Comparison of wind loads on high-rise buildings with vertical ribs obtained by force balance and pressure measuring tests
In order to investigte the influence of vertical ribs on the wind loads of high-rise buildings,multiple point synchronous pressure(MPSP)and high-frequency force balance(HFFB)testing in a wind tunnel was carried out.On each face of the high-rise structures,the wind pressure distribution was examined in relation to the effect of the rib extension length to building width ratio(b/B).Then the mean and standard deviation of base shears obtained using MPSP and HFFB tests were compared.The testing results show that the outermost wind pressures on the windward side of the building are significantly reduced and even change to negative pressure in the windward direction.Furthermore,the absolute value of negative wind pressure on the leeward side of the building decreases with increase of the b/B.When b/B is in the range of 1％-3％,the mean base shears obtained from the HFFB tests are larger than those obtained from the MPSP tests for all wind angles.This is mainly due to the fact that the MPSP tests cannot consider the wind-resistant contribution of the rib,and the discrepancy between the two results will be especially large under oblique wind angles with the maximum discrepancy reaching 14.89％.Regarding the standard deviation of the base shear,the results of HFFB tests are larger than those of MPSP tests for the model without ribs,whereas the HFFB results are less than the MPSP results when the b/B is in the range of 1％-4％.When the rib length is noticeably big(e.g.,b/B ≥2％),it is strongly advised to utilize the HFFB test rather than the MPSP test to determine the wind load on high-rise buildings.The calculation methods for the mean base shear modification factor caused by the presence of the vertical ribs were established based on the results of the HFFB.The fitting formula can be used to evaluate the average base shear force of high-rise buildings with different arrangements of vertical ribs.
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