Wind-induced internal pressure response for structure with single windward opening and background leakage

Theoretical analysis and wind tunnel tests were carried out to study wind-induced internal pressure response for the structure with single windward opening and background leakage. Its governing differential equation was derived by the Bernoulli equation in an unsteady-isentropic form. Numerical examples were provided to study the additive damping caused by background leakage in laminar and turbulent flow, and the influence of background leakage on fluctuating internal pressure response was quantized. A series of models for low-rise building with various opening ratios and background leakage were designed and wind tunnel tests were conducted. It is shown that the fluctuating internal pressure reduces when the background leakage are considered and that the effect of background leakage can be predicted accurately by the governing differential equation deduced in this paper.

Statistical extremes and peak factors in wind-induced vibration of tall buildings

In the structural design of tall buildings,peak factors have been widely used to predict mean extreme responses of tall buildings under wind excitations.Vanmarcke's peak factor is directly related to an explicit measure of structural reliability against a Gaussian response process.We review the use of this factor for time-variant reliability design by comparing it to the conventional Davenport's peak factor.Based on the asymptotic theory of statistical extremes,a new closed-form peak factor,the so-called Gamma peak factor,can be obtained for a non-Gaussian resultant response characterized by a Rayleigh distribution process.Using the Gamma peak factor,a combined peak factor method was developed for predicting the expected maximum resultant responses of a building undergoing lateral-torsional vibration.The effects of the standard deviation ratio of two sway components and the inter-component correlation on the evaluation of peak resultant response were also investigated.Utilizing wind tunnel data derived from synchronous multi-pressure measurements,we carried out a wind-induced time history response analysis of the Commonwealth Advisory Aeronautical Research Council(CAARC) standard tall building to validate the applicability of the Gamma peak factor to the prediction of the peak resultant acceleration.Results from the building example indicated that the use of the Gamma peak factor enables accurate predictions to be made of the mean extreme resultant acceleration responses for dynamic serviceability performance design of modern tall buildings.

Behavior of reinforced concrete structural walls with various opening locations: experiments and macro model

Two experimental tests of three-storied reinforced concrete structural walls having large openings were performed.Based on an original macro model,a multiple modified macro-model was proposed to develop a simple method to design a reinforced concrete structural wall with large openings and various opening locations.The interaction between reinforcement ties and concrete struts formed along the perimeter of openings was neglected in the original model.However,the strut-and-tie node was proposed to take account of such interaction in the proposed model.The predicted behavior of two specimens using such a proposed model was compared with the experimental results.It is shown that the behavior of structural walls with large openings could be modeled well using the proposed model.Moreover,the study indicates that the proposed model is applicable even in cases of multi-story structural walls having large openings and various opening locations.