Contemporary Wind Engineering Studies in India

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The Eighth Asia-Pacific Conference on Wind Engineering,
December 10–14, 2013, Chennai, India
Contemporary Wind Engineering Studies in India
Nagesh R. Iyer
Director, CSIR-Structural Engineering Research Centre & Chairman, APCWE VIII,
CSIR Campus, Taramani, Chennai-600 113, India, director@serc.res.in
Introduction
Loads and actions due to turbulent atmospheric wind and their effects are extremely important in
many constructed facilities. Wind is the dominant loading in many structures. Load combinations
and load factors are major concerns of engineers designing these facilities. With the thrust by the
Government in investing about US$ 1.3 trillion in the 12th Five Year Plan in the development of
physical infrastructure, there has been a growing trend in design and construction of several highrise residential cum commercial complexes, flyovers, bridges with unconventional architectural
shapes. Further, with Indian Government’s initiatives for upgrading and augmenting the power
plants, chimneys of height as tall as 275 m and cooling towers of height of about 170 m are becoming realities. Most of these are highly wind sensitive with straight forward solution for design,
detailing and construction. One the most effective solutions would be to conduct investigations of
wind induced dynamic response of structural scaled models in boundary layer wind tunnels
(BLWT). CSIR-Structural Engineering Research Centre (SERC), Chennai which is a national
research laboratory under the Council of Scientific and Industrial Research, and other academic
institutions such as Indian Institute of Technology Roorkee (IIT), Roorkee; Indian Institute of
Technology Kanpur (IIT), Kanpur; Visveswaraya National Institute of Technology (VNIT),
Nagpur are some of the well known institutions engaged in active wind engineering research in
our country. A brief account of recent developments in the area of R&D in wind engineering in
India is presented in this paper.
Wind Engineering R&D Activities in India
Boundary Layer Wind Tunnel (BLWT) Testing
CSIR-SERC, IIT, Kanpur, and IIT, Roorkee have atmospheric BLWT facilities for undertaking
experimental investigations. Nevertheless, R&D activities which are analytically based are being
carried out in other institutions also.
The BLWT facility at CSIR-SERC is a world class facility (Fig. 1). The open circuit blower type
BLWT has a total length of 52m with a test section size of 2.5m x 1.8m x 18.0m and a maximum
wind speed of about 55m/s can be generated. As high as 1.1m depth on boundary layer can be
satisfactorily developed. Some of the typical view of the models of industrial structures recently
tested using the BLWT under isolated and interference conditions are given in Figs. 2.1 to 2.5
(Selvi Rajan et al., 2013 and Ramesh Babu et al., 2013). The laboratory is also equipped with sophisticated equipment of Particle Image Velocimetry (PIV) system; high frequency force balance;
computer controlled transverse system, etc.
IIT, Roorkee, has undertaken a pressure measurement study on 1:25 scale model of TTU building and compared the mean, RMS and minimum pressure coefficients of selected roof taps with
the full-scale measured values (Narayan and Gairola, 2011). Even though the comparison was
reasonable for some roof taps, the study emphasized the need to simulate the turbulence intensities and small scale turbulence content in the incident flow. Similarly Nikhil Agarwal et al. (2012)
Copyright © 2013 APCWE-VIII. Published by Research Publishing Services.
ISBN: 978-981-07-8012-8 :: doi:10.3850/978-981-07-8012-8_Key-07
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(a) 600HP Fan
(b) Precision Turntable for Positioning Structural Models
(c) Boundary Layer Wind Tunnel
Fig. 1.
The Boundary Layer Wind Tunnel (BLWT) Facility at CSIR-SERC.
Fig. 2.1.
Building – 300 m Tall.
carried out a wind tunnel study on a 1:400 aeroelastic model of a rectangular building with 1:3
plan ratio and 1: 12 aspect ratio under three terrain conditions to measure tip acceleration, and
base shear and bending moment. The evaluated Gust Response Factor values, Peak acceleration
values, base shear and bending moment values have been compared with the values calculated
using various international standards. The experimental results showed more or less similar
trends in comparison to international standards, except for the case of wind direction normal to
shorter side under heavy suburban terrain.
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Contemporary Wind Engineering Studies in India
Fig. 2.2.
Fig. 2.4.
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Tall Chimney Model (H= 275m-full scale).
Fig. 2.3.
Cooling Tower Model (H = 173 m-full scale).
Model of green building (H = 99m-full scale).
