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Ho C.L.,Defence Science and Technology Agency | Li K.Y.,University of Canterbury | Spearpoint M.J.,University of Canterbury
Fire and Materials | Year: 2013

Smoke contamination of balconies due to a channelled spill plume at a lower level in an atrium might occur during a fire and could affect occupant safety during an evacuation. Previous experimental work has investigated the extent of smoke contamination, and this work describes a numerical modelling comparison of the experiments using the Fire Dynamics Simulator (FDS) computational fluid dynamics programme. Temperature, severity and height of smoke contamination are selected as the key parameters for comparison. The predictions of severity and height of smoke contamination are generally similar to the experimental results using a 'most severe point assessment of smoke contamination' assessment method. Although predicted temperatures are slightly lower than experimental values, FDS temperature slice files can be used at the most severe smoke contaminated point using a 10 °C temperature rise. This 10 °C threshold matches the criterion proposed in the previous experimental research. On the basis of the comparisons for the height of smoke contamination, the simulation results generally match a previously proposed equation for the height of smoke contamination above a balcony spill plume. © 2012 John Wiley & Sons, Ltd.

Xu J.,Nanyang Technological University | Lee C.K.,Nanyang Technological University | Fan S.C.,Nanyang Technological University | Kang K.W.,Defence Science and Technology Agency
International Journal of Impact Engineering | Year: 2014

In this study, the ricochet phenomenon of concrete debris impacting on sand is investigated by both experiments and numerical simulations. Three types of debris, including 50 mm â̂... concrete spheres, 60 mm and 100 mm chamfered concrete cubes, are employed in the tests. The relationship between the debris impact responses and the incident condition is studied. A numerical modelling is established to simulate the impact of the three types of debris against sand. A parametric study based on the numerical modelling is carried out to study the influence of the sand internal friction angle on the debris impact responses. © 2013 Elsevier Ltd. All rights reserved.

Zhou Y.,Defence Science and Technology Agency | Zhao J.,Monash University
Tunnelling and Underground Space Technology | Year: 2015

Underground space development has become an economic imperative for land-scarce Singapore. In 2007, the government, under the Ministry of National Development, set up an inter-agency Underground Master Planning Task Force that aims to map out the long-term development of the underground space, bringing the underground space development to a strategic level. In 2010, the Economic Strategies Committee made developing underground space part of the government's long-term economic strategy with specific recommendations on master planning, geological investigations, investment in research and development, and various policy issues. The ESC report also recommended that the government should take the lead in catalysing the use of underground space. Based on these recommendations, the Singapore government have taken various initiatives and studies, and initiated various research projects in support of these initiatives.This paper gives a review of the history of underground space development, highlights the potential utilisations, and discusses the various recent studies and planning issues, and examines possible strategies for future use of underground space in Singapore. © 2015 Elsevier Ltd.

Shen J.,Swinburne University of Technology | Shen J.,RMIT University | Lu G.,Nanyang Technological University | Ruan D.,Swinburne University of Technology | Chiang Seah C.,Defence Science and Technology Agency
International Journal of Mechanical Sciences | Year: 2015

This paper is concerned with the lateral crushing behaviour of short sandwich tubes, which consist of two concentric aluminium tubes of different diameters filled with aluminium foam. Experimental results and corresponding analytical models are presented. Aluminium sandwich tubes 50 mm long and of different values of diameter to thickness ratios were laterally crushed using an MTS machine at a displacement rate of 2 mm/min. Two bonding cases between the foam and monolithic component tubes, i.e. fully bonded and bonding free, were employed for all the configurations. Load-displacement curves were obtained. Deformation mechanisms were observed and three different crushing patterns have been identified. The experiments reveal that the bonding between the tubes and core for sandwich tubes played a different role in the three crushing patterns. Analytical models using rigid, perfectly plastic theory have been developed, which agree well with the corresponding experimental results. © 2013 Elsevier Ltd. All rights reserved.

Li J.C.,CAS Wuhan Institute of Rock and Soil Mechanics | Ma G.W.,University of Western Australia | Zhou Y.X.,Defence Science and Technology Agency
Rock Mechanics and Rock Engineering | Year: 2012

A theoretical approach is presented to study the ground motion induced by an underground tunnel explosion. The ground motion is caused by two coupled stress waves, i.e., the reflected body wave and the secondary surface wave or Raleigh wave. Based on the principle of conservation of momentum at the wavefronts, the reflected body waves along the ground surface are derived. The interaction of the body wavefront and the ground surface induces the secondary surface wave which transfers outwards on the ground. The particle velocity and particle acceleration on the ground surface are subsequently derived. The analytical results are compared with results from numerical simulations and empirical formulae with different material damping ratios. The effects of the loading density and the material damping on the ground motion are investigated. Finally, the limitations of the proposed theoretical approach for ground motion prediction are discussed. © Springer-Verlag 2011.

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