scholarly journals Random Parameters and Sources of Uncertainty in Practical Fire Safety Assessment of Steel Building Structures

2016 ◽  
Author(s):  
Pawel Artur Król
Keyword(s):  
Fire Safety ◽  
Safety Assessment ◽  
Elevated Temperatures ◽  
Probabilistic Approach ◽  
Steel Structures ◽  
Building Structures ◽  
Sources Of Uncertainty ◽  
Proposed Model ◽  
Structural Resistance ◽  
The Impact

The purpose of this article is to identify sources of uncertaintyand outline the basis of probabilistic safety assessmentof steel structures exposed to fire conditions. Awareness of theexistence of unavoidable uncertainties and non-deterministicnature of many phenomena and parameters may be essentialfor a proper understanding of the issues of structural reliabilityin the event of extreme or accidental actions.The study highlights various sources of uncertainty associatedwith practical fire safety assessment of steel structureswhich significantly affects the reliability of estimates. Universalfactors influencing random structural resistance in alldesign conditions were separately described. A significant partof the paper is devoted to issues that relate only to an accidentaldesign situation of fire. Reference was made to the uncertaintyof the analytical model describing the bearing capacityof the structure in terms of probabilistic approach. A syntheticsummary on the impact of the method of carrying out materialtesting in elevated temperatures on the strength parameters,was made. In the conclusion it has been underlined that, interalia, due to the lack of relevant statistical data, conducting afully reliable probabilistic analysis of random structural resistanceunder fire is currently not possible. A unique part of thepaper contains the proposed model of probability-based analyticalapproach to assess random structural resistance in fireconditions, incorporating an authorial modification to modelsused for standard conditions.

A comparative analysis of the requirements of Russia and the United States to the fire resistance of building structures of oil refineries and petrochemical plants

2021 ◽  
Vol 30 (5) ◽  
pp. 5-22
Author(s):  
B. A. Klementev ◽  
A. V. Kalach ◽  
M. V. Gravit
Keyword(s):  
Comparative Analysis ◽  
Fire Resistance ◽  
Fire Safety ◽  
Probabilistic Approach ◽  
The United States ◽  
National Standards ◽  
Building Structures ◽  
Oil Refineries ◽  
Regulatory Documents ◽  
Energy Complex

Introduction. Currently, national standards and codes of practice contain deterministic values of the fire resistance of building structures of facilities of the Russian fuel and energy complex (FEC), while a probabilistic approach to determining their fire resistance is not specified in the Russian regulatory documents. The methodology of the probabilistic approach to the fire resistance of structures is detailed in API 2218 “Fireproofing Practices in Petroleum and Petrochemical Processing Plants”, developed by the American Petroleum Institute.Methods. A comparative analysis of the Russian regulatory documents on fire safety and API 2218 in terms of the established concepts of fireproofing and requirements for the fire resistance limits of building structures of oil and gas industry facilities, is carried out.Results. It was established that the Russian Federation has no regulatory documents establishing methods based on the probabilistic approach, including determination of the required fire resistance limits and points of application of fire-resistant coatings at facilities of the fuel and energy complex by analogy with international standard API 2218.Conclusion. Based on the analysis, it was concluded that approaches to the philosophy of the fire resistance of structures of buildings and structures of the fuel and energy complex in the documents under consideration are fundamentally different. In order to improve the Russian regulatory and technical framework, governing fire safety and fire resistance, it is proposed to consider the requirements of foreign documents that take into account proven international engineering and technical practices, in particular, the use of a probabilistic approach taking into account hydrocarbon fires.

scholarly journals Aamks: the platform for assessing fire safety of humans in buildings

2018 ◽  
Vol 247 ◽  
pp. 00001
Author(s):  
Karol Kre´nski ◽  
Mateusz Fliszkiewicz
Keyword(s):  
Risk Assessment ◽  
User Interface ◽  
Open Source Software ◽  
Fire Safety ◽  
Probabilistic Approach ◽  
Fire Risk ◽  
Geometry Processing ◽  
Fire Risk Assessment ◽  
Automatic Planning ◽  
The Impact

