Development of New Method and Its Application Software for Numerical Analysis of Dynamic Fracture Process of Reinforced Concrete

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It is desired to clarify the mechanism of local cracking, its development and falling out of steel frame in the RC structure at near-source earthquakes such as the great Hanshin-Awaji earthquake. These fracture processes are affected by the initial strong motion due to near-source earthquake. At the term 1998-1999, an all-purpose software for 2-dimensional numerical analysis, which is useful for clarifying those fracture processes, was newly developed based on the discrete-element method. Some analyses of simple dynamic problems were conducted for verification, and the calculation with good accuracy was confirmed by the comparison with the past analytical results and those obtained by other all-purpose programs.The numerical analyses for case study were also conducted by the dynamic finite-element method. For example, the uckling problems of T-type and Gate-type bridge piers were investigated.At the term 2000-2001, the developed software was extended to be able to deal with 3-dimensional problems, and the accuracy of calculation was also examined. The pre/post-processing parts and the numerical calculation part were programmed by using Visual C++ and FORTRAN, respectively, and each function was enhanced greatly. In the pre-processing part, the rezoning function written in dialogue was realized, and the setting of conditions such as load, restriction etc. become very easy. The analysis of large-scale problem was realized by the cooperation with another all-purpose finite-element code.The numerical analyses based on the dynamic finite-element method for case study were also conducted continuously. The brittle fracture of the bridge bearing of the Nielsen bridge type and that of the box column of the tall-building were investigated. The obtained numerical results show a high possibility that the brittle fractures were caused by dynamic load.