考虑海洋环境损伤的钢筋混凝土框架节点受火性能试验研究

为了研究海洋环境下锈胀裂缝对钢筋混凝土框架节点受火性能的影响，设计了5个配筋相同的足尺钢筋混凝土框架节点试件，以沿梁、柱箍筋方向裂缝宽度最大值为损伤指标，通过快速氯离子侵蚀试验模拟海洋环境下氯离子侵蚀，使4个试件产生不同宽度的锈胀裂缝，然后对4个已损伤框架节点试件以及未损伤的对比节点试件进行火灾试验。结果表明：通过快速氯离子侵蚀试验产生了横向裂缝，其位置与箍筋位置大致相同，其间距与箍筋间距大致相等；初始裂缝宽度对构件高温下的梁、柱端位移变化速率影响显著，锈胀裂缝越宽，构件高温下梁、柱端位移变化速率越快；裂缝的存在加快了热量的传输，导致截面温度场发生畸变；裂缝的存在也会提高钢筋和混凝土的升温速度，加快其力学性能退化，对构件高温下的承载力退化影响显著。

Experimental research on fire resistance performance of RC frame joints with damage caused by marine environment

Five full-scale RC frame joints with the same reinforcement were designed to study the effects of corrosive cracks due to marine environment on the fire resistance performance of RC frame joints. Four joints were designed to produce corrosive cracks of different widths along the stirrups by electrochemistry accelerated corrosion test to simulate marine environment. The maximum width was set as the damage index. One joint was the contrast. Then fire tests were carried out until the joints were damaged. The results show that the transverse cracks induced by the electrochemistry accelerated corrosion test are along the stirrups. The separation of the transverse cracks is similar to that of the stirrups. The initial crack width has a significant effect on the deformation incremental rate of the ends of beams and columns, which will change more rapidly with the enlargement of the width at high temperature. Cracks can accelerate the heat transfer, leading to the distortion of temperature field. The presence of cracks can affect the heating rate of steel bars and concrete, and the bearing capacity of joints with corrosion cracks decrease significantly after fire.