Analysis For Load Carrying Capacity And Dynamic Response Of Bidirectional Orthogonal Pipe Truss Composite Floor

The steel-concrete composite structure has wide application prospect in the large-span space structure because of its "lightweight,large-span,and rapid construction",especially in recent years,with the rapid improvement of social quality of life,the rapid development of culture,sports and industrial production,people's need for spatial structure,especially for large-span space composite structure.Compared with the traditional composite grid structure and I-shaped steel-concrete composite floor structure,the study of the composite tubular truss structure at this stage is still relatively small.In this paper,the finite element method is adopted to study the load carrying capacity and the influence factors of dynamic response for bidirectional orthogonal truss composite trusses,which provides the basis for the design of bidirectional pipe truss composite floor.Based on the computational theory of combined pipe trusses in elastic phase from existing documents,and on existing theory and calculation method of seismic design,a series of 27 models are established.And the nonlinear finite element method is used to study the influence of the depth-span ratio,the aspect ratio of the cross section,and the trusses span ratio on orthogonal space tube truss steel grid structure cycle,normal stress of lower chord and abutment.The results show:(1)the first cycle of the integrated steel pipe truss composite has a decreasing trend with the increase of the depth-span ratio,the highest increase is 36%.And it is not affected by the change of the aspect ratio.With the increase of the truss span,the first cycle increases first and then decreases,the largest decrease variation is 43.2%.(2)with reasonable parameters,the moal of the bidirectional orthogonal pipe truss composite floor is in accordance with the modal characteristics of the classical building structure.It's seismic response is similar to that of the traditional structure,and the research of dynamic response can by carried out by the traditional structural research method.(3)Increasing the high span ratio appropriately can increase the overall lateral stiffness of the structure,improve the ability of the structure to resist the earthquake.While,if the lateral stiffness is too large,it may relatively weaken the vertical stiffness,leading to the first formation of the structure changing into vertical vibration.(4)with the increase of the depth-span ratio,the first cycle of the orthogonal pipe truss composite floor decreases.The variation is from-1.6% to 20.0%.The influence of the aspect ratio is not significant.With the increase of the truss span,the first cycle increases first and then decreases,and the variation range is relatively large.The maximum increase is 43.5% and the maximum decrease is-18.3%.This paper summarizes the relationship between the parameters and gives the proposed value of each parameter,which can provide some reference for the structural design of the pipe truss composite floor.