Adverse Impact On Seismic Performance Analysis Of Frame Structure Considering Soil-Structure-Interaction

Soil-Structure-Interaction(SSI)is a hot area of engineering in recent years. The traditional structure design is based on the assumption of rigid foundation, which consider soil-structure-interaction is beneficial to improve the seismic performance of the structure. With the further study of the problem, it was found that soil-structure-interaction will be also harmful to the structure. At present, the concrete frame structure is widely used in residences, hospitals, schools, etc. At the same time, as the various requirement of structural function, there are more and more vertical irregular structures not considering soil-structure-interaction. The destruction of the structure will be disastrous. So it is significant to study the effect of SSI on seismic performance of frame structure. Based on ABAQUS finite element software, the paper uses the regular framework structure and vertical irregular frame structure as the research object, to analyze adverse effects which brings from soil-structure-interaction.Using different performance of the structure such as acceleration, the lateral displacement, axial force, moment, the story drift to evaluate effects. The result in this paper can provide reference for the analysis and design of similar structures. Finally, in order to assess soil-structure-interaction effects on structural seismic performance, the paper set up the vulnerability relationship between earthquake parameters and structure parameters which has been considered the effect of soil-structure-interaction, and evaluate structure damage state considering SSI at the level of vulnerability to achieve structure comprehensively and reliable performance, so that it can provide reference for engineering design and analysis. The main researches and conclusions are as follow:(1) In order to reasonably simulate the soil-structure-interaction, This paper summarized the numerical simulation about the basic theory, including the material constitutive relation, the contact theory of soil and pile, seismic inversion and so on.the model has been verified before analyzing the adverse impact of SSI to regular frame structure. Main conclusion as followed: Adverse impacts of the SSI are mainly in roof displacement, beam moment, story drift. During the small earthquake, after considering soil-structure-interaction, the roof displacement, beam moment and story drift respectively increase by 5.2%, 7.9%, 15.6%. The roof displacement, beam moment and story drift respectively increase by 4.0%, 5.9%, 3.6% during the stronger earthquake. Besides SSI makes the acceleration lower and has a little influence on axial force. With the stiffness of the structure increase, acceleration becomes stronger, roof displacement and story drift become smaller, axial force and moment almost the same. Compare with C30 structure, the acceleration of the C40, C50 structure increase by 4.8%-17%, roof displacement decrease by 6.2%-32.2% and story drift decrease by 7.7%-14.2%. Similar conclusions can be acquired for 4, 8 layer' structure. After considering SSI, roof displacement, beam moment and story drift increase in difference range. So, when analysis the structure SSI should be considered.(2) In order to analysis vertical irregular frame structure considering soil-structure-interaction, Two kinds of common vertical irregular frame structure were used which called the bottom vertical irregular, the central vertical irregular structure. Through the analysis of structural performance considering soil-structure-interaction, Acquired the following conclusion: after considering soil-structure-interaction, the bottom vertical irregular structure's roof displacement, beam moment and story drift respectively increase by 44.1%, 31.6%, 33.8%. During the strong earthquake the roof displacement, beam moment and story drift respectively increase by 9.1%, 5.3%, 1.6%. the central vertical irregular structure's roof displacement, beam moment and story drift respectively increase by 24.7%, 15.7%, 35.1%. During the strong earthquake the roof displacement, beam moment and story drift respectively increase by 16.2%, 9.3%, 17.7%. During study of irregular type's influence on the soil-structure-interaction system, it found that: The bottom irregular has big impact on acceleration, roof displacement, axial foces, beam moment; the central irregular has big impact on story drift of the SSI structure.(3) For comprehensive evaluation of soil-structure-interaction on seismic performance of structure, This paper analyzed the vulnerability of the structure considering soil-structure, the probability curve of the SSI structure beyond the life safe state, slight damage, moderate damage, severe damage are higher than rigid foundation structure. When the structure suffered small earthquake, comparing structure on considering the soil-structure-interaction to that without considering the interaction of structure's probability of beyond life safe state slight damage, moderate damage, severe damage respectively increase 45.1%, 43.1%, 44.0%, 41.6%.When the structure suffered strong earthquake, comparing structure considering SSI to that without considering the interaction of structure probability of beyond slight damage, moderate damage, severe damage respectively increase 8.4%, 13%, 17.4%, 19.0%. Therefore, Soil-structure-interaction increases the probability of failure of the structure, so it is vital to pay attention to the effects of soil-structure-interaction on the structure. Based on vulnerability curve and the results of the analysis, judge the performance of the structure, provide certain reference for the earthquake damage prediction.