We introduce an open-source software for fire risk assessment named Aamks. We provide a brief overview of the following aspects of the platform: the motivation for creating Aamks, the architecture of the platform, the user interface, the intended workflow for conducting fire safety analyses, the probabilistic approach to fire risk assessment, the geometry processing, the reasoning from the topology of the building (i.e. automatic planning of exit routes), the interactions amongst the moving evacuees, the impact of smoke on humans and finally the results and the visualization.

scholarly journals Ground Risk Assessment of UAV Operations Based on Horizontal Distance Estimation under Uncertain Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yang Liu ◽  
Xuejun Zhang ◽  
Zhi Wang ◽  
Ziang Gao ◽  
Chang Liu
Keyword(s):  
Drag Force ◽  
Safety Assessment ◽  
Local Population ◽  
Assessment Model ◽  
Flying Height ◽  
Weather Data ◽  
Horizontal Distance ◽  
Proposed Model ◽  
Failure Point ◽  
The Impact

In this paper a ground safety assessment model is introduced based on the probability estimation of possible impact positions when unmanned aerial vehicle (UAV) crashes on the ground. By incorporating the random uncertainties during the descending process, risks associated with UAV’s ground crash are estimated accurately. The number of victims on the ground per flight hour is selected as the indicative index to evaluate the risk levels of the corresponding ground area. We mainly focus on the analysis of uncertainties that usually appear in drag coefficient which would generate a great amount of effects on the travelled horizontal distance from the failure point to the impact point on the ground, which further influences the possible impact positions. The drag force in the air, failure velocity of a UAV, and wind effects in the local area are all considered in the proposed model, as well as ground features, including sheltering effects on the ground, UAV parameter settings, and distribution of local population. Uncertainties in drag force when a UAV descends, UAV’s initial horizontal and vertical speeds at failure point, and local wind patterns are all considered as the indispensable factors in the proposed model. Especially the probability of fatality once hit by the UAV’s debris is explored to make the safety assessment more reliable and valuable. In the end, the actual UAV parameters and official historical weather data are used to estimate the risks in a real operation environment when a failure event happens at a legal flying height. Experimental results are given based on different types of UAVs and random effects in the descent. The results show that all the operations of all kinds of UAVs selected in the validation are so dangerous that the safety of people on the ground cannot be guaranteed, whose value is much bigger than the manned aircraft safety criterion 10−7.

scholarly journals Elastic modulus formulation of cementitious materials incorporating carbon nanotubes: Probabilistic approach

2020 ◽  
Author(s):  
Mahyar Ramezani ◽  
Young Hoon Kim ◽  
Zhihui Sun
Keyword(s):  
Carbon Nanotubes ◽  
Elastic Modulus ◽  
Probabilistic Approach ◽  
Cementitious Materials ◽  
Matrix Composition ◽  
Extensive Literature ◽  
Selection Procedures ◽  
Sources Of Uncertainty ◽  
Proposed Model ◽  
High Degree

Carbon nanotube (CNT) is one of the most promising nanomaterials to increase the elastic modulus of cementitious composites. However, CNT characteristics, dispersion procedure, and matrix composition/hydration are critical and correlated with a high degree of uncertainty in achieving a desirable performance. This paper proposes a mechanics-based model to predict the elastic modulus of CNT reinforced cementitious materials based on the Halpin-Tsai equation. The current study employs a probabilistic approach to consider the influences of multiple experimental variables and various sources of uncertainty associated with them. To this end, first, a Bayesian methodology is adopted to perform the model validation, evaluation, and selection procedures using extensive literature test data. Then, the optimum rangesof variables are found to maximize the chance of achieving a certain target modulus (herein, 50% more than control) using a reliability analysis. The proposed model suggests that the highest elastic modulus is achieved when using CNT aspect ratio ranges from 400 to 800 and concentration between 0.08 and 0.18 c-wt%. Also, the experimentally observed elastic modulus and the proposed probabilistic model exhibit a similar trend. For example, the importance of hydration age increases as CNT concentrationincreases. Finally, the proposed model can be used to reliably predict the elastic modulus, guiding futureresearchers to design more efficiently.

