预应力钢绞线锈胀及混凝土开裂预测

EXPANSION OF PRESTRESSED STRAND CORROSION PRODUCTS AND CONCRETE CRACKING PREDICTION

  • 摘要: 针对钢绞线锈蚀导致混凝土开裂现象,开展了不同应力状态下混凝土的锈胀开裂试验,基于红外和热重分析研究了预应力钢绞线锈蚀产物的膨胀率,分析了预应力对保护层临界开裂时间和裂缝宽度的影响,综合考虑预应力、铁锈膨胀率和混凝土开裂损伤等因素,建立了开裂初始和发展全过程的锈胀裂缝预测模型,并通过试验结果进行了验证。结果表明:预应力会加速混凝土的锈胀开裂,在钢绞线抗拉强度75%的预应力水平下,保护层初始开裂时间降低了22%,裂缝扩展速率增加了9%;建立的模型具有较好的精度,可以合理地预测预应力混凝土的锈胀开裂。

     

    Abstract: Strand corrosion would induce the cracking of prestressed concrete. An experimental study is conducted to investigate the corrosion-induced cracking of concrete under various prestress. The expansion ratio of prestressed strand corrosion products is studied based on the infrared (IR) spectroscopy and the thermal gravimetry (TG) analysis. The effects of prestress on the critical time of cover cracking and crack widths are discussed. An analytical model is proposed to predict the concrete cracking from corrosion initiation to crack propagation. The model can consider the combined effects of the prestress, rust-expansion ratio and residual strength of cracked concrete. The model was verified by experimental data. The predicted results show that prestress can accelerate the corrosion-induced cracking process. When the prestress is 75% strand tensile strength, the critical time of cover cracking decreases 22% and the crack propagation rate increases 9%. The model can reasonably predict the corrosion-induced cracking of prestressed concrete.

     

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