Full-scale dynamic testing of non-ductile reinforced concrete frame retrofitted with high-strength steel rebar and CFRP wrapped columns (Frame #2)

This experiment presents the results of a full-scale dynamic test of a non-ductile reinforced concrete frame that was retrofitted using a combination of high-strength near surface mounted rebar and carbon fiber column wraps. The large inertial shaker from nees@UCLA was used to provide input at the roof. The smaller 4600A eccentric mass shaker was used between larger tests to measure the shift in dynamic properties of the specimen. The specimen prior to retrofit was identical (nominally) to the frame tested during experiment #4. (Frame #1) The key findings of the study show that the retrofit is capable of changing the failure mechanism of the structure. The first natural frequency of the system dropped nearly 30%, owing largely to the pullout of the bottom reinforcing bars at the beam-column joints. The interstory drifts were also distributed more evenly than those on frame 1.

本实验报道了采用高强度近表面埋置钢筋（near surface mounted rebar）与碳纤维柱面包裹（carbon fiber column wraps）组合加固方式的非延性钢筋混凝土框架足尺动力试验结果。本次试验使用来自nees@UCLA的大型惯性激振器（inertial shaker）为结构屋顶施加输入激励；在大型试验的间隙阶段，采用小型4600A型偏心质量激振器（eccentric mass shaker）以测试试件的动力特性偏移情况。加固前的试件与第4号试验（1号框架）中测试的框架名义上完全一致。本研究的关键发现表明，该加固方案能够改变结构的破坏机制。由于梁柱节点底部纵筋发生拔出破坏，系统的一阶固有频率（natural frequency）下降了近30%。此外，层间位移（interstory drifts）的分布也比1号框架更为均匀。