scholarly journals Laboratory and Numerical Analysis of Steel Cold-Formed Sigma Beams Retrofitted by Bonded CFRP Tapes

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4339 ◽  
Author(s):  
Ilona Szewczak ◽  
Katarzyna Rzeszut ◽  
Patryk Rozylo ◽  
Sylwester Samborski
Keyword(s):  
Numerical Analysis ◽  
Numerical Models ◽  
Load Capacity ◽  
Steel Structures ◽  
Bottom Flange ◽  
Building Structures ◽  
Inner Surface ◽  
Carbon Fibre Reinforced Polymer ◽  
Thin Walled ◽  
The Impact

In this paper, the retrofitting method of thin-walled, cold-formed sigma beams using bonded carbon fibre reinforced polymer (CFRP) tapes is proposed. The effectiveness of the presented strengthening method is investigated by the means of laboratory tests and numerical analysis conducted on simply supported, single-span beams made of 200 × 70 × 2 profile by “Blachy Pruszyński” subjected to a four-point bending scheme. Special attention is paid to the evaluation of possibility to increase the load capacity with simultaneous limitation of beams displacements by appropriate location of CFRP tapes. For this purpose, three beams were reinforced with CFRP tape placed on the inner surface of the upper flange, three with CFRP tape on the inner surface of the web, three beams with reinforcement located on the inner surface of the bottom flange, and two beams were tested as reference beams without reinforcement. CFRP tape with a width of 50 mm and a thickness of 1.2 mm was used as the reinforcement and was bonded to the beams by SikaDur®-30 adhesive. Precise strain measurement was made using electrofusion strain gauges, and displacement measurement was performed using two Aramis coupled devices in combination with the Tritop machine. Numerical models of the considered beams were developed in the Finite Element Method (FEM) program Abaqus®. Experimental and numerical analysis made it possible to obtain a very high agreement of results. Based on the conducted research, it was proved how important is the impact of the applied reinforcement (CFRP tapes) in thin-walled steel structures, with respect to the classic methods of strengthening steel building structures.

Test of Mediation and Moderation between Employee Empathy and Customers’ Advocacy

2020 ◽  
Author(s):  
Sajjad Ahmad Afridi ◽  
Asad Shahjehan ◽  
Maqsood Haider ◽  
Dr Uzma Munawar
Keyword(s):  
Factor Analysis ◽  
Customer Loyalty ◽  
Service Sector ◽  
Mediating Effect ◽  
First Line ◽  
Private Hospitals ◽  
Proposed Model ◽  
Confirmatory Factor ◽  
The Impact ◽  
Significant Moderator

This study examined the impact of employee empathy on customers’ advocacy directly and indirectly through customers’ loyalty. Moreover, the interacting effect of customers’ trust was verified between the association of customers’ loyalty and advocacy. The attributes of the proposed model were examined in the context of first line employee and patients’ interactions. A total of 220 responses were collected for analysis from the private hospitals of Peshawar. The model fitness was confirmed through confirmatory factor analysis and hypotheses were examined. Findings confirmed the positive and significant impact of employee empathy on customers’ advocacy. Further, the mediating effect was examined and found that loyalty partially mediates employee empathy and customers’ advocacy. Additionally, trust was found a significant moderator between the association of customer loyalty and advocacy. Furthermore, findings revealed that trust based loyalty significantly and positively mediates employee empathy and customers’ advocacy. Findings of the present study provide understanding for the service sector, particularly in healthcare, to enhance customers’ loyalty, advocacy, and trust through service employee’s empathic aptitude. Keywords: Employee empathy, Service Eco-system, Customers’ Loyalty, Customers’ Advocacy, Trust-Based Loyalty, Healthcare, S-D Logic

