Blast response and safety evaluation of a composite column for use as key element in structural systems

This paper presents the blast response, damage mechanism and evaluation of residual load capacity of a concrete–steel composite (CSC) column using dynamic computer simulation techniques. This study is an integral part of a comprehensive research program which investigated the vulnerability of structural framing systems to catastrophic and progressive collapse under blast loading and is intended to provide design information on blast mitigation and safety evaluation of load bearing vulnerable columns that are key elements in a building. The performance of the CSC column is compared with that of a reinforced concrete (RC) column with the same dimensions and steel ratio. Results demonstrate the superior performance of the CSC column, compared to the RC column in terms of residual load carrying capacity, and its potential for use as a key element in structural systems. The procedure and results presented herein can be used in the design and safety evaluation of key elements of multi-storey buildings for mitigating the impact of blast loads.

RMAA safety performance : how does it compare with Greenfield projects?

Gross value of cons truction work in the repair , maintenance, minor alte ration and addition (RMAA) sector in Hong Kong has expanded dramatically by 58% from 1998 to 2007, accounting for over 53% of the whole construction market in 2007. Unfortunately, the portion of industrial accidents arising from this sector also increased substantially during the same period. It is important to improve the safety performance of the RMAA sector. This paper has set out the objectives to examine safety statistics of RMAA works; to compare them with those of green field projects; and more importantly, to highlight potential hurdles en countered in the process of comparison and finally to provide effective recommendations for overcoming these impediments. To strive for continuous safety improvement of RMAA works, comparable safety statistics should be compiled for this sector.

Online teacher education : lessons from the cyber-trenches

This paper provides an overview of ‘lessons learned’ from the author’s decade long involvement in online teaching and learning, including eight years in the development, implementation, teaching and administration of a wholly online Master of Arts in Applied Linguistics coursework degree program, which attracted several hundred students annually from around the world, and has won awards for innovation, including being identified as a ‘flagship’ program during an external review of the university.

A game theoretical approach to construction safety in the Repair, Maintenance, Alteration and Addition (RMAA) sector

Safety has long been a problem in the construction industry. Repair, maintenance, alteration and addition (RMAA) sector has emerged to play an important role in the construction industry. It accounted for 53% of the total construction market in Hong Kong in 2007. Safety performance of the RMAA words has been alarming. Statistics indicate that the percentage of fatal industrial accidents arising from RMAA work in Hong Kong was over 56% in 2006 while the remaining 44% was from new works. Effective safety measures to address the safety problems and improve safety performance of the RMAA sector are urgently needed. Unsafe behaviour has been attributed to one of the major causes of accidents. Traditional cost-benefit analysis of workers' safety behaviour seems to be inadequate. This paper proposes to adopt a game theoretical approach to analyse safety behaviour of RMAA workers. Game theory is concerned with the decision-making process in situations where outcomes depend upon choices made by one or more players. A game theoretical model between contractor and worker has been proffered. Mathematical analysis of this game model has been done and implications of the analysis have been discussed.

Construction safety for ethnic minorities in Hong Kong

The construction industry of Hong Kong is experiencing an ageing problem and a labour shortage. To alleviate the shortage of construction workforce, the government has initiatives to assist ethnic minorities to join the construction industry. It is foreseeable that more people from the ethnic minorities will join the construction industry. The safety of workers from the ethnic minorities in construction has attracted growing research interest in many developed countries. Statistics show that workers from the ethnic minorities were nearly 30 percent more likely to have work-related injuries than local workers. However, in Hong Kong, official statistics on the safety of workers from the ethnic minorities are not available. This reflects the racial or ethnic insensitivity of the construction industry in Hong Kong. As the safety of ethnic minorities has not received the attention, this research seeking to contribute to efforts to improve the safety of workers from the ethnic minorities in the construction industry of Hong Kong is all the more urgent. This paper provides an initial report of a research project which focuses on improving the safety of ethnic minority construction workers. Qualitative and quantitative research methods applied in conducting the research are first discussed. Preliminary statistics of construction accidents involving ethnic minority construction workers will then be reported.

