受拉钢筋锈蚀后混凝土箱梁抗剪承载能力研究

Shear capacity of concrete girder with corroded longitudinal reinforcing steel bars

为了研究不同服役时间的箱型截面混凝土桥梁上部结构抗剪受力性能和破坏机理,按1/4缩尺比设计制作了3片剪跨比1.27的工字型截面钢筋混凝土梁.首先进行纵向受力钢筋恒电流电化学快速腐蚀,3个试件的受拉纵向钢筋锈蚀率分别为0、10%和20%,然后用两点加载法在万能试验机上进行抗剪承载力加载试验.结果表明:从S1到S3试件,随着纵向受力钢筋锈蚀率的增大,梁的峰值荷载降低,峰值荷载对应的挠度降低,极限位移降低;20%峰值荷载以下时S1和S2试件混凝土应变沿高度方向基本满足平截面假定,锈蚀率较大的S3试件则不满足平截面假定;非锈蚀钢筋混凝土梁用公预规斜截面抗剪承载力公式计算较为准确,3种钢筋锈蚀混凝土斜截面抗剪承载力计算方法的结果基本一致,但随着钢筋锈蚀率增大,3种方法的计算精度均有所降低.

In order to study the shear resistance and failure mechanism of the box-section concrete bridge superstructure with different service time, three I-section reinforced concrete beams with a 1/4-scale ratio of 1.27 are designed and fabricated. Firstly, the electrochemical stress rapid corrosion of the longitudinally stressed steel bar was carried out. The corrosion rates of the longitudinal steel bars of the three specimens were 0, 10% and 20%, respectively, and then the shear capacity was tested on a universal testing machine by two-point loading method. The results show that from the S1 test piece to the S3 test piece, the peak load of the beam decreases with the increase of the corrosion rate of the longitudinally loaded steel bar, the deflection corresponding to the peak load decreases, and the ultimate displacement decreases. S1 and S2 are below the 20% peak load. The specimen concrete strain satisfies the flat section assumption in the height direction, and the S3 specimen with large corrosion rate does not satisfy the flat section assumption. The non-corroded reinforced concrete beam is calculated accurately with the common pre-standard oblique section shear capacity formula. The results of three types of calculation method of the shear capacity of the steel corrosion concrete oblique section are basically the same, but with the increase of the corrosion rate of the steel, the calculation accuracy of the three methods is reduced.