Study Of Stack Effect For High-Rise Buildings By Means Of Field Measurement, Wind Tunnel Test And Numerical Simulation

Stack effect of high-rise buildings is an uncontrolled indoor-outdoor air infiltration phenomenon which happened in high-rise buildings at certain seasons.Stack effect mainly depends on temperature differences between indoor and outdoor,the heights of elevator shafts,air leakage characteristics of exterior walls and internal separations,and wind loads.Serious problems can be caused by strong stack effect,such as elevator malfunction,aerodynamic noise,energy inefficiency,etc.These are interdisciplinary problems that super high-rise buildings are often confronted with,involving both architecture design and elevator manufacture design.However,the amount of relative research is far less than the amount of high-rise buildings.For systematical study of stack effect,comprehensive methods,such as field measurements,wind-tunnel test,and numerical simulation,combined with practical projects,are conducted in this paper.The contents are as followings:1)Field measurements were undertaken on 5 different high-rise buildings at different regions to obtain the patterns of pressure difference across elevator doors,by which a formula based on the idealized model was recommended for approximating maximum values of pressure differences.2)A full-scale wind-tunnel test of elevator doors was designed to simulate the stack pressure by wind pressure.By changing different wind speeds,the threshold value of pressure difference was obtained by the reoccurrence of malfunction of elevators.Several technological augments were tested to enhance the performance of elevator doors against stack pressure.3)Referring to CONTAM(a multizone analysis computer program),a program was coded based on certain assumptions and idealizations,which is more applicable in practical projects.Furthermore,Changsha IFS was simulated to confirm its applicability by comparison with its field measurement.Different simulation results of Changsha IFS by controlling different parameter settings shows that,the accuracy of numerical simulation is mostly determined by the accuracy of parameters of the main flow path,upon which the elevator influenced most by stack effect was located.4)Several possible approaches for alleviating strong stack effect of Changsha IFS,in which may be proposed to its practical project in future,were discussed and evaluated,such as improving the airtightness of the hall,opening elevator doors at certain floor,and drilling holes on the walls of elevator shafts.The research of this paper will provide references for the evaluation and optimal design of high-rise buildings,and the improvement on the relevant design standards in the future.