Research On Fire Resistant Mechanics Behavior And Collapse Control Technology Of Petrochemical Steel Structures

It is a challenge work for the fire resistant analysis of steel plate shear wall (SPSW)and steel frame in petrochemical equipment because the material constitutive relation ischanged continuously as the hydrocarbon fire temperature rising. Researches indicatethat the finite element method is a useful tool, which deals with the material andgeometrical nonlinear calculations, but is not widely applied in engineering design sincethe modeling is very complexity. In this thesis, the plastic limitation analysis method isproposed for steel structure on the hydrocarbon fire situation, which indicates it issimple and useful. The analysis results can be satisfied the requirements of engineeringapplications.In normal temperature, SPSW under buckling does not imply that the bearingcapacity is lost, in contrast, the stress under buckling can rise to many times than theelastic buckling strength because that the effect of diagonal tensile is similar as a seriesof braces. The idea of utilizing the post-buckling strength of SPSW was first formulatedby Canadian Thorburn et al in1983as String Model (SM), which was adopted in theNorth-American Steel Code now. In this thesis, it can be found that the essentialdifferences in fire are the complexity tensile force distribution from strings in SPSW.The Temperature String Model (TSM) is proposed for the tensile string computationmodel to the different temperature fields, which are changed from the bottom(left) totop(right) on the wall. The minimum total potential energy principle is used to deducethe formula to calculate the string incline angle and variation law. Based on theplastic limitation analysis theorem, the uniform or upper bound solutions of bearingload are deduced for SPSW after buckling.At present, the research on the mechanics behavior of steel frame under fire hasbeen carried out progressively. The main methods are the finite element method inlower bound and the simple calculation processes. However, it is usually meeting thecalculation convergence problem since the constitutive relations are changedcontinuously. Therefore, based on the upper bound theorem of plastic limitationanalysis, the method is proposed to use superposition of essential failure mechanisms.The non-linear programming is solved through the quasi-Newton method to find the critical load multiplier corresponding to the minimum internal work. Then, as thetemperature is re-increased, the minimum load multiplier by the iterative method to findthe critical temperature corresponding to the failure of steel frame.In the structure progressive collapse control technology under fire, the secondinternal force path method is very effective. By selecting a sensible degree to determindkey members, whose strength and inflexibility decrease simultaneity, software STAADwas applied to the petrochemical cracking furnace to analyse the limit temperature, bywhich the optimizing design goals are achieved. Now the experiments of outdoor steelultrathin fire coating under hydrocarbon fire are a limited numbers in China, thefoaming tests were carried out for domestic products. Also, apply the datum of timberfire standard curve to determind the coating characteristic under hydrocarbon fire by theequal exposure fire theory.In this thesis, the fire resistance of petrochemical steel structure and progressivecollapse control technology are investigated under hydrocarbon fire. The load bearingcalculation formula of SPSW is established based on the fire disaster and the upperbound computation method is proposed to determine the critical temperature for thesteel frame. A computation program for the fire resistant of steel frame is implemented,which is used in analyzing the fire scene and providing the theoretical basis for the steelstructure performance design. The engineering computation and design method areproposed for the steel structure fire protection field.