Vulnerability assessment of vertical irregularities in medium-rise reinforced concrete structures using lead rubber bearing

Medium-rise reinforced concrete structures with vertical irregularities experience vulnerable behavior during seismic forces. To mitigate this vulnerable behavior, the base isolation technique is more effective than the strategies used to protect the civil structure against seismic excitation, as Iuliis (2008) stated. Base isolation is a technique to separate the structure from the seismic effect developed in the form of ground acceleration. The acceleration parameter, base shear, story displacement at the top and ground floors, story drift ratios, and target periods are considered for parametric study. The results demonstrate that the base isolator with stiffness coefficient reduces the structure's base shear and top floor displacement.

Similarly, the combined effects of base isolation and SSI create a more complex system that does not behave straightforwardly compared to simpler models. The use of LRB shows results similar to those of medium-stiff soil strata during building analysis. The LRB reduces the sudden increase in the inter-story drift at the stiffness irregularity location.