In order to study the influence of uneven in-plane stiffness distribution on the seismic performance of bottom frame structures,a concept called local average stiffness ratio is proposed. Finite element models with different local average stiffness ratios were designed in ABAQUS,then elasto-plastic time-history analysis was carried out.The analysis results show that the uneven distribution of in-plane stiffness can lead to serious damage to local walls and accordingly affect the safety of the whole structur...