锈蚀预应力混凝土梁承载力及破坏模式研究

随着服役时间增长，侵蚀环境下预应力混凝土梁因受力筋发生锈蚀而造成其延性与承载力降低，严重影响结构的安全使用。为分析侵蚀环境下预应力混凝土梁的承载性能，以集中荷载作用下锈蚀预应力混凝土梁为研究对象，分析混凝土梁锈蚀后各材料性能的劣化与预应力对其承载能力的影响，基于桁架-拱模型给出了桁架作用与拱作用的荷载分配系数，建立了预应力混凝土梁承载力计算模型及破坏模式判别方法，并通过76根预应力混凝土梁的试验数据对建议模型进行验证。研究结果表明:预应力混凝土梁承载力试验值与计算值之比的平均值为1.116，方差为0.033，吻合较好；基于建议分析模型对预应力混凝土梁破坏模式的预测判别与试验梁破坏模式符合程度较高，且该模型能反映预应力混凝土梁随着锈蚀程度增大其破坏模式发生演变这一特征。该文建议的理论模型可用于锈蚀预应力混凝土梁的承载力计算与破坏模式预测分析。

LOAD BEARING CAPACITY AND FAILURE MODE OF CORRODED PRESTRESSED CONCRETE BEAMS

With the increase of service time, prestressed concrete beams under corrosive environment attacking will gradually exhibit the deterioration of ductility and load bearing capacity due to the corrosion of stressed tendons in erosion environment, which seriously affects the safety of building structures. In order to study the load bearing capacity of prestressed concrete beams under a corrosive environment, the corroded prestressed concrete beams under concentrated loads was taken as the research object, and the deteriorated property of corroded materials and the effect of prestressing for load bearing capacity were analyzed. Based on the truss-arch model, the distribution coefficients of truss role and arch role were calculated, and the calculation formula for load bearing capacity along with the assessment method of failure mode of the prestressed concrete beams were proposed. The experimental data of 76 prestressed concrete beams were used to validate the suggested model. The results show that: for the load bearing capacity of prestressed concrete beams, the calculated values are in a good agreement with the test values, and the mean value and the variance of the ratio between them are 1.116 and 0.033, respectively. Using the proposed model, the prediction of the failure mode agrees well with the observed failure mode of experimental concrete beams, and the suggested method can reflect the fact that the failure mode of the concrete beams changed by time as the corrosion degree increases. Thus, the proposed model can be applied to calculate the load bearing capacity and assess the failure mode of corroded prestressed concrete beams.