scholarly journals Practical method to predict the axial capacity of RC columns exposed to standard fire

2018 ◽  
Vol 9 (4) ◽  
pp. 266-286 ◽  
Author(s):  
Salah F. El-Fitiany ◽  
Maged A. Youssef
Keyword(s):  
Concrete Strength ◽  
Practical Method ◽  
Simple Method ◽  
Rc Columns ◽  
Content Type ◽  
Natural Fire ◽  
Rc Structures ◽  
Axial Capacity ◽  
Standard Fire ◽  
Structural Engineers

Purpose Existing analytical methods for the evaluation of fire safety of reinforced concrete (RC) structures require extensive knowledge of heat transfer calculations and the finite element method. This paper aims to propose a rational method to predict the axial capacity of RC columns exposed to standard fire. Design/methodology/approach The average temperature distribution along the section height is first predicted for a specific fire scenario. The corresponding distribution of the reduced concrete strength is then integrated to develop expressions to calculate the axial capacity of RC columns exposed to fire from four faces. Findings These expressions provide structural engineers with a rational tool to satisfy the objective-based design clauses specified in the National Code of Canada in lieu of the traditional prescriptive methods. Research limitations/implications The research is limited to standard fire curves and needs to be extended to cover natural fire curves. Originality/value This paper is the first to propose an accurate yet simple method to calculate the axial capacity of columns exposed to standard fire curves. The method can be applied using a simple Excel sheet. It can be further developed to apply to natural fire curves.

scholarly journals Performance-based design of RC beams using an equivalent standard fire

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Robert Kuehnen ◽  
Maged Youssef ◽  
Salah El-Fitiany
Keyword(s):  
Performance Based Design ◽  
Rc Beams ◽  
Fire Event ◽  
Content Type ◽  
Natural Fire ◽  
Standard Fire ◽  
Fire Scenarios ◽  
The Moment ◽  
Equivalent Method ◽  
Fire Design

Purpose The design of buildings for fire events is essential to ensure occupant safety. Supplementary to simple prescriptive methods, performance-based fire design can be applied to achieve a greater level of safety and flexibility in design. To make performance-based fire design more accessible, a time-equivalent method can be used to approximate a given natural fire event using a single standard fire with a specific duration. Doing so allows for natural fire events to be linked to the wealth of existing data from the standard fire scenario. The purpose of this paper is to review and assess the application of an existing time-equivalent method in the performance-based design of reinforced concrete (RC) beams. Design/methodology/approach The assessment is established by computationally developing the moment-curvature response of RC beam sections during fire exposure. The sectional response due to natural fire and time equivalent fire are compared. Findings It is shown that the examined time equivalent method is able to predict the sectional response with suitable accuracy for performance-based design purposes. Originality/value The research is the first to provide a comprehensive evaluation of the moment-curvature diagram of RC beams using time-equivalent standard fire scenarios that model realistic fire scenarios.

Numerical analysis of the shear strength of circular reinforced concrete columns subjected to cyclic lateral loads using linear genetic programming

2020 ◽  
Vol 37 (7) ◽  
pp. 2517-2537
Author(s):  
Mostafa Rezvani Sharif ◽  
Seyed Mohammad Reza Sadri Tabaei Zavareh
Keyword(s):  
Numerical Modeling ◽  
Shear Strength ◽  
Reinforced Concrete ◽  
Numerical Analysis ◽  
Genetic Programming ◽  
Linear Genetic Programming ◽  
Rc Columns ◽  
Content Type ◽  
Alternative Approach ◽  
Engineering Problems

