An Application of Seismic Retrofit Technique of Thick Hybrid Wall Using Additional Concrete Sandwiched by Steel Plates and PC Bar Prestressing

在2005年的AIJ年会上，首次提出了利用钢板夹芯混凝土和预应力混凝土钢筋加固厚壁结构的抗震加固概念。提出了采用现浇厚混合开洞式翼墙或非开洞式板墙对钢筋混凝土框架柱进行改造，以及将钢筋混凝土框架剪力墙或混凝土砌块墙的薄壁改造成厚混合墙进行改造的技术。为了验证所提出的加固技术的有效性，在恒定的竖向荷载下进行了循环荷载试验，单层单跨钢筋混凝土框架，钢筋混凝土框架剪力墙和混凝土砌块墙，和两层单跨钢筋混凝土框架pilotis。试验结果表明，所提出的加固技术提高了结构的抗侧强度和延性。此外，在非开洞式墙板试件中，通过在顶部连接处设置钢板夹芯混凝土和预应力PC钢筋，以及通过在底部连接处设置后锚固件，来加强顶部连接和底部连接，从而证实了防止冲切破坏的必要应力传递机制。然而，直到约2%的偏移角，由于连续断裂的纵向钢筋所造成的高局部应变集中在大的偏移角的延性。此外，两层单跨试点框架第一层柱中钢筋无粘结，其延性仅为2%多一点。然而，在实际设计偏移角为1%的情况下，建议的改造技术可用于大地震激励。

A seismic retrofit concept of thick hybrid wall using additional concrete sandwiched by steel plates and PC bar prestressing was introduced first in the annual meeting of AIJ in 2005. This technique was proposed for RC pilotis frame, which was retrofitted by installing cast-in-site thick hybrid opening type wing wall or non-opening type panel wall; and for RC framed shear wall or concrete block wall which was retrofitted by converting its thin wall into thick hybrid wall. To ascertain the effectiveness of the proposed retrofit technique, the cyclic loading tests under a constant vertical load were carried out on one-story one-bay RC pilotis frames, RC framed shear walls and concrete block walls, and two-story one-bay RC pilotis frames. Experimentally it was verified that the proposed retrofit technique enhanced both the lateral strength and ductility. Moreover, in non-opening type panel wall specimen, the necessary stress transfer mechanism to protect the punching shear failure through the top and bottom connections were confirmed by strengthening the top connection with casting additional concrete sandwiched by steel plates and PC bar prestressing up to beam, and the bottom connection by providing post-installed anchors. However, the ductility was obtained until a drift angle of about 2% due to the successive breakage of longitudinal rebars caused by the high local strain concentration at large drift angles. Moreover, by allowing the rebars as unbonded in column at the first story of two-story one-bay pilotis frame, the ductility was obtained a little more than 2% only. However, in the context of practical design drift angle of 1%, the proposed retrofit technique can be recommended for large seismic excitations.