Numerical investigations of flow and passive pollutant exposure in high-rise deep street canyons with various street aspect ratios and viaduct settings

2017 ◽  
Vol 584-585 ◽  
pp. 189-206 ◽  
Author(s):  
Lejian He ◽  
Jian Hang ◽  
Xuemei Wang ◽  
Borong Lin ◽  
Xiaohui Li ◽  
...  
Keyword(s):  
Street Canyons ◽  
Numerical Investigations ◽  
High Rise ◽  
Aspect Ratios

scholarly journals Impact of Gust and Tectonic Drags on Irregular High Rise Structures

2020 ◽  
Vol 9 (9) ◽  
pp. 427-439
Keyword(s):  
Urban Infrastructure ◽  
High Rise ◽  
Aspect Ratios ◽  
Irregular Structures ◽  
Dynamic Forces ◽  
Gust Loads ◽  
Irregular Buildings ◽  
Structural Failures ◽  
The Impact ◽  
Base Width

As the population is growing and land becomes limited and new materials and construction technologies are built together, structural structures of this nature are growing larger and smaller, which are prone to two types of dynamic forces, tectonic drags and wind powers. In developing countries like India the exponential growth of the urban population has prompted a reassessment of the value of high – rise irregular buildings. For the construction of high - rise irregular buildings, the impact of gust loads is to be remembered. In India, gust caused numerous structural failures. IS 875:2015 Part-3 considers the gust loads on various kinds of irregular structures and IS 1893 (Part-1):2016 recognizes tectonic drags. The study focuses on peculiar constructions of different aspect ratios i.e. the impact of tears and tectonic drags. H / B ratio, with H being the overall construction system height; and B being the base width of the structure frame using STADD , Structure mass irregularities using E-TABS; from this paper we are examining the impact of wind (gusts), seismic (tectonical) load on building height by changing the number of floors with a the aspect rate. H / B ratio Many researchers design a system that is immune to tectonic drags, but the tectonic drag framework can not be built without causing damage. A large proportion of existing urban infrastructure is composed of vertical irregular structures.

scholarly journals The influence of aspect ratios and wall heating conditions on flow and passive pollutant exposure in 2D typical street canyons

2020 ◽  
Vol 168 ◽  
pp. 106536 ◽  
Author(s):  
Jian Hang ◽  
Xieyuan Chen ◽  
Guanwen Chen ◽  
Taihan Chen ◽  
Yuanyuan Lin ◽  
...  
Keyword(s):  
Street Canyons ◽  
Aspect Ratios ◽  
Wall Heating

Large-Eddy Simulation of Reactive Pollutant Dispersion Over Street Canyons of Different Aspect Ratios

2014 ◽  
Author(s):  
T. Z. Du ◽  
Chun-Ho Liu ◽  
Y. B. Zhao
Keyword(s):  
Aspect Ratio ◽  
Large Eddy Simulation ◽  
Chemical Reactions ◽  
Pollutant Dispersion ◽  
Pollutant Removal ◽  
Street Canyons ◽  
Eddy Simulation ◽  
Aspect Ratios ◽  
Large Eddy ◽  
Reactive Pollutant

In urban areas, pollutants are emitted from vehicles then disperse from the ground level to the downstream urban canopy layer (UCL) under the effect of the prevailing wind. For a hypothetical urban area in the form of idealized street canyons, the building-height-to-street-width (aspect) ratio (AR) changes the ground roughness which in turn leads to different turbulent airflow features. Turbulence is considered an important factor for the removal of reactive pollutants by means of dispersion/dilution and chemical reactions. Three values of aspect ratio, covering most flow scenarios of urban street canyons, are employed in this study. The pollutant dispersion and reaction are calculated using large-eddy simulation (LES) with chemical reactions. Turbulence timescale and reaction timescale at every single point of the UCL domain are calculated to examine the pollutant removal. The characteristic mechanism of reactive pollutant dispersion over street canyons will be reported in the conference.

scholarly journals The Influence of High-Rise Buildings on Pedestrian-Level Wind in Surrounding Street Canyons in an Urban Renewal Project

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2745
Author(s):  
Tzu-Ling Huang ◽  
Chien-Yuan Kuo ◽  
Chun-Ta Tzeng ◽  
Chi-Ming Lai
Keyword(s):  
Urban Renewal ◽  
Natural Ventilation ◽  
Practical Case ◽  
Street Canyons ◽  
High Rise ◽  
Taipei City ◽  
Renewal Project ◽  
Urban Renewal Project ◽  
Shielding Effects

