钢板加固受火后高强钢筋混凝土连续T形梁力学性能试验研究

Experimental research on mechanical behavior of fire-damaged RC continuous T-beams with high-strength rebar strengthened with steel plate

对6个受火后高强钢筋混凝土连续T形梁试件分别采用粘贴钢板加固与螺栓锚接钢板加固,并研究其力学性能和破坏形态。结果表明：受火后高强钢筋混凝土连续T形梁粘贴钢板加固后,承载力提高39.1%-58.2%,破坏挠度降低17.8%-53.2%;采用螺栓锚接钢板加固后,承载力提高36.7%,破坏挠度仅下降4.4%。采用螺栓锚接钢板加固后,初始弯曲刚度与未受火对比试件相当;粘贴钢板加固后,初始弯曲刚度较未受火对比试件明显增大。距跨中越近,梁底钢板拉应变越大,应变变化梯度越大。受火后梁底粘贴一层钢板或螺栓锚接一层钢板加固后,位移延性系数提高53.4%-62.0%、能量延性系数提高62.6%-72.6%;受火后梁底和梁顶中支座附近各粘贴一层钢板加固后,其位移延性系数降低8.2%、能量延性系数降低7.2%。采用折算面积法计算钢板加固受火后高强钢筋混凝土连续T形梁的承载力误差为-0.2%-13.2%,符合工程精度要求。

To investigate the mechanical properties and failure mode of fire-damaged RC continuous T-beams with high-strength rebars strengthened with glued steel plates and screwed steel plate, six specimens were experimentally studied by static load tests. The test results show that the flexural capacity of strengthened specimens glued with steel plates has a 39. 1% -58.2% increase, the ultimate displacement has a 17.8% -53.2% decrease, the flexural capacity of strengthened specimen screwed with steel plate has a 36.7% increase and the ultimate displacement only has a 4. 4% decrease. The initial flexural stiffness of the screwed strengthened specimen is as the same as the unexposed control specimens, and the glued strengthened specimen has an obvious increase. The amplitude and gradient of the strain of steel plate are bigger near the mid-span than other places. The deformation ductility factor of strengthened specimens with one layer of steel plate has a 53.4% - 62.0% increase, while the energy ductility factor has a 62.6% ~ 72.6% increase. With the strengthening steel plate both on the bottom and on the top near the mid- support, the deformation ductility factor has an 8.2% decrease, while the energy ductility factor has a 7. 2% decrease. Based on the reduction of cross-section method, the calculated flexural capacity of strengthened specimens only has a -0.2% -13.2% error compared to the test results, which can completely satisfy the engineering precision requirement.