Analysis Of Mechanics Characteristics Of Prestressed Steel Beam In High Temperature (Fire) Condition

With the advances in engineering technology and improvement of people’sworking and living environment requirements,prestressed steel structure has beendeveloping rapidly in recent years,this technique not only saves material and makesstructure force reasonable,so it is widely applied in various large-span structuresengineering,and the prestressed steel beam is one of the most typical form of membersin prestressed steel structure system.But it is well known fire resistance of steel ispoor,the environment of high temperature significantly changes its physical andmechanical properties. However, prestressed steel structure is in most cases part ofunbonded prestressed system so that the steel cables are not adequatelyprotected.Therefore,the prestressed steel beam of great energy inside while worknormally once caught in fire, probably leads to a collapse as a result of several factorssuch as inner force redistribution and the deterioration of structural steel property.Thus,the research on fire resistance of prestressed steel beam has very important theorymeaning and practical value.The article on the basis of the research by others’ research on fire resistance ofprestressed concrete structure and steel structure,combines with the existing relevanttechnical specifications, according to the requirements of fire science theory and thefire resistance design of structures,utilise the method of structural mechanics and finiteelement analysis,the author analyse the mechanics behavior of prestressed steelstructures on high temperature(fire) condition theoretically and numerically.This paper theoretically analyzes the type and size of prestressing loss,bearingcapacity and deformation of prestressed steel beam under high temperatureenvironment,and the calculus of critical moment and deflection has been formulated,the effect on the mechanical properties of components in the high temperature (fire)environment which exerted by different parameters such as tension control,loadforms,cable arrangement height and the form of bearing is covered in the samecondition,at the same time,the temperature distribution and disciplines over developingwith time of prestressed steel beam under fire conditions within a certain time isstudied by ANSYS,the thermal-stress coupled effect is analyzed in the foundation ofthermal analysis,discusses the differences between numerical analysis and theoretical calculation under the same condition to further explore the damage mechanism ofprestressing steel beam under high temperature(fire) condition.This paper expected to be helpful to provide a reference related fire resistantdesign for practical engineering through the study on the mechanical properties ofprestressed beams at high temperatures.