Paper Title
Study of the Loading of Simple Bridge Pillar Structure due to External Force from Rocky Debris Flash Flood Flow

Abstract
Well-designed bridge pillar usually have good resistance to design loads. However, based on Standard Nasional Indonesia (SNI) 1727:2013, the calculation of flood hydrodynamic load are still unclear especially for flow speed above 3.05 m/s. Therefore, the design of the pillars that have been built so far has not gone through a mature design calculation process. One solution that proposed in this study is to increase the durability of the bridge pillar structure through two choices, namely by enlarging the diameter of the pillar or by increasing the number and adjusting the position of the pillar to the transverse span of the flood flow control volume. This study aims to find the most appropriate step in holding back the flow of rocky debris flash flood through the analysis of structural responses, such as stress, strain, and deformation on the pillar. To achieve this goal, a software called ANSYS 2019 R1 is used as a modeling tool. The results showed that the step of enlarging the diameter of the pillar is the better choice in increasing the durability of the structure such as stress, strain, and deformation; as well as the increasing density of the flood flow will increase the value of the pillar’s structural responses. Keywords - Bridge Pillar, Rocky Debris Flash Flood, Durability, Structural Responses