Research On Multi-dimensional Seismic Response And Performance-based Seismic Design Method Of Frame-bent Structure For Thermal Power Plant

Irregular structures appear inevitably because of functional requirements and artisticeffects. Theoretical studies and seismic disasters show that the damage of irregular structuresis serious due to the decrease of seismic performance. At present, the anti-seismic research onirregular structures which have the characteristics of lateral-torsional coupling and weak storyobtained some valuable results. However, some special and important structures remain to befurther research.Thermal power occupies an important place in the electric energy structure whether nowor in the future. In order to meet the requirements of productive technology, the thermalpower plant always use frame-bent structure consists of multilayer frame connected withsingle bent. Because of complex equipments and irregular structure arrangement, thedistribution of mass and stiffness is uneven, which leads to poor seismic performance. Thethermal power plant must has well anti-seismic property and reliable structural safety toensure the safe operation of power facilities.Based on the study of irregular structure, the paper focuses on analysis and research ofthe frame-bent structure for thermal power plant. Research results can provide basic researchdata and guide the engineering design. The research is of great significance for earthquakedamage effects of power facilities. The main research work and achievements include thefollowing aspects of content.(1) Internal and external factors which lead to structural torsional response are discussed.The causes of accidental torsion and suggestions on the value of accidental eccentricity areanalyzed and given. Comparative study can give the advantages and disadvantages fortorsional calculation method. Model analysis indicates the influence law of parameters for thetorsional analysis.(2) According to the characteristics of thermal power plant, the three-dimensional analysis model was established based on finite element program to investigate the mechanicalbehavior. The dynamic property of different formal structures is analyzed comparatively tomaster the fundamental torsion properties. The subject is SRC frame-RC few walls mainbuilding. Firstly, the study of elastic torsion reaction rule shows the force and deformationcharacteristics under single-, bi-and multi-dimensional seismic action. The amplificationfactor caused by torsion in different locations and irregular flat and vertical indicators aregiven. Plastic damage and failure process under the action of earthquakes of variousmagnitudes are analyzed through research of plastic reaction rule. Finally, the concept designprinciples and torsional control measures for frame-bent structure are proposed. Theresearch can help to master earthquake reaction rule and torsion performance undermultidimensional earthquake.(3) A1/7scale space model with three-bay substructures selected from the SRC frame-RC few walls main building is established to carry out pseudo-dynamic test. The experimentalstudy includes damage process analysis, stiffness degradation rule, deformation capacity,hysteretic behavior and energy dissipation capacity. Based on the performance of damage, theabnormal joints are designed and build to carry out pseudo-static test. The study can revealthe effect of damage on seismic performance, including strength, stiffness and hystereticenergy capacity. The capacity calculation formula is given through the analysis of stressmechanism. Based on the test results of structure and components, the damage model isestablished to calculate damage indexes under different conditions.(4) Pushover analysis and seismic performance evaluation are conducted on frame-bentstructure. Pushover method using for irregular structure is investigated, which indicates themethod applied in thermal power plant need to consider the impact of multidimensional andhigher modes. Capacity curve and failure modes under different loading modes are analyzedcomparatively to discuss the differences about overall displacement, interlayer displacementangle and shear distribution. The MPA method can effectively compensate the error caused bythe basic assumptions. ATC40capacity spectrum and the improved capacity spectrum methodare applied for thermal power plant to give suggestions on seismic performance evaluation.Furthermore, both methods are compared in the advantages and disadvantages of demandspectrum and performance points.(5) Based on relevant standards and the characteristics of industrial structure, theframe-bent structure for thermal power plant is divided to five quantified performance levels.Research shows the value recommend of performance index corresponding five levels andhow to choose the performance goals. Key issues about Direct Displacement-based SeismicDesign (DDBSD) are discussed when using for thermal power plant. The selection of structure style of the thermal power plant with unit capacity600MW and1000MW indifferent intensity zones is proposed. The SRC frame-RC few walls main building isdesigned by the DDBSD method. The results show that the method with highly practical caneffectively control the performance level of critical floor and overall objectives. Therelationship between damage performance levels, range of indicators and deformation indexescan provide a reference for seismic performance evaluation, reinforcement and repair. Theresults also can provide basic research data and contents for damage performance-basedseismic design.