Challenges and alternative approaches for simulating the response of steel structures exposed to fire

Although structurally significant building fires are rare events, their occurrence can cause substantial damage and may lead to partial or complete system collapse. While fireproofing has proven to be effective in mitigating the effect of severe fires, it is rated for only a certain time and will eventually fail to provide adequate protection during a large or extended fire event. Furthermore, fireproofing typically is rated using a standard fire exposure, such as ISO 834 or ASTM E119, neither of which represent realistic fire exposures in an actual building. With the worldwide move toward performance-based fire protection engineering, understanding and quantifying system behavior through advanced numerical simulations, especially during the heating and cooling phases of realistic fire exposures, is essential for establishing proper performance-based provisions for fire engineering that ensure both safe and economical design. This paper highlights current challenges in simulating the effect of fire on steel components and frames, including proper representation of loading and boundary conditions, geometrical nonlinearities, material inelasticity, and numerical instabilities. The structural models considered include 2-D line elements, 3-D continuum elements, and multi-resolution models. In addition, the advantages and drawbacks of these models are highlighted and the implication of their features is discussed. The highlighted modeling approaches and the corresponding results shown can be used by engineers for selecting the most economical and effective techniques for simulating the response of components and structural systems to scenario fire hazards accurately

An approximate dynamic programming approach to food security of communities following hazards

Food security can be threatened by extreme natural hazard events for households of all social classes within a community. To address food security issues following a natural disaster, the recovery of several elements of the built environment within a community, including its building portfolio, must be considered. Building portfolio restoration is one of the most challenging elements of recovery owing to the complexity and dimensionality of the problem. This study introduces a stochastic scheduling algorithm for the identification of optimal building portfolio recovery strategies. The proposed approach provides a computationally tractable formulation to manage multi-state, large-scale infrastructure systems. A testbed community modeled after Gilroy, California, is used to illustrate how the proposed approach can be implemented efficiently and accurately to find the near-optimal decisions related to building recovery following a severe earthquake.Comment: As opposed to the preemptive scheduling problem, which was addressed in multiple works by us, we deal with a non-preemptive stochastic scheduling problem in this work. Submitted to 13th International Conference on Applications of Statistics and Probability in Civil Engineering, ICASP13 Seoul, South Korea, May 26-30, 201

Reasons behind the Secondary Stage Low Achievement in English and Math from the Teachers’ Perspectives in schools of Tulkarm District

This study aims to investigate the main reasons behind low achievement in English and math among the secondary stage students in the schools of Tulkarm District. To achieve this purpose, the researchers used two tools: A 30-item questionnaire which was distributed among 50 male and female teachers from the government schools of Tulkarm city and its Suburbs. A representative sample of 10 from the same teachers was chosen randomly and was interviewed by the researchers to gain more information about the same purpose. The study results showed that there were significant differences at (α = 0.05) on the low achievement among the secondary stage learners in the schools of Tulkarm city and its Suburbs due to gender in favor of females. Results also showed that , there were significant differences at (α = 0.05) on the low achievement among the secondary stage learners in the schools of Tulkarem city and its Suburbs due to the study variables of qualifications, experience, specialization and training sessions. Moreover, the interview results support the results of the questionnaire. In the light of these findings, the researchers recommended the following: Using simplified pedagogical methods, establishing good rapport between students and teachers and preferably the number of classes should be five instead of three per week mainly for the commercial stream. Key words: Low Achievement, English and Math, the teachers’ Perspectives

Ownership structure’s effect on financial performance : an empirical analysis of Jordanian listed firms

This study aims to examine the impact of the ownership structure on firm performance in the Jordan. This study employed the multiple-regression model and fixed regression effect to analyse the data. The sample included all Jordanian first market firms listed on the Amman Stock Exchange (ASE) from 2012 to 2018. The paper’s findings reveal a positive and significant relationship between institutional ownership and both accounting measure Return on Assets (ROA) and market measure Tobin’s Q (TQ). Other ownership structure types, such as concentration of ownership, also affect ROA and TQ. While managerial ownership shows a negative relationship with ROA, but there is no association with TQ. This study has broad and comprehensive practical implications that are good for policymakers. On the one hand, it adds to the debate on agency theory from the ownership structure and firm’s performance relationship. On the other hand, it helps the Jordanian Government formulate policies and regulations to strengthen corporate governance (CG), which increases the interests of all stakeholders in the Jordanian market.Peer reviewe

A Framework for Performance-Based Fire Following Earthquake Engineering

The occurrence of fires igniting during and immediately following a seismic event represents an important design scenario that should be accounted for. Building concentration, construction type, weather conditions, and other factors can combine to create a situation in which fire following an earthquake is the principal cause of damage. Records from past earthquakes show that the damage caused by the subsequent fire can be very significant, often exceeding the damage caused by the earthquake. The current seismic design philosophy permits certain degree of damage during earthquakes, making the structures more vulnerable when exposed to the additional demand of fire loading. Fire resistance of steel frames is implemented using passive or active fire resisting systems, which have shown high variability in their sustained damage due to the seismic event. In this paper, a new framework for performance-based fire following earthquake engineering is developed and discussed. The framework is established through combining stability analysis of isolated columns with system-level finite element analysis of a steel building while accounting for randomness in parameters associated with post-flashover fire, passive fire protection, and mechanical loads. Fragility surfaces for column instability as a function of various levels of fire load density and inter-story drift ratios are produced. The results demonstrate that instability can be a major concern in steel structures, both on the member and system levels, under the sequential events and highlights the need to develop provisions for the design of steel structures subjected to fire following earthquake