Seismic Response Analysis On Steel Frame Structure-raft Foundation And Karst Soil-Foundation Interaction

The area of karst region accounts for about one third of the total of our country, is one of the largest area of karst regions in the world; our country lies between the world’s two seismic zone, so the high frequency of seismic activity, the intensity is also very large, is one of the most earthquake-hit countries suffering from the world; currently, the construction of high-rise buildings in the karst foundation major design methods are still using conventional design methods or experience in law, likely to cause human error, especially when building seismic analysis the calculated results and the actual discrepancy will be greater, thus enhancing the karst foundation-foundation-superstructure interaction research is very necessary.In this paper, numerical simulation of steel frame structure-piled raft foundation-Karst Subsoil the following research areas:(1) The EduShake software was used on the El-Centro wave to inversion, inversion geological conditions at the site using a karst area, after the El-Centro wave amplitude in accordance with specifications, from the surface to the bedrock at the inversion, After analysis of seismic waves come karst geology has magnified the role and " filtering effect".(2) The Karst Foundation- raft foundation- a common role model steel frame structure was Established, through the foundation soil infinite size for comparison with the model to determine the finite element- the size of the infinite element coupling soil finite element model part:That is, Lateral dimensions of the structure coupled model infinity considered together, the finite element section size not less than 15 times-when using the finite element.(3) The Karst Foundation-raft foundation-a common role model steel frame structure was Established, through the foundation soil infinite size for comparison with the model to determine the finite element-earth Size infinite element coupling model infinite element section:That is, when the finite element is greater than the value of extending the length of the finite element-infinite element when the soil away from the center of the interface is 1.5 times the size of the error is very small, but because of the length of the infinite element extends almost no effect on the calculation of time-consuming, it can be try to get a little big.(4) The size and dimensions of the coupling model using finite element part of Turkey infinite element was part of the establishment of karst foundation-raft foundation-a common role model steel frame structure interaction analysis to consider the impact on the seismic performance of the upper structure:That is, considering joint action after the bottom of the upper structure deformation and internal forces do not consider joint action relatively large compared to the increase, the number of layers increases, increasing the amplitude decreases, the cause of this phenomenon is due to consider the common after the role of raft foundation uneven settlement, making the bottom of the frame column had a greater secondary stress, secondary stress with increasing number of layers decreases.(5) The Karst Foundation-raft foundation-a common role model steel frame structures was Established, analysis of existing land-hole seismic performance of joint function:The results indicate that the presence of soil in the hole,, makes the soil foundation soil stiffness decreases, under the effect of the earthquake led to the hole than the soilless soil when large deformation, and thus have a greater superstructure internal forces and deformation.