The Studies Of Static Behaviors Of Irregular Lattice Shell

The irregular Lattice Shell has been widely used in big span structure at foreign as a newtype structure because of the unique Structure form. The domestic study of the irregular latticeshell is still in the primary stage due to its structure form and complexity mechanicalcharacteristics，so it is necessary to expand the research about irregular lattice shell.Based on polyhedron theory and lattice shell mechanics analysis method, thecharacteristics and laws of geometric model was studied and the static and dynamicmechanical characteristics was studied using commercial software ANSYS.The main studies are listed as following：1. The geometric characteristics and laws of irregular lattice shell have been analyzedand a method of geometric modeling was concluded. First，the basic unit was built bydetermining node coordinate the net type，then rotating and coping the basic unit because ofthe symmetry of lattice shell，a lattice shell is established. This procedure was performed bycommercial software ANSYS, and it proved that the method is feasible and can be drawn thegeometry characteristic.2. The static mechanical characteristics was analyzed using finite element analysisANSYS. Three types of triangle lattice shell with increasing “m” were studied under thevertical load, m is defined as the ratio of external diameter and wall thickness. The resultsshow that stress decreases at first, then increases with ‘m’(steel quantity) increasing. Theequivalent stress, vertical displacement, axial force and bending moment were compared witha invariable ‘m’. The mechanical analyse of122surfaces shell structure were performed withthe same of load and steel quantity. The240surface is the best configuration when themechanics, economic and other factors were considered.3. The first-order buckling calculation of irregular triangle configuration lattice shellwith the same steel quantity were performed to studied the critical load calculating formulawithout considering initial defect and other factors.4. The dynamic property of three kinds irregular triangle configuration lattice shell wasstudied. The anasysis of the front5order frequency modes provides some reference forseismic research.Through the above research a method of geometric modeling was concluded, and theimportant factors effecting mechanical properties of lattice shell were drawn. The number of basic units, sectional area of the bar, number of the joint and the mesh of basic units were allthe important factors that should be considered in the lattice shell design.