| Reasonable failure mode is one of the decisive factors to ensure the good seismic performance of the structure under the action of strong earthquake.Chinese codes aim to achieve the expected failure mode by structural measures like ‘strong column weak beam',‘strong shear weak bending' and ‘strong joints weak components' and design like keeping up the reinforcement.However,it's not realistic to simply believe the failure mode that the code advocates is reasonable and achievable because the earthquake damage proves otherwise.Performance-based seismic design can be used to determine its seismic targets and seismic fortification standards based on the importance and the use of the building,which the structure owns the expected function in the future earthquake.‘Safety' and ‘cost' are the main contradictions that cannot be avoided in the design of the structure and directly affect the failure mode of the structure.The simplified evaluation method for the failure mode of the frame-shear wall structure is not established at present.Therefore,it is necessary to propose the simplified method for the evaluation of the seismic performance based on safety,cost and comprehensive indicators according to the need of the owners or designers have for the building on condition of meeting the minimum safety requirement.The simplified evaluation method for the seismic performance of RC frame-shear wall structure is more complicated and less studied.Therefore,this paper uses RC frame-shear wall structure as the research object.In this paper,we analyze the factors that influence the failure mode of the frame shear structure and determine the stiffness eigenvalue as the research variable and determine the range of the characteristic value of the stiffness and verify the rationality of the range.We design a series of RC frame shear structure with different stiffness eigenvalues to study the relationship between plastic hinge,hysteretic energy dissipation,damage index,shear force,story drift angle and stiffness eigenvalue of structural members.We calculate the structural safety index,economic index,comprehensive index and analyze the relationship between different indexes and stiffness eigenvalues.According to the analysis results,we establish the simplified evaluation method for the seismic performance and provide reference for the quantitative evaluation for the frame-shear wall structure.Based on the research above,this paper draws the following conclusions:(1)The failure mode of the frame-shear wall structure is closely associated with the stiffness eigenvalues.We can evaluate the seismic performance of the frame-shear wall structure by adjusting the stiffness eigenvalues to furthermore establish the simplified evaluation method for the seismic performance,which can provide reference for the quantitative evaluation of the seismic performance of the frame-shear wall structure and is considered reasonable and pratical.(2)Based on the method,this paper summarizes and analyzes some rules and presents advice on design.1)The failure mode of the frame-shear wall structure is directly associated with the stiffness eigenvalues.According to the code,we design the RC shear wall structure based on the concept of ‘strong-column-weak-beam' and ‘strong-shear-weak-bending' and adopt the idea of ‘weak coupling beam'.The final hinge sequence of the frame shear structure is good.The bottom coupling beam shows the hinge first.Then the frame beam shows the hinge.When the stiffness eigenvalue increases to 3.0,the bottom shear wall shows the hinge.When the stiffness eigenvalue increases to 3.6 the frame column shows the hinge.2)When stiffness eigenvalue ? changes in the range of(1.9,2.2),the slope of the relation curve between the stiffness eigenvalue and the safety,economy and comprehensive performance of RC frame-shear structure changes obviously.Therefore,when ? equals to 1.9,it is a better value for the frame-shear structure.When ? changes in the range of(2.2,3.6),the designer can choose the less financial input to obtain a more rational seismic performance.When ? changes in the range of(1.0,1.9),the designers can get a more rational seismic performance based on the decrease of the financial input.The innovation of this paper is summarized as follows(1)We use the RC frame shear failure mode evaluation method and combine the feasible failure mode of the frame shear structure with the validity of the standard measures to establish the simplified method for the evaluation of the seismic performance of the RC frame-shear wall structure based on quantification.(2)Based on the stiffness eigenvalue as the parameter variables,we design different RC frame shear structural models to study the relationship between the stiffness eigenvalues and the structural economics,safety and comprehensive indexes and obtain the range of the stiffness eigenvalue under different performance. |
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