基于光纤传感技术的大跨连续刚构桥施工阶段张拉预应力监测

Tension Prestress Monitoring of Large Span Continuous Rigid Frame Bridge during Construction Stage Based on Optical Fiber Sensing Technology

在为了研究山区复杂气候条件下预应力张拉对桥梁受力的影响,实时监测大跨桥梁预应力张拉过程中的混凝土受力状况,以万龙山大桥施工为例,采用预埋式高精度光纤光栅应变计,对大桥2号墩12#块的预应力张拉过程进行了全程监测。在监测过程发现,当采用非对称张拉的施工方式进行预应力张拉时,箱梁截面上存在着拉压应变交替产生的现象,张拉顶板时,底板和腹板上产生较大的拉应力,而未被张拉的另一侧腹板也存在较大的拉应力;顶板钢束产生的预应力效果相比于底板预应力钢束明显。12#块预应力张拉结束后,箱梁截面顶板处产生了-120με压应变,腹板和底板分别产生了40με和80με拉应变,直观的反映出了应力张拉效果。

In order to study the influence of the pre-stressing tension on the bridge force under complex climatic conditions in mountain areas and monitor in real time the concrete stress of long-span bridge in the process of pre-stressing tension, by taking the construction of Wanlongshan Bridge as an example, plastered fiber grating sensor with high-accuracy was adopted to monitor the whole process of pre-stressing tension in Block 12 of Pier2. The research results show that when the prestressing tension is carried out by using the asymmetrical tension method, the phenomenon of alternating tension-compression strains occurs in the box girder section. When the tension occurs in the roof, the bottom board and web produced obvious tension stress, and the web of the other side without tension also produced obvious tension stress; the prestressed steel beam of the roof produced more obvious prestressing force than that of the bottom board. After the prestressing of 12 # block was completed, a compressive strain of-120με was produced at the top of box girder section, and tensile strain of 40με and 80μεwere produced respectively at web and bottom board, which directly reflected the effect of stress tension.