Fig. 2.5.
Row of chimney models (H = 72 m-full scale).
Experimental investigations on parabolic dish antenna, tall residential tower buildings under
stand-alone and interfering conditions, and aerodynamic study on single flue and multi-flue
chimneys have been carried out at the National Wind Tunnel Facility, IIT, Kanpur. Fig. 3 shows
photographic view of some of the studies carried out at IIT, Kanpur.
(a) 200 m Tall Residential Tower Model
being Tested in the Wind Tunnel
Fig. 3.
(b)Tall Residential Towers Tested under
Interfering Condition
Typical Wind Tunnel Tests Carried out at IIT, Kanpur.
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Fig. 4.
Typical View of Simulated Whirly winds around Group of Buildings in BLWT.
Simulation of cyclone wind effects in BLWT still remains a challenging task all over the world.
Towards this, CSIR-SERC has succeeded to limited extent, through an innovative experimental
technique, in simulating the whirly winds using the state-of-the-art boundary layer wind tunnel
(BLWT) (Lakshmanan, et al., 2009). This would enable us to study the interaction of vortex flows
over smooth and rough terrains as also flow modifications that would occur. Wind tunnel experiments have been conducted on simple vortex flows and the interaction of terrain, and model
scaled to 1 and 2 orders in dimensions. Efforts are in progress for simulation of appropriate length
scales and enhanced turbulence intensity levels (Fig. 4).
CSIR-Central Road Research Institute (CRRI), New Delhi has a wind tunnel having a crosssection of 1m x 1m, which has been used to study many problems relating to industrial
aerodynamics including interference effects on a group of chimneys and a group of cooling towers. CSIR-CRRI has conducted studies for aerodynamic parameters of bridges through wind
tunnel testing, numerical algorithms have been developed to compute the vortex induced
response of bridge and buffeting response using frequency domain approach. Further, Lakshmy,
et al. (2009) have carried out a time domain buffeting analysis of a cable stayed bridge deck section to study the effect of 6 different types of deck support on its response.
Research group at VNIT, Nagpur has carried out an analytical work on wind response control of tall RC chimneys using existing maintenance platforms as tuned mass dampers for
reducing wind induced oscillations (Reddy et al., 2011).
Full-Scale Field Experiments
While full-scale testing and evaluation have been recognized as an important requirement, only
CSIR-SERC has been carrying out these activities continuously since 1995. Thus, besides wind
tunnel testing, the wind engineering team at CSIR-SERC has developed, over years, expertise in
carrying out for measurements of wind data and wind induced structural response data on several lattice towers (Fig. 5) and other structures (Lakshmanan et al., 2008).
Studies on Wind Turbine Supporting Towers
CSIR-SERC has also developed, over the years, the expertise in analyzing and designing lattice
towers supporting wind turbines, and also in carrying out full-scale field measurement of structural response of these lattice towers under various operating conditions.
CSIR-SERC is also involved in developing indigenous design of a complete low-cost horizontal axis wind turbine (CSIR-NMITLI, 2009) in collaboration with a sister Laboratory of CSIR,
India, along with an industrial partner for execution of the first prototype working model of the
designed wind turbine at a site near Tirupur in the state of Tamil Nadu under (Fig. 6). The complete structural design of a tilt-up/down tubular tower and its foundations was carried out.
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(a) 52m Tall Lattice Tower at SERC Campus
Fig. 5.
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(b) 101m tower
Typical full scale measurements on towers for wind and structural response data.
(a) Operational wind turbine load measurements using a new portable
32-channel data acquisition system
(b) Telemetry receiver at Field site
Fig. 6.
(c) Telemetry Transmitter in mobile field van
Typical views of field measurements on a wind turbine support tower.
Studies on Wind Induced Fatigue
The fluctuating wind loads form the basis for estimation of wind-induced fatigue on dynamically
wind sensitive structures. For slender structure, a generalized gust response factor based bimodel spectral method for the evaluation of fractional fatigue damage has been formulated for
practical design of metallic structures. An expression for effective frequency of background component due to wind turbulence has been suggested to be used with the usual gust response factor
method for estimating fatigue damage in various bins wind speed ranges (Gomathinayagam et
al., 2006). Based on the analytical approach formulated to estimate fatigue life, it is recommended
to use fractional fatigue damage obtained either from the field measurements or from analytical
predictions along with probability density function of mean wind speeds at a site for the cumulative possible fatigue in the design of life of the structure.
