Engineered Cementitious Composites for Ductile R/C Columns

据报道，1995年1月17日发生在日本神户的灾难性地震对建筑物造成了严重破坏。这些损害引起了人们对柱子设计的关注。具体来说，当前设计规范在防止柱脆性破坏方面的充分性受到质疑。这个问题不仅限于日本建筑规范（AIJ 1989），也延伸到美国规范（ACI 1995）。这两个规范都建立在类似的基本概念上，通过紧密排列的横向钢筋来确保结构在过大地震荷载下的延性，从而防止结构倒塌。然而，在神户观测到的结构破坏表明，横向加固不一定能为构件提供足够的延性，进一步的设计考虑是必要的，以提高地震安全性。密歇根大学先进材料研究实验室开发出了极限拉伸应变容量超过5%的超延性胶凝复合材料。这些工程胶凝复合材料（ECC）已应用于剪力梁和梁柱节点。初步的试验研究表明，混凝土对提高结构性能，特别是延性方面有广泛的贡献。我们有理由期待ecc的应用能够显著提高柱的延性，与横向配筋协同作用，从而降低地震风险。本项目旨在建立一种专门用于弱柱的ECC材料的适当设计。本文主要研究了ECC柱结构抗震设计的解析分量，以及ECC和ECC柱响应的试验验证。将研究延性胶凝复合材料及其设计程序在其他关键结构元件中的应用，以提高建筑物和民用基础设施的抗震安全性。本项目为美国国家科学基金会“复合材料与混合结构”项目第二年资助项目（NSF-94-154）。

Serious damages in buildings were reported in the disastrous earthquake which occurred in Kobe, Japan on January 17, 1995. Those damages has raised concern on the design of columns. Specifically, the adequacy of the current design code in preventing brittle failure of columns is called into question. This problem is not limited to the Japanese building code (AIJ 1989) but also extends to the US code (ACI 1995). Both codes are constructed on similar fundamental concept, in which structural collapse is prevented by ensuring ductility in structures under excessive seismic load by means of closely arranged transverse reinforcement. However, structural damage observed in Kobe revealed that transverse reinforcement does not necessarily provide the elements with sufficient ductility, and that further design consideration is necessary to enhance seismic safety. The Advanced Material Research Laboratory at the University of Michigan has developed super ductile cementitious composites with ultimate tensile strain capacity over 5%. These engineered cementitious composites (ECC) have been applied to shear beams and beam-column joints. The initial experimental investigations demonstrated that ECCs contribute extensively to enhancing structural performance especially in terms of ductility. It is reasonable to expect that the application of ECCs could lead to substantial improvement in ductility of columns synergistic with transverse reinforcement, resulting in the reduction of seismic risks. This project is aimed at establishing the proper design of a ECC material specifically for use in weak columns. The research involves analytic components on seismic design of structures with ECC columns, as well as experimental verification of ECC and ECC column response. Applications of ductile cementitious composite and its design procedure to other critical structural elements for improved seismic safety of buildings and civil infrastructures will be investigated. This is a project supported under the second year program of NSF initiative or `Composite and Hybrid Structures`, NSF-94-154.