Numerical Analysis And Monitoring Of Unloading Process Of Cantilever Steel Truss Structure

In recent 40 years,with the gradual development of the forms of building structures in China towards diversification and complexity,the complexity of building structure forms leads to many potential safety hazards in the unloading process.It is necessary to conduct simultaneous finite element simulation and monitoring of the structure to ensure the safety of the unloading process.Based on the relevant theoretical basis and case study and analysis of similar projects,this paper takes four double-layer cantilever steel trusses and cantilever supported steel trusses of Ganzhou concert hall as the research object,carries out the finite element simulation and analysis of the unloading project of cantilever steel truss structure based on the actual engineering design parameters,and at each stage of the construction process,According to the comparative analysis between the simulation value and the monitoring value at this stage,the bending moment shared by each truss in the next stage is calculated to ensure that the demolition process in each stage is under safe and controllable construction.The main research contents and results are as follows:(1)Based on the actual engineering design parameters,the structural finite element model is established,and the structural stress and displacement changes under the two unloading schemes are simulated.Through the comparative analysis of the two unloading schemes,the numerical value and change trend of component internal force and deformation of key components in the demolition process are simulated and calculated,and the key points of unloading and monitoring are put forward to improve the component safety in the unloading process,Through the comparison of numerical simulation,the optimal unloading scheme a is confirmed,that is,the scheme of gradually removing the moulding bed from both sides to the middle.(2)Based on the results of finite element simulation analysis,a targeted monitoring scheme for unloading stage is formulated.By gradually comparing the actual monitoring results of each stage with the numerical simulation calculated values,the analysis shows that the two have basically the same change trend,which proves the rationality of the numerical simulation results,At the same time,the numerical simulation results and field monitoring results show that the stress and deformation of each position of the structure are within the safe range,which shows that the structure is relatively safe in the unloading process,which provides a theoretical basis for the subsequent unloading stage.At the same time,for the difference between the simulation value and the monitoring value,it is preliminarily judged that the two trusses on the inner side actually bear part of the structural load.(3)In order to further prove that the difference between the simulation value and the monitoring value is due to the fact that the two inner trusses actually participate in the load-bearing structure,the distribution proportion of the internal and external bending moment when the two middle cantilever trusses are rigidly connected with the shear wall is 48.42% according to the virtual work principle,and the distribution proportion of the bending moment shared by the two middle trusses in the actual project is 44.82% of the overall bending moment,It can be seen that the actual connection mode of the two inner trusses is closer to the rigid connection,and this connection mode can effectively reduce the bending moment borne by the two inner trusses and further ensure the unloading safety of the project.