Study On Seismic Behavior And Seismic Design Method Of Steel Frame-bent Structures Of Large Thermal Power Plant Main Buildings

In China, the reinforced concrete frame-bent structure often are used in the mainstructure of the thermal power plant, while the height and span of the main power houseincreased with the increasing of the power plant unit capacity, the steel structure withflexible layout, light weight, high strength,quickly construction, good seismicperformance advantages, has become the main structure of the main plant of largethermal power plants.In particular, it has become the preferred form of construction oflarge thermal power plants in the earthquake-proof.The mechanical behavior of irregularjoints of steel structure of large thermal power plants have been studied. Based on theprevious studies, the research on seismic performance and design method of steelframe-bent structures of large thermal power plant main buildings is systematicallyperformed in this dissertation.According to the experimental study on a1:10model of steel frame-bent structureunder pseudo-dynamic test.The seismic responses such as acceleration,displacement,varying stiffess,hysteretic property and energy consumption were analyzed. The resultsshow that the steel frame-bent structure has good ductility and strong plastic deformationcapacity. The maximum story drift angles of the model structure under intensity8frequent and rare earthquakes are all less than their limit values regulated by the presentseismic code. Steel frame-bent structures satisfied the demand of seismic design in8intensity zones,and has good seismic behaviors. After the pseudo-dynamic test, theexperimental study on the model of a three-bay and five-story steel frame-bent structuresunder low cyclic reversed loading was to do. The failure condition of frame-bent structures is observed. The load-displacement hysteretic loops and skeleton curve oftested model are obtained. The failure mechanism, hysteretic behavior, ductility, energydissipation capacity and stiffness degeneration were investigated. The results show thatthe failure mechanism of steel frame-bent structures is the first occurrence of beam-hingeand then column-hinge mechanism.The hysteretic loops are a plump.The average of theoverall ductility factors is greater4.The equivalent viscous dampings coefficient is0.185.The steel frame-bent structures exhibits excellent seismic behavior, and can beadopted in high seismic fortification zones. The inter-story displacement rotation isrelatively large on the bottom floor and the second floor, namely the weak floor. Andthere is larger earthquake action at the coal hopper beams, which must be paid attention indesign.The time history response analysis on flat steel frame bent structure were carried outby using SAP2000.The calculated results agree well with experimental results.According to the calculated results, the deformation performance are analyzed, the plastichinges in the order and law under strong earthquakes are got. The influence of structureproperties from split-level, coordination between the frame and bent work.The elastic time history response analysis method, dynamic elastic-plastic analysismethod, static pushover analysis method are used to study the deformation, weak parts,loading capacity and failure mechanisms of steel frame-bent structures of large thermalpower plant main buildings by using Midas/gen. The results show that the steelframe-bent structure has good ductility, strong plastic deformation capacity and seismicperformance. But the horizontal frame-bent and longitudinal frame-supporting structureshave much weak parts, and there is larger earthquake action at the coal hopper beams,which must be paid attention when designed.It should be used the space modelconsidering the effect of torsion on the structure to calculate and analysis.Refer to the domestic and foreign relevant norms，four performance levels are putforward for steel frame-bent structures, which are normal operation, basic operation, lifesafety and collapse prevention. The seismic levels and four performance levels arecombined to form the seismic performance target. Based on the results of seismicperformance tests on steel frame-bent structures, the maximum inter-story drift anglecorresponding to different performance levels are presented for the steel frame-bent structures. The displacement-based seismic design(DBSD) method was proposed to steelframe-bent structures. The procedure of the DBSD was given, and taking one steelframe-bent structure of main building as an example, the design process wasdemonstrated.The seismic optimal design of the steel frame-bent structures based on structuraldamage expectations was proposed. The seismic optimal design mathematical model ofthe steel frame-bent structures was set up and the optimized design steps were given.Theseismic optimal design program of the steel frame-bent structures was compiled by usingAPDL based on the secondary development platform in ANSYS. The feasibility ofoptimizing idea and method was verified by an engineering example.Based on experimental study and theoretical analysis, combined the characteristicsof thermal power plants and high-rise steel structure design method,the seismic designrecommendations of steel frame–bent structures of main buildings were proposed,whichcan provide a reference for engineering applications.