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Nagesh R. Iyer
Research Studies using Computational Fluid Dynamics (CFD)
Research in the field of Computational Fluid Dynamics has also been taken up in the recent
years in several of R&D institutions including CSIR-SERC. Some of the recent studies carried
out in this field include (i) Numerical simulation of wind flow over prismatic buildings (Ghosh,
2009); (ii) Experimental and numerical evaluation of wind induced response of a square building (Harikrishna et al., 2009) and (iii) Simulation of dry axi-symmetric microburst flow field
(Das et al., 2010). In the first study, the author reviews the chronological development of numerical modeling applied to flow over prismatic buildings. It is specifically mentioned that
although the use of numerical modeling to solve wind engineering started about three decades
ago, many uncertainties still persist about numerical simulation due to complicated flow field
generated as wind flows over prismatic building structures with sharp corners. Development
of a suitable turbulent model which can account for small eddies is reported as the main channel for the researchers.
In the second study, the author has carried out wind tunnel experiments on 1:300 scale model
with an aspect ratio of 1:6 in simulated open terrain conditions. Measurements were made to evaluate along-wind and across-wind base bending moments and the results were compared with
those given in the Code. Numerical simulations have also been carried out on an isolated square
building using Realizable k-ε model and SST-ω turbulence models. Based on comparison with the
results of the experimental values, the author suggests the mean along-wind base bending
moment coefficient can be reliably predicted using the above models for the evaluation of overall
wind loads on the building.
In the third study, the authors have attempted to numerically simulate the dry microburst for
investigating the macro flow dynamics, scale (Reynolds Number) dependency and the effect of
surface conditions (roughness). The axi-symmetric impinging jet model is used to develop the
numerical code that uses large eddy simulation (LES) for the turbulence. Predicted solutions are
compared with the results of the famous empirical relations of Holmes and Oliver (2000) and fair
agreement was reported.
Status on Codes of Practice
CSIR-SERC has significantly contributed to the Codes of Practice on wind loads (IS: 875 (Part 3)1987). This code is presently under revision. A major portion of the code on pressure/force
coefficients has not been altered. The earlier version has considered different averaging periods
depending on the largest dimension of the structures for obtaining the basic wind speeds. In the
proposed draft, area modification factors have been introduced. The main purpose of the draft has
been to introduce analytical expressions wherever feasible as against tables. The express purpose
of this is the advantage that would be derived in computational algorithms. The draft is currently
being finalized by Bureau of Indian Standards (BIS) and would be sent for wide circulation for
eliciting the comments of the academicians, researchers, and practicing engineers.
CSIR-SERC is actively pursuing research in the area of across-wind loads and effects on tall
RC chimneys and suggests an alternate method for modeling the across wind force and response
of a circular chimney including lock-in effects (Arunachalam and Lakshmanan, 2009). CSIR-SERC
is thus actively involved in the revision of the current Indian code on concrete chimneys (IS:49981992). CSIR-SERC has also contributed in collaboration with IIT Madras to the revision by
developing the interaction curves for limit state design of RC chimneys with and without openings (Harikrishna et al., 2012).
A draft for wind loads on Bridges Clause 212 of IRC 6:2000 has been prepared by CSIR-CRRI.
The draft specifies hourly mean wind velocities for different terrains at various altitudes. Methods
have been specified to compute transverse, longitudinal, and vertical wind loads on the bridge
structure. All the codes of practice specify wind tunnel testing for non-standard cases and for
computing interference effects.
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Revisit of Design Wind Speed Map of India using Long Term Hourly Wind Data
As part of the revision of the present IS code, IS:875 (part 3)1987, CSIR-SERC revisited the basic
wind speed map of India . Hourly wind speed data from as many as 70 meteorological centres of
India Meteorological Department (IMD) in India has been collected and the daily gust wind data
has been processed for annual maximum wind speed for each regional site where the long term
IMD data has been available. Using the Gumbel probability paper approach the extreme value
statistics have been fitted to derive the parameters of the extreme value distribution. Using the
annual maximum gust wind at any given location, a design basic wind speed as appropriate for
the site for a standard return period of 50 years has been evaluated (Lakshmanan, et al., 2009). The
results of the extreme wind data analysis is used for highlighting the site specific variations of the
wind speeds in the contemporary wind zone map used for wind load computation on buildings
and structures. The suggested modified basic wind speed map of India is given in Fig. 7.
