Wind-resistant Reliability Analysis Of Long-span Roof Structures Based On CFD Numerical Simulation

The long-span roof structure is a typical wind-sensitive structure,and the wind-resistant design has become the key to its structural design theory.At present,domestic and foreign scholars have had a certain research basis for the study on the stadium's long-span cantilevered roof and its wind-reducing measures.However,the examples of damage to these buildings under wind loads are common,which have caused incalculable losses.Presently,there is no relevant specification for this type of wind load design.Therefore,it is necessary to study the structure of long-span roofs.Based on the CFD(Computational Fluid Dynamics)numerical simulation method,the wind load distribution characteristics and mechanism of the open circular roof are analyzed,and the accuracy of the results is verified by wind tunnel test.Thus,the wind pressure of the long-span roof under wind load is obtained.Besides,open a hole in the position where the wind pressure is large to study the effect of the opening on the average wind load of the roof.Furthermore,aiming at the common damage forms of the roof,based on the JC checkpoint method as well as the PNET method,the multiple failure modes roof and its skeleton failure mode are established,in order to establish the roof reliability analysis model,and the wind resistance reliability of the long-span roof structure is carried out.analysis.Firstly,the CFD model is established according to the wind tunnel test model,and the wind load calculation is carried out at intervals from 0° to 330° at 30°.The calculated results are compared with the wind tunnel test,showing that the numerical simulation results and the results of the hole test are basically consistent,meeting the research requirements;the outer ridge of the roof is a positive wind pressure sensitive area,while the inner ridge is a negative wind pressure sensitive area.The most unfavorable area of the outer ridge of the roof is located at the lower part of the roof,and the most unfavorable wind direction angle is 270°(90°).The most unfavorable area of the inner ridge is located at the higher position of the roof,and the most unfavorable wind direction angle is 300°(30°).Secondly,opening a hole in the wind sensitive part,the opening ratio and the opening position are studied respectively.The wind pressure distribution characteristics of the roof and the wind loading mechanism are studied.According to the numerical simulation results,the flow field distribution on the surrounding of the long-span roof before and after the opening is obtained.The results show that when the wind direction angle is perpendicular to the outer ridge of the roof and flows along the slope direction,parts of the airflow directly hits the upper surface of the roof to produce a positive pressure,while the other part of the airflow separates on the lower surface without obvious vortices,resulting in a negative pressure,so that the roof is in the "pressing on the upper side while pulling on the lower side" situation.The air flows through the hole after opening,which reduces the phenomenon that the airflow hits the roof,so that the wind pressure of the roof is significantly reduced,and as the opening rate increases,the wind pressure decreases more obviously;when the wind direction angle is vertical at the inner ridge and flows in the direction of the reverse slope,the airflow generates a significant vortex on the upper surface of the roof,generating a negative pressure,and the lower surface airflow collides with the roof,so that the roof is “pushed up and down”.In thecase of the top,although the formation of the edge vortex is disturbed after the opening,the vortex is still generated at the trailing edge of the hole.As the opening ratio increases,the high vortex area does not decrease significantly,so the reduction of the negative pressure is not obvious.Finally,by taking advantage of the structural probability reliability design method,based on several common failure modes of the skin,the reliability model of the skin multiple failure modes is established.At the same time,the skin failure probability is incorporated into the skeleton reliability model for the long-span roof,in order to analyze wind resistance reliability of the long-span roof.The research shows that the reliability model of the roof is considered,the correlation between the multiple failure modes of the skin and the influence of the skin on the reliability of the skeleton structure are considered,and the reliability of the skin and its skeleton can be accurately calculated.It can be applied to the reliability analysis of many structural systems consisting of skin and bone architecture.It is further concluded in the study that the wind-resistant measures in the wind-sensitive part reduce the area of the skin failure,while at the same time improve the reliability of the skeleton,and more reflect the multi-level fortification concept..