高温喷水冷却后方与圆钢管高强混凝土界面黏结性能对比分析

COMPARATIVE ANALYSIS ON INTERFACE BOND PERFORMANCE OF HIGH-STRENGTH CONCRETE FILLED SQUARE OR CIRCULAR STEEL TUBE AFTER BEING SUBJECTED TO ELEVATED-TEMPERATURES AND SPRAY COOLING

为研究高温喷水冷却后方与圆钢管高强混凝土界面黏结性能差异,主要考虑历经最高温度、混凝土强度、恒温时长、锚固长度和冷却方式的影响,对方、圆钢管高强混凝土试件(各22个)进行高温冷却后的静力推出试验,观察试件的破坏过程,对比分析方与圆钢管试件的黏结强度、剪切黏结刚度及界面耗能的差异。结果表明:随着历经最高温度的升高,高温喷水冷却后两种截面形式钢管试件的界面黏结性能差异较大,圆钢管试件的各性能指标均优于方钢管试件的;混凝土强度的提高,可以提高钢管与混凝土间的黏结强度;方钢管试件的黏结强度受恒温时长的影响更大,随着恒温时长的增加,两种截面形式的钢管试件的剪切黏结刚度变化规律相反;锚固长度的增加,会造成界面黏结强度降低,其对圆钢管试件剪切黏结刚度和耗能能力的影响更大;与自然冷却试件相比,喷水冷却试件的黏结强度、剪切黏结刚度均较低,耗能能力较高。

In order to study the difference of interface bond performance of recycled concrete filled square and circular steel tube (RCFSST,RCFCST) short column after being subjected to elevated temperatures and spray cooling,22 RCFSST and 22 RCFCST specimens were designed for push-out test,with the variable parameters of maximum temperature,concrete strength,constant temperature time,anchorage length and cooling mode considered.The mechanical failure pattern of specimens was observed,and the mechanical properties such as bond strength,shear bond stiffness and interface energy dissipation of the specimens were compared and analyzed. The results showed that with the increase of the maximum temperature,the difference of the interface bond performance between the two sections of steel tube subjected to elevated temperatures and spray cooling was large,and the performance indexes of circular specimen were better than those of square specimen. The increase of concrete strength could improve the bond strength between steel tube and concrete. The influence of constant temperature time on the bond strength of square specimen was greater,with the increase of constant temperature time,the change rule of shear bond stiffness of specimens with two cross-section was opposite. With the increase of anchorage length,the interface bond strength would be reduced,which had a greater impact on the shear bond stiffness and energy dissipation capacity of the circular specimens. Compared with the natural cooling specimens,the spray-cooled specimens had lower bond strength and shear bond stiffness,and higher energy dissipation capacity.