Safety climate : recent developments and future implications

Safety climate is a current interest to construction practitioners and researchers. The concept of safety climate has been actively explored in the field of Industrial and Organizational (I/O) psychology but yet in the construction industry. This paper aims to review the literature of safety climate in a systematic manner and highlight future directions for safety research and development of safety practices in the construction industry. The value of safety climate lies on its ability to predict safety behavior. Safety climate, as a mediator, unfolds the relationship between organizational variables and safety behavior. It, as a moderator, affects the effectiveness of any safety initiatives to improve safety performance. Future research directions would be likely to look at relationship between organizational factors and safety climate using multi-level analysis. To the construction industry, safety climate measurement is a good indicator to assess safety performance. Empirical studies show that frontline supervisor would be the best conduit to create a positive safety climate at workgroup level. It is believed that this paper is beneficial to researchers interested in behavioral aspect of construction safety and industry practitioners striving for safety on site.

A model of workplace safety incorporating worker interactions and simple interventions

Although there was substantial research into the occupational health and safety sector over the past forty years, this generally focused on statistical analyses of data related to costs and/or fatalities and injuries. There is a lack of mathematical modelling of the interactions between workers and the resulting safety dynamics of the workplace. There is also little work investigating the potential impact of different safety intervention programs prior to their implementation. In this article, we present a fundamental, differential equation-based model of workplace safety that treats worker safety habits similarly to an infectious disease in an epidemic model. Analytical results for the model, derived via phase plane and stability analysis, are discussed. The model is coupled with a model of a generic safety strategy aimed at minimising unsafe work habits, to produce an optimal control problem. The optimal control model is solved using the forward-backward sweep numerical scheme implemented in Matlab.

Risk-management of UAS robust autonomy for its integration into civil aviation safety frameworks

This paper discusses a model of the civil aviation reg- ulation framework and shows how the current assess- ment of reliability and risk for piloted aircraft has limited applicability for Unmanned Aircraft Systems (UAS) with high levels of autonomous decision mak- ing. Then, a new framework for risk management of robust autonomy is proposed, which arises from combining quantified measures of risk with normative decision making. The term Robust Autonomy de- scribes the ability of an autonomous system to either continue or abort its operation whilst not breaching a minimum level of acceptable safety in the presence of anomalous conditions. The decision making associ- ated with risk management requires quantifying prob- abilities associated with the measures of risk and also consequences of outcomes related to the behaviour of autonomy. The probabilities are computed from an assessment under both nominal and anomalous sce- narios described by faults, which can be associated with the aircraft’s actuators, sensors, communication link, changes in dynamics, and the presence of other aircraft in the operational space. The consequences of outcomes are characterised by a loss function which rewards the certification decision

Experimental and numerical characteristics of portable water-filled road safety barrier system under different impact conditions

This research has developed an innovative road safety barrier system that will enhance roadside safety. In doing so, the research developed new knowledge in the field of road crash mitigation for high speed vehicle impact involving plastic road safety barriers. This road safety barrier system has the required feature to redirecting an errant vehicle with limited lateral displacement. Research was carried out using dynamic computer simulation technique support by experimental testing. Future road safety barrier designers may use the information in this research as a design guideline to improve the performance and redirectional capability of the road safety barrier system. This will lead to better safety conditions on the roadways and potentially save lives.

Revolute joint approach to model joint mechanism in water-filled road safety barriers

Portable water-filled road barriers (PWFB) are roadside structures placed on temporary construction zones to separate work site from traffic. Recent changes in governing standards require PWFB to adhere to strict compliance in terms of lateral displacement and vehicle redirectionality. Actual PWFB test can be very costly, thus researchers resort to Finite Element Analysis (FEA) in the initial designs phase. There has been many research conducted on concrete barriers and flexible steel barriers using FEA, however not many was done pertaining to PWFB. This research probes a new technique to model joints in PWFB. Two methods to model the joining mechanism are presented and discussed in relation to its practicality and accuracy. Moreover, the study of the physical gap and mass of the barrier was investigated. Outcome from this research will benefit PWFB research and allow road barrier designers better knowledge in developing the next generation of road safety structures.

