- Dale, J; Irwin, P; Kumar, S; Kilpatrick, J; Galsworthy, J
- Internal pressure can be a significant component of the overall net pressure the cladding would experience during wind storms. These internal pressures are in the order of about 10% to sometimes even 50% of the overall pressure exerted on the cladding elements. The higher percentages are usually the result of a dominant opening on the facade. Such a dominant opening in the middle of the facade of an apartment with single face exposed to the exterior could in fact decrease the loading. In such situation, instead of assuming the dominant opening, RWDI consider nominal leakage suggested by the code as the internal pressure. For corner apartments, where orthogonal building faces have been exposed to wind, the opening in one facade could exert high internal pressure to the orthogonal facade in phase with the high external pressure acting on it. This could result in very high overall pressure. Note that the area of internal pressures die to wind has received very little attention in the past. Also, the available past research by others has very little touch to the practical application. In the past, RWDI has developed a novel methodology accounting for the above aspects of internal pressures assuming a certain probability of breakage. Although there has been an increase in the amount of research into wind borne debris and the resistance of various glazing materials to an impact, application of these results in relation to the probability of breakage and the design for wind loading needs to be investigated. The aim of this paper is to propose a link between the research considering wind borne debris damage and the approximation of internal pressures from the results of wind tunnel pressure tests. The random and chaotic nature of many of the variables involved in the cause of an opening in the building facade, and the subsequent formation of internal pressures makes a deterministic solution almost impossible to achieve. As such, the paper outlines a probabilistic approach to merge the two lines of research. The results of research presented on the subjects of damage due to wind borne debris are used as the basis for determining the probability of a dominant opening occurring on a building facade. Differences in relationships between this probability of an opening and the positive and negative internal pressure scenarios are also investigated. Internal pressures are estimated corresponding to a selected reasonable risk level, or return period, using the probability of an opening applied to the results of wind tunnel tests. © ASCE and ATC 2013.
- November 18, 2013
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