Base shear is an estimate of the maximum expected lateral force that will occur due to seismic ground motion at the base of a structure. Calculations of base shear (V) depend on:

• soil conditions at the site
  
  
• proximity to potential sources of seismic activity (such as geological faults)
  
  
• probability of significant seismic ground motion
  
  
• the level of ductility and overstrength associated with various structural configurations and the total weight of the structure
  
  
• the fundamental (natural) period of vibration of the structure when subjected to dynamic loading