STOCHASTIC MODELLING OF WIND LOADS IN A WELL BEHAVED WIND CLIMATE (NIGERIA AS A CASE STUDY)
STOCHASTIC MODELLING OF WIND LOADS IN A WELL BEHAVED WIND CLIMATE (NIGERIA AS A CASE STUDY)
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Date
1996-06
Authors
ANYANWU, UCHENNA DANIEL
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Abstract
Wind loading estimation is one facet of the entire design process. Wind speed as a
climatic process which is time-dependent requires proper assessment in order to predict its
speed for specified return periods. This requires a good understanding of the wind process
within the lower atmosphere (where the designer of civil engineering structures has interest)
and then modelling it by applying stochastic methods. This is basically what this thesis
addresses.
The wind speed data for twenty (20) synoptic meteorological stations in Nigeria were
collected and analyzed using statistical and probability approaches. The means, variances and
coefficients of variation for all the stations were computed. An empirical selection of a most
probable stochastic model based on the understanding of the underlying physical
phenomenon and literature is done.
The selected empirical and theoretical model turned out to be the extreme maximum
value Type I Probability model (EV-I), also referred to as the Gumbel distribution Type I of
the largest values. The model is tested using the acquired data. The parameters of the model
are estimated using three methods of parameter estimation. These are then used in the
statistical testing for the goodness-of-fit. The tests employed validate the selected model. The
results of the predictions performed for twelve (12) return periods for all the stations are
compared with those obtained by Soboyejo (1971) who worked on the distribution of extreme
wind in Nigeria. The results from this present work are found to be more acceptable.
It is concluded that the use of design wind speed estimates higher than the more
realistic estimates implies allocating scarce resources to areas having no necessary need, and
therefore does not give the appropriate balance between safety and economy. The use of the
new wind speed estimates developed in this work is advocated and the need to undertake
further research into the stochastic modelling of wind loads taking into consideration the
subject of wind directionality is recommended.
Description
BEING A THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL,
AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE
REQUIREMENTS FOR THE AWARD OF THE MASTER OF SCIENCE DEGREE
IN STRUCTURAL ENGINEERING
DEPARTMENT OF CIVIL ENGINEERING
AHMADU BELLO UNIVERSITY
ZARIA
NIGERIA
JUNE, 1996
Keywords
STOCHASTIC,, MODELLING,, WIND LOADS,, WELL BEHAVED WIND CLIMATE,, (NIGERIA AS A CASE STUDY)