## 1 Introduction  
[PERSON] [1] provided a comprehensive review and highlighted inconsistencies in the commonly accepted silo analysis and design methods. The main points that could be added to what was included in [PERSON] [1] are fundamental improvements that were recently identified by [PERSON] and [PERSON] [2] and [PERSON] [3], and the relevance of the method called Equation of Silo Quaking proposed by [PERSON] [4]. The Equation of Silo Quaking was derived based on scientific principles of physics equilibrium considering a discharging silo as a varying mass dynamic problem. The Equation of Silo quaking differs from Janssen-based methods because the flexibility of the structure, discharge rate and material properties are required in determining the dynamic loads, whereas Janssen-based methods only require the material properties and ignore the effects induced by the flexible structure and discharge rate. As such, this correspondence explains the relevance of the 'Equation of Silo Quaking' in the analysis and design of silos, and highlights areas requiring fundamental improvements in the commonly accepted silo analysis and design methods in the journal article published by [PERSON] [1]. According to [PERSON] [3], while existing methods appear scientifically sound within the problem formulated, such methods require fundamental improvements to follow some established scientific principles and engineering mechanics, such as Conservation of Energy, Conservation of Momentum, [PERSON]'s laws of motion, [PERSON]'s law, [PERSON]'s modulus of elasticity, Vibration, and Fatigue. To fully understand the scientific principles cited [3], it is necessary to systematically evaluate and consider the conditions of the silo prior to discharge to understand how such laws of applied physics and fundamentals of engineering apply to the phenomena observed during discharge:1. The silo is loaded with the material before discharge. The load due to the material causes the silo to deform elastically--bulging of the container, elongation of the container, and shortening of the columns (Figure 1). Conservation of Energy suggests that the potential energy is stored in the elastic deformations in the silo structure;
2. When the gate is opened to discharge the material inside the silo, the forces that cause the initial elastic deformations are lost. The sudden loss of such forces causes the elastic deformations to spring back to their unloaded positions ([PERSON]'s law); therefore, the potential energy is converted to kinetic energy (Conservation of Energy);
3. As suggested by the Conservation of Energy, the potential energy (elastic deformations) is equal to the kinetic energy (motions of the silo structure). As such, the rate of loss of the forces that caused the elastic deformations prior to discharge is compensated by the rate of development of the spring-back forces ([PERSON]'s laws of motion). There are many examples of this phenomenon, for example, a simple spring-mass system. When the rate of loss in mass is insignificant, it can be observed that the spring returns to its original position slowly compared to a much quicker rate of loss of the mass. One can install strain gauges, accelerometers and other instruments on the silo to validate;
4. Prior to discharge, the silo is initially stretched longitudinally, radially, and the columns are shortened, causing it to behave like a slingshot (Figure 1). Upon the release of the loads that cause the elastic deformations, the stored material is lifted and dropped. 5. The impact forces caused by the stored material being lifted and dropped can cause buckling in the short term and induce accelerations that cause fluctuating pressures as per [PERSON]'s laws of motion for the entire duration of the discharge cycle;
6. The amplitudes of the motion are dependent on the dynamic structural properties of the silo and its supporting structure such as mass, damping and stiffness; and
7. The fluctuating pressures will cause the entire silo to vibrate.