Abstract

In this work, dynamic performance of precast reinforced concrete beam connected by unbonded prestressing tendon under impact loads was conducted using the numerical simulations. First, a detailed numerical model for cast-in-place beam was established, and the simulation method was verified with the available test observations. Then, the numerical model of precast beam connected by unbonded prestressing tendon was established. The parameters of impact velocity, impact position, concrete strength and prestressing level were investigated, respectively. The results show that the failure modes of precast beam with prestressing tendon is shear failure mode which is similar to that of cast-in-place beam under impact loads, and a large number of shear cracks are formed in the mid-span impact location. The interface of precast beam is the weak area, and it is easy to form through shear cracks under impact loads. The residual displacement of precast beam is smaller than cast-in-place beam due to its good self-resetting ability. It should be noted that with the decrease of prestressing level, peak displacement, residual displacement and damage degree of precast beam increase gradually. Additionally, with the increase of concrete strength, the peak displacement of precast beam decreases gradually.

摘要

在这项工作中，使用数值模拟对冲击载荷下由无粘结预应力筋连接的预制钢筋混凝土梁的动力性能进行了研究。首先，建立了现浇梁的详细数值模型，并通过可用的试验观测验证了模拟方法。然后，建立了无粘结预应力筋连接预制梁的数值模型。分别研究了冲击速度、冲击位置、混凝土强度和预应力水平等参数。结果表明，预应力筋预制梁在冲击荷载作用下的破坏模式为与现浇梁相似的剪切破坏模式，在跨中冲击位置形成大量剪切裂缝。预制梁的界面是薄弱区域，在冲击载荷作用下易形成贯穿剪切裂纹。预制梁由于具有良好的自复位能力，残余位移比现浇梁小。需要注意的是，随着预应力水平的降低，预制梁的峰值位移、残余位移和破坏程度逐渐增大。另外，随着混凝土强度的增加，预制梁的峰值位移逐渐减小。