Fig. 7.
Suggested modification of Design Wind Speed Map of India.
Cyclone Hazard Mitigation
Cyclones, typhoons or hurricanes cause colossal loss including loss of life every year in different
parts of the world. Developing countries such as Bangladesh, India, Philippines, Malaysia, Sri
Lanka and also the developed countries such as Australia, Japan and the U.S.A. experience heavy
losses due to cyclones or typhoons. Cyclones are considered to be most dangerous among all the
natural hazards, when viewed in terms of intensity, duration and the extent of destruction.
Around eighty tropical cyclones occur each year around the globe, of which about 5 to 6 on average occur over the north Indian Ocean. The Bay of Bengal is one of the six most vulnerable
cyclone-prone regions of the world. When a cyclone hits a region, besides killing people it brings
about large scale damage to crops, houses and buildings, roads, electrical transmission lines,
communication facilities, water supply systems, etc. It is of concern to note that there has been an
increase in the number of wind storms and the losses to the economy over the years. The economic losses during the decade 1989–1998, was reported as US$ 137.7 billion, which implies a five
times increase over the decade 1960–1969 (TCDC Workshop, 1999). Among the five continents of
the world, Asia is the worst hit in respect of human deaths and economic loss suffered. The
Hurricane Andrew in August 1992 in US resulted in a property insurance amount of as high as
US$18 billion and the Katrina Hurricane in US in 2005 caused US$28 billion economic loss.
Similarly, the different typhoons which struck Japan in 2004 caused US$8 billion (Tamura, 2009).
Therefore, cyclone disaster management and mitigation assumes great importance both
nationally and internationally. Disaster management/mitigation requires multi-disciplinary effort
involving financial, scientific and technological inputs, managerial effectiveness, social understanding and above all dedicated efforts of all concerned agencies. Major activities and players in
cyclone disaster mitigation and their role are shown in Fig. 8.
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Post Disaster Relief and Rehabilitation
ƒ Restoration of Electrical
Power, Communications
ƒ Restoration of Transportation
Infrastructure
ƒ Damage Assessment
ƒ Financial Relief
ƒ Measures to Restore Working
Conditions
ƒ Facilitate Rehabilitation
− ii, xiii
− ii, vii, xiii
− i ,ii, vii,
iv, xiv
− iv, i, vii, vi
− i, ii, vi, v,
xiii
− i, ii, vi, v,
xiv
Disaster Management
ƒ Early Warning of Hazard
ƒ Rescuing People
Evacuation to Safer Places
ƒ Providing Temporary Shelters
ƒ Supply of Food, Water, Blankets
and Medical Help
ƒ Establish Communications
ƒ Precautions to Contain Epidemics
− iii, i, v, xi
− i ,v, xiii, vi
ƒ Construction of Cyclone
Shelters
ƒ Maintenance/Strengthening
of Important Buildings/
Structures
ƒ Educating and Training of
People
ƒ Development of S&T
− Assessment of Vulnerability
− Preparation of Guidelines/
Codes for Reducing Risk
Fig. 8.
Disaster
− i ,v, vi, ii
− i, v, vi, xiii
Mitigation
− ii, xiii, xi, i
− i, v, xii, ii
Disaster Preparedness
ƒ Stocking of Essential Items
Cyclone
− i, iv,xii,
xiii
− i, ii, ix, x,
viii, xiv
− ii, ix, viii,
x
− viii, ix,
xi, vi
− viii, ix,
xiv
i.
Local Administration
ii.
Engineering Departments
iii.
Meteorology Department
iv.
Policy/Decision Makers
v.
People
vi.
Voluntary Agencies
vii.
Financial/Insur ance Agencies
viii.
Academic Institutions
ix.
R&D and other apex Institutions
x.
Design/Construction Agencies
xi.
Publicity/Media
xii.
Medical/Health Organizations
xiii.
Defense Services
xiv.
International Organizations
Major Activities and Players in Cyclone Disaster Mitigation.
One of the major causes for loss of human life due to natural disasters is that people live in
disaster-prone areas and that the houses, buildings and other structures are not disaster-proof.
The expert group set up by the Government of India under Ministry of Urban Affairs and
Employment on Natural Disaster Prevention, Preparedness and Mitigation having a bearing on
housing and related infrastructure has brought out guidelines (Vulnerability Atlas of India, 1998),
which include among other things distribution of houses, for each district of the country, and their
classification based on the predominantly used materials for roofing and walling.
