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Volume 7, Issue 11, November – 2022 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165
IJISRT22NOV378 www.ijisrt.com 170
Comparison of Wind Load among Bangladesh
National Building Code (BNBC) and Other
International Codes
Md Lixon
Structural Design Engineer,
BCL Associates
Ltd.,
Sanjida Alam Sharna
Senior Executive
Engineer,
BRAC
Rafiq Md. Shahriar
Bridge Design Engineer,
Development Design Consultants
Ltd.
Abstract: - The structures, or Bridges and Buildings, as
well as their components, must be built to withstand the
prescribed wind loads. Wind load-resisting structures,
including structural components, components, and
cladding, must be designed to withstand shearing, sliding,
overturning, and uplifting forces as a result of wind
forces. Because wind loads are a component of rational
loads, following a standard and tested building code can
be used to provide this function. The Bangladesh
National Building Code (BNBC) and the Japan Road
Association (JRA) were issued in 1993 and 1947,
respectively, to fulfill this purpose in Bangladesh and
Japan, respectively. Because of the way lateral loads are
applied and handled in various codes, the antedated 1993
BNBC is replaced by a subsequent BNBC code that is
commonly named the BNBC 2020, which was issued in
Bangladesh in 2021. In this paper, the BNBC codes are
studied and compared with each other and with JRA
2012, AASHTO 2012, AASHTO 2020, and ASCE 7-05.
The investigation reveals that the percentages of the
basic wind speed increase according to BNBC 1993 and
BNBC 2020 significantly increased compared to the
recent codes, but the investigation also reveals that the
designed wind pressure in different exposures is slightly
higher according to BNBC 1993 than BNBC 2020.
Design wind pressure and applied wind load according
to BNBC 2020 is equal to or higher than ASCE 7-05.
Designed wind pressure is comparatively less and
slightly higher for BNBC 2020 compared to AASHTO
2012 and AASHTO 2020. JRA 2012 has the greatest
design wind pressure value for all the cases. The main
purpose of the study will be to apply wind loads to
bridge structures using BNBC, and then compare these
results with those obtained using other codes as
mentioned in BNBC. Because there is no specific
guideline for the use of wind loads in BNBC.
Keywords:- COMPARISON OF WIND LOAD,
BANGLADESH NATIONAL BUILDING CODE (BNBC),
BNBC 1993 BNBC 2020, JRA, JRA 2012, AASHTO 2012,
AASHTO 2020, ASCE 7-05, FACTORED TOTAL WIND
PRESSURE.
I. INTRODUCTION
Wind is a suddenly varying dynamic incident & a
function of time & velocity. This is caused by the air
flowing when air is moving from high pressure to low
pressure. Before BNBC 1993 a simple empirical formula is
used to determine wind load which do not consider the
effect of surrounding objects and height of structure in wind
pressure. This shortcoming has overcome in BNBC 1993 by
introducing the concept of exposure category and gust factor.
The effect of surrounding objects and height of structures is
further upgraded in BNBC 2020.
The Bangladesh National Building Code (BNBC) was
first organized in 1993 (Atique & Wadud, 2001).
Subsequently, it has been updated to reflect changes in the
building industry and a new gazette copy has already been
published in 2021. A total change at wind load provision in
BNBC 2020 is noticeable. The new wind load provision in
BNBC 2020 is an adaptation from ASCE 7-05. The Japan
Road Association (JRA) is known as the JRA code and was
first published in 1947. This code has been continuously
updated to account for changes in loading conditions and
lateral load most importantly. In this study, it will be
examined with a very well-known international code, that is
American Association of State Highway and Transportation
Officials (AASTHO). The two codes have different methods
of calculating wind loads; however, both codes consider
climate factors such as extreme environmental cyclones.
The Japan Road Association (JRA) code and the
American Association of State Highway and Transportation
Officials (AASHTO) code are commonly used in the design
of roadways. Although there is no other civil engineering
practice code in Bangladesh, the Bangladesh National
Building Code is compared with the JRA and AASHTO
codes for design purposes. It is essential to show that any
project funded by JICA, World Bank and ADB, World Bank,
JRA & AASHTO most of the time requires calculation
using these codes.
This paper compares the provisions of wind load
analysis given in BNBC 1993 and BNBC 2020. The
justification for these results is made by examining other
international codes, such as JRA 2012, AASHTO 2012 &
AASHTO 2020. Engineers who use BNBC 1993 as their
basis for calculations will gain from this comparative study
an understanding of how the design wind load has changed
in relation to the old code and how much factor of safety
against wind disasters has been increased or decreased by
Volume 7, Issue 11, November – 2022 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165
IJISRT22NOV378 www.ijisrt.com 171
adoption of the new code. The comparison of BNBC with
other building codes will also inform whether our country's
economic and population circumstances are being taken into
account when these codes are being revised.
