Research On Multi-objective Aseismic Optimization Of SRC Frame-RC Core Wall Hybrid Structure

SRC frame-RC core wall hybrid structure, which was a new structural system withexcellent seismic performance and durability, was widely used in high-rise and superhigh-rise buildings. This paper aimed to study the optimization of the elements and thestructure of SRC frame-RC core wall hybrid structure by the way of theoreticalmodeling, and the main contents were as follows:1. The minimum project cost and the maximum flexural capacity of SRC framebeam were taken as the optimization objectives which were dimensionless, and whoseevaluation function could be adjusted by weighting factors and the linear weightedwhich transformed the multi-objective optimization problem into multiple singleobjective optimization problems. According to the the characteristics of SRC elements,the analytic hierarchy process was introduced to give each variable weight in theencoding process of genetic algorithms, thus, the analytic hierarchy process geneticalgorithm (AHPGA) is established. Considering the related design specifications andconstraints, the SRC frame beam was optimized by the AHPGA. The practical examplewas analyzed to verify the rationality of the proposed optimization method and thought.2. The minimum project cost and the maximum diagonal shear capacity were takenas the optimization objectives, and the bond slip constitutive equation was applied innumerical model based on experimental results to simulate the characteristics of SRCframe column more accurately. Meanwhile, considering the main design variable ofSRC elements were the size of concrete, by which the sizes of steel section, longitudinalreinforcement diameter and number etc.can be searched quickly, and the computationalefficiency was greatly improved. Based on this, the analytic hierarchy processoptimization criterion genetic algorithm (AHPOCGA) was established by thecombination of the AHPGA with the optimization criterion. Considering the related design specifications and constraints, the SRC frame column was optimized by theAHPOCGA. The practical example was analyzed to verify the rationality of theproposed optimization method.3. Based on the characteristics of SRC frame, the minimum cost and the structureinterlayer displacement difference of SRC frame were taken as the optimizationobjectives. According to the mechanical characteristics of the structure, the two stagesoptimization design method was presented: the optimization of component section andconcrete volume was actualized assuming that only the concrete works under minorearthquake; the optimization of steel volume was implemented for meeting therequirement of structure under moderate and severe earthquake. Taking the variousconstraints into consideration, the SRC frame was optimized by using AHPOCGA. Thepractical example was analyzed to verify the rationality of the proposed optimizationthought.4. Taking the failure modes of SRC frame-RC core wall hybrid structure asbackground, the minimum project cost and damage were taken as the optimizationobjectives by introducing damage function. According to the three-level seismicfortification criterion, as well as the mechanical characteristics of the structure, thethree-level fortification criterion optimization design method was presented: theoptimization of component section and concrete volume of core wall, frame beams andframe columns under minor earthquake; the optimization of steel volume was broughtinto effect for meeting the requirement of minimum displacement difference betweentwo adjacent storey under moderate earthquake, in which the frame and shear wall arein collaborative working state; the optimization of steel volume was implementedfarther for meeting the requirement of minimum structure damage under severeearthquake, in which the structure is in plastic state and the shear wall is out of work.This method transformed the multi-objective optimization problem into multiple singleobjective optimization problems. Taking the various constraints into consideration, thefailure modes-based three-level optimization design of SRC frame-RC core wall hybridstructure was actualized by using AHPOCGA. A numerical example was analyzed toverify the rationality of the proposed optimization thought.5. Based on the cost-effectiveness criterion of life-cycle cost optimization theory, the mathematical model of life-cycle cost damage-reduction optimization wasestablished by introducing damage-reduction design in the stage of optimal fortificationintensity, and a numerical example was analyzed to verify the rationality of theproposed optimization thought. Furthermore, the mathematical model of failuremode-based life-cycle cost damage-reduction optimization of SRC frame-RC core wallhybrid structure was established by introducing failure modes optimization theory.