Field Measurement And Simulation Of Pressure Difference Characteristics Of Stack Effect On Super High-rise Buildings

The stack effect of super high-rise building refers to a special air infiltration phenomenon that outdoor air penetrates to the interior of the building through the cracks of enclosure structure such as doors,windows and curtain walls due to thermal pressure,converges in the elevator shaft,and finally penetrates to the outside through the cracks of enclosure structure.It is mainly related to the temperature difference between indoor and outdoor,the height of elevator shaft,meteorological conditions of outdoor wind,the design of building and elevator.And it is often manifested as the closing failure of elevator door.Therefore,the stack effect of super high-rise building is a problem caused by the complex system of"super high-rise building?design?-elevator?design?".At present,the inadequate research on this interdiscipline and the lag of related design standards and codes lead to the problem of strong stack effect after the completion of many super high-rise buildings.In this paper,the author systematically analyzed the stack effect of super high-rise buildings from building design to elevator products through field measurement,theoretical analysis,numerical simulation and wind tunnel test.The main contents include:Combining the field measurement data of super high-rise commercial buildings and residential buildings,the stack pressure coefficient of elevatorC_SP is introduced,and a modified extreme pressure difference estimation model is proposed based on the classic theoretical pressure difference model;the stack pressure coefficient of elevatorC_SP is obtained through field measurement to evaluate the airtightness of the building components and predict the pressure difference of elevator door under different indoor-outdoor temperature difference.For high-rise residential buildings,a method for estimating the height of the NPL?Neutral Pressure Level?is further proposed,and reduction coefficient of pressure difference on elevator door C_RC is introduced;according to the measured results of pressure difference and the threshold of pressure difference on elevator door,the equivalent leakage area of the building components that need to be added can be calculated,so as to provide support for optimizing the architectural design and improving the performance of building against strong stack effect.Based on CAARC standard model for testing wind pressure of high-rise buildings,a general high-rise building model for analyzing the stack effect is designed;the multi-zone network model method is used to analyze the influence of different factors such as outdoor meteorological environment and internal design of buildings on the pressure difference of elevator doors,and some regular knowledge are obtained.A multi-zone network model method is used to evaluate the stack effect of a super high-rise commercial building under the combined action of wind pressure and thermal pressure;based on the statistics of local temperature and wind weather,the probability distribution model of temperature,wind speed and wind direction is established to predict the probability and frequency of the failure of elevator door.And according to the evaluation result,the corresponding optimization design and transformation strategy are proposed,which is taking the threshold value of the pressure difference on elevator door as the evaluation criteria.Using the new idea of wind pressure simulating the effect of thermal pressure on elevator door system,a wind tunnel test device is designed to simulate the physical process of elevator door failure caused by excessive pressure,and CFD numerical simulation of elevator door movement process is carried out by using dynamic grid.Through wind tunnel test and numerical simulation,the critical pressure threshold of this kind of elevator door system and the characteristics of pressure difference on the front and side of elevator door under the action of stack effect are obtained.