COMPARATIVE STUDY OF WIND LOADS ESTIMATED FROM NUMERICALLY SIMULATED WIND TUNNEL TEST RESULTS AS PER THE PROVISIONS OF BANGLADESH NATIONAL BUILDING CODE

Abstract

Bangladesh has recently landed in the era of tall buildings. Wind load generally governs over earthquakes for tall buildings. However, research on the effect of wind load on structures is limited in Bangladesh. International and local codes evaluate wind effects on regular shape buildings. But they are not recommended for complex-shaped structures. For those, a wind tunnel test is required. This research aimed to determine the performance of the local codes in calculating the wind effect on structures such as BNBC 2020 and BNBC 2006 in addition to the numerical wind tunnel. The other objective was to formulate empirical equations from the numerical wind tunnel test data to improve the evaluation process of wind effect, precisely the wind pressure coefficient (Cp). Computational Fluid Dynamic analysis in a finite element software, named RWIND, was used to perform the numerical wind tunnel test. The numerical model was first validated with physical wind tunnel test data. Four-building of the various geometric property was modeled and simulated to compare the wind pressure coefficient. Another twenty models with different length-width ratios were simulated and analyzed to develop empirical equations for calculating the wind pressure coefficient. The study concluded that the proposed empirical equations evaluate the wind loads better than the BNBC 2020. The proposed empirical equations demonstrated a mean variation of about 15 percent in the long direction to the numerical wind tunnel, while the BNBC 2020 showed about 50 percent variation. Moreover, in the short direction, the proposed equations showed a mean variation of about 28 percent compared to 53 percent of the BNBC 2020. The BNBC 2020 and BNBC 2006 showed a considerable variation in calculating the wind pressure coefficient. The storywise average variation ranged from 47% to 53% in the long direction and 37% to 47% in the short direction. The numerical wind tunnel following the BNBC 2020 showed relatively less variation in the calculation of the shear force than the BNBC-2020 manual, and the average variation was 20% to 30% in the long direction and 16% to 33% in the short direction.