Matrix Calculation of Fire Safety Assessment on Multi-purpose Buildings

2005 ◽  
Vol 13 (3) ◽  
pp. 231-255
Author(s):  
J. Chi ◽  
Y. Huang ◽  
C. Chen ◽  
J. Chen ◽  
C. Su
Keyword(s):  
Fire Safety ◽  
Safety Assessment ◽  
Matrix Calculation

Fire Safety Assessment of Exterior Thermal Insulation Materials using a Cone Calorimeter

2012 ◽  
Vol 22 (1) ◽  
pp. 131-141
Author(s):  
Qi Yanjun ◽  
Wang Xuegui ◽  
Cui Yu ◽  
Zhang Heping
Keyword(s):  
Thermal Insulation ◽  
Fire Safety ◽  
Cone Calorimeter ◽  
Safety Assessment ◽  
Insulation Materials

The impact of duration observations on precision of results GNSS measurements

2017 ◽  
Vol 921 (3) ◽  
pp. 7-13 ◽  
Author(s):  
S.V. Grishko
Keyword(s):  
Measurement Accuracy ◽  
Functional Dependence ◽  
Observation Time ◽  
Satellite Networks ◽  
Satellite Measurements ◽  
Proposed Model ◽  
Actual Error ◽  
Gnss Measurements ◽  
The Impact ◽  
Qualitative Characteristics

This paper shows that the accuracy of relative satellite measurements depend not only on the length of the baseline, as it is regulated by the rating formula of accuracy of GNSS equipment, but also on the duration of observations. As a result of the strict adjustment much redundant satellite networks with different duration of observations obtained covariance matrix of baselines, the most realistic reflecting the actual error of satellite observations. Research of forms of communication of these errors from length of the baseline and duration of its measurement is executed. A significant influence of solar activity on accuracy of satellite measurements, in general, leads to unequal similar series of measurements made at different periods, for example, in the production of monitoring activities. The model of approximation of the functional dependence of accuracy of the baseline from its length and duration of observations having good qualitative characteristics is offered. Based on the proposed model, we analyzed the dynamics of changes in measurement accuracy with an increase in observation time.

scholarly journals The impact of quarantine on Covid-19 infections

2021 ◽  
Vol 10 (s1) ◽  
Author(s):  
Pablo Marshall
Keyword(s):  
Health System ◽  
Infection Rate ◽  
District Level ◽  
Infection Model ◽  
Social Distancing ◽  
Proposed Model ◽  
Lower Infection ◽  
The Impact ◽  
Lower Infection Rate ◽  
Over Time

Abstract Objectives: Coronavirushas had profound effects on people’s lives and the economy of many countries, generating controversy between the need to establish quarantines and other social distancing measures to protect people’s health and the need to reactivate the economy. This study proposes and applies a modification of the SIR infection model to describe the evolution of coronavirus infections and to measure the effect of quarantine on the number of people infected. Methods: Two hypotheses, not necessarily mutually exclusive, are proposed for the impact of quarantines. According to the first hypothesis, quarantine reduces the infection rate, delaying new infections over time without modifying the total number of people infected at the end of the wave. The second hypothesis establishes that quarantine reduces the population infected in the wave. The two hypotheses are tested with data for a sample of 10 districts in Santiago, Chile. Results: The results of applying the methodology show that the proposed model describes well the evolution of infections at the district level. The data shows evidence in favor of the first hypothesis, quarantine reduces the infection rate; and not in favor of the second hypothesis, that quarantine reduces the population infected. Districts of higher socio-economic levels have a lower infection rate, and quarantine is more effective. Conclusions: Quarantine, in most districts, does not reduce the total number of people infected in the wave; it only reduces the rate at which they are infected. The reduction in the infection rate avoids peaks that may collapse the health system.

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