Stress Analysis Of Long0-Span Lattice Grid Bearing Crane Beam

Now, there are many studies on the lattice grid structure dynamic responses at home and abroad, but for the great span grid structure with crane load fatigue simulation analysis is not enough. The crane load is different from the seismic load and wind load,which is composed of three stages:namely lifting stage, the operation stage and unloading stage. And each stage has its respective characteristic. In the steel structure fatigue problem is a very important topic, therefore, it is also inevitable for the supporting truss which withstanding the crane dynamic load. In the design of lattice grid structure the member's maximum value stress and maximum value stress range are the key parameter for lattice grid structure's fatigue.ANSYS analysis software is used to this paper, and has done massive simulation analysis work to the great span steel supporting truss, mainly divides into two parts:Static analysis and dynamic analysis. Main purpose of Static analysis's is to obtain some factors which influence the fatigue of lattice grid structure. In this part, we mainly analyze the member's stress and stress range's change rule which following the lattice grid integral rigidity, load and crane beam high and also studied the member's stress sensitivity. Dynamic analysis mainly includes two parts:modal analysis and transient dynamic analysis. Modal analysis is the beginning of the dynamic analysis. Supporting truss'natural characteristic can be studied through modal analysis. Transient dynamic analysis is the most important part for dynamic analysis in this paper. The supporting truss' dynamic responses under crane dynamic load mainly be studied in this part. The member's stress-time curve is obtained. The member's stress and stress range's change rule along with the crane load value as well as the time also be studied. And the following main conclusions are reached.(1) The improve of the grid stiffness can control the growth of the member's forces.(2) It is not desirable that simply raising the height of crane beam to improve the fatigue performance of lattice grid.(3) The member's maximum stress, stress amplitude and the cross-displacement linearly increase with the crane load.(4) The web and bottom chord braces are more sensitive to the stress, so it should be strongly considered as fatigue design.(5) The member's stress amplitude linearly increase with the load.