Numerical Analysis Of The Fire Resistance Of Pre-stressed Composite Space Truss

Pre-stressed composite space truss is a new kind of space structure system developed on the basis of pre-stress and space truss, which consists of steel and reinforced concrete. It is widely used in the buildings of store and school, which have condensed human in long time. If the pre-stressed composite space truss collapses in fire before people leave the building safely, it will cause large-scale casualties and loss of properties. But, present the study of it mostly focus on its static and dynamic properties and its design and building methods. So it is necessary to make a profound study on fire resistance of pre-stressed composite space truss.Firstly, axisymmetric element is used to simulate the welded hollow spherical joint, and arc-length method is used to analyze the ultimate compressive and tensile capacity of welded hollow spherical joint under high temperatures. Then, the temperature reduction factor was put forward with regressive method.Secondly, with thermal-structural coupled-field analysis, 33 welded hollow spherical joints under different load levels are analyzed to study its fire resistance by using finite element analysis program ANSYS. And the influences of load level, diameter and thickness of the joint are studied.Finally, based on a practical pre-stressed composite space truss, its fire resistance is studied with finite element method. Pre-stressed composite space trusses with different truss type are compared, and the influences of joint rigidity, support condition and so on are studied.The temperature reduction factor of the bearing capacity of the welded hollow spherical joint based on calculation can be easily used in the design process. The analysis of the welded hollow spherical joint under ascending temperature presents evidences to evaluate its fire resistance property. With the analysis of the practical pre-stressed composite space truss, the fire resistance of pre-stressed composite space truss and its influence factors are possessed, and it can be used to guide practical projects.