Engineered Cementitious Composites for Ductile R/C Columns

1995年1月17日，日本科比发生大地震，建筑物遭受严重破坏。 这些损坏引起了人们对柱设计的关注。 具体而言，在防止柱的脆性破坏的当前设计规范的充分性被称为问题。 这一问题不仅限于日本建筑规范（AIJ 1989），而且也延伸到美国规范（ACI 1995）。 这两个规范是建立在类似的基本概念，其中结构倒塌是通过确保在过度地震荷载下的结构，通过紧密排列的横向钢筋的延性防止。 然而，在科比观察到的结构损坏表明，横向钢筋并不一定提供足够的延性的元素，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已经开发出极限拉伸应变能力超过5%的超韧性水泥基复合材料。 这些工程水泥基复合材料（ECC）已被应用于剪切梁和梁柱节点。 初步的实验研究表明，ECC有助于广泛提高结构性能，特别是在延性方面。 这是合理的预期，ECC的应用可能会导致大幅改善柱的延性协同横向钢筋，从而降低地震风险。 该项目旨在建立ECC材料的适当设计，专门用于弱柱。 研究内容包括ECC柱结构抗震设计的分析部分，以及ECC和ECC柱反应的实验验证。 韧性水泥基复合材料的应用和它的设计程序，以提高建筑物和民用基础设施的地震安全性的其他关键结构元件将进行调查。 这是一个在NSF倡议或“复合材料和混合结构”NSF-94-154的第二年计划下支持的项目。

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.