The Study Of Seismic Behavior Of Single-floor To Single-bay SRUHSC Frame

The steel reinforced ultra-high strength concrete(SRUHSC)structures are playing a much more important role in the engineering community,because is don't only satisfy the development requirement of high load bearing capacity and favorable seismic behavior,but also satisfies the developmental requirement for future structures such as high strength,low power consumption.Accordingly,this dissertation focuses on the seismic behavior of SRUHSC frame structures,and the specific research contents can be summarized as follows:(1)Comparative experimental analyses are conducted for six terms of SRUHSC columns and frames,respectively,dominantly focus on the seismic behavior from single column to entire frame structure as well as the seismic behavior variation of column has an influence on the entire structure.The main parameters to be analyzed include axial compression ratio,shear span ratio,steel ratio and sectional strength ratio.The main distinction will be discussed including failure modes,hysteretic curves,displacement ductilities,degradations of strength and stiffness and residual drifts of SRUHSC column and frame under cyclic loading.The influence of different test parameters on the seismic behavior of SRUHSC structures is studied,and clarifies the relationship of seismic coefficient between single column and frame structure,which lays the foundation for further study of the seismic behavior and design of this kind of structures.(2)The test on the seismic behavior of single story to single span SRUHSC structures is conducted under pseudo-static reversed cyclic load,and the influence of different axial compression ratio,shear span ratio,steel ratio and sectional strength ratio on the seismic performance of the structure is studied.A higher axial compression ratio results in larger peak loading and smaller lateral drift ratio.Meanwhile,the reduction of shear span ratio exhibits a more distinct influence on the structure,such as appreciably increased peak loading,the change of propagating direction of concrete cracks and failure mode of column base,as well as a faster spalling of concrete at column base.Also,no obvious influences of the increase of steel ratio and sectional strength ratio on the seismic behavior of single story to single span SRUHSC frame structures are observed in the test except for the increase of structure ultimate displacement and the reduction in magnitude for the residual drifts,signifying the improvement of structural stability and safety.Furthermore,the flexural-shear modal for SRUHSC frames is established with the use of flexural and shear deformation in the structures.(3)A comparative analysis is performed in terms of the seismic behavior of single story to single span SRUHSC structures with high and low axial compression ratios under loading rates of 0.5mm/s and 20mm/s,respectively.The purpose of this analysis is to figure out the seismic behavior of SRUHSC frame under high loading rate,to make comparisons between the testing results of dynamic loading and pseudo-static loading and to establish the relationship of the seismic behavior between the two frames under different loading conditions.The horizontal force is dramatically increasing within the range of elastic and elastic-plastic stages under rapid loading,and the value of horizontal force is proximity in the plastical stage,indicating that rapid loading rate has a significant influence on the seismic behavior of structures in the elastic rage and less dominantly influence on the yield stage.The degradation rate of horizontal force is also decreased under rapid loading,meanwhile the lateral deformation capacity and structural stability are correspondingly increased to some extent.(4)Parametric analysis is performed for the single story to single span SRUHSC frame structures based on OpenSees software platform.The parameters to be researches includes axial compression ratio,shear span ratio,steel ratio,sectional strength ratio and concrete of different strength.The critical axial compression ratio of 0.45 and critical sectional strength ratio of 1.3 are obtained through numerical simulations.Based on the criterion of stiffness degradation,the hysteretic model reflecting the loading and unloading characteristics for single story to single span SRUHSC frame structures is proposed,which lays the foundation for the further study of seismic behavior and hysteretic model of SRUHSC structures.