Session B.pdf - Clarkson University

accepted). In addition to it, a situation with a much earlier ice movement relative to the
Amur river on the large tributary – the Ussuri river was taken into consideration.
The heaviest ice situation is formed according to the modeling data (as it is observed in
nature) above the mentioned bridge via the Amur river.
In such cases the aim of mathematical modeling is creation of a stable software package
fulfilling a scope of calculations sufficient for forecasting negative ice phenomena on
the bridge structure (ice jams, mixing, damages of supports and ice cutters, wedging of
ice etc.).
Development of bridge crossing on the rivers which are not enough studied from the
point of view of glaciology and on the rivers with changeable ice environment can be
simplified a little due to the possibility of forecasting the situation of passing the ice
through the bridge spans. At the same time it is possible to obtain the necessary for
calculation data long before the beginning of the bridge reconstruction by processing the
data of weather observations, comparison with analogical structures on similar rivers of
the same climatic area.
When creating similar programs at initial stages it is extremely desirable to use the
formulas and theories proved by the time and engineering experience as an estimation
basis which will allow to expect a general sufficient correctness of the obtained results.
The most detailed and reliable method seems to be calculation of ice interaction with
engineering structures, this method was worked out by K.N.Korzhavin in the middle of
the last century. The basic calculation formula used when developing the program
determines the dependence of the ice force of masses on the structure or its elements
depending on the power of the ice cover. All this data can be directly or indirectly
installed according to the data inquired by the program.
For modeling each situation a similar program package must inquire a number of
parameters accessible for clarification of main components participating in
consideration. This data can be united in four main big groups: parameters of the bridge,
water, channel and ice. Calculation of the necessary values brings to the assignment of
well-known basic parameters and choice of the arrangement scheme which ensures
most favorable conditions. When projecting large objects it will be allowed to quickly
and with low costs compare different variants of placement of supports, forms and
attack angle of ice cutters heads and ice protective structures. Reduction of labor and
time on fulfillment of the comparison analysis will make it possible to consider a big
number of variants and choose the optimal one on a technical plane.
Data transfer from the hydraulic model HEC-RAS environment to the working windows
of the estimation program of the ice passing through bridge crossings is preliminarily
carried out manually which is laborious and provokes involuntary mistakes caused by
man’s factor. Extremely desirable seems development and creation of the programmediator
capable to automatically draw out the necessary data from exit files of model
HEC-RAS and transfer them into the corresponding input data cells of the program of
bridges calculations. Such improvement demands an access to the roots of the HEC-
RAS file environment and it is still technically difficult.
The obtained program “symbiosis” allows to solve rather difficult engineering tasks not
accessible for solving each component separately (though each program is autonomous
and can be successfully used separately). It is clear that the output data of the program
complex needs checking and verification with natural data, the geometric model must
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