Aerodynamic Shape Optimization For The Roof To Resist Wind Pressure

The long-span roofs have been widely used in engineering, these structures are very sensitive to wind load because of the long span, light weight and low damp, so reducing the wind load becomes one of the most important issues of the wind engineering. According to the principles of aerodynamics, the wind load on long-span roofs are closely related to the shape of structures. And aerodynamics measures, such as modifying the shape of structures, are regarded as the most economical and direct ways to improve wind resisting behaviors of the wind sensitive structures.Dome roof structures, cylinder roofs and flat roofs are all typical types of long-span structures. The paper makes these three types of long-span structures as the objects of the study, to find the best shapes of the structures for resisting wind load. This research uses the numerical simulation as the main tool and relies on the data of wind tunnel tests to confirm the reliability of the simulation, the main contents are as follows:(1)The CFD software, CFX14.5, is used in this research, and RANS method is chosen as the turbulence simulation method. Besides, SST model is used as the uniform turbulence model. The mean wind pressure on five different rise-span ratio models of dome roof, three different rise-span ratio models of cylinder roof and one flat roof model has been simulated. After being compared with the data of wind tunnel tests, the reliability of the numerical simulation has been confirmed.(2)The wind-resistant performances of these roofs have been evaluated from the perspective of local peak wind pressure coefficient and global lift coefficient. Smaller peak coefficient, better local wind-resistant performance, smaller lift coefficient, better global wind-resistant performance. When local and global wind-resistant performance can not be best simultaneously, local wind-resistant performance should be satisfied firstly to induce the failure probability of roofs(3)The mean pressure distribution and peak coefficient laws of dome roofs and cylinder roofs with rise-span ration changing have been summarized. Basing these laws, more simulation cases of dome roofs (1/7,9/60 and 9.5/60) and cylinder roofs (1/7, 9/60) have been added, at last, the rise-span ratio range of the dome roof,1/7-1/6, and the rise-span ratio of the cylinder roof,1/8-1/6, have been put forward as the best to resist the wind load from the perspective of local and global wind-resistant performance.(4) This part mainly studies the effect to reduce wind pressure of flat roofs, by rounding the right-angle connection between the wall and the roof. The change laws of the peak wind pressure coefficient and lift coefficient on flat roofs with different rounding radiuses has been summarized. The best wind-resistant rounding radius range, 5m-8m, has been put forward from the perspective of local and global wind-resistant performance.