Study On Fire Resistance Of Single-layer Reticulated Shell Structure Of Welded Hollow Spherical Joints With H-beams

Space lattice structure has many advantages such as light weight,high strength,economic cost,and simple construction.It is one of the most widely used large-span building structure forms.Welded hollow spherical joints with steel tubes are widely used in traditional space lattice structures.Based on the requirements of modern space lattice structures with beautiful shapes and structural stresses,Welded hollow spherical joints with H-beams have been applied in engineering.At present,the research mainly focuses on the mechanical properties of welded hollow spherical joints with steel tubes under fire and high temperature,while the high temperature mechanical properties of welded hollow spherical joints with H-beams are rarely involved.Based on the finite element analysis software,this paper carried out a systematic research on the fire resistance performance of H-shaped steel reticulated shell structures including nodes and overall structures,and provided a theoretical basis for the rational design of space structure fire resistance design and building safety assessment under fire.The main contents are as follows:(1)The mechanical properties of welded hollow spherical joints with H-beams under high temperature under eccentric compression and eccentric tension were studied.The effects of steel material properties,eccentricity,welded hollow sphere size parameters,section steel size and ribbing on the mechanical properties of welded hollow spherical joints with H-beams are considered.The failure modes,loaddisplacement relationships and ultimate bearing of joints are obtained and analyzed.The variation law of force with the increase of temperature;on the basis of parametric analysis,the fitting calculation formula of reduction factor of ultimate bearing capacity of eccentric compression and eccentric tension at high temperature is proposed.(2)The bending mechanical properties of welded hollow spherical joints at high temperature were studied.The influence of parameters such as welded hollow spherical size and profile size on the bending mechanical properties of welded hollow spherical joints with H-beams is considered,and the failure mode,bending moment-rotation relationship,bending capacity and bending stiffness of welded hollow spherical joints with H-beams are obtained and analyzed.The law of change in bending stiffness with increasing temperature;based on parametric analysis,formulas for calculating the plastic bearing capacity,ultimate bearing capacity,and initial bending stiffness of welded hollow spherical joints with H-beams at high temperature are proposed;The bending performance of welded hollow spherical joints with steel tubes was studied.and the degradation laws of bending capacity and initial stiffness of welded hollow spherical joints with steel tubes at high temperature were summarized.(3)Based on ABAQUS finite element analysis software,a fire-resistant design method for single-layer reticulated shell structure is proposed.By considering factors such as the initial defects of the overall structure,temperature field distribution,and joint stiffness degradation at high temperatures,the fire resistance numerical analysis method of the single-layer reticulated shell structure of welded hollow spherical joints with H-beams is specifically described to achieve the overall structure fire resistance purpose of security analysis.