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Lessons from Post-Disaster Damage Surveys
2011 Tamilnadu
1996 Andhra
1989 Andhra
2013 Odisha
1996 Andhra
1999 Orissa
1998 Gujarat
CSIR-SERC has been conducting post-disaster damage surveys and analyzing the damage and
failure of structures due to cyclones since the Andhra Pradesh cyclone in 1977. Recently, after
cyclone ‘THANE’ crossed at Cuddalore on 30th December 2011, a post-disaster damage survey
was conducted by CSIR-SERC scientists. Further, after cyclone ‘PHAILIN’ crossed Odisha coast
near Gopalpur on 12th October 2013, another post-disaster damage survey was conducted by
CSIR-SERC scientists. Typical damages suffered by some structures during cyclonic storms are
shown in Fig. 9. In addition to the common observations such as flying off of roof tiles and
asbestos roofing sheets, failures of compound walls and damage to non-engineered buildings,
etc., there were a number of cases of damage or failure of engineered buildings and structures. To
quote an example, the analysis of failure of an elevated water tank revealed the importance of taking into account the dynamic effects of wind gusts and soil-structure interaction, besides the
Odisha 2013
Fig. 9.
Typical damage to structures due to cyclones.
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influence of reinforcement detailing on the ultimate strength of the structure. Thus, the post-damage surveys and analysis can help in identification of: i) Vulnerable locations, orientations and
geometries, ii) Vulnerable elements in structural systems, iii) Inadequacies in load path, iv) Weak
links in joints and connections, v) Influence of structural detailing on connections of the structure,
vi) Improvements needed in design and construction.
Analysis of damage clearly points out that much of the damage or failures of engineered
structures could be avoided by paying more attention for estimating the design wind loads,
detailing of connections, and quality of construction and maintenance. Also, a detailed dynamic
analysis, instead of an equivalent static analysis, is recommended for wind sensitive structures.
Based on the research and development activities in the field of wind engineering and cyclone disaster mitigation conducted at CSIR-SERC over the years, guidelines for design and construction
of buildings and structures in cyclone-prone areas have been brought out which have been incorporated by Bureau of Indian Standards (IS:15498, 2004). The Research Centre has thus
significantly contributed to the Guidelines brought out by Bureau of Indian Standards (IS:15499,
2004) for carrying out post-disaster damage surveys and scientific evaluation of damage.
Studies on Normal and Cyclonic Wind Characteristics
During the recent years, CSIR-SERC has developed methodologies, facilities and expertise for
conducting field experiments on measurement of wind characteristics at different heights of an
instrumented tower, as well as its structural response. The characteristics of wind and the
response of a 101 m high lattice tower were studied by making measurements with cup anemometers and piezo-electric type accelerometers at various levels. The experimental structure was
located in a sub-urban area in Chennai very near to the sea coast. The mean values of power law
coefficient, surface roughness length, shear friction velocity, surface drag coefficient, turbulence
intensity and length scales have been calculated. Power spectrum of wind speeds at different levels were compared with recommended spectra of Davenport, Harris, Hino and Shiotani. Good
agreement was noted between various experimental values with corresponding values given in
the literature for a similar type of terrain.
Full-scale experiments on tropical cyclonic wind characteristics were also conducted using the
52 m tall steel lattice tower located in the campus. Data collected from the instrumented tower
during tropical cyclones in June and December 1996, were analyzed and compared with characteristics obtained during normal wind conditions. One of the significant conclusions of this
study was that cyclonic spectral characteristics are significantly different from those corresponding to well-behaved normal winds. In the case of cyclonic wind speeds, gust energy can be noted
even at frequencies beyond 1 Hz (Shanmugasundaram et al., 1999), as can be seen from Fig. 10.
Fig. 10.
Power Spectrum of Cyclonic Winds.
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This has significance for design of structures in tropical cyclone -prone regions. The damage
suffered by some of the well-engineered lattice towers during cyclones may be explained by the
above observation.
Wind Monitoring Program Along East-Coast of India
Recently, CSIR-SERC has initiated cyclone wind monitoring program along the coast of India for
evaluating cyclone wind characteristics and to mitigate structure damage due to cyclones. As part
of this program, a wind monitoring system has been established at CSIR-SERC campus, Chennai
by considering the existing 52 m lattice tower instrumented with UVW-propeller and Sonic
anemometers at 4 different levels.
