| Ladder form rib-ring type of spherical reticulated shell is a new type of reticulated shell.The surface of this structure has terraced shape, which has a strong architectural aestheticfeeling. However, this kind of structure use very little in the present practical engineering, andthe study on mechanical performance of the structure is still far from perfect.Firstly, according to engineering practice, this paper established the two structural typesof ladder form rib-ring type of spherical reticulated shell, namely Model A and Model B.And then, the finite element analysis software ANSYS was used to analyze the staticperformance, dynamic performance and linear stability of this new form of structure.Secondly, the geometric nonlinear stability and elastic-plastic stability of this novel structurewere detailedly studied in different initial imperfections and different load distribution,including different rise-span ratio, different structural span and different constraint conditionsof the boundary. Meanwhile, the results were compared with that of single-layer rib-patternedreticulated spherical shell. Finally, this paper carried out some exploration into the seconomicspan and researched on the structure optimization of this new kind structure by the factors ofeffectiveness of rod, cross-section form and sectional size. Through above work, someconclutions could be got as follows:a. The static displacement of ladder form reticulated shell is slightly larger than thatof single-layer reticulated shell. Axial force of radius members gradually increasesfrom the inner to the outer rings, and that of circle members gradually increasesfrom the ends to the centre rings. Distribution of axial force of circle members ineach ring will obey the following rule: upper circle members<central circlemembers (model A)<lower circle members.b. The geometric nonlinear and elastic-plastic ultimate bearing capacity of ladderform reticulated shell is slightly larger than that of single-layer reticulatedshell.And the ultimate bearing capacity will obey the following rule: model A>model B>single-layer reticulated shell. The stability capability of both elasticityand elastoplasticity have optimal rise-span ratio, namely1/6. c. Initial imperfection or constraint conditions of the boundary have much influenceon the ladder form reticulated shell’s stability capability of both elasticity andelastoplasticity. Thus, in engineering design, the influence of initial geometricimperfections should be considered and the boundary constraint stiffness should beimproved as much as possible.d. In the condition of asymmetric load distribution, the geometric nonlinear ultimatebearing capacity is larger than that in the condition of symmetric load distribution.But for the elastic-plastic ultimate bearing capacity, the conclusion above isopposite.e. At the same stability capability of elastoplasticity, comparing to the single-layerreticulated shell, the amount of steel per unit area of ladder form reticulated shellis not more than20%. The structure within100m span is considered to beeconomical in the practical engineering.f. For ladder form reticulated shell, the effectiveness of radius members and circlemembers from high to low in turn is: radius members, lower circle members,central circle members (model A) and upper circle members. And the webmembers among the circle members can significantly improve the stabilitycapability. The radius members should adopt closed-section steel, but notopened-section steel. The priority of the steel for the radius members will obey thedescending order: rectangular tube, circular tube and H-section steel. |
