Resistance Analysis Of Space Truss Structure Of Different Fire Plume Model Fire

Large space building due to the special use of the function,the roof system is often used in the form of steel or composite structure,and poor fire resistance of steel,making such a building structure of the fire resistance design has become particularly prominent.The IS0834 temperature rise curve used in the general fire resistance design is a monotonically increasing curve,and can not reflect the real fire,but also does not consider the building within the combustible distribution,opening size,flue gas radiation and other factors.Although China's current?Technical code for fire safety of steel structure in buildings?in the large space building temperature curve to consider the above factors,but only for axis symmetry plume,did not consider the angle plume and wall plume situation.In this paper,the temperature field distribution of the three plumes is analyzed emphatically from the difference of the three plumes.Finally,the influence of the three plumes on the building structure is illustrated by a square pyramid model.The main contents are as follows:(1)The applicability of the three classical axisymmetric plumes is analyzed.On this basis,the difference between the plume of the wall plume,the angle plume and the axis symmetry plume is pointed out.Then,the simplified calculation equation of the temperature field of the plume and the wall plume is deduced from the classical axisymmetric plume model.Finally,the correctness of the simplified equation is verified by FDS.(2)The internal force distribution and displacement of the truss structure under axisymmetric plume,wall plume and corner plume was calculated respectively with ANASYS based on a square quadrangular pyramid.The results show that under the same fire power,the overall displacement of the truss structure is the biggest under the action of the wall plume,the plus-minus phenomenon of tension and pressure is the most significant in the case of corner plume.