Purpose The shear strength of reinforced concrete (RC) columns under cyclic lateral loading is a crucial concern, particularly, in the seismic design of RC structures. Considering the costly procedure of testing methods for measuring the real value of the shear strength factor and the existence of several parameters impacting the system behavior, numerical modeling techniques have been very much appreciated by engineers and researchers. This study aims to propose a new model for estimation of the shear strength of cyclically loaded circular RC columns through a robust computational intelligence approach, namely, linear genetic programming (LGP). Design/methodology/approach LGP is a data-driven self-adaptive algorithm recently used for classification, pattern recognition and numerical modeling of engineering problems. A reliable database consisting of 64 experimental data is collected for the development of shear strength LGP models here. The obtained models are evaluated from both engineering and accuracy perspectives by means of several indicators and supplementary studies and the optimal model is presented for further purposes. Additionally, the capability of LGP is examined to be used as an alternative approach for the numerical analysis of engineering problems. Findings A new predictive model is proposed for the estimation of the shear strength of cyclically loaded circular RC columns using the LGP approach. To demonstrate the capability of the proposed model, the analysis results are compared to those obtained by some well-known models recommended in the existing literature. The results confirm the potential of the LGP approach for numerical analysis of engineering problems in addition to the fact that the obtained LGP model outperforms existing models in estimation and predictability. Originality/value This paper mainly represents the capability of the LGP approach as a robust alternative approach among existing analytical and numerical methods for modeling and analysis of relevant engineering approximation and estimation problems. The authors are confident that the shear strength model proposed can be used for design and pre-design aims. The authors also declare that they have no conflict of interest.

Scenario based evaluation of a cost risk model through sensitivity analysis

2015 ◽  
Vol 22 (4) ◽  
pp. 403-423 ◽  
Author(s):  
Önder Ökmen ◽  
Ahmet Öztaş
Keyword(s):  
Risk Factors ◽  
Risk Analysis ◽  
Risk Model ◽  
Practical Method ◽  
Cost Evaluation ◽  
Sensitivity Analyses ◽  
Analysis Model ◽  
Content Type ◽  
Detailed Evaluation ◽  
Cost Risk

Purpose – Actual costs frequently deviate from the estimated costs in either favorable or adverse direction in construction projects. Conventional cost evaluation methods do not take the uncertainty and correlation effects into account. In this regard, a simulation-based cost risk analysis model, the Correlated Cost Risk Analysis Model, previously has been proposed to evaluate the uncertainty effect on construction costs in case of correlated costs and correlated risk-factors. The purpose of this paper is to introduce the detailed evaluation of the Cost Risk Analysis Model through scenario and sensitivity analyses. Design/methodology/approach – The evaluation process consists of three scenarios with three sensitivity analyses in each and 28 simulations in total. During applications, the model’s important parameter called the mean proportion coefficient is modified and the user-dependent variables like the risk-factor influence degrees are changed to observe the response of the model to these modifications and to examine the indirect, two-sided and qualitative correlation capturing algorithm of the model. Monte Carlo Simulation is also applied on the same data to compare the results. Findings – The findings have shown that the Correlated Cost Risk Analysis Model is capable of capturing the correlation between the costs and between the risk-factors, and operates in accordance with the theoretical expectancies. Originality/value – Correlated Cost Risk Analysis Model can be preferred as a reliable and practical method by the professionals of the construction sector thanks to its detailed evaluation introduced in this paper.

A collaborative application of design thinking and Taguchi approach in restaurant service design for food wellbeing

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
G. Rejikumar ◽  
Asokan-Ajitha Aswathy ◽  
Ajay Jose ◽  
Mathew Sonia
Keyword(s):  
Food Industry ◽  
Design Thinking ◽  
Service Design ◽  
Service Research ◽  
Taguchi Approach ◽  
Simple Method ◽  
Content Type ◽  
Wellbeing Index ◽  
Food Movement ◽  
Practical Implications

PurposeInnovative restaurant service designs impart food wellbeing to diners. This research comprehends customer aspirations and concerns in a restaurant-dining experience to develop a service design that enhances the dining experience using the design thinking approach and evaluates its efficiency using the Taguchi method of robust design.Design/methodology/approachThe sequential incidence technique defines diners' needs, which, followed by brainstorming sessions, helped create multiple service designs with important attributes. Prototype narration, as a scenario, acted as the stimulus for evaluators to respond to the WHO-5 wellbeing index scale. Scenario-based Taguchi experiment with nine foodservice attributes in two levels and the wellbeing score as the response variable helped identify levels of critical factors that develop better FWB.FindingsThe study identified the best combination of factors and their preferred levels to maximize FWB in a restaurant. Food serving hygiene, followed by information about cuisine specification, and food movement in the restaurant, were important to FWB. The experiment revealed that hygiene perceptions are critical to FWB, and service designs have a significant role in it. Consumers prefer detailed information about the ingredients and recipe of the food they eat; being confident that there will be no unacceptable ingredients added to the food inspires their FWB.Research limitations/implicationsTheoretically, this study contributes to the growing body of literature on design thinking and transformative service research, especially in the food industry.Practical implicationsThis paper details a simple method to identify and evaluate important factors that optimize FWB in a restaurant. The proposed methodology will help service designers and technology experts devise settings that consider customer priorities and contribute to their experience.Originality/valueThis study helps to understand the application of design thinking and the Taguchi approach for creating robust service designs that optimize FWB.

