DETERMINATION OF WIND-DRIVEN-RAIN INTENSITY ON BUILDING FACES

The weather resistance design of building facades requires adequate kn owledge on the wind and rain environment around the building. It is im portant to know both the wind speed as well as the associated rainfall intensity impinging onto the building faces. However, wind-driven-rai n around a building is complicated and it is a topic not well understo od. Usually wind speed and rain intensity are considered separately an d their values for weather resistance design are just guesses based on engineering experience. A method is proposed in the present paper, wh ere wind-driven-rain intensities impinging on building faces are calcu lated taking into account all the relevant factors such as the interac tions between wind, rain and building, and also the joint probability of occurrence of wind and rain. The method comprises the following ste ps: (a) using computational fluid dynamics method to calculate the flo w pattern around a building, (b) raindrop trajectories in the flow fie ld are obtained by solving the force equations, (c) obtain the probabi lity of joint occurrence of wind and rain from the analysis of meteoro logical records, (d) rainfall intensities on building faces are comput ed as a function of return period by coupling (b) and (c). The method is applied onto a rectangular building located in Sydney and the extre me wind-driven-rain intensities on various portion of its faces calcul ated.