Quantiles of critical separation distance for nonstationary seismic excitations

2006 ◽  
Vol 28 (7) ◽  
pp. 985-991 ◽  
Author(s):  
S.S. Wang ◽  
H.P. Hong
Keyword(s):  
Separation Distance ◽  
Seismic Excitations ◽  
Critical Separation

scholarly journals Determination of Critical Separation Distance Between Dwellings in Informal Settlements Fire

2021 ◽  
Author(s):  
Yu Wang ◽  
Lesley Gibson ◽  
Mohamed Beshir ◽  
David Rush
Keyword(s):  
Heat Flux ◽  
Informal Settlement ◽  
Informal Settlements ◽  
Fire Risk ◽  
Fire Spread ◽  
Separation Distance ◽  
Flame Length ◽  
Critical Distance ◽  
Fire Disaster ◽  
Critical Separation

AbstractApproximately one billion people across the globe are living in informal settlements with a large potential fire risk. Due to the high dwelling density, a single informal settlement dwelling fire may result in a very serious fire disaster leaving thousands of people homeless. In this work, a simple physics-based theoretical model was employed to assess the critical fire separation distance between dwellings. The heat flux and ejected flame length were obtained from a full-scale dwelling tests with ISO 9705 dimension (3.6 m × 2.4 m × 2.4 m) to estimate the radiation decay coefficient of the radiation heat flux away from the open door. The ignition potential of combustible materials in adjacent dwellings are analyzed based on the critical heat flux from cone calorimeter tests. To verify the critical distance in real informal settlement fire, a parallel method using aerial photography within geographic information systems (GIS), was employed to determine the critical separation distances in four real informal settlement fires of 2014–2015 in Masiphumelele, Cape Town, South Africa. The fire-spread distances were obtained as well through the real fires. The probabilistic analysis was conducted by Weibull distribution and logistic regression, and the corresponding separation distances were given with different fire spread probabilities. From the experiments with the assumption of no interventions and open doors and windows, it was established that the heat flux would decay from around 36 kW/m2 within a distance of 1.0 m to a value smaller than 5 kW/m2 at a distance of 4.0 m. Both experiments and GIS results agree well and suggest the ignition probabilities at distances of 1.0 m, 2.0 m and 3.0 m are 97%, 52% and 5% respectively. While wind is not explicitly considered in the work, it is implicit within the GIS analyses of fire spread risk, therefore, it is reasonable to say that there is a relatively low fire spread risk at distances greater than 3 m. The distance of 1.0 m in GIS is verified to well and conservatively predict the fire spread risk in the informal settlements.

The multi-energy critical separation distance

2003 ◽  
Vol 16 (2) ◽  
pp. 111-120 ◽  
Author(s):  
A.C. van den Berg ◽  
N.H.A. Versloot
Keyword(s):  
Separation Distance ◽  
Critical Separation

Critical separation distance needed to form weak menisci between the head and the disk — A molecular simulation study

2008 ◽  
Vol 138 (1-3) ◽  
pp. 120-123
Author(s):  
Mohammed S. Mayeed ◽  
Abdulhakeem M. Al-Mekhnaqi ◽  
Takahisa Kato ◽  
Golam M. Newaz
Keyword(s):  
Molecular Simulation ◽  
Simulation Study ◽  
Separation Distance ◽  
Critical Separation

Coalescing of geostrophic vortices

1987 ◽  
Vol 178 ◽  
pp. 73-97 ◽  
Author(s):  
R. W. Griffiths ◽  
E. J. Hopfinger
Keyword(s):  
Separation Distance ◽  
Relative Vorticity ◽  
Critical Distance ◽  
Outer Edge ◽  
Ekman Pumping ◽  
Rotating Fluid ◽  
Rigid Boundary ◽  
Ocean Eddies ◽  
Critical Separation ◽  
Baroclinic Vortices

Close interactions between pairs of two-dimensional vortices of like sign were investigated in experiments with barotropic vortices and baroclinic vortices. The vortices were generated by sources or sinks in a rotating fluid which, respectively, was homogeneous or contained a two-layer density stratification. For two identical anticyclonic, unstratified vortices there was a critical separation distance beyond which the vortices coalesced to form a single larger anticyclone. The critical distance d*, scaled by the radius R of a core having non-zero relative vorticity, was d*/R = 3.3 ± 0.2. This value is in agreement with results of previous numerical simulations for finite-area vortices in non-rotating flows. The effects on vortex structure of Ekman pumping due to the presence of a rigid boundary caused cyclonic vortices to coalesee from larger distances. Baroclinic vortices in a two-layer stratification were also found to coalesce despite a potential-energy barrier. However, the critical separation distance depended on the internal Rossby radius. When the Rossby radius was large compared with the core radius, vortices coalesced from distances much greater than the critical distance for barotropic vortices. Coalescing of two vortices of equal size and strength led to two symmetric entwined spirals of water, while close interaction of unequal vortices caused the weaker vortex to be wrapped around the outer edge of the stronger. Implications of these results are discussed for ocean eddies and intense atmospheric cyclones.

scholarly journals Study on Methods to Control Interstory Deflections

Geosciences ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 75 ◽  
Author(s):  
Seyed Mohammad Khatami ◽  
Hosein Naderpour ◽  
Seyed Mohammad Nazem Razavi ◽  
Rui Carneiro Barros ◽  
Anna Jakubczyk-Gałczyńska ◽  
...  
Keyword(s):  
Base Isolation ◽  
Lateral Displacement ◽  
Separation Distance ◽  
Lumped Mass ◽  
Seismic Excitations ◽  
Mass Model ◽  
Adjacent Structures ◽  
Depth Analysis ◽  
Lumped Mass Model ◽  
Story Building

One of the possibilities to prevent building pounding between two adjacent structures is to consider appropriate in-between separation distance. Another approach might be focused on controlling the relative displacements during seismic excitations. Although the majority of building codes around the world recommend the use of some equations of various distances between structures to avoid pounding; a lot of reports after earthquakes have obviously shown that safety situation or economic consideration is not always provided due to the collisions between buildings and high cost of land; respectively. The aim of the present paper is to focus the analysis on the properties of structures and conduct an in-depth analysis of available methods to control interstory deflections so as to prevent pounding. For this purpose, a numerical lumped mass model of the five-story building has been considered and its response under different earthquake records has been investigated. Firstly, the influence of the change in structural properties (story stiffness; mass and damping) has been examined. Then the application of tuned mass damper, base isolation and base isolation with rubber bumpers has been considered. The results of comparative analyses clearly indicate that using base isolation, with the addition of bumpers, can be selected as the best method to control building deflections and decrease absolute lateral displacement between two buildings so as to prevent their pounding during earthquakes

Sign in / Sign up

Export Citation Format

Share Document