According to ACI 318-19(SI), in the plastic hinge zone of RC beams, the longitudinal reinforcement at each corner and every other longitudinal reinforcement must be enclosed by the corner of the closed hoop or the hooks of crossties. However, in RC construction practice, the longitudinal reinforcement of RC beams is densely arranged, making construction difficult. In this study, four large RC beam specimens were designed and fabricated to conduct experiments to verify the effect of hoop spacing and crosstie configuration on the cyclic performance of reinforced concrete beams. It is found that: (1) The crosstie configuration with seismic hook engaging the longitudinal reinforcement at the bottom is recommended and that during construction, within the range of twice the beam depth from the RC column outer face, the bottom and side formwork should be completed after the crossties are assembled, which should solve the problem of difficult construction. (2) The transverse reinforcement spacing between 4 and 6 times the smallest longitudinal reinforcement diameter of RC beams may have no significant effect on the cyclic performance of RC beams. (3) The requirement that in the plastic hinge zone of RC beams, every corner and alternate longitudinal bar on the perimeter must have lateral support provided by the corner of a tie or crosstie in ACI 318-19(SI) may not have a major impact on the cyclic performance of the RC beam. (4) The ultimate drift angle of each specimen in the negative direction was between 4.3% rad and 4.5% rad; thus, all the specimens satisfied the ACI requirement. However, the cyclic performance (plasticity rotation angle) of all specimens basically did not meet the requirement of 3.0% rad for earthquake-resistant structures.

中文翻译：

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箍筋间距和枕木配置对钢筋混凝土梁循环性能影响的试验研究

根据ACI 318-19(SI)，在RC梁的塑性铰区，每个角部的纵向钢筋和每隔一个纵向钢筋必须用封闭箍的角部或枕木的钩子包围。但在RC施工实践中，RC梁纵向钢筋布置密集，施工难度大。在本研究中，设计并制作了四个大型RC梁试件进行实验，以验证箍筋间距和枕木配置对钢筋混凝土梁循环性能的影响。研究发现：（1）推荐采用底部纵筋钩挂抗震钩的枕木结构，施工时距RC柱外表面2倍梁深范围内，应将底部模板和侧模板枕木组装完毕后即可完成，应解决施工难的问题。 (2) 钢筋混凝土梁横向钢筋间距在4～6倍最小纵向钢筋直径之间，对钢筋混凝土梁的循环性能影响不显着。 (3) ACI 318-19(SI)中关于RC梁塑性铰区中每个角部和周边交替纵向钢筋必须具有由拉杆或横拉杆角部提供侧向支撑的要求，可以不具有主要的支撑力。对RC梁循环性能的影响。 (4) 各试件负向极限漂移角在4.3%rad~4.5%rad之间；因此，所有样本均满足ACI要求。但所有试件的循环性能（塑性旋转角）基本未满足抗震结构3.0%rad的要求。