| The glass curtain walls of high-rise buildings are prone to breakage under the impact of flying objects,while the glass debris flying objects formed by the broken curtain walls of tower clusters under strong wind may also cause continuous damage to the surrounding building curtain walls.Accurately predicting the flight trajectory of glass debris flying objects is the basis for conducting research on the vulnerability of high-rise building curtain walls to wind damage caused by flying objects;However,previous studies have rarely focused on the flight trajectories of particulate missiles in complex unsteady wind fields around high-rise buildings.This article adopts the CFD numerical simulation method and combines it with a wind disaster case of a practical high-rise building group to study the prediction method and application of flying trajectories of glass curtain wall debris in tower groups.The main content is as follows:(1)Research on numerical simulation method for predicting the flight trajectory of particle flying object.Firstly,the synthesis method of inflow pulsation for this study was determined through large eddy simulation of the airspace wind field,Then,a large eddy simulation of a single high-rise building was conducted,and the effectiveness of the method and parameters in this paper was verified through comparison with experimental results.Based on Newton’s second law,a motion equation for the flight trajectory of a particle flying object was established,and the effectiveness of the method was verified through a uniform flow field example;Taking the large eddy simulation of unsteady wind field around a single building as a target,a suitable spatial interpolation method of wind velocity field is determined by comparative analysis.The results show that using the vortex method based on self preserving boundary conditions to synthesize inflow pulsations can effectively predict the unsteady wind load and wind speed field around the structure;The linear interpolation method based on triangulation can be used for spatial interpolation to better obtain the required instantaneous wind speed field in the movement area of particulate flying object.Combined with the motion equation of particulate flying object established in this paper,it can provide a solution for the prediction of the trajectory of particulate flying object in three-dimensional turbulent flow.(2)Research on Large Eddy Simulation of twin towers and analysis of flight trajectories of curtain wall fragments.The large eddy simulation of unsteady flow around the wind field in the turbulent boundary layer was carried out based on an actual wind disaster case of twin tower buildings;Analyzed the cause and location of debris on the glass curtain wall of the upstream tower,predicted its impact position on the surface of the downstream curtain wall,and discussed the impact of different flow field conditions and the presence and absence of podiums on the flight trajectory of debris on the curtain wall.The results indicate that the numerical simulation method and parameters in this article have well reproduced the wind damage of the tower group.The simulation results of debris flight trajectories in ideal uniform flow and three-dimensional free turbulent flow fields are relatively close,but there is a significant difference between them and the predicted results of three-dimensional unsteady flow fields.Ignoring the turbulence of the incoming flow in three-dimensional free turbulent flow fields will increase the flying distance and reduce the flying speed of debris;In the three-dimensional unsteady flow field,there is a significant difference in particle trajectories at different initial positions,which may have a significant impact on the final evaluation results.Therefore,full consideration should be given to the influence of the three-dimensional unsteady flow field around the building complex and the possible initial failure location.In contrast,the impact of having and without podiums is relatively small.(3)Analysis of the impact of different vertical and horizontal spacing on the flying trajectory of curtain wall debris in the twin tower complex.Taking the double tower in a wind disaster case as the object,without considering the influence of the podium,the effects of the vertical and horizontal distance of the tower on the structural surface wind pressure,unsteady wind speed field,and the flight trajectory of curtain wall debris were studied.The effects of different particle shapes were also analyzed.The results indicate that the changes in the longitudinal and transverse spacing of the twin towers mainly affect the flow separation and reattachment points around the upstream tower,as well as the size of the side separation vortices and the leeward recirculation zone,resulting in a certain degree of regular changes in the surface wind pressure distribution of the structure.The difference in resistance coefficient values between cubic and spherical particles affects the prediction of vertical flight distance of fragments,but the impact on flight speed and lateral flight distance is relatively small;As the release position of the particles gradually moves away from the flow separation zone at the corner of the upstream tower,the influence of the shape difference of the particle projectile on its vertical and horizontal flight distance correspondingly weakens.The distance between towers mainly affects the flying distance of curtain wall debris.The horizontal flying distance of debris decreases with the increase of tower horizontal distance,while the vertical and horizontal flying distances both increase with the increase of tower vertical distance.The change in the horizontal spacing of the twin towers will cause changes in the surrounding unsteady wind field,thereby affecting the flight trajectory of debris and the possibility of impacting downstream buildings.Therefore,in the evaluation of wind induced debris damage to the curtain walls of tower groups,the impact of the relative position of the buildings should also be considered. |
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