Final answer:
The ASCE / SEI 7 standard stipulates that the effective seismic building weight includes the total weight of the building and any permanent fixtures, but not the weight of occupants or their belongings. Seismic design principles also require buildings to maintain a stable equilibrium, with net external forces and net torques equal to zero to withstand seismic events.
Step-by-step explanation:
According to the ASCE / SEI 7 standard, the effective seismic building weight should include the total weight of the building and any permanent fixtures. This includes the weight of the structural elements, walls, floors, roofs, fixed service equipment, and other permanent attachments such as cladding, plumbing, and electrical systems. The weight of the occupants and their belongings, or live loads, are generally not considered part of the effective seismic weight, except for special circumstances where live loads are fixed or immobile. Seismic design considers the potential resonance effects and how earthquake energy might be transmitted and amplified within a structure. Constructive and destructive interference patterns can lead to localized zones of intense shaking and can result in damage far from an earthquake's epicenter.
Engineers also take into account that conditions for equilibrium require that the net external force and the net torque be zero. This principle holds true not just for gravitational forces, but for all forces, including those generated during seismic events. Ensuring stable equilibrium means that buildings are designed to be resilient against both gravitational stresses as well as lateral seismic forces.