per node that uses bilinear interpolation. Because the S4R element contains only one
sample point while five layers are assumed across the thickness, the spread of plasticity is
considered through both the thickness and plane of the element. This shell element, which uses
reduced integration, is applicable to both thin and thick shells, and can be used for finite strain
applications.
In the analysis, both material and geometrical nonlinearities are considered. For large
displacement analysis, the elements are formulated in the current configuration, using current
nodal positions. Elements therefore distort from their original shapes as the deformation increases.
The stiffness matrix of the element is obtained from the variational principle of virtual work. The
modified Newton-Raphson iteration technique coupled with the displacement control method is
used in the analysis (Zienkiewicz, 1977). The displacement convergence criterion is adopted and
the convergence tolerance is taken as 10-5. The details of elastoplastic large-displacement
formulation and solution scheme are reported in the work by the author (Mamaghani, 1996).
*Corresponding author (Iraj H.P. Mamaghani). Tel: +1-701-777 3563, Fax: +1-701-777
3782. E-mail address: iraj.mamaghani@engr.und.edu. 2012. American Transactions on
Engineering & Applied Sciences. Volume 1 No.1 ISSN 2229-1652 eISSN 2229-1660
79
Online Available at http://TUENGR.COM/ATEAS/V01/75-90.pdf
6. 3.2 Analytical Modeling
A series of numerical studies on the cyclic behavior of steel braces are carried out using the
numerical finite element method described in the previous section, and the results are compared
with the experiments. The results for three typical examples, S7A, S7B, and S7C (Elchalakani et
al., 2003), presented hereafter are intended to verify the accuracy of the numerical method. These
specimens are subjected to three loading histories in order to better understand the cyclic behavior
of cold-formed circular hollow-section braces. The details of the test can be found in Elchalakani et
al. ( 2003).
Figure 1: Analyzed circular hollow section steel brace and initial imperfection.
Table 1: Properties of the analyzed braces.
Test Number Specimen Shape Ag (mm2) L (mm) λs λc δ y (mm) Py (kN)
S7A CHS 139.7x3.5 1498 2820 0.06 0.4 5.34 568
S7B CHS 139.7x3.5 1498 2820 0.06 0.4 5.34 568
S7C CHS 139.7x3.5 1498 2820 0.06 0.4 5.34 568
The shape and dimensions of the analyzed braces are given in Table 1. For comparison, the
selected brace parameters ( λc = 0.4 and λs = 0.06 ) are kept the same. These parameters represent
a non-compact member having inelastic behavior. The analyzed fixed-end tubular braces subjected
to cyclic concentric axial loading are modeled as shown in the Figure 1. An initial imperfection of
⎛ πx ⎞
γ x = γ 0 sin ⎜ ⎟ (5)
⎝ L ⎠
is assumed in the analysis, where the initial deflection at midspan of the member γ 0 is taken as the
measured value of L/3160 during the test.
80 Iraj H.P. Mamaghani
7. Figure 2: Tri-linear stress-strain model for steel.
3.3 Material Model
The analyzed cold-formed circular hollow sections are AS 1163 grade C350L0 (equivalent to
ASTM A500 tubes) with the yield stress of σ y = 379 MPa and the ultimate tensile strength of
σ u = 451 MPa. In the analysis, the material nonlinearity is accounted for by using the kinematic
hardening rule. Figure 2 shows the tri-linear stress-strain material model adopted in the analysis.
The Young modulus of elasticity of the steel is assumed to be E = 200 GPa. The strain hardening
modulus is assumed to be 2 percent of the initial Young modulus ( E st = 0.02 E ).
Figure 3: Meshing details and boundary conditions.
*Corresponding author (Iraj H.P. Mamaghani). Tel: +1-701-777 3563, Fax: +1-701-777
3782. E-mail address: iraj.mamaghani@engr.und.edu. 2012. American Transactions on
Engineering & Applied Sciences. Volume 1 No.1 ISSN 2229-1652 eISSN 2229-1660
81
Online Available at http://TUENGR.COM/ATEAS/V01/75-90.pdf
8. 3.4 Cyclic Loading History
In the analysis three cyclic loading histories are applied. The first loading history is a large
compression-tension monocycle with a maximum normalized displacement amplitude
m = δ max / δ y , where δ m ax is the maximum displacement in the compression-half cycle at load
reversal and δ y = ε y L = Py L / EA is the yield displacement corresponding to the squash load of cross
section Py = σ y A (A = area of the cross-section; σ y = yield stress; L= the length of the brace). The
large amplitude used in the monocycle is applied to examine the inelastic response of the brace
when subjected to a very large seismic demand during a possible near-field excitation (Krawinkler
et al., 2000). The second loading history is a uniform increase of displacement amplitude up to
failure with the maximum normalized displacement amplitudes of m = 1, 2, 3, …, where each
amplitude is repeated only once. In the third loading history, a uniform increase of the
displacement is used similar to the second loading history except that the oscillations are repeated
three times at each amplitude ( m = 1, 2, 3, …, etc.).