II. METHODOLOGY
For wind loads, BNBC 2020 has been compared with
BNBC 1993, AASTHO 2012, AASHTO 2020, and JRA
2012. In order to determine wind loads, a number of design
parameters are taken into account. First, the design wind
load is determined by calculating velocity pressure.
According to design considerations such as geographic
location, structure type, exposure category, occupancy,
importance factor, enclosure classifications, and many
others, the calculation is made. When comparing wind loads
with other codes, the assumed and considered values must
be justified. The exposure of a structure to wind forces is a
function of terrain type, vegetation and built-up environment
in the surrounding area and pressure coefficient considers
the direction of wind relative to the structure and roof slope.
In JRA 2012, design wind pressure at various heights
is determined first based on geographical location, air
density, structural geometry and other factors. The design
wind pressure in AASHTO 2012 is determined by imputing
the surface condition, structure type and geometry, as well
as frictional factor. This is similar to the BNBC 1993.
Comparison of building codes with respect to wind
force determination:
According to BNBC 2020 & ASCE 7-05
Design wind pressure,
Whereas,
According to BNBC 1993
Design wind pressure,
Whereas,
According to AASHTO LRFD 2012
Design wind pressure,
Whereas,
AASHTO LRFD 2020
Design wind pressure,
Whereas,
JRA 2012
Design wind pressure,
Whereas,
III. ILLUSTRATIONS
A. Basic wind speed V & Vb
In comparing the basic wind speeds given between BNBC
1993 and BNBC 2020, it is important to note that BNBC
1993 specifies fastest-mile wind speeds whereas BNBC
2020 provides basic wind speed in terms of 3-second gust
wind speeds. The fastest mile speed is the average speed of a
particle traveling with the wind over the distance of one mile.
The 3-second gust speed is the peak gust speed averaged
over a short time interval of 3 seconds duration. Both BNBC
1993 and BNBC 2020 provide basic wind speed associated
with an annual probability of occurrence of 0.02 (50-year
recurrence interval) measured at a point 33 ft (10m) above
the mean ground level in a flat and open terrain. In both
BNBC 1993 & BNBC 2020, tornadoes have not been
considered in developing the basic wind speed distribution.
Since square of the basic wind speed is used in determining
Volume 7, Issue 11, November – 2022 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165
IJISRT22NOV378 www.ijisrt.com 172
sustained wind pressure, the increased wind speed results in
approximately 26.58 percent increase in sustained wind
pressure. Following equation is found satisfactory for
converting fastest mile per hour wind speed into three
second gust wind speed and used later for comparison.
Divisional percentage increase of wind speed according to BNBC 2020 from BNBC 1993:
Division
BNBC 2020 Basic Wind
Speed V (m/s)
BNBC 1993 Basic
Wind Speed Vb (m/s)
V/Vb
(V/Vb)2
% Increase of
Wind Speed
Barishal
78.7
71.11
1.11
1.22
22.48%
Chattogram
80
72.22
1.11
1.23
22.70%
Dhaka
65.7
58.33
1.13
1.27
26.85%
Khulna
73.3
66.11
1.11
1.23
22.93%
Rajshahi
49.2
43.06
1.14
1.31
30.58%
Rangpur
65.3
58.06
1.12
1.27
26.51%
Mymensingh
67.4
60.28
1.12
1.25
25.03%
Sylhet
61.1
54.17
1.13
1.27
27.24%
Table 1: Divisional percentage increase of wind speed according to BNBC 2020 from BNBC 1993
Whether the basic velocity pressure is prescribed or
the design wind pressure, there is an average 26.58%
increase in wind speed from the BNBC 1993 to the BNBC
2020. It's vital to keep in mind that when comparing the
basic wind speeds between BNBC 1993 and BNBC 2020,
BNBC 1993 specifies fastest-mile wind speeds, whereas
BNBC 2020 gives basic wind speeds in terms of 3-second
gust wind speeds. The average speed of a particle moving
with the wind over a mile is the quickest mile speed. The
peak gust speed averaged over a brief period of 3 seconds is
the 3-second gust speed. It should be noted that the provided
graphic (Chart-1 & Chart-2) only illustrates one possible
scenario for how changing wind conditions may affect the
design wind pressure estimate.
