预制预应力混凝土箱梁典型质量缺陷试验研究

Experimental Study on Typical Quality Defects of Prefabricated Prestressed Concrete Box Girders

【目的】为存在缺陷的预制预应力混凝土箱梁的单梁承载能力判定提供数据依据及建议。【方法】依据公路桥梁荷载试验规程确定试验方案,对一批存在缺陷的预制预应力混凝土箱梁进行单梁静载试验。【结果】试验梁在等效荷载作用下:L/4截面挠度校验系数是0.34~0.56,L/2截面挠度校验系数是0.51~0.67,3L/4截面挠度校验系数是0.41~0.55,各截面相对残余挠度是-13.02%~9.42%;L/4截面各测点应变校验系数是0.67~1.77、0.48~0.79、0.56~0.88,L/2截面各测点应变校验系数是0.54~1.30、0.43~0.79、0.51~0.89,3L/4截面各测点应变校验系数是0.77~1.56、0.42~0.80、0.53~0.85,各截面1#测点相对残余应变是-20.95%~34.91%,各截面2#、3#测点相对残余应变是-2.46%~18.70%。【结论】存在缺陷的预制预应力混凝土箱梁的受力特征已改变,箱梁在同一截面应变比例失调,向着箱梁顶板腹板交接区域集中。箱梁随缺陷影响程度的增大而导致应变校验系数或相对残余应变超过规范限值。同一箱梁,缺陷对应变的影响程度大于对挠度的影响程度。

[Purposes]This paper aims to provide data accumulation and suggestions for the determination of single beam bearing capacity of precast prestressed concrete box beams with defects.[Methods]The test scheme was designed according to the load test regulations of highway Bridges,and the single beam static load test was carried out on a batch of precast prestressed concrete box beams with defects.[Findings]Under equivalent static load,the deflection check coefficient of L/4 section is 0.34~0.56,and that of L/2 section is 0.51~0.67,and that of 3L/4 section is 0.41~0.55,and the relative residual deflection of each section is-13.02%~9.42%.The strain check coefficients of L/4 section are 0.67~1.77,0.48~0.79,0.56~0.88,and the strain check coefficients of L/2 section are 0.54~1.30,0.43~0.79,0.51~0.89.The strain calibration coefficients of 3L/4 sections are 0.77~1.56,0.42~0.80 and 0.53~0.85.The relative residual strain at the 1#measuring point of each section is-20.95%~34.91%,and the relative residual strain at the 2#and 3#measuring points of each section is-2.46%~18.70%.[Conclusions]The stress characteristics of the precast prestressed concrete box girder with defects have changed,and the strain ratio of the box girder at the same section is misaligned,and the box girder is concentrated towards the joint area of the roof web.With the increase of defect influence degree,the strain check coefficient or relative residual strain exceeds the standard limit.For the same box girder,the influence of defects on strain is greater than that on deflection.