Stability Analysis Of Long-span Glulam Timber Shallow Arch Structure

In current building market,long-span glulam wood structure has been more and more widely used,We can see its figure in different occasions.Arch structure,as a traditional building structure,has superior structural performance.Glulam timber structure is green and environmentally friendly,which can give full play to the strength of the material and make curved beams.The long-span glulam timber shallow arch structure can combine the advantages of the two structures and give full play to the advantages in engineering application.In this paper,the stability of large-span glulam shallow arch structure is studied by catastrophe theory and finite element software.In this paper,.The major job content as follows:The stability of long-span glulam shallow arch structure under static load is analyzed.The equilibrium equation of the structure under snow load is established based on the catastrophe theory,the formula is transformed into the standard equation of the single-cusp catastrophe model.According to the equilibrium surface,when the structure is in an absolutely stable state,for the rectangular section the ratio of the section height to rise is greater than 3^1/2,for circular sections,the ratio of diameter to rise is greater than 2.If not,the structure is in a conditional stable state.WhenΔ≥0,the structure can keep stable.The expression of the critical load of buckling can be obtained and the magnitude of the critical load can be calculated.The variation characteristics of the rise of the structure under static load are studied.The influence factors of buckling critical load and displacement are analyzed.The expression of the critical buckling load of the structure under shear deformation is obtained.It is found that the shear deformation has little effect on the stability of long-span structuresThe stability of long-span glulam timber shallow arch structure under seismic wave is analyzed.Based on the principle of total potential energy and variational principle,the motion equation of structural under earthquake wave is established and transformed into the standard equation of double-cusp catastrophe model by using trigonometric function formula.According to the stable condition,the expression of natural vibration frequency is obtained when the structure is in a stable state,and the expression of seismic coefficient k when the structure keeps steady vibration is obtained.The influencing factors of k are analyzed,and the boundary values of parameters such as height of rise,span and natural vibration frequency are given for practical engineering reference.The displacement amplitudes of the structures under different conditions are obtained and the influencing factors of the amplitudes are analyzed.The finite element model of long-span glulam timber shallow arch structure is established.The load-displacement curves of structures under static loads are obtained by using static general method and arc length method,and the critical load is obtained.The vibration characteristics of each order mode of the structure and the natural frequency of vibration are analyzed by means of modal analysis,the amplitudes of the structure under seismic wave in different frequency are analyzed by dynamic implicit analysis.The results are consistent with the catastrophe theory analysis.In order to study the stability of the structure under the action of actual earthquake,according to the code,two natural earthquakes and one artificial seismic wave are selected and the stability under the action of 7 degree rare earthquakes is analyzed,the peak acceleration of seismic wave is changed.Amplitude mutation instability phenomenon does not occur under different peak acceleration,the structure can maintain stable vibration.Under under the action of 8 degree rare earthquakes,the structure can still meet the seismic requirements and has good seismic performance.