整体式RC-ECC混合桥墩延性抗震设计方法研究

With the development of our country’s comprehensive national power, the requirements of seismic performance of lifeline bridge engineering are also increasing. Light damage, less repair work caused by earthquake and quick function recovery after the earthquake are the new trends of bridge seismic research. The earthquake damage showed that when the reinforced concrete bridge pier designed according to current ductility design method is subjected to strong ground motions, the pier may still experience severely damage and hence difficult to get repaired. ECC has the distinguished characteristics of strain hardening and multi-slit cracking. In foreign countries, it has been applied to different types of bridge piers to improve energy dissipation and reduce the earthquake induced damages of the pier potential plastic zone. However, the ECC related research is lagged in our country. Therefore, a new integrated RC-ECC bridge hybrid pier is proposed herein, it does not change the existing construction method of the bridge pier, but utilizes the collaborative action between the ECC material and the reinforcements, which will reduce the damage of the preset plastic zone under earthquakes, enhance the structural bearing capacity and improve the seismic performance of the pier under strong earthquakes. The main tasks of this project include: 1) the design parameters of the RC-ECC pier; 2) the hysteretic energy dissipation and ductility capacity of the RC-ECC pier; 3) the seismic response characteristics of bridge structures with RC-ECC piers and 4) the damage control based ductility design method of integrated RC-ECC piers.

随着我国综合国力的夯实，对桥梁工程的抗震性能的要求也在不断提高。强震作用下损伤小、震后易修复、能快速恢复通行能力已是桥梁抗震研究的新趋势。已有震害表明，按延性抗震设计的钢筋混凝土桥墩，在强震作用下依然可能产生严重的损伤，震后修复困难。ECC材料具有应变硬化和多缝开裂的特性，国外已将其应用于不同形式的桥墩抗震体系，来提高潜在塑性区的耗能能力，减小塑性区的损伤，但我国对此还缺乏必要的研究。因此，本项目提出整体式RC-ECC混合新型桥墩，不改变既有桥墩的施工方法，充分发挥ECC与钢筋的协同作用，减小地震作用下预设塑性区的损伤，提高结构的损伤承受能力，改善桥墩在强震作用下的抗震性能。主要研究工作包括：1）RC-ECC混合桥墩的设计参数；2）RC-ECC混合桥墩的滞回耗能及延性能力；3）采用RC-ECC混合桥墩的桥梁结构地震反应特性；4）基于损伤控制的新型RC-ECC桥墩延性抗震设计方法。

随着我国综合国力的夯实，对桥梁工程的抗震性能的要求也在不断提高。强震作用下损伤小、震后易修复、能快速恢复通行能力已是桥梁抗震研究的新趋势。已有震害表明，按延性抗震设计的钢筋混凝土桥墩，在强震作用下依然可能产生严重的损伤，震后修复困难。ECC材料具有应变硬化和多缝开裂的特性，可以提高潜在桥墩塑性区的耗能能力，同时减小其地震损伤，但现阶段距离其实际应用还缺乏进一步的研究。因此，本项目提出RC-ECC混合新型桥墩，既可以采用传统的CIP现浇施工，也可以采用承插式等预制装配连接施工，充分发挥ECC与钢筋的协同作用，改善桥墩在强震作用下的抗震性能。针对RC-ECC单柱桥墩，重点围绕其抗震能力、性能目标以及损伤变化展开。结合数值分析，模型拟静力试验和振动台试验，研究了桥墩的非线性损伤过程和抗震性能，探究了新型桥墩中ECC段的无箍筋设计和承插连接可行性。在此基础上，建立了可靠的有限元模型，初步提出了RC-ECC桥墩设计方法，评估了其整体抗震效能。