Shear Concentration in Shear Walls Immediately above the Transfer Floor in Tall Buildings under Seismic Loading

Shear concentration in shear walls is a critical factor in the seismic design of tall buildings. In structures incorporating transfer floors, the redistribution of storey shear forces plays a significant role in governing overall stability and structural performance. A comprehensive understanding of this behaviour is therefore essential for enhancing both the safety and efficiency of tall buildings. This study examines shear concentration in shear walls located immediately above the transfer floors in a series of planar symmetric rectangular tall building models subjected to seismic loading conditions representative of Sri Lanka. Five three-dimensional finite element models were developed, with transfer floors modelled using solid elements while varying both depth and vertical position. The findings reveal that an optimal transfer floor depth minimises storey shear demand in the shear walls directly above, whereas both shallower and deeper slabs increase these forces. Additionally, positioning the transfer floor at a higher elevation is shown to reduce shear concentrations in the overlying walls. A comparative assessment of Time History Analysis (THA) and Response Spectrum Analysis (RSA) further demonstrates that. However, the THA reveals localised deformations in the transfer slab that RSA fails to capture, highlighting its importance for more realistically assessing behaviour. These findings provide practical guidance for seismic design, particularly in moderate to low seismicity regions where transfer structures are commonly employed.