Cyclone wind data has been collected during the following tropical cyclones which crossed
near and around Chennai: (i) Between 18th and 19th May 2010, the tropical cyclone ‘LAILA’ moved
close to Chennai at distance of about 200 km and crossed Andhra Pradesh coast on 20th May 2010,
(ii) On 6th November 2010, tropical cyclone ‘JAL’ crossed Chennai, (iii) On 30th December 2011,
tropical cyclone ‘THANE’ crossed the Tamilnadu coast near Cuddalore, which is about 150 km
away from south of Chennai and (iv) On 31st October 2012, tropical cyclone ‘NILAM’ crossed the
Tamilnadu coast near Mahabalipuram, which is about 50 km away from south of Chennai. During
these measurements, the measured wind speeds indicated a maximum 3s gust wind speed of
about 20 m/s at CSIR-SERC campus, Chennai. Further, the analysis of measured cyclone wind
data indicated that for hourly mean wind speeds more than 5 m/s at 52 m level, the 3-s Gust
Velocity Factor value as observed to be as high as 2.1 to 2.3, which is more than the average value
of 1.63 observed during normal wind conditions. This indicated higher turbulence levels during
cyclonic wind conditions. The measured spectrum was observed to be comparable to von Karman
spectrum in all frequency regions.
CSIR-SERC was also associated with CSIR-CMMACS in establishing a 32 m tall guyed lattice
tower instrumented with propeller vane and sonic anemometers at Puducherry, which is about
100 km away from south of Chennai. Statistical cyclone wind data has been collected during the
crossing of tropical cyclone ‘THANE’ near Cuddalore, which is about 50 km away from south of
Puducherry. During these measurements, the measured wind speeds indicated a maximum 3s
gust wind speed of about 32 m/s.
Further, in collaboration with Annamalai University, Chidambaram another wind monitoring
system consisting of a 32 m tall guyed lattice tower instrumented with propeller vane anemometers at 3 levels (Fig. 11) has been established at their Parangipettai campus, which is about 200 km
Fig. 11.
Typical View of the Instrumented 32 m Tall Guyed Lattice Tower at Parangipettai.
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away from south of Chennai. Wind data has been collected during the crossing of tropical cyclone
‘NILAM’. The highest instantaneous maximum and 3s gust wind speeds are observed to be 26.7
m/s and 24.9 m/s at 32 m level. The turbulence intensities obtained at 10 m level (ave. value: 0.28)
are more than those obtained at 20 m and 32 m (ave. value: 0.23 and 0.22). The gust velocity factors obtained at 10 m level (ave. value: 2.0) are more than those obtained at 20 m and 32 m (ave.
value: 1.80 and 1.74).
Even though, the observed turbulence intensities and gust velocity factors are more during
cyclone wind conditions than during normal wind conditions, the variation of gust velocity factor for a gust duration (t) of 3s with turbulence intensity has been observed follow same trend
(Ramesh Babu et al., 2012). These observed trends have been observed to compare well with the
trends reported in literature.
Cyclonic Wind Speed for Design of Buildings and Structures
Based on the earlier research carried out at CSIR-SERC, on risk analysis of cyclonic wind speeds,
a cyclonic wind speed map of for the coastal regions of the country was developed (Fig. 12)
(Venkateswarlu et al., 1985). After deliberating among academicians, researchers, consultants and
others, the basic wind speed for cyclonic region was recommended as 65m/s. To account for this,
the enhancement factor for cyclone, ‘f’, was recommended as 1.0, 1.15 and 1.30 respectively for
dwellings, industrial buildings and for structures of post-cyclone importance. Further, the values
of the parameters A and B for use in computation of the risk coefficient, k1 given in IS:875 (Part
3)-1987 were computed as 95 kmph and 35 kmph respectively. These findings are incorporated in
the Indian code which gives guidelines for Design and Construction of Buildings and Structures
in Cyclone-Prone Areas (IS:15498-2004).
Fig. 12.
Cyclonic Wind Speed Map of Coastal India.
