The wind is air in motion relative to the surface of the earth. The primary cause of wind is traced to the earth’s rotation and differences in terrestrial radiation. The radiation effects are mainly responsible for convection current either upwards or downwards. The wind generally blows horizontal to the ground at high speeds. Since vertical components of atmospheric motion are relatively small, the term ‘wind’ denotes almost exclusively the horizontal wind while ‘vertical winds’ are always identified as such. The wind speeds are assessed with the aid of anemometers or anemographs, which are installed at meteorological observatories at heights generally varying from 10 to 30 meters above the ground. Before BNBC 1993 a simple empirical formula is used to determine wind load which does not consider the effect of surrounding objects and structure height in wind pressure. This shortcoming has been overcome in BNBC 1993 by introducing the concept of exposure category and gust factor. The effect of surrounding objects and the height of structures is further upgraded in the proposed BNBC 2020. This thesis aims the comparison of provisions of wind load analysis given in existing BNBC 1993 to that in proposed BNBC 2020. Both are studied and compared in terms of wind load using parameters termed as Basic wind speed, Height and exposure coefficient, Gust factor, Sustained wind pressure, External pressure coefficient, and Design wind pressure. This study reveals that wind load in urban areas according to BNBC 2020 found considerably higher than BNBC 1993. But wind load in obstructed and unobstructed open terrain type areas according to BNBC 2020 is found significantly lower than BNBC 1993.

1. COMPARISON OF WIND LOAD
ALONG WITH BNBC 1993, BNBC
2020 AND NBC 2016
U N I V E R S I T Y O F A S I A PA C I F I C
D E P A R T M E N T O F C I V I L E N G I N E E R I N G
SUBMITTED BY-
MD. RUYEL MIAH
ruyel587124@gmail.com

2. • BACKGROUND
• OBJECTIVES
• METHODOLOGY
• BNBC 1993 WIND LOAD PROVISION
• BNBC 2020 WIND LOAD PROVISION
• NBC 2016 WIND LOAD PROVISION
• COMPARISON ANALYSIS
• RESULT
• CONCLUSION
• REFERENCE
University of Asia Pacific
Department of Civil Engineering
OUTLINE

3. BACKGROUND
Bangladesh National Building Code (BNBC) was first
introduced in the year of 1993. The code is further
updated in proposed BNBC 2020 wind provision. The
design of wind loads on a building is substantially
more complex as a result a comparative study has
been made to see the basic difference between BNBC
1993 and proposed BNBC 2020.
University of Asia Pacific
Department of Civil Engineering

4. OBJECTIVES
• To observe the variation of wind load on structures.
• To compare the calculation parameters for different code.
• To design a structure by considering wind load
University of Asia Pacific
Department of Civil Engineering

5. METHODOLOGY
For comparison of wind load between BNBC 1993 and BNBC 2020,
different parameters i.e., design wind load, basic wind speed, height and
exposure coefficient, gust factor, sustained wind pressure, external pressure
coefficient etc. are considered. Finally, exposure conditions A have been
studied for a typical multistoried residential building to identify the
changes in analysis and design with BNBC 2020 as compared to BNBC
1993.
University of Asia Pacific
Department of Civil Engineering

6. BNBC 1993
qz=CCCICZVb
qz = sustained wind pressure at height z, kN/m2
Cc = velocity-to-pressure conversion coefficient= 47.2x10-6
CI = structure importance coefficient
Cz = combined height and exposure coefficient
Vb = basic wind speed in km/hr (HBRI and BSTI, 1993:6-32)
University of Asia Pacific
Department of Civil Engineering

7. BNBC 1993
Pz=CGCPqz
pz = design wind pressure at height z , kN/m2
CG = gust coefficient Cp=pressure coefficient for structures or components
(HBRI and BSTI, 1993:6-34)
University of Asia Pacific
Department of Civil Engineering

8. BNBC 2020
qz=0.000613KzKdKztV2I
qz = velocity pressure at height z, kN/m2
Kz = velocity pressure exposure coefficient
Kd= wind directionality factor Kzt= topographic factor
I = structural importance factor
V = basic wind speed in m/s (HBRI and BRTC, 2020: Part 6-Chap 2)
(ASCE/ SEI 7-05, 2006: chap 6-page 27)
University of Asia Pacific
Department of Civil Engineering

9. BNBC 2020
P=qGCp-qi(GCpi)
p = design wind pressure
G = gust effect factor
Cp = external pressure coefficient GCpi =internal pressurecoefficient
(HBRI and BRTC, 2020: Part 6-Chap 2)
(ASCE/ SEI 7-05, 2006: chap 6-page 28)
University of Asia Pacific
Department of Civil Engineering

10. Vz = Vb k1 k2 k3 k4,
Where,
Vz = design wind speed at any height z in m/s,
k1 = probability factor (risk coefficient)
k2 = terrain roughness and height factor
k3 = topography factor, and
k4 = importance factor for the cyclonic region.
NBC 2016
University of Asia Pacific
Department of Civil Engineering

11. Pz=0.6Vz
2
Where.
pz = wind pressure in N/m2 at height z, and
Vz = design wind speed in m/s at height z.
NBC 2016
University of Asia Pacific
Department of Civil Engineering

12. COMPARISON ANALYSIS
The comparison is based on-
1. Exposure Category
2. Topographic Effects
3. Gust Effect Factor
4. Sustained Wind Pressure and Velocity Pressure
5. Design Wind Pressure
6. Pressure and Force Coefficient
7. Design of Wind load
University of Asia Pacific
Department of Civil Engineering

13. RESULT
FACTORED
WIND
PRESSURE
(KN/SQM)
BNBC-1993 BNBC-
2020
6
5
4
3
2
1
0
0 20 40 60
HEIGHT
(M)
80 100 120
Fig.: Factored total Wind Pressure for Exposure A condition
University of Asia Pacific
Department of Civil Engineering

14. CONCLISION
The change in factored total wind pressure with height in BNBC 2020 is more uniform
than BNBC 1993.
Factored wind pressure in BNBC 2020 is 7-12% higher than BNBC 1993 up to 50 m.
Then it gradually decreases with the increase of height.
At the height of 50 m, both BNBC 2020 & BNBC 1993 shows same factored total
wind pressure.
University of Asia Pacific
Department of Civil Engineering

15. BNBC 1993, Bangladesh National Building Code (BNBC), Bangladesh House Building
Research Institute, Dhaka.
BNBC 2020, Bangladesh National Building Code (Proposed), Bangladesh House Building
Research Institute, Dhaka.
Faysal, R. M., 2014, Comparison of Wind Load among BNBC and other codes in different
types of areas, International Journal of Advanced Structure and Geotechnical Engineering.
Hasan, M. R. and Hoque, M. T., 2007, Comparative studies of Different Building Codes in
Contex of Bangladesh National Building Code
University of Asia Pacific
Department of Civil Engineering
REFERENCES

16. QUESTION
PLEASE…..!!!!