ISSN: 1813-0410

Author : Majid Abbas Al-Rammahi, Ayaat


Optimum Shape of Concrete Flood Walls Under Hydrodynamic Load

Abdul-Hassan K. Al-Shukur; Atheer Zaki Mohsin Al-Qaisi; Ayaat Majid Abbas Al-Rammahi

journal of kerbala university, 2017, Volume 13, Issue 1, Pages 141-154

2D (Plain strain) wall ‒ water ‒ foundation interaction problem is modeled via ANSYS 11.0 to find the optimum shape of concrete flood walls considering the principle of fluid‒soil‒structure interaction analyses. Concrete gravity and cantilever flood walls types are subjected to hydrodynamic and impact loads have been considered in this research. Hydrodynamic load are a function of a wave velocity and structural geometry. Low velocity hydrodynamic forces are defined as situations where floodwater velocities do not exceed 3 m/sec, while high velocity hydrodynamic forces involve floodwater velocities in excess of 3 m/sec. Impact loads are imposed on the structure by debris carried by the moving water. The optimization process is simulated by ANSYS /APDL language programming depending on the available optimization commands. The components of the optimization process are the objective function (OBJ) is to minimize the cross‒sectional area of the concrete flood walls, the state variables (SVs) are the factors of stability (sliding 〖FS〗_s and overturning 〖FS〗_o) and safety (maximum stress of foundation q_max , exit gradient 〖FS〗_eg , and uncracked section e) of the flood wall, and the design variables (DVs) are the dimensions of the wall. The results showed that the optimum design method via ANSYS is a successful strategy prompts to optimum values of cross‒sectional area with both safety and stability factors as compared with ordinary design. For gravity flood wall the reduction percentage of safe section area is 17.64%; while for cantilver flood wall, the reduction percentage of both safe section area and reinforcement are 0.8% and 27.76%; respectively. In other hand, it has been taking various heights of gravity and cantilver flood walls as 0.90m, 1.20m, and 1.50 m for gravity flood wall and 2.40m, 2.75m, and 3m for cantilever flood wall. The results showed that when the height of gravity flood wall is increased by 33.30% from (0.90 to 1.20m), the optimum cross-sectional area increases in a percent of (52.6%). While, in cantilever flood wall, the optimum cross‒sectional area is increased by 46.89% when the value of the height are increased by (25%) from 2.40 to 3m. Moreover, from studying several common sections of gravity flood walls which have been designated in this research as sections (1 to 4), it is found that section 2 is the most safe compared with other sections.