3.5 Finite Element Meshing and Boundary Conditions
The details of the finite-element meshing pattern adopted in the analysis of hollow circular
sections are shown in Figure 3. The brace is subdivided into a total number of 2100 shell elements
(70 elements along the brace length and 30 elements in the circumferential direction). A finer mesh
pattern is used at the center and the ends of the brace, where large deformation is expected, as
shown in Figure 3. In the analysis, the left end of the brace is fully fixed and the right end is
modeled as a guided support to apply axial displacement, as shown in Figure 3. The axial load, P,
and vertical deflection at midspan, V, are obtained from analysis.
4. Numerical Results
4.1 Example 1
The first example is concerned with the analysis of the brace S7A, which has a nominal length
of 2820 mm, a member slenderness parameter of λc = 0.4 and a section slenderness of λs = 0.06
(Table 1). These parameters represent a non-compact member having inelastic behavior.
This brace is subjected to a large compression-tension monocycle with maximum normalized
displacement amplitude of m = 18.24 (the first loading history) to examine the inelastic response of
82 Iraj H.P. Mamaghani
9. the brace under a very large seismic demand. This value is larger than the upper limit for m = 10 ,
which is likely to occur in a near-source excitation (Krawinkler et al., 2000). In order to check the
effects of mesh density and loading increment (loading time steps) on the inealstic cyclic behavior
of the brace, three analyses are carried out on this brace. The first analysis, designated as the
original analysis, uses the original meshing pattern shown in Figure 3 with a total number of 2100
shell elements. The second analysis, designated as the mesh-increment analysis, uses a finer mesh
density at the central segment and at the ends of the brace by doubling the mesh number in these
regions with a total number of 3300 shell elements. The third analysis, designated as the
step-increment analysis, utilizes the original meshing but doubling the time step by reducing the
displacement increment to half of that used in the original analysis. Figures 4a and 4b compare the
normalized axial load P / Py -axial deformation δ / δ y hysteresis loop obtained from the
experiment and analyses. With reference to these figures, the following observations can be made:
1. The initial stiffness and buckling load capacity are slightly lower in the experiment than
those predicted by the analyses using various mesh sizes and loading incremens. This may
be due to the experimental boundary conditions (unavoidable rotation at the fix-ends) and
the assumed initial imperfection in the analysis. In the analysis the cross-section
out-of-straightness and residual stress are not accounted for. It is worth noting that the
previous research by the author indicates that the initial residual stresses and initial section
imperfections significantly decrease the initial stiffness and initial buckling load capacity
and have almost no effect on the subsequent cyclic behavior of the member (Mamaghani et
al., 1996a, Banno et al., 1998).
2. Under compressive load, the overall buckling was followed by local buckling at the center
and brace ends. From Figures 4a and 4b, it can be observed that the overall shape of the
predicted hysteresis loop is significantly closer to the experiment.
3. Under tension load, the behavior of the brace is well predicted up to δ / δ y = 9.3 , where there
is a sharp decrease in predicted tensile strength beyond this displacement. The observed
discrepancy between experimental and analytical results when the specimen is stretched
beyond δ / δ y = 9.3 might be due to the formation of a plastic hinge at the member
midspan under combined biaxial hoop stress and axial stress. By further stretching the
*Corresponding author (Iraj H.P. Mamaghani). Tel: +1-701-777 3563, Fax: +1-701-777
3782. E-mail address: iraj.mamaghani@engr.und.edu. 2012. American Transactions on
Engineering & Applied Sciences. Volume 1 No.1 ISSN 2229-1652 eISSN 2229-1660
83
Online Available at http://TUENGR.COM/ATEAS/V01/75-90.pdf
10. member, the spread of plasticity fully covered the whole cross section at midspan and
extended on both sides of this section, leading to the reduction of load carrying capacity,
see Figure 5.
1.5
1.5
1
1
0.5
0.5
0
0 -20 -10 0 10 20
-20 -10 0 10 20
-0.5 δ/δy
-0.5 δ/δy
Original analysis
-1 Step-increased
-1
Test Mesh-increased
P/Py
P/Py
Analysis -1.5 Test
-1.5
(a) Axial load versus axial displacement. (b) Effects of mesh density and load steps.