78.7
80
65.7
73.3
49.2
65.3
67.4
61.1
71.11
72.22
58.33
66.11
43.06
58.06
60.28
54.17
0
10
20
30
40
50
60
70
80
90
Comparison of BNBC 1993 & BNBC 2020 with respect to basic wind speeds
for eight division of Bangladesh
BNBC 2020 Basic Wind Speed V (m/s)
BNBC 1993 Basic Wind Speed Vb (m/s)
Chart 1: Comparison of BNBC 1993 & BNBC 2020 with respect to basic wind speeds for eight division of Bangladesh
Volume 7, Issue 11, November – 2022 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165
IJISRT22NOV378 www.ijisrt.com 173
22.48%
22.70%
26.85%
22.93%
30.58%
26.51%
25.03%
27.24%
0.00%
5.00%
10.00%
15.00%
20.00%
25.00%
30.00%
35.00%
Comparison of BNBC 1993 & BNBC 2020 with respect to basic wind speeds
for eight division of Bangladesh
% Increase of Wind Speed
Chart 2: Percentage of increase the basic wind pressure of BNBC 1993 &
BNBC 2020 with respect to basic wind speeds for eight division of Bangladesh
Average increase of the basic wind speed compares to BNBC 2020 refer to BNBC 1993 for eight division of Bangladesh is
25.54%.
A comparison of BNBC 1993 & BNBC 2020 with respect to basic wind speeds for different location of Bangladesh is given
below;
Location
BNBC 1993 Basic
Wind Speed Vb
(kmph)
BNBC 2020 Basic
Wind Speed V
(m/s)
BNBC 1993
Basic Wind
Speed Vb (m/s)
V/Vb
(V/Vb)2
% Increase
of Wind
Speed
Angarpota
150
47.80
41.67
1.15
1.32
31.61%
Bagerhat
252
77.50
70.00
1.11
1.23
22.58%
Bandarban
200
62.50
55.56
1.12
1.27
26.56%
Barguna
260
80.00
72.22
1.11
1.23
22.70%
Barishal
256
78.70
71.11
1.11
1.22
22.48%
Bhola
225
69.50
62.50
1.11
1.24
23.65%
Bogra
198
61.90
55.00
1.13
1.27
26.66%
Brahmanbaria
180
56.70
50.00
1.13
1.29
28.60%
chandpur
160
50.60
44.44
1.14
1.30
29.62%
Chapai
130
41.40
36.11
1.15
1.31
31.44%
Chittagong
260
80.00
72.22
1.11
1.23
22.70%
Chuadanga
198
61.90
55.00
1.13
1.27
26.66%
Comilla
196
61.40
54.44
1.13
1.27
27.18%
Cox's Bazar
260
80.00
72.22
1.11
1.23
22.70%
Dahagram
150
47.80
41.67
1.15
1.32
31.61%
Dhaka
210
65.70
58.33
1.13
1.27
26.85%
Dinajpur
130
41.40
36.11
1.15
1.31
31.44%
Faridpur
202
63.10
56.11
1.12
1.26
26.46%
Feni
205
64.10
56.94
1.13
1.27
26.71%
Gaibandha
210
65.60
58.33
1.12
1.26
26.47%
Gazipur
215
66.50
59.72
1.11
1.24
23.99%
Gopalganj
242
74.50
67.22
1.11
1.23
22.82%
Volume 7, Issue 11, November – 2022 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165
IJISRT22NOV378 www.ijisrt.com 174
Habiganj
172
54.20
47.78
1.13
1.29
28.69%
Hatiya
260
80.00
72.22
1.11
1.23
22.70%
Ishurdi
225
69.50
62.50
1.11
1.24
23.65%
Joypurhat
180
56.70
50.00
1.13
1.29
28.60%
Jamalpur
180
56.70
50.00
1.13
1.29
28.60%
Jessore
205
64.10
56.94
1.13
1.27
26.71%
Jhalkathi
260
80.00
72.22
1.11
1.23
22.70%
Jhenaidah
208
65.00
57.78
1.12
1.27
26.56%
Khagrachhari
180
56.70
50.00
1.13
1.29
28.60%
Khulna
238
73.30
66.11
1.11
1.23
22.93%
Kutubdia
260
80.00
72.22
1.11
1.23
22.70%
Kishoreganj
207
64.70
57.50
1.13
1.27
26.61%
Kurigram
210
65.60
58.33
1.12
1.26
26.47%
Kustia
215
66.90
59.72
1.12
1.25
25.48%
Laksmipur
162
51.20
45.00
1.14
1.29
29.45%
Lalmonirhat
204
63.70
56.67
1.12
1.26
26.36%
Madaripur
220
68.10
61.11
1.11
1.24
24.18%
Magura
208
65.00
57.78
1.12
1.27
26.56%
Manikgonj
185
58.20
51.39
1.13
1.28
28.26%
Meherpur
185
58.20
51.39
1.13
1.28
28.26%
Maheshkhali
260
80.00
72.22
1.11
1.23
22.70%
Moulvibazar
168
53.00
46.67
1.14
1.29
28.98%
Munshiganj
184
57.10
51.11
1.12
1.25
24.81%
Mymensingh
217
67.40
60.28
1.12
1.25
