R/R: Repair and Rehabilitation of Nonductile R.C. Frames Using High Performance Fiber Reinforced Cement Composites

摘要：在美国地震地区建造的老式钢筋混凝土框架结构通常是无延性的，因此被认为是危险的。实验室研究表明，在新建筑中使用“普通”纤维增强混凝土（FRC）大大改善了地震反应，但传统的抗震改造技术尚未利用FRC或高性能FRCs （HPFRCs）。frp的优点是其延性比传统的钢筋混凝土有显著的提高。HPFRC的优点是，当加载超过弹性极限时，这些材料在破坏前承受进一步增加的应力和应变的能力显著提高。这种抗拉强度和延性的增加导致结构框架耗散能量的能力大大增加，这是抗震设计特别需要的特征。***本研究项目的目标是开发一种创新技术，用于非延性钢筋混凝土框架的抗震改造，使用最近开发的HPFRCs，其在非弹性范围内的复合应变和应力能力显着增加。使用这种材料可以解决钢筋混凝土框架的以下常见问题：(1)梁中不连续的底部钢筋锚固不足，(2)柱搭接接头约束不足，(3)节点约束不足。该研究有望为利用新开发的HPFRC复合材料进行非延性结构的抗震修复和修复开辟一个新的领域。本项目由美国国家科学基金项目“结构抗震修复与修复研究”资助

ABSTRACT: Older reinforced concrete frame structure constructed in seismic areas of the United States are usually non-ductile and are thus identified as hazardous. Laboratory studies have shown that the use of "ordinary" Fiber Reinforced Concrete (FRC) in a new construction has substantially improved seismic response, but conventional seismic retrofit techniques have not yet taken advantage of FRCs or High Performance FRCs (HPFRCs). The advantage of FRCs is a significant increase in ductility over that of conventional reinforced concrete. The advantage of HPFRC is that, when loaded beyond the elastic limit, these materials exhibit a significant improvement in the ability to undergo further increase in stress and strain before failure. This increase in tensile strength and ductility leads to an enormous increase in ability of the structural frame to dissipate energy-a feature particularly desirable for earthquake-resistance design. ***The goals of this research project herein is to develop an innovative technique for seismic retrofit of nonductile reinforced concrete frames using recently developed HPFRCs which exhibit significant increase in the composite strain and stress capacity in the inelastic range. Use of this material can solve the following common problems of reinforced concrete frames: (1) Inadequate anchorage of the discontinuous bottom reinforcement in beams, (2) inadequate confinement of the column lap splices, and (3) inadequate confinement of the joint. The research is expected to open up a new area for seismic repair and rehabilitation of non-ductile structures by using newly developed HPFRC composites. The project is supported under NSF Initiative "Repair and Rehabilitation Research for Seismic Resistance of Structures."***