1.5 1.5
S7A
1
1
0.5
0.5
0
0
-400 -300 -200 -100 0 100
-50 -40 -30 -20 -10 0 10
v (mm) -0.5
Local buckling -0.5
progress (mm)
Node 1088 -1
Node 1104 -1
P/Py
-1.5
P/Py
-1.5
(c) Deflection at the top face (Node 1088) (d) Local buckling progress at midspan
and bottom face (Node 1104) of the
cross-section at midspan.
Figure 4: Comparison between experimental and predicted hysteretic loop for brace S7A.
4. The results in Figure 4(b) show that the increase in time step and use of fine mesh do not
have significant effects on the overall predicted behavior except for a slight improvement in
postbuckling behavior where the predicted results closely fit the test results. Under tensile
loading beyond the δ / δ y = 9.3 , the predicted tensile load capacity drops slightly earlier
84 Iraj H.P. Mamaghani
11. for the analysis using fine mesh as compared with the other analyses. This is because the
spread of plasticity and formation of the plastic hinge takes place faster for the fine mesh
model.
Figure 4(c) shows normalized axial load P / Py versus vertical deflection V, at the top face
(Node 1088) and bottom face (Node 1104) of the cross-section at the midspan of the member
(Figure 3), obtained from the analysis. The results in this figure show that the relative vertical
deflection at the top and bottom faces of the cross-section at midspan increases as the member
undergoes large axial deformation. The difference between the vertical displacements of the top
face and bottom face at midspan indicates the progress of local buckling, which is plotted in Figure
4(d). Figure 5 shows the deformation of the specimen at the end of compression load and tension
stretching. Under compression load, the overall buckling was followed by local buckling at the
center and brace ends. A smooth kink formed at midspan of the brace under compression load. A
semi-elephant-foot (an outward folding mechanism) was formed at the fixed ends of the brace, as
shown in Figure 5. During the tensile stretching, the brace suffered excessive stretching at the
midspan because of the development of a plastic hinge caused by a very large accumulation in local
deformation. This represents a tear-through-failure mode, as the specimen exhibited during the test
(Elchalakani et al., 2003). These observed behaviors under compression and tension loads are
reflected in the normalized load-displacement hysteretic loop shown in Figure 4.
4.2 Example 2
The second example is concerned with the analysis of the brace S7B, which has a nominal
length of 2820 mm, a member slenderness of λc = 0.4 and a section slenderness of λ s = 0.06 (Table
1). This brace is subjected to a uniform increase of displacement amplitude up to failure with the
maximum normalized displacement amplitudes of m = 1, 2, 3, …, where each amplitude is
repeated only once (the second loading history). The original meshing pattern shown in Figure 3,
with a total number of 2100 shell elements, is utilized in the analysis.
*Corresponding author (Iraj H.P. Mamaghani). Tel: +1-701-777 3563, Fax: +1-701-777
3782. E-mail address: iraj.mamaghani@engr.und.edu. 2012. American Transactions on
Engineering & Applied Sciences. Volume 1 No.1 ISSN 2229-1652 eISSN 2229-1660
85
Online Available at http://TUENGR.COM/ATEAS/V01/75-90.pdf
12. Figure 5: Deformed configuration of brace S7A at the final stage of compression and tension cyclic
loading.
Figure 6(a) compares the normalized axial load P / Py -axial deformation δ / δ y hysteresis
loops obtained from the experiment and analysis. Figure 6(b) shows the normalized axial load
P / Py versus vertical deflection V, at the midspan of the member (Figure 3), obtained from the
analysis. Comparison between hysteresis loops in Figure 6(a) shows that there is a relatively good
agreement between analytical results and experiments. An observed small discrepancy between
experimental and analytical hysteresis loops is that the predicted cyclic load capacities in
compression direction of loading are slightly higher than those of the experiment. The possible
reasons are: (a) the tri-linear kinematic hardening rule adopted in the analysis does not accurately
consider the reduction of the elastic range due to plastic deformation (Bauschinger effect). In this
model the size of the elastic range is taken to be constant which does not represent the actual
behavior of structural steel (Mamaghani et al. 1995; Shen et al., 1995). More accurate results can
be obtained from analysis using a cyclic constitutive law representing the more realistic behavior of
the material; (b) the brace fixed-end boundary conditions may have shown some degree of
flexibility during the tests, which is not considered in the analysis; and (c) in the analysis the
cross-section’s out of straighness and residual stresses, which affect the initial buckling load, are
not considered.
86 Iraj H.P. Mamaghani
13. 1.5
1 1.5
0.5 1
0.5
0
-8 -4 0 4 8
δ/δy 0
-0.5 -200 -150 -100 -50 0
V (mm)
-0.5
-1
Test
-1
P/Py
Analysis
P/Py
-1.5 Analysi
-1.5
(a) (b)
Figure 6: Comparison between experimental and predicted hysteretic loop for brace S7B.