Experimental study on fire resistance of a full-scale composite floor assembly in a two-story steel framed building

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lisa Choe ◽  
Selvarajah Ramesh ◽  
Xu Dai ◽  
Matthew Hoehler ◽  
Matthew Bundy
Keyword(s):  
Natural Gas ◽  
Fire Resistance ◽  
Full Scale ◽  
System Level ◽  
Compartment Fire ◽  
Content Type ◽  
Standard Fire ◽  
Fire Experiment ◽  
The Usa ◽  
Floor System

PurposeThe purpose of this paper is to report the first of four planned fire experiments on the 9.1 × 6.1 m steel composite floor assembly as part of the two-story steel framed building constructed at the National Fire Research Laboratory.Design/methodology/approachThe fire experiment was aimed to quantify the fire resistance and behavior of full-scale steel–concrete composite floor systems commonly built in the USA. The test floor assembly, designed and constructed for the 2-h fire resistance rating, was tested to failure under a natural gas fueled compartment fire and simultaneously applied mechanical loads.FindingsAlthough the protected steel beams and girders achieved matching or superior performance compared to the prescribed limits of temperatures and displacements used in standard fire testing, the composite slab developed a central breach approximately at a half of the specified rating period. A minimum area of the shrinkage reinforcement (60 mm2/m) currently permitted in the US construction practice may be insufficient to maintain structural integrity of a full-scale composite floor system under the 2-h standard fire exposure.Originality/valueThis work was the first-of-kind fire experiment conducted in the USA to study the full system-level structural performance of a composite floor system subjected to compartment fire using natural gas as fuel to mimic a standard fire environment.

Empirical Formulae To Predict Pressure And Impulsive Asymptotes For P–I Diagrams Of RC Columns Strengthened With FRP

2011 ◽  
Author(s):  
A. A. Mutalib ◽  
Norhisham Bakhary
Keyword(s):  
Concrete Strength ◽  
Numerical Results ◽  
Fiber Reinforced Polymer ◽  
Blast Loads ◽  
Fiber Reinforced ◽  
Rc Columns ◽  
Pressure Impulse ◽  
Reinforced Polymer ◽  
Blast Response ◽  
Parametric Studies

Kajian terhadap keupayaan struktur dalam menahan beban letupan menggunakan Fiber Reinforced Polymer (FRP) adalah sangat terhad. Dalam kajian ini, satu analisis terhadap keupayaan FRP bagi menahan beban letupan dilakukan. Tujuan analisis ini adalah untuk memperolehi hubungan antara kekuatan FRP, bilangan lapisan ketebalan FRP dan susunatur FRP bagi menahan kekuatan sesuatu beban letupan. Kajian ini dilakukan mengunakan model tiang diperkukuh dengan FRP yang dibina menggunakan perisian LS–DYNA. Ia melibatkan beberapa siri simulasi untuk meramalkan tindakbalas letupan dan kerosakkan pada tiang sekiranya sesuatu beban letupan dikenakan. Melalui simulasi ini, kekuatan FRP, bilangan lapisan ketebalan FRP dan susunatur FRP dapat ditentukan. melalui keputusan–keputusan yang diperolehi, pressure–impulse diagram (P–I) bagi tiang yang diperkukuhkan dengan FRP dapat dibentuk. Kata kunci: Pengukuhan; beban letupan; FRP; P–I diagrams There are only limited studies that directly correlate the increase in structural capacities in resisting the blast loads with the fiber reinforced polymer (FRP) strengthenin. In this paper, numerical analyses of dynamic response and damage of reinforced concrete (RC) columns strengthened with FRP to blast loads are carried out using the commercial software LS–DYNA. A series of simulations are performed to predict the blast response and damage of columns with different FRP type. The simulations also involved parametric studies by varying the FRP thickness, configuration, different column dimension, concrete strength, and longitudinal and transverse reinforcement ratio. The numerical results are used to develop pressure–impulse (P–I) diagrams of FRP strengthened RC columns. Based on the numerical results, the empirical formulae are derived to calculate the pressure and impulse asymptotes of the P–I diagrams of RC columns strengthened with FRP. Key words: Strengthening; blast loads; FRP; P–I diagrams

