Numerical Analysis And Fire Safe-guard Condition Of Suspen-dome Under Fire

Large space steel structures are widespread used in public buildings due to theirtremendous space benefits，lightweight and various modeling. High temperaturecaused by fire can have significant influence on mechanics of steel materials, and thatis especially important for pre-stressed structure systems. Stress relaxation in highstrength steel due to high temperature might lead to structural collapse. Mechaniccapability and response to fire vary in large space pre-stress steel structures.Mechanic capability, damage mechanism, sensitive coefficient, fire safe-guardconditions under fire are discussed in this paper.First of all, basic features and current research situations of suspend-dome areanalyzed basing on as-researched principles, and drawbacks of them are summarized.Research in this paper revolves around the fire resistance capability and firesafe-guard conditions of suspend-dome.Secondly, combined with atmospheric rising temperature, the wholefire-resistant performance of suspend-dome under large space structure fire wassimulated by using finite analysis software ANSYS, and the mechanics feature andfailure mechanism of the structure under fire were analyzed. The results shows thatbulging deformation is the main deformation behavior of suspend-dome under fire;that different degree of the prestress loses appearing in the lower support systemreduces the structure bearing capacity; that the effect of lower support system wearsoff, making the load transfer path shifts to upper latticed shell structure; and that thestructure not yet fails within90min, proving the excellent fire resistance.Finally, regarding temperature field, loading ratio, geometry and boundarycondition et al as sensitive parameters, numerical simulation is done. As a result of it,approaches to verify fire safe-guard conditions of suspend-dome structure are putforward as follows: Distribution of temperature field shows transparent influence ondeformation feature, internal force, critical temperature and damage mechanism.Furthermore, total fire resistance of structure is especially sensitive to surroundingtemperature; Increment of loading ratio gradually decrease critical temperature in the presence of fire and deformation amplitude; in non-uniform temperature field,damage style varies from middle local failure to total structural collapse. Normalconstraint boundary condition impairs lower soften support system of suspend-domedrastically in the presence of fire, which is unfavorable. Therefore, it is inappropriateto apply normal constraint boundary condition to analyze fire resistance capability.With the help of finite elements numerical analysis, different structural criticaltemperatures are obtained by varying temperature decaying coefficient η and loadingratio R. Hence, direct critical temperature verification method is regarded as theapproach to check fire safe-guard conditions, which provides references for furtherfire resistance research of suspend-dome structure.