Study On The Numerical Simulation Of Wind Loads On Membrane Structure Based On CFD Theory

The main wind-resistant methods of structure include wind tunnel test, theoreticalanalysis, field measurement and numerical simulation. With the rapid development ofcomputer technology of hardware and software in last30years, the technology of CWE(Computational Wind Engineering) that based on CFD (Computational Fluid Dynamics)plays an increasingly important role for its significant advantages in the wind-resistantfield of structure.The membrane structure is very popular among architects for its beautiful shape,weight light, economy and ease of construction, and it is widely used at home andabroad. However, compared with traditional structure, the membrane structure is verysensitive to wind loads as a flexible structure, so the wind loads play a control role inthe design of membrane structure. The current codes only provide the wind shapecoefficient of the structure in simple shape. But the membrane structure has variousforms and complex shape. The wind shape coefficient that every country’ codes offeredabout the structure in complex shape is very limited, and the general practices of this isdetermining the wind shape coefficient by wind tunnel test. However, the wind tunneltest research for membrane structure is so insufficient that we can’t summarize thegeneral rules of the membrane structure under wind loads. And it is difficult to measurethe pressure synchronously on top and bottom surfaces of the membrane by wind tunneltest.In the first part of this paper, the wind loads on saddle, umbrella and umbrellacombination membrane structure is numerical simulated by adopting SST (Shear StressTransport) k-ω turbulence model in software Fluent to summarize the general rulesof the membrane structure under wind loads. The form-finding of membrane structure iscarried on in software ANSYS and the geometric model is extracted. Then, the fluiddomain and structure domain are meshed in software Icem CFD to establish thecalculation model of the flow around membrane structure. Finally, the wind loads onmembrane structure is numerical simulated in software Fluent. The influence of windangle, height-span ratio on wind pressure of membrane’s surface is analyzed. Thecontour maps of membrane’s top and bottom surfaces’ mean wind pressure coefficientand the contour map of membrane’s absolute wind pressure coefficient are given asreference in engineering design. The main conclusions are as follows:①The extreme value of positive and negative pressure region of the saddle membrane structure appearat the windward edge and the center close to the leeward side in wind angle0and90, and when the wind angle is45, the extreme value of positive and negativepressure region appear at the lower and higher corner of windward edge. The extremevalue of positive and negative pressure region of umbrella and umbrella combinationmembrane structure appear at windward edge and the area near the umbrella hole. Atthe same time, the wind pressure on the connection region of the umbrella combinationmembrane structure is greater than the wind pressure around the connection region.These areas should be given adequate attention in engineering design.②The globalforce of saddle membrane structure is about0in wind angle45. And the global forcein wind angle0and90are pressure and lift, respectively. Furthermore, the force issubstantially equal. The global force of umbrella and umbrella combination membranestructure manifest as lift.③The global force of saddle membrane structure in windangle0and90, umbrella and umbrella combination membrane structure will reducewith the decrease of height-span ratio in addition to the saddle membrane structure inwind angle45.④The global force of regular hexagon umbrella membrane structureis smallest in wind angle90, and the global force of square umbrella and umbrellacombination membrane structure is smallest in wind angle0.In the second part of this paper, the steady flow around the awning of a large spanmembrane structure is numerical simulated by adopting three commonly usedturbulence model: RNG k-ε model、SST k-ω model and RSM reynolds stressmodel in software Fluent. Then the absolute wind pressure coefficient in threeturbulence model is compared with the results in wind tunnel test. And find that besidesthe wind pressure of the structrue’s windward edge where flow begin separating isoverestimated, the results of numerical simulation is consistent to the results of windtunnel test. The comparison verifies the reliability of the numerical wind tunnel method.