Evaluation of Interference Factor Among Tall Buildings Using Genetic Programming

Abstract

Wind loading on Tall buildings has been an area of active investigations due to increasing public concern towards severe damage caused by wind storms in recent years. Design wind loading is mainly obtained from different codes, wherein the major source of information on which specifications are based is wind tunnel testing of scaled rigid models under simulated flow. Any tall building can vibrate in both the directions of Along wind and Across wind caused by the flow of wind. Modern tall buildings designed to satisfy lateral drift requirements, still may oscillate excessively during wind storm. These oscillations can cause some threats to tall buildings as buildings with more and more height becomes more vulnerable to oscillate at high winds. Sometimes these oscillations may even cause discomfort to the occupants even if it is not in a threatening position for the structural damage. One successful tall building in a particular location attracts more such constructions there. The final scene of a society center thus consists of one or more tall building(s) surrounded by a few medium rises and many low rise structures and other topographical features. The wind pattern is bound to change due to presence of other buildings in vicinity causing either shielding or increased wind pressure coefficients on test building. The study reported in this thesis is an effort to examine the efficacy of Genetic Programming (GP) to predict the aerodynamic Interference in tall rectangular buildings on the basis of the data obtained from the wind tunnel testing done by Gupta (1996). Data collected on wind induced interference effects on building has been analyzed and compared in order to identify common points of agreement and area of concern. Given the limited and inconsistent available data coupled with large numbers of variables involved, empirical generalizations was difficult to obtain. In order to overcome these limitations the thesis suggests Genetic Programming (GP) approach for the assessment of wind induced interference effects on design loads for buildings. The ability of GP to be trained to generalize when presented with limited data examples makes it an attractive application for knowledge acquisition on wind interference effects where there is no acceptable theory, empirical generalization or mathematical model existing at present. The dimensions of the interfering building, reduced velocity and coordinates have been used as Input parameters for development of equations for the estimation of Interference Factor (IF) in respect of Maximum & v Mean Displacement and Acceleration in alongwind and acrosswind direction for tall buildings. The results obtained in this thesis using GP fairly describe the behavior of tall building due to Interference, although in few cases it’s at the variance to the experimental data. Still this work will provide designers a preliminary data to prepare the wind tunnel experiment setup and final results can be verified after Wind Tunnel Experiment.