不同保护层厚度下微锈蚀钢筋混凝土粘结性能梁式试验研究

Influence of Cover Thickness on Bond Behaviors Between Concrete and Slight Corroded Bars

采用稳压恒流电源对钢筋进行加速锈蚀,通过法拉第定律控制锈蚀量,对微锈蚀钢筋混凝土梁式试件进行粘结性能试验研究,并依据试验结果开展理论分析。试验测量了试件角部的钢筋和底边中部的钢筋在不同保护层厚度下的钢筋各点的应变,由测得应变,通过微段平衡求解出各测点的粘结应力。根据各测点的粘结应力拟合出粘结应力沿整个锚固长度的变化曲线。并结合试件自由端的荷载-滑移曲线分析保护层厚度、钢筋位置、锈蚀程度对试件粘结性能的影响。试验结果表明,钢筋的轻微锈蚀提高了试件的极限粘结强度,但使粘结应力沿锚固长度的分布更不均匀,降低了锚固长度的利用率;另外,位于梁底中部钢筋的粘结强度要高于位于梁底角部钢筋,同时,保护层厚度的增加有利于粘结强度的提高。

DC regulated power supply was used to accelerate corrosion of steel bars,the rate of steel corrosion was controlled by the Faraday＇s law,bonding behaviors of non-corroded bars and slight corrosion bars between concrete were comparatively investigated on test beams,and the theoretical analysis developed on the basis of experimental results. In this test,the strain of the steel located at the corner and the middle of the specimen was measured,and then the bond stresses of each measuring point by mini-element balance were calculated. Finally the bond stress curve along bond length was fitted by the bond stress of the measuring point. According to the distribution of bond stresses and the load-slip curves,the effects on bond property caused by concrete cover thickness,location of steel bar and slight corrosion of steel bar was analyzed. The tests showed that slight corrosion of steel bar could increase the ultimate bond stress,but decrease the utilization rate of bond length and made the distribution of bond stress more uneven. Besides,the bond strength of specimen with steel bar placed at middle was higher than that placed at corner. Moreover,the increase of cover thickness improved the bond strength between steel and concrete.