Study On The Application Of Large-span Flat Double-layer Spherical Latticed Shell In A Gymnasium Project

In recent years,with the development of economy,more and more large-span roofs are used and their shapes are various.Spherical latticed shells are favored by more and more architects because of their concise shape and practical interior space.Especially,their horizontal projection is circular,and the interior space is divided freely,symmetrically and internally.Therefore,they are widely used in large-scale gymnasium roofs.With the pursuit of large-scale and large-space requirements in recent years,the span of spherical latticed shells is getting larger and larger,and the rise-span ratio is getting smaller and smaller.Based on the design and analysis of a gymnasium project,the linear mechanical properties and overall stability of large-span and small-rise-span ratio double-layer spherical latticed shells are systematically analyzed,and their application in practical engineering is studied.At present,the rise-span ratio of spherical latticed shells is more than one-seventh in engineering.Special analysis and research should be carried out on the flat latticed shells(whose rise-span ratio is less than one-seventh).In this paper,combined with a gymnasium project,the large-span double-layer latticed shells with rise-span ratio less than one-seventh,different rise-span ratio and latticed shell thickness are calculated and analyzed by using the software of 3D3S/midas Gen.The YJK/midas Gen software is used to calculate and analyze the integral combination of the upper latticed shell and the lower concrete supporting structure,which mainly includes the following contents:(1)The problem of large horizontal thrust at the support of large-span flat double-layer spherical latticed shell with small rise-span ratio is analyzed,and the optimal solution of setting circumferential reinforced truss under elastic support is putforward.(2)The overall stability of large-span flat double-layer latticed spherical shells is analyzed.When the rise-span ratio is about 1/14,considering the initial geometric imperfection(L/300)latticed shells thickness of L/50,the overall stability load factor of large-span double-layer latticed spherical shells with elastic supports is less than 4.2.It is suggested that the large-span flat double-layer latticed spherical shells with elastic supports should be considered when the rise-span ratio is about 1/14.Even if the thickness of latticed shells is greater than L/50,the overall stability checking should be carried out.(3)Considering that the upper part of the gymnasium is steel latticed shell and the lower part of the supporting structure is reinforced concrete structure,the connection relationship between them is considered and the seismic response calculated by the integrated model is weaker than that calculated by the simplified model of the lower part of the latticed shell.The radial chord pressure and the horizontal reaction force of the support increase by 30%.Horizontal displacement of elastic support increases by about 70% under earthquake action.It is necessary to calculate and analyze the whole combination of the upper latticed shell and the lower concrete support structure,and to check the cross section and support design of the latticed shell.In this paper,through the design calculation and analysis of practical engineering,it provides some reference for the related theory and practical engineering of large-span flat double-layer spherical latticed shell structure.