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

因此，需要明确在坂神淡路大地震等近源地震作用下钢筋混凝土结构的局部开裂、发展和钢框架脱落的机理。这些破裂过程受到近源地震初始强震动的影响。在1998-1999年，一个通用的二维数值分析软件，这是有用的澄清这些断裂过程，新开发的离散单元法的基础上。对一些简单的动力问题进行了分析验证，并与以往的分析结果和其他通用程序的计算结果进行了比较，证实了本文计算的精度较高，同时还对算例进行了动力有限元数值分析。2000-2001年，对开发的软件进行了扩展，使其能够处理三维问题，并对计算精度进行了检验。前、后处理部分和数值计算部分分别用Visual C++和FORTRAN语言编写，大大增强了各部分的功能。在前处理部分，实现了以对话框形式编写的重分区功能，使加载、约束等条件的设置变得非常容易。通过与另一通用有限元程序的协作，实现了对大规模问题的分析，并继续进行了基于动力有限元法的算例分析。对尼尔森桥型桥梁支座和某高层建筑箱形柱的脆性断裂进行了研究。数值结果表明，脆性断裂是由动载荷引起的可能性很大。

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.