UNDP-SERC Project on Cyclone Disaster Mitigation
CSIR-SERC executed an UNDP assisted project entitled “Engineering of Structures for mitigating
of Damage due to Cyclones” and the following are some of the salient outcomes of this project:
i. establishment of state-of-the-art wind engineering laboratory with fully equipped atmospheric boundary layer wind tunnel facility,
ii. capability attained to undertake boundary layer wind tunnel testing on models of structures, field experiments on dynamic response of full-scale structures, post-cyclone damage
assessment,
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iii. development of guidelines on construction methods for safe and economical design of structures,
iv. training of scientists in world renowned institutions,
v. training a minimum of 100 professional engineers, architects and planners in selected technical areas by scientists of CSIR-SERC,
vi. developed a novel cyclone damage model which is very useful for the Government to implement relief and reliability operations (Lakshmanan, 2004),
vii. guidelines and development of methodologies for adoption in Indian codes for cyclone
resistant construction and design of structures, and
viii. dissemination of knowledge by conducting Advanced Courses and Workshops in the area
of wind engineering and cyclone disaster mitigation.
CSIR-SERC was adjudged by the UNDP evaluation Team as the Centre of Excellence in
Cyclone Disaster Mitigation. The CSIR-SERC technology for the design of cyclone shelter had been
adopted by the Indian and German Red Cross Societies at 23 different sites at Orissa (Fig. 13).
Each of these cyclone shelters not only withstood the fury of the 1999 Super Cyclone at Orissa, but
each shelter saved around 2000 people .The Centre along with IIT, Roorkee, has played an active
role in formulating the Guidelines on “Structural Mitigation Measures”, as part of the National
Disaster Management Guidelines brought out by the National Disaster Management Authority,
Government of India (NDMA (2008)).
Fig. 13.
Typical view of the Cyclone Shelter designed by CSIR-SERC in Orissa Coast, India.
Information Technology (IT) for Disaster Mitigation
Presently, application of IT for disaster management and mitigation in India is limited.
Methodologies and strategies have to be developed for taking the best advantage of developments in computer and Information Technologies. One of the ways is that all the major
organizations involved in disaster management and mitigation may create a web site with data
and information that they can share. Geographic Information System (GIS) can also be effectively
used in creating necessary data bases required for analysis.
Some of the recent R&D studies being pursued at CSIR-SERC include:
i.
Experimental Techniques to simulate effects of extreme wind such as cyclone in a Boundary
Layer Wind Tunnel.
ii. Efforts are underway to collaborate with other R&D Institution/ Universities to setup towers
along the coastal regions and carry out field measurements on cyclonic wind data and study
cyclonic characterization as applied to design of structures.
iii. To augment R&D in the field of wind energy as a future potential green energy.
iv. Efforts on R&D studies for predicting across-wind loads/response of tall RC chimneys due to
vortex shedding (VS) and suggest empirical models, only with use of structural damping (i.e.
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Nagesh R. Iyer
without the use of negative aerodynamic damping concept). The present findings are showing encouraging results and this is being pursued further.
Indian Society for Wind Engineering (ISWE)
The Indian Society for Wind Engineering was established in 1993 with Prof. Prem Krishna as the
Founder President. The Society organizes National Conference on Wind Engineering once in
every two years since 2002 and provides a platform for technical interaction among the designers,
consultants, researchers, academicians, industries etc., and to promote wind engineering activities
in India. The Society also brings about a bi-annual Journal of Wind and Engineering.
Future Scope for Research Studies
Owing to the continued R&D efforts during the last two and a half decades, wind engineering in
India has been gaining momentum among the designers and construction engineers. Further, the
demand by the growth in infrastructure and modernization in civil engineering construction
industry, supported by the Government initiatives continues to raise the level of challenges for the
wind engineers (Prem Krishna, 2009). The following are some of the future needs/challenges of
R&D in wind engineering:
i. Wind induced damage to buildings and disaster risk reduction
ii. Studies on unsteady aerodynamics in regions of flow separation, vortex formation and wake
development
iii. Turbulence modeling using CFD
iv. wind induced Interference effects between buildings or chimneys
v. studies on wind turbine tower systems
vi. innovative experimental techniques for simulating effects of extreme winds in a wind tunnel
Concluding Remarks
Wind engineering in India is one of the emerging R&D fields of engineering. Besides wind disaster
mitigation, with today’s booming construction activities in infrastructure, tall buildings, wind energy
towers, power plant structures etc., there is a greater scope and challenge for the wind engineering
community. The present scenario of wind engineering research in various institutions and in particular, at CSIR-SERC, is briefly discussed. Some of the future needs/challenges are also indicated.
Acknowledgement
The author gratefully acknowledges the contributions of the scientists and staff of the Wind
Engineering Laboratory, CSIR-SERC.
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