25.03%
Naogaon
175
55.20
48.61
1.14
1.29
28.95%
Narail
222
68.60
61.67
1.11
1.24
23.75%
Narayanganj
195
61.10
54.17
1.13
1.27
27.24%
Narshingdi
190
59.70
52.78
1.13
1.28
27.95%
Natore
198
61.90
55.00
1.13
1.27
26.66%
Netrokona
210
65.60
58.33
1.12
1.26
26.47%
Nilphamari
140
44.70
38.89
1.15
1.32
32.12%
Noakhali
184
57.10
51.11
1.12
1.25
24.81%
Pabna
202
63.10
56.11
1.12
1.26
26.46%
Panchagarh
130
41.40
36.11
1.15
1.31
31.44%
Patuakhali
260
80.00
72.22
1.11
1.23
22.70%
Pirojpur
260
80.00
72.22
1.11
1.23
22.70%
Rajbari
188
59.10
52.22
1.13
1.28
28.07%
Rajshahi
155
49.20
43.06
1.14
1.31
30.58%
Rangamati
180
56.70
50.00
1.13
1.29
28.60%
Rangpur
209
65.30
58.06
1.12
1.27
26.51%
Shatkhira
183
57.60
50.83
1.13
1.28
28.39%
Shariatpur
198
61.90
55.00
1.13
1.27
26.66%
Sherpur
200
62.50
55.56
1.12
1.27
26.56%
Volume 7, Issue 11, November – 2022 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165
IJISRT22NOV378 www.ijisrt.com 175
Sirajganj
160
50.60
44.44
1.14
1.30
29.62%
Srimangal
160
50.60
44.44
1.14
1.30
29.62%
St. Martin
260
80.00
72.22
1.11
1.23
22.70%
Sunamganj
195
61.10
54.17
1.13
1.27
27.24%
Sylhet
195
61.10
54.17
1.13
1.27
27.24%
Sandip
260
80.00
72.22
1.11
1.23
22.70%
Tangail
160
50.60
44.44
1.14
1.30
29.62%
Teknaf
260
80.00
72.22
1.11
1.23
22.70%
Thakurgaon
130
41.40
36.11
1.15
1.31
31.44%
Table 2: Comparison of BNBC 1993 & BNBC 2020 with respect to basic wind speeds for different location of Bangladesh
Average increase of the basic wind speed compares to
BNBC 2020 refer to BNBC 1993 for sixty-four district of
Bangladesh is 26.58%
B. Factored total wind pressure comparison of different
codes
The basic wind speed is determined on the basis of three
second gust speed for all the discussed codes except for
BNBC 1993. BNBC 1993 specifies basic wind speed on the
basis of fastest-mile wind speed. So, for comparison wind
speed of Cox’s Bazar, the highest considered wind speed in
Bangladesh, that is 260 km/hr (80 m/s) has taken for all
codes. ASCE 7-05 is not compared separately as proposed
BNBC 2020 gives factored total wind pressure exactly same
to ASCE 7- 05. So, ASCE 7-05 and BNBC 2020 can be
used interchangeably.
The effect of surrounding objects and height of
structures are considered through various parameters in
different building codes such as class, Terrain category,
Exposure category etc. These parameters are not same for all
codes. So, for comparison purpose surrounding conditions
are broadly classified into three categories. They are urban,
obstructed open terrain and unobstructed open terrain type
areas which are defined in BNBC as exposure A, B and C
respectively. All the codes are compared for these major
surrounding conditions. For the comparison purpose only,
the open terrain topography without hills with no cyclone
prone area with 37.0m (equivalent to the height of a 10-
storied building & bridge pier height) concrete structural
height and carrying general importance (I=1.0) structural
data is considered. Finally, all pressures are multiplied with
respective wind load factor to calculate factored total wind
pressure The following pressure variation is typical for
structures of 37 m height. Both length and width of the
structures have taken equal to 20 m. Corresponding
parameters used in the respective codes are presented in the
following table and the comparison results are presented
graphically in the chart.
