Debonding bearing capacity calculation of RC beam flexural strengthened with high strength steel wire mesh
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摘要: 为分析高强不锈钢绞线网加固的钢筋混凝土梁抗弯剥离破坏, 以加固梁端部锚固区域的剥离破坏为研究对象, 以8根钢筋混凝土加固梁端部锚固试验为基础, 对计算FRP加固梁和粘贴钢板加固梁端部剥离破坏的Smith和Teng模型进行修正, 建立适合高强钢绞线网加固技术的端部剥离承载力计算模型。以加固梁中部的剥离破坏为研究对象, 取加固梁跨中部位两弯曲裂缝之间的部分为计算单元, 分析钢绞线网的受力状态, 建立加固梁中部剥离破坏的粘结剪应力和剥离正应力计算模型, 提出中部剥离破坏准则, 并对所建立的模型进行了验证。研究结果表明: 端部剥离承载力计算模型上限值取0.57, 与试验相符; 中部剥离承载力模型计算值与试验值仅相差3.77%, 计算模型可行。Abstract: In order to research the debonding failure of reinforced concrete(RC) beam flexural strengthened with high strength stainless steel wire mesh, the debonding failure in the anchorage area of strengthened beam plate-end was taken as research object, Smith-Teng model was revised to calculate the debonding failure of beam strengthened with fiber reinforced plastics(FRP) or bonding steel based on anchorage tests at the plate-end of 8 strengthened RC beams. The calculation model of debonding bearing capacity at the plate-end of beam strengthened with high strength steel wire mesh was established. The debonding failure at the middle part of strengthened beam was taken as research object, the middle part between two nearby flexural cracks of RC beam was regarded as arithmetic element, the stress condition of steel wire mesh was analyzed, and the calculation models of bonding shear stress and debonding normal stress at the middle part of strengthened beam were deduced. The debonding criteria at the middle part of strengthened beam were proposed, and the models were validated. Analysis result indicates that the upper limit of the calculation model of debonding bearing capacity at plate-end equals 0.57, it is in accordance with test result. The difference between the value calculated by the model of debonding bearing capacity at the middle part and test result is approximately 3.77%, so the calculation model is feasible.
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图 5 抗弯加固梁跨中剥离计算单元
Figure 5. Debonding calculation unit at middle part of flexural strengthened beams
表 1 抗弯加固梁端部剥离荷载
Table 1. Debonding capacities at plate-end of flexural strengthened beams
试件编号 Vdb/kN Vc/kN Vdb/Vc Mdb/(kN·m) Mu/(kN·m) Mdb/Mu τdp, max /MPa 锚固长度/m 破坏模式 RCL-1 28.80 21.41 1.35 11.52 15.84 0.73 2.379 0.150 端部剥离破坏, 跨中混凝土未压坏, 钢绞线未屈服 RCL-2 27.90 21.69 1.28 12.56 15.35 0.82 2.640 0.100 端部剥离破坏, 跨中混凝土未压坏, 钢绞线未屈服 RCL-3 30.75 21.56 1.43 11.99 16.91 0.71 2.379 0.160 端部剥离破坏, 跨中混凝土未压坏, 钢绞线未屈服 RCL-4 31.45 21.32 1.48 12.42 17.30 0.72 2.379 0.155 端部剥离破坏, 跨中混凝土未压坏, 钢绞线未屈服 RCL-5 31.85 20.86 1.53 11.08 17.52 0.63 2.118 0.202 端部剥离破坏, 跨中混凝土接近压碎, 钢绞线屈服 RCL-6 33.65 22.54 1.49 11.78 18.51 0.64 2.118 0.200 端部剥离破坏, 跨中混凝土接近压碎, 钢绞线屈服 RCL-7 33.15 21.94 1.51 9.05 18.23 0.50 1.701 0.277 跨中混凝土接近压碎, 钢绞线拉断 RCL-8 32.15 21.88 1.47 8.71 17.68 0.49 1.701 0.279 跨中混凝土压碎, 钢绞线接近拉断 
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表 2 抗弯加固梁跨中剥离荷载计算
Table 2. Debonding capacity calculation at middle part of flexural strengthened beam
试件编号 σswA/MPa σswB/MPa σzp/MPa τzp/MPa MPa τbu/MPa 相对差值/% RCBF-2 918.66 1 100 0.115 0.249 0.511 0.531 3.77
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