Bilateral open-door cervical expansive laminoplasty with hydroxyapatite spacers and titanium screws

2002 ◽  
Vol 96 (1) ◽  
pp. 22-28 ◽  
Author(s):  
Masakazu Takayasu ◽  
Teruhide Takagi ◽  
Toshihisa Nishizawa ◽  
Koji Osuka ◽  
Takehiko Nakajima ◽  
...  
Keyword(s):  
Screw Fixation ◽  
Cervical Spinal Cord ◽  
Intraoperative Complications ◽  
Fixation Strength ◽  
Open Door ◽  
Quick Method ◽  
Simple Method ◽  
Content Type ◽  
Titanium Screws ◽  
Fine Print

Object. The authors report a simple method for bilateral open-door cervical expansive laminoplasty in which hydroxyapatite (HA) spacers are secured by titanium screws. A biomechanical study was also conducted to confirm the strength of the screw fixation. Methods. A unilateral posterior approach was used to allow preservation of the posterior supporting elements (the posterior tension band) until the laminae were cut at the base. A bilateral open-door expansive laminotomy was then performed in standard fashion. Appropriate-sized HA spacers were selected, held with a specially designed holder, and placed between the split laminae. The screw holes were made in the laminae along the direction of the screw holes in the spacer, and two screws were inserted ventrolaterally to the laminae, resulting in instantaneous fixation. This procedure was performed in 15 patients; clinical results were successful, and there were no significant intraoperative complications. Follow-up radiological studies revealed no evidence of displacement of the spacers or screw backout. The screw artifacts observed on magnetic resonance imaging were minimal, allowing evaluation of the cervical spinal cord. The sagittal alignment of the cervical spine was well preserved. In the biomechanical studies the authors found that the screw fixation was of satisfactory strength, compared with other methods of fixation. Conclusions. Bilateral open-door cervical expansive laminoplasty in which HA spacers are secured by titanium screws is a simple and quick method that yields sufficient fixation strength.

scholarly journals PERFORMANCE BASED COUPLED CFD-FEM ANALYSIS OF 3-BAY HIGH INDUSTRIAL HALL UNDER NATURAL FIRE

2016 ◽  
Author(s):  
Michal Malendowski ◽  
Adam Glema ◽  
Wojciech Szymkuc
Keyword(s):  
Heat Exposure ◽  
Fem Analysis ◽  
Structural Elements ◽  
Fire Load ◽  
Natural Fire ◽  
Standard Fire ◽  
Complex Approach ◽  
Main Emphasis ◽  
Low Probability ◽  
And Performance

In this paper, the main emphasis is put into showing differences between standard fire design of structural elements and performance based approach, that takes into account analysis of structure under natural fire. The exemplary structure is a 3-bay 65,0x110,0 m in plane and 22,0 m high industrial hall with heavy cranes. Because of the significant volume with respect to fire load, there is a low probability that the fully developed fire can occur, nonetheless regarding technological process, a significant local fire could take place and affect the neighbour structure. The most complex approach used in this work is based on coupled CFD-FEM analysis of influence of local fire onto structure.Fire exposure of structural elements is calculated by the coupling scripts, taking into account real heat exposure of section by using adiabatic surface temperature approach.

