Many researchers have studied the silo lateral pressure, and some have proposed theoretical analysis methods. Janssen’s theory [
2], for example, introduced the lateral pressure coefficient to derive the static silo side pressure. Airy’s theory [
3] introduced the concept of the sliding wedge in geomechanics to the calculation of silo lateral pressure. Veletsos and Younan’s theory [
4,
5] used a simplified approximation method for seismic analysis when taking bulk material effects into account in both static and dynamic cases. The classical Coulomb and Rankine theory [
6] was introduced later into silo analysis. And the famous M-O theory [
7] was well known in the calculation of the simplified seismic earth pressure. Most studies [
8,
9,
10,
11,
12] since then have been based on these theories, but almost all have focused on the study of lateral pressure in the static and unloaded states. Some researchers have used experimental methods; Weixng SHI [
13] used a scale model of a coal storage silo and simulated the seismic response of the silo using a shaking table test. Fang Yuan [
14] conducted six tests on three large-diameter grain silos to obtain the stored material lateral pressure and distribution characteristics. Lujian Zhang [
15] also conducted seismic shake tests and analyzed the dynamic characteristics and the lateral pressure distribution during an earthquake, then concluded that the seismic lateral pressure was larger than the static lateral pressure and much larger than the silo code value. Hang J [
16] conducted a series of shaking table tests on three models with different silo-filling conditions to investigate the interaction law of the wheat material and steel silo structure system. Gandia R M [
17] tested six different types of silo geometries and obtained the resulting pressures in a full-scale silo from assays performed on a test station using a free-flowing product. Some researchers have used numerical simulation methods, Livaoglu R [
18] used a simplified seismic analysis procedure to estimate the distribution and the magnitude of dynamic material pressures on ground-supported silos and incorporated a three-dimensional finite element model to represent a more realistic structure. Djelloul Z [
19] investigated the reliability of the European guidelines employed for designing steel silos subjected to seismic excitations through full finite element analysis of a flat-bottomed slender steel silo, taking into account the nonlinear time history analysis, wall flexibility, geometric imperfections, soil-structure interaction, and multidirectional components. Shunying JI [
20] studied the granular silo flow, considering gravity as the sole driving force to demonstrate the influence of external pressure. And Temsah Y [
21] simulated the structural response of grain silos under blast loads and defined the explosion magnitude and the structural state of the remaining silos. Weiwei SUN [
22] analyzed the pressure evolution under loading and unloading conditions and Hang JING [
23] studied the side pressure distribution based on the Duncan-Zhang model. These works of research were mainly based on finite element or discrete element methods to simulate the dynamic silo characteristics under different load conditions. In addition, it focused on the seismic performance of the reinforced concrete shear walls. Faraone G [
24,
25] established a numerical model capable of representing coupled shear–flexure interactions and validated it against tests conducted on three full-scale reinforced concrete walls, predicting the deformation and cracks pattern to provide insight into the likelihood of the impact of concrete damage. Almasabha G [
26] studied a popular seismic force-resisting system consisting of rectangular concrete squat structural walls to improve its limitations in shear strength and drift ductility. The studies outlined above provide a reliable basis for the seismic design of structures.
In general, the existing literature has mainly focused on static characteristics based on the five theories mentioned above and the true seismic dynamic response according to shaking table tests or numerical simulation, such as silo displacement, reloading and unloading stiffness degradation, strain rate effect, etc. However, the existing studies and the silo codes [
27,
28,
29] in different countries do not give a specific theoretical calculation formula for the silo lateral pressure during earthquakes, and they only consider multiplying an over-pressure coefficient on the calculation results of Janssen’s formula. Therefore, the current research focused on a simplified method to directly derive the calculation formula of the seismic lateral pressure in a squat silo, which will provide a reference basis for improving the calculation of the seismic lateral pressure in silo specifications. Unlike the existing literature on the dynamic and static response of silos, this paper regarded squat silos as curved retaining walls and focused on similar engineering problems to the study object, based on Coulomb theory. We then introduced the equivalent simplification of seismic forces using the pseudo-static method and the rotating seismic angle method to derive the calculation formula of the silo seismic lateral pressure before finally verifying the formula accuracy using example analysis and numerical simulation. The method flow chart is shown in
Figure 1.