Research On Wind Effect Of Twin-tower High-rise Building With Corridor Based On Large Eddy Simulation

The twin-tower high-rise building with the connecting corridor is a more common structural form,which is very sensitive to wind loads.The setting of the connecting corridor can change the aerodynamic shape of the structure and affect the structural wind effect.In this paper,a Modified Narrow Band Synthesis Random Flow Generation(MNSRFG)and Large Eddy Simulation(LES)are used to investigate the wind effects on single structures,double tower structures without connecting corridors,and double tower structures with connecting corridors using CAARC standard model.The comparative study of wind effects on a single structure,twin-tower structure without connecting corridor,and twin-tower structure with a connecting corridor are carried out by the CAARC standard model of a high-rise building.The main work and conclusions are as follows.(1)The surface wind pressure and basement wind load of the CAARC standard model are obtained by large eddy simulation and compared with the wind tunnel test results to verify the feasibility of the MNSRFG inlet turbulence generation method and basin setting and grid division adopted in this paper.the average wind pressure coefficients and local body shape coefficients of seven typical measurement point layers on the CAARC standard model,the MNSRFG method,and the wind tunnel test The results are overall more consistent,and the variation trends remain consistent.And the obtained pulsating wind pressure coefficients at the corner measurement points are in good agreement with the wind tunnel tests.The power spectral density of the moment coefficient at the base of the building is in good agreement with the wind tunnel test results,and the highest agreement is with the power spectral density of the moment coefficient in the crosswind direction.In the transverse wind spectrum,the values of the transverse coordinate(Strohal number St)corresponding to the peak of the spectrum are very close to the wind tunnel test results,and the overall energy curve distribution is also consistent with the wind tunnel test results,which provides a strong guarantee for the accurate calculation of the critical transverse wind response of the structure;the errors of the peak base moments in the downwind,transverse wind and torsion directions obtained from the simulation and the wind tunnel test results are 3.27%,4.77%,and 10.77%,respectively.Therefore,the MNSRFG method is able to achieve a better prediction of the structural control direction of wind load;through the comparison of different calculation time data,it is suggested that the total calculation time is 10 s for similar simulations of the CAARC standard model,which can obtain more accurate numerical simulation results and meet the requirement of actual sampling over 10 min,and also can save computing resources.(2)The MNSRFG method is used to simulate the twin-tower model with large eddies,and the surface wind pressure characteristics of the twin-tower high-rise building are studied,and the formation mechanism is investigated through its peripheral winding analysis.The results show that compared with the monolithic structure,both the unconnected twin towers and the connected twin towers destroy the vortex shedding on both sides of the monolithic surface,which has a relatively large impact on the cross-wind aerodynamics.The existence of the connecting corridor makes the downstream flow field rapids more complex,and the shorter length of the connecting corridor also leads to more vortices between buildings and more turbulent flow lines;in the structural design,attention should be paid to the appearance of the central interval of the non-connected twin towers causing the slit effect,the increase of the average wind pressure coefficient on the inner side,the symmetry of the average wind pressure coefficient on the leeward side is destroyed,and the value of the average wind pressure coefficient at the measurement points near the inner side increases.The root means square wind pressure coefficients on the surface of the structure with and without the twin towers are decreased to different degrees compared with the single structure,and the degree of decrease is the largest with the twin towers,which indicates that the installation of the corridor makes the change of the incoming wind become smooth,which is beneficial to the safety of the structure.(3)The wind load characteristics of the corridor itself were studied.The wind pressure of the corridor body is closely related to its height.The average wind pressure coefficient and root mean square wind pressure coefficient of the windward side of the corridor body increase and then decrease as the height of the corridor body rises,reaching a peak at the E level(0.8H)and then dropping abruptly near the top.The opposite is true for the leeward side,where the mean wind pressure coefficient and root mean square wind pressure coefficient decrease and then increase as the corridor body rises,with a peak at the F level(0.98H),and the decrease in the length of the corridor increases the peak,so this phenomenon should be considered when designing the corridor body.(4)The influence of parameters such as the presence or absence of the connecting corridor,the height of the connecting corridor,and the length of the connecting corridor on the wind-induced base moment of the structure was studied.Compared with the twin towers without the corridor,the corridor with the twin towers has a better reduction effect on the peak of the power spectrum density spectrum of the moment coefficient in the cross-wind direction and torsion direction,and the best reduction effect is the corridor at the E level(the height of the center of the corridor is 0.8H)and the length is set to 40m(minimum spacing).The installation of the corridor has less effect on the downwind direction and only affects the fluctuation of the power spectrum density curve of the basal moment coefficient.The installation of the corridor also significantly reduces the cross-wind peak base moment,and its reduction is negatively correlated with the length of the corridor as a whole.The best reduction effect is achieved by installing the corridor in the middle and high levels,with the spacing of the twin towers at 40 m and the corridor at the E and D levels.The reduction in peak base moment in the other two directions is also achieved by setting the connecting corridor,with the reduction in the downwind direction ranging from 1% to 14%,and it should be noted that setting the corridor above the E level and at the bottom of the junction increases the peak value compared to the non-connected twin towers.The reduction effect of torsional direction is conservatively calculated between 9%-27%.(5)The structure of the twin towers is symmetrically arranged side by side with respect to the incoming wind,but the wind response of the two towers does not have a certain symmetry,there is a certain numerical gap,so the above conservative calculation is taken from the calculation results of the large data.Such a gap exists,and the analysis in this paper suggests that the wind acts on the structure as a random load and the resulting flow field is not regular,so the resulting vibration is also more random and not uniformly distributed.In addition,the vibration of two towers of a conjoined building is usually random and asynchronous when it occurs,i.e.,the two towers do not move neatly in the same direction at the same moment,there is a relative displacement,and one of the towers will pull the other tower to limit its wind-driven response.(6)The setting of the connecting corridor has a significant reduction in the wind vibration effect of the twin towers,there is also a local increase in wind vibration values,in addition,considering the practicality of the connecting corridor,generally will not be set up near the bottom,therefore,based on the similar twin towers of this paper connected structure,it is recommended to set the connecting corridor at 0.67-0.8H of the twin towers(H is the height of the twin towers),the value of the length of the connecting corridor can be slightly less than the length of the towers(this paper takes 40m).