SA (spectral acceleration) is approximately what is experienced by a building, as modeled by a particle on a massless vertical rod having the same natural frequency of vibration as the building.

• 而谱加速度大致上是一座建筑物感受到的加速度，科学家把一颗与目标建筑物具有相同自然频率的粒子放在一个近似无质量的垂直控制棒上进行模拟得出此数据。