The pedestrian wind environment in a street canyon is affected by a multitude of factors, including the height and geometric shape of the surrounding buildings, the street width, the wind direction, and speed. Wind-tunnel tests were performed to determine the effects of constructing high buildings in an urban renewal project in New Taipei City, Taiwan on the pedestrian wind environments in the surrounding street canyons. The results show that replacing the original low-rise buildings with high-rise buildings could decrease the wind speed and natural ventilation potential in certain surrounding street canyons. The flow fields generated by approaching winds in various street canyons are highly complex in this practical case study. Thus, the pedestrian wind patterns in the street canyons cannot be interpreted in terms of channeling and shielding effects alone, as is typically reported in the literature.

scholarly journals Flow and Pollutant Transport in Urban Street Canyons of Different Aspect Ratios with Ground Heating: Large-Eddy Simulation

2011 ◽  
Vol 142 (2) ◽  
pp. 289-304 ◽  
Author(s):  
Xian-Xiang Li ◽  
Rex E. Britter ◽  
Leslie K. Norford ◽  
Tieh-Yong Koh ◽  
Dara Entekhabi
Keyword(s):  
Large Eddy Simulation ◽  
Pollutant Transport ◽  
Street Canyons ◽  
Urban Street ◽  
Eddy Simulation ◽  
Urban Street Canyons ◽  
Aspect Ratios ◽  
Large Eddy

Effect of Aspect Ratio on High Rise Structures with Diagrid

2021 ◽  
Vol 6 (3) ◽  
Author(s):  
A. Vimala ◽  
A. Vimala
Keyword(s):  
Aspect Ratio ◽  
Numerical Study ◽  
Percentage Increase ◽  
Base Shear ◽  
High Rise ◽  
Aspect Ratios ◽  
Drift Ratio ◽  
Time Period ◽  
Diagrid Structure ◽  
Building Behaviour

Urbanization and population explosion in the present times has led to increase in demand for land and residencies but the availability of land is scare i.e reason a trend has evolved for construction of high rise structures in high rise structures major emphasis given to lateral load resisting systems. As diagrid structural system is lighter, stiffer and is effective in resisting the lateral loads, the present investigation carried out to study the performance diagrid on high rise structures varying aspect ratio. The study is carried out to observe the performance of diagrid structures ranging from 30 to 90 storeys. Diagrid structures are modelled with 3 storey module and performance of 7 models with different storeys i.e 30, 40, 50, 60, 70, 80, 90 (aspect ratio 3.67-10.86) and with fixed plan area. As a part 1 investigation to optimise the diagrid angle a 30 storey Diagrid structure performance is studied with 4 different diagrid angles one storey module angle 35°45’, Two storey module angle 55°13’, Three storey module 65°9’, Four storey module 70°51’. The optimized diagrid angle is used for different aspect ratio high rise structures to investigate the performance in terms of Storey displacement, Storey drift ratio, base shear and time period. For all the models plan area is fixed. Second part of investigation was a numerical study carried out by utilizing identified optimum angle of diagrid is applied on high rise buildings with aspect ratios 3.67, 4.86, 6.06, 7.26, 8.46, 9.67, 10.86 (Aspect ratio is the total height of the building to the width of the building). Behaviour of the Diagrid buildings due to change in aspect ratio is analysed based on parameters such as Storey displacements, Storey drift ratio, Base shear, Time period. As a part of investigation parameters such as Storey displacements and storey drift ratio were evaluated if they were within the limits as per IS code provisions. Percentage increase in storey displacements, maximum storey drift ratio,

Proposal for an Efficient Damping System for High-Rise Buildings in Major Earthquakes

2016 ◽  
Vol 11 (1) ◽  
pp. 106-117
Author(s):  
Katsuhide Murakami ◽  
◽  
Masato Ishii ◽  
Kentaroh Miyazaki ◽  
Yasuhiro Tsuneki
Keyword(s):  
Vibration Control ◽  
Protection Mechanism ◽  
High Rise ◽  
Aspect Ratios ◽  
Individual System ◽  
Combined Use ◽  
New Type ◽  
Viscous Mass ◽  
Shearing Deformation ◽  
Damping Effects

Recent vibration resistant designs for buildings in Japan often adopt a vibration control structure with dampers arranged in the framework. Generally, the dampers are arranged in the building’s core in a geometry that works most effectively to protect against story shearing deformation. It is already known, however, that the above-mentioned arrangement of dampers does not provide good damping effects for the upper stories of high-rise buildings with large aspect ratios, because the protection mechanism is designed to decrease the shearing deformation components of the building’s horizontal deformation caused by its horizontal loads. A new type of dampers, called force-restricted tuned viscous mass dampers (FRTVMD), has been recently developed for such circumstances, amplifying the deformation of viscous dampers with their tuned mass effects. This paper, therefore, first presents a tuned mass damper (TMD) system, effective for high-rise buildings with large aspect ratios against great earthquakes, and then proposes a new vibration control structural system capable of generating better damping effects with FRTVMD. In addition, we review its characteristics and effects by analyzing its vibration response, as well as verify that a combined use of such vibration control structural systems will generate far greater damping effects than an individual system.

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