Applied Codes
& Standards
Velocity
(m/s)
Velocity/Sustained Wind
Pressure (kN/m2)
Design Wind
Pressure (kN/m2)
BNBC 1993
80
7.2453
11.0648
BNBC 2020
80
4.9422
6.8866
AASTHO 2012
80
-
10.1478
AASTHO 2020
80
-
6.7518
ASCE 7-05
80
4.9422
6.8866
JRA-2012
80
-
11.9701
Table 3: Different design wind pressure according to the international codes
Since the main land of Japan is frequently affected by
cyclones and other environmental forces, such as the
typhoon that caused the issue, JRA rules follow the greatest
design wind pressure. As a result, the established equation in
JRA code takes the cyclone phenomenon into account. The
investigation also reveals that the designed wind pressure in
various exposures is slightly higher according to BNBC
1993 than BNBC 2020, despite the fact that it shows that the
percentages of the basic wind speed increase according to
BNBC 1993 and BNBC 2020 significantly increased
compared to the recent codes. The BNBC 2020 code,
however, does not significantly differ from ASCE 7-05,
leading to about the same design wind pressure.
Volume 7, Issue 11, November – 2022 International Journal of Innovative Science and Research Technology
ISSN No:-2456-2165
IJISRT22NOV378 www.ijisrt.com 176
0
2
4
6
8
10
12
14
11.0648
6.8866
10.1478
6.7518
6.8866
11.97
BNBC 1993
BNBC 2020
AASTHO 2012
AASTHO 2020
ASCE 7-05
JRA-2012
Design wind pressure (kN/m2)
Design Wind pressure
Chart 3: Comparison of design wind pressure according to the international codes
IV. CONCLUSIONS
Before BNBC 1993, a straightforward empirical
formula was used to calculate wind load, which ignored the
impact of nearby objects and the height of nearby structures
on wind pressure. By introducing the concepts of exposure
category and gust factor, this flaw was fixed in BNBC 1993.
In the planned BNBC 2020 wind provision, the impact of
nearby objects and structure height is further upgraded.
Because of this, BNBC 2020 finds that the Wind load in
urban areas (Exposure A) is significantly larger (6–11%)
than BNBC 1993. However, BNBC 2020 revealed that the
wind load in exposed B and C (obstructed and unobstructed
open terrain type areas) was significantly lower (1–15%)
than BNBC 1993. Further wind load according to BNBC
2020 is found exactly equal to wind load according ASCE 7-
05 & AASTHO 2020 and considerably less (20-38%) than
2012. Typhoon and other extreme weather impacts are taken
into account, and JRA assigns a larger value (5–23%) when
compared to all the code that has been mentioned. In
Bangladesh, there is no prescriptive code for assessing
bridge-type structures. Instead, design pressure in
accordance with BNBC 2020 or the value of wind speed are
used to account for wind forces on substructures and
superstructures in wind load analyses. This example
demonstrates that while using the BNBC 2020 value for a
wind load study of a bridge structure is customary, it is also
necessary to use the AASTHO 2020 in order to provide
cost-effective and excellent structural findings. For any
Bangladeshi design, it will not be practical to take wind
pressure into account in accordance with JRA 2012.
REFERENCES
[1.] Faysal, R.M. 2013 . A comparative study on Wind
Load analysis of Bangladesh National Building Code
(BNBC) with other building codes .Undergraduate
thesis, Faculty of civil engineering, BUET.
[2.] ASCE/SEI 7-05, 2006. A.S.C.E. Minimum design
loads for buildings and other structures, Reston
Virginia
[3.] Atique, F. & Wadud, J. 2001. A comparison of
BNBC-93 with other building codes with respect to
earthquake and wind analysis. The Eighth East Asia-
Pacific Conference on Structural Engineering and
Construction, Nanyang Technological University,
Singapore
[4.] BIS, 2005. National Building Code of India, New
Delhi.
[5.] Ministry of Housing and Public Works Government
of The People’s Republic of Bangladesh,
“Bangladesh National Building Code 2020”, 2021.
[6.] Faysal R.M., July 2014, Comparison of Wind Load
among BNBC and other Codes in different type of
areas, International Journal of Advanced Structures
and Geotechnical Engineering ISSN 2319-5347, Vol.
03, No. 03.
[7.] Shafi, S. A. 2010. Keynote Paper on National
Building Code and Its Implementation, Round Table
Discussion on Implementation of National Building
Code, Press Club, Dhaka. Retrived from-
http://www.blast.org.bd/content/key-note/national-
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