Figure 6(b) shows that there is a residual midspan deflection at the end of tensioning in each
cycle. The residual deflection of the brace at the end of the previous tensioning has a large effect
on the buckling capacity and subsequent cyclic behavior. Figure 6(b) shows the progress of
residual midspan deflection due to cycling obtained from analysis. In spite of large progress in
buckling, the buckling load does not decrease significantly due to cyclic strain hardening.
4.3 Example 3
The third example is concerned with the analysis of the brace S7C, which has a nominal length
of 2820 mm, a member slenderness of λ c = 0.4 and a section slenderness of λs = 0.06 (Table 1).
This brace is subjected to a uniform increase in displacement amplitude up to failure with the
maximum normalized displacement amplitudes of m = 1, 2, 3, …, where each amplitude is
repeated three times (the third loading history). The original meshing pattern as shown in Figure 3,
with a total number of 2100 shell elements, is utilized in the analysis.
Figure 7(a) compares the normalized axial load P / P -axial deformation δ / δ y hysteresis loop
y
obtained from experiment and analysis. Figure 7(b) shows the normalized axial load P / Py versus
vertical deflection V, at the midspan of the member (Figure 3), obtained from the analysis.
Comparison between hysteresis loops in Figure 7(a) shows there is a relatively good agreement
*Corresponding author (Iraj H.P. Mamaghani). Tel: +1-701-777 3563, Fax: +1-701-777
3782. E-mail address: iraj.mamaghani@engr.und.edu. 2012. American Transactions on
Engineering & Applied Sciences. Volume 1 No.1 ISSN 2229-1652 eISSN 2229-1660
87
Online Available at http://TUENGR.COM/ATEAS/V01/75-90.pdf
14. between analytical results and experiments. These results indicate 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 axially loaded fixed-end steel braces of
circular hollow sections.
1.5
1.5
1
1
0.5
0.5
0
-8 -4 0 4 8 0
-200 -150 -100 -50 0
δ/δy
-0.5
V (mm) -0.5
-1 Test
-1
Analysis
P/Py
P/Py
-1.5 Analysis
-1.5
(a) (b)
Figure 7: Comparison between experimental and predicted hysteretic loop for brace S7C.
5. Conclusions
This paper dealt with the inelastic cyclic elastoplastic finite-element analysis and stability
(strength and ductility) evaluation of steel tubular braces subjected to axial tension and
compression. The most important parameters considered in the practical seismic design and
ductility evaluation of steel braces of tubular sections, such as brace slenderness, cross-section
slenderness, material behavior, and loading history, were presented. The elastoplastic cyclic
performance of cold-formed steel braces of circular hollow sections was examined through
finite-element analysis using the commercial computer program ABAQUS and employing a
tri-linear kinematic strain hardening model to account for material nonlinearity. The details of
finite element modeling and numerical analysis were described. The accuracy of the analytical
model employed in the analysis was substantiated by comparing the analytical results with the
available test data in the literature. The effects of some important structural, material, and loading
history parameters on cyclic inelastic behavior of steel braces were discussed and evaluated with
reference to the experimental and analytical results. It has been shown that the numerical method
and finite element modeling employed in the numerical analysis can predict with a reasonable
88 Iraj H.P. Mamaghani
15. degree of accuracy the experimentally observed cyclic behavior of axially loaded fixed-end steel
braces of circular hollow sections.
6. References
ABAQUS / Standard User’s Manual. (2005). Ver. 6.5, Hibbitt, Karlsson and Sorensen, Inc.
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*Corresponding author (Iraj H.P. Mamaghani). Tel: +1-701-777 3563, Fax: +1-701-777
3782. E-mail address: iraj.mamaghani@engr.und.edu. 2012. American Transactions on
Engineering & Applied Sciences. Volume 1 No.1 ISSN 2229-1652 eISSN 2229-1660
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Iraj H.P. Mamaghani is an Associate Professor of Civil Engineering at University of North
Dakota. He received his B.Sc. in Civil Engineering from Istanbul Technical University with
Honors in 1989. He continued his Master and PhD studies at University of Nagoya, Japan, where
he obtained his Master and Doctor of Engineering degrees in Civil Engineering. Dr. Mamaghani
has published several papers in professional journals and in conference proceedings. Dr.
Mamaghani works in the area of civil engineering, with emphasis on structural mechanics and
structural engineering. He focuses on cyclic elastoplastic material modeling, structural stability,
seismic design, advanced finite element analysis and ductility evaluation of steel and composite
(concrete-filled steel tubular) structures.
Peer Review: This article has been internationally peer-reviewed and accepted for publication
according to the guidelines given at the journal’s website.
90 Iraj H.P. Mamaghani