Impact and energy absorption of portable water-filled road safety barrier system fitted with foam

Portable water-filled barriers (PWFBs) are roadside appurtenances that are used to prevent errant vehicles from penetrating into temporary construction zones on roadways. A numerical model of the composite PWFB, consisting of a plastic shell, steel frame, water and foam was developed and validated against results from full scale experimental tests. This model can be extended to larger scale impact cases, specifically ones that include actual vehicle models. The cost-benefit of having a validated numerical model is significant and this allows the road barrier designer to conduct extensive tests via numerical simulations prior to standard impact tests Effects of foam cladding as additional energy absorption material in the PWFB was investigated. Different types of foam were treated and it was found that XPS foam was the most suitable foam type. Results from this study will aid PWFB designers in developing new generation of roadside structures which will provide enhanced road safety.

Effect of joint mechanism on vehicle redirectional capability of water-filled road safety barrier systems

Portable water-filled barriers (PWFBs) are roadside appurtenances that prevent vehicles from penetrating into temporary construction zones on roadways. PWFBs are required to satisfy the strict regulations for vehicle re-direction in tests. However, many of the current PWFBs fail to re-direct the vehicle at high speeds due to the inability of the joints to provide appropriate stiffness. The joint mechanism hence plays a crucial role in the performance of a PWFB system at high speed impacts. This paper investigates the desired features of the joint mechanism in a PWFB system that can re-direct vehicles at high speeds, while limiting the lateral displacement to acceptable limits. A rectangular “wall” representative of a 30 m long barrier system was modeled and a novel method of joining adjacent road barriers was introduced through appropriate pin-joint connections. The impact response of the barrier “wall” and the vehicle was obtained and the results show that a rotational stiffness of 3000 kNm/rad at the joints seems to provide the desired features of the PWFB system to re-direct impacting vehicles and restrict the lateral deflection. These research findings will be useful to safety engineers and road barrier designers in developing a new generation of PWFBs for increased road safety.

Crisis on impact : responding to cyber attacks on critical information infrastructures

In the developing digital economy, the notion of traditional attack on enterprises of national significance or interest has transcended into different modes of electronic attack, surpassing accepted traditional forms of physical attack upon a target. The terrorist attacks that took place in the United States on September 11, 2001 demonstrated the physical devastation that could occur if any nation were the target of a large-scale terrorist attack. Therefore, there is a need to protect criticalnational infrastructure and critical information infrastructure. In particular,this protection is crucial for the proper functioning of a modern society and for a government to fulfill one of its most important prerogatives – namely, the protection of its people. Computer networks have many benefits that governments, corporations, and individuals alike take advantage of in order to promote and perform their duties and roles. Today, there is almost complete dependence on private sector telecommunication infrastructures and the associated computer hardware and software systems.1 These infrastructures and systems even support government and defense activity.2 This Article discusses possible attacks on critical information infrastructures and the government reactions to these attacks.

Improving safety for driverless city vehicles : real-time communication and decision making

This paper elaborates on the Cybercars-2 Wireless Communication Framework for driverless city vehicles, which is used for Vehicle-to-Vehicle and Vehicle-to-Infrastructure communication. The developed framework improves the safety and efficiency of driverless city vehicles. Furthermore, this paper also elaborates on the vehicle control software architecture. On-road tests of both the communication framework and its application for real-time decision making show that the communication framework is reliable and useful for improving the safe operation of driverless city vehicles.

Towards increased road safety : real-time decision making for driverless city vehicles

This work elaborates on the topic of decision making for driverless city vehicles, particularly focusing on the aspects on how to develop a reliable approach which meets the requirements of safe city traffic. Decision making in this context refers to the problem of identifying the most appropriate driving maneuver to be performed in a given traffic situation. The overall decision making problem is decomposed into two consecutive stages. The first stage is safety-crucial, representing the decision regarding the set of feasible driving maneuvers. The second stage represents the decision regarding the most appropriate driving maneuver from the set of feasible ones. The developed decision making approach has been implemented in C++ and initially tested in a 3D simulation environment and, thereafter, in real-world experiments. The real-world experiments also included the integration of wireless communication between vehicles.