外部粘贴预应力碳纤维板技术加固桥梁结构的工程应用与评估

Engineering Application and Evaluation of the Bridge Structure Strengthened with Prestressed CFRP Plate

采用外部粘贴预应力碳纤维板技术对金刚桥进行加固。金刚桥是一座已使用40多年的钢筋混凝土简支T形梁桥,开裂严重,抗弯刚度退化,在汽车荷载作用下梁体挠曲变形明显,需要进行加固并提高其通行荷载。根据正截面承载力验算结果,确定在主梁底部和梁肋两侧尽可能接近底部的位置粘贴预应力碳纤维板进行加固,以提高抗弯强度。加固过程中采用结构基座式的预应力张拉设备对碳纤维板施加1 000 MPa的初始应力,并在桥梁支座处通过永久性锚具设置了可靠的锚固。加固完成后采用标准荷载对桥梁进行荷载试验。试验结果表明:应用预应力碳纤维板加固技术,桥梁结构承载力满足加固设计荷载要求,且挠曲变形显著减小,桥梁结构的内力分布得到明显改善。

Jingang Bridge was strengthened with prestressed CFRP plates. Jingang Bridge which was a simply supported reinforced concrete T-beam bridge had served for over 40 years. The flexural rigidity of the bridge has degraded a lot owing to the cracks and the flexural deflection of the girder has become more visible under vehicle load, so the bridge needs strengthening to improve the trafficking load. According to the checking calculation results of the normal section load-bearing capacity, the prestressed CFRP plates were installed at the subfaces of the girders and both sides of the girder rib near to the bottom of the girders to enhance the flexural strength. CFRP plates were prestressed to 1 000 MPa initial stress by a structural base-tensionor and at both ends of the plates near the bridge bearings permanent anchors were located to provide reliable anchorage. Controlled truckload tests were conducted to evaluate the effectiveness of the strengthening system after the CFRP laminates were installed. Test results show that the strengthening of the bridge with prestressed CFRP plates had achieved the design objective： the deflection of the girders was restricted significantly and the stress distribution of the bridge structure was ameliorated significantly.