Real-time velocity scaling and obstacle avoidance for industrial robots using fuzzy dynamic movement primitives and virtual impedances

2018 ◽  
Vol 45 (1) ◽  
pp. 110-126 ◽  
Author(s):  
Iman Kardan ◽  
Alireza Akbarzadeh ◽  
Ali Mousavi Mohammadi
Keyword(s):  
Real Time ◽  
Obstacle Avoidance ◽  
Time Constant ◽  
Fuzzy System ◽  
Industrial Robots ◽  
Simple Method ◽  
Content Type ◽  
Dynamic Movement ◽  
Steering Mechanism ◽  
Novel Method

Purpose This paper aims to increase the safety of the robots’ operation by developing a novel method for real-time implementation of velocity scaling and obstacle avoidance as the two widely accepted safety increasing concepts. Design/methodology/approach A fuzzy version of dynamic movement primitive (DMP) framework is proposed as a real-time trajectory generator with imbedded velocity scaling capability. Time constant of the DMP system is determined by a fuzzy system which makes decisions based on the distance from obstacle to the robot’s workspace and its velocity projection toward the workspace. Moreover, a combination of the DMP framework with a human-like steering mechanism and a novel configuration of virtual impedances is proposed for real-time obstacle avoidance. Findings The results confirm the effectiveness of the proposed method in real-time implementation of the velocity scaling and obstacle avoidance concepts in different cases of single and multiple stationary obstacles as well as moving obstacles. Practical implications As the provided experiments indicate, the proposed method can effectively increase the real-time safety of the robots’ operations. This is achieved by developing a simple method with low computational loads. Originality/value This paper proposes a novel method for real-time implementation of velocity scaling and obstacle avoidance concepts. This method eliminates the need for modification of original DMP formulation. The velocity scaling concept is implemented by using a fuzzy system to adjust the DMP’s time constant. Furthermore, the novel impedance configuration makes it possible to obtain a non-oscillatory convergence to the desired path, in all degrees of freedom.

scholarly journals Probing of Microbial Biofilm Communities for Coadhesion Partners

2014 ◽  
Vol 80 (21) ◽  
pp. 6583-6590 ◽  
Author(s):  
Stefan Ruhl ◽  
Andreas Eidt ◽  
Holger Melzl ◽  
Udo Reischl ◽  
John O. Cisar
Keyword(s):  
Dental Plaque ◽  
Solid Phase ◽  
Screening Method ◽  
Bacterial Strains ◽  
Mixed Species ◽  
Simple Method ◽  
Content Type ◽  
Glycan Receptors ◽  
Fimbrial Adhesin

ABSTRACTInvestigations of interbacterial adhesion in dental plaque development are currently limited by the lack of a convenient assay to screen the multitude of species present in oral biofilms. To overcome this limitation, we developed a solid-phase fluorescence-based screening method to detect and identify coadhesive partner organisms in mixed-species biofilms. The applicability of this method was demonstrated using coaggregating strains of type 2 fimbrial adhesin-bearing actinomyces and receptor polysaccharide (RPS)-bearing streptococci. Specific adhesin/receptor-mediated coadhesion was detected by overlaying bacterial strains immobilized to a nitrocellulose membrane with a suspended, fluorescein-labeled bacterial partner strain. Coadhesion was comparable regardless of which cell type was labeled and which was immobilized. Formaldehyde treatment of bacteria, either in suspension or immobilized on nitrocellulose, abolished actinomyces type 2 fimbrial adhesin but not streptococcal RPS function, thereby providing a simple method for assigning complementary adhesins and glycan receptors to members of a coadhering pair. The method's broader applicability was shown by overlaying colony lifts of dental plaque biofilm cultures with fluorescein-labeled strains of type 2 fimbriatedActinomyces naeslundiior RPS-bearingStreptococcus oralis. Prominent coadhesion partners included not only streptococci and actinomyces, as expected, but also other bacteria not identified in previous coaggregation studies, such as adhesin- or receptor-bearing strains ofNeisseria pharyngitis,Rothia dentocariosa, andKingella oralis. The ability to comprehensively screen complex microbial communities for coadhesion partners of specific microorganisms opens a new approach in studies of dental plaque and other mixed-species biofilms.

Sign in / Sign up

Export Citation Format

Share Document