干式连接装配式混凝土框架抗连续倒塌静力试验研究

大变形下梁柱节点的力学行为是影响干式连接装配式混凝土框架结构抗连续倒塌性能的关键因素。对3个梁柱子结构试件进行了静力连续倒塌试验,包括1个螺栓连接试件、1个后张拉无黏结预应力连接试件和1个现浇对比试件。根据试验结果分析了节点和子结构在不同变形下的破坏模式和结构静力倒塌抗力,并采用能量原理分析了子结构的动力倒塌抗力。和现浇试件相比,螺栓连接试件的受拉区端板屈曲,使结构在压拱机制下的静力和动力倒塌抗力分别降低41%和45%,而连接角钢和螺栓的断裂使悬链线机制下的静力和动力倒塌抗力分别降低27%和37%。对于预应力连接试件,由于受压区混凝土提前破坏使得压拱机制下的静力和动力倒塌抗力分别降低39%和45%。虽然悬链线机制下预应力筋使得结构静力倒塌抗力提高了52%,但由于压拱机制下累积耗能较低,动力倒塌抗力反而比现浇结构降低17%。

Static progressive collapse test on precast concrete frames with dry connections

The mechanical behavior of beam-column joints under large deformation is the key factor affecting the progressive collapse resistance of precast concrete frame structures with dry-connections. In this paper, a static progressive collapse test was conducted on three beam-column substructure specimens, including one bolted connection specimen, one unbonded prestressed connection specimen and one cast-in-situ specimen. The failure modes of joints and the static collapse resistance of substructures under different deformations were analyzed via test results. The dynamic collapse resistance of substructures was also investigated based on the energy conservation principle. Compared with the cast-in-situ specimen, the static and dynamic collapse resistances of the bolted connection specimen under the compression arch mechanism are reduced by 41% and 45%, respectively, due to the buckling of connection steel plate which has been exposed to the tensile force at beam ends. These resistances under the catenary mechanism are also reduced by 27% and 37%, respectively, owing to the fracture of connection angle steel and bolts. For the unbonded prestressed connection specimen, the static and dynamic collapse resistances under the compression arch mechanism are reduced by 39% and 45%, respectively, comparing with the cast-in-situ specimen due to the early crush of concrete. Although the static collapse resistance under the catenary mechanism is increased by 52%, which is contributed by the prestressed steel bars, the corresponding dynamic collapse resistance of the unbonded prestressed connection specimen is 17% lower than that of the cast-in-situ specimen due to the smaller accumulated dissipating energy under the compression arch mechanism.