Research On Performance-based Fire-resistance Of K8 Single-layer Spherical Latticed Dome

In recent years,large-space building structure is developing rapidly around the world,latticed dome is one of the most broadly used forms in large-space building structures.Latticed dome is mainly made of steel,but the elastic modulus and yield strength of steel will be drastically reduced under fire,it eventually results in the destruction of the structure and seriously threatens the safety of people's life and property.Therefore,it is necessary to deeply research the fire-resistance performance under fire,and take corresponding measures to protect structure.This article involves in performance-based fire safety design concept,which is based on fire prevention purpose made by performance index to qualitatively and quantitatively analyse and assess the impact of structure under fire in order to obtain the best fire prevention program.The fire-resistance analysis of steel structures is usually divided into three steps:analysis of fire temperature field,heat transfer analysis of steel structures and structural analysis.K8 single-layer spherical latticed dome is selected as the research object,and the unfavorable situation such as high-power fire or external load that much larger than the design load was considered in this paper.The fire prevention purpose is made as extending the fire-resistance time under the adverse circumstance,improving elastic-plastic stability bearing capacity under fire and avoiding the overall instability at high temperature.Firstly,non-uniform temperature field of different fire situations was simulated by taking temperature-rising curve in the large-space fire,and temperature zone divided according to the distribution and change of temperature field.Secondly,a full-range analysis of structure was carried out by ANSYS,it is concluded that displacement characteristic,stress change,ultimate load and buckling mode of the structure under fire.The influence of different structural parameters(rise-span ratio,span,load ratios and constraint arrangement)on the fire-resistant time and ultimate displacement was elucidated,the influence of initial defect on elastic-plastic stability bearing capacity in the different moments of the fire was analyzed,and fire improvement plan was formulated by making a summary about the location of failure bars and the weak parts of structure.Lastly,the research results of the fire-resistance performance is combined with the fire-resistance advantage of the double-layer spherical latticed dome to make plan that contains spraying fire retardant coating and strengthening local structure.The optimal spray plan was selected by assessing the feasibility of the overall plan.