Final answer:
Base shear force during an earthquake is directly proportional to the shear modulus of the material and the force applied perpendicular to its initial length and parallel to its cross-sectional area. This proportionality relates to how materials react to shear stress, which is critical for building design in earthquake-prone areas.
Step-by-step explanation:
The base shear force resulting in an earthquake is directly proportional to the shear modulus (S) of the material and the force applied (F) perpendicular to the initial length (Lo) of the material and parallel to the cross-sectional area (A). This relationship is expressed as Ax = ¹⁄S (F·Lo), where Ax is the shear deformation. Shear modulus is a measure of the material's ability to resist shear stress, and the force applied refers to the sideways stress or shearing force.
In earthquake engineering, base shear is an estimate of the maximum lateral force that will occur due to seismic activity. It's a crucial factor for designing buildings and structures to withstand earthquakes. As shear stress is caused by forces that act parallel to the surface, the shear modulus and the shear force are fundamental in determining the potential shear stress a structure might undergo during an earthquake.