预应力钢丝绳-聚合物砂浆面层抗弯加固持荷RC梁数值分析及承载力计算

建立预应力钢丝绳-聚合物砂浆面层抗弯加固钢筋混凝土(RC)梁的有限元模型(FEM),并利用已有的试验数据验证模型的准确性.基于有限元模型,进行不同持荷比下加固梁的力学性能研究.结果表明:建立的有限元模型可较好地解决持荷条件下钢丝绳-聚合物砂浆面层与RC梁之间单元不协调变形等问题;随着持荷比的提高,加固梁的极限承载力提高幅度逐渐减小;当预加载低于未加固梁极限承载力的20%时,混凝土损伤较小,不考虑预加载的影响;当预加载高于未加固梁极限承载力的20%时,需考虑加固材料滞后应变对加固试件极限承载力的影响.基于平截面假定和钢丝绳滞后应变,提出抗弯加固持荷RC梁的极限承载力计算公式,其计算结果与数值分析结果吻合良好.

Numerical Analysis and Flexural Capacity Calculation of RC Beams Strengthened With Prestressed Steel Wire Ropes-Polymer Mortar Composite Under Preload

The finite element model(FEM)of the reinforced concrete(RC)beams strengthened with prestressed steel wire ropes-polymer mortar composite was established and validated by available test results. Based on the FEM model, the flexural behaviors of the strengthened beams under different preload ratios were studied. The results show that the FEM model could solve the problem of uncoordinated deformation between steel wire ropes-polymer mortar composite layer and RC beam under the preload. As the preload ratios increase, the increasing range of ultimate capacity of the strengthened specimen gradually decreased. When the preload ratio is less than 20% of the ultimate capacity of unstrengthened RC beams, the effect of preload can be neglected due to the minor damage in the concrete. When the preload ratio is greater than 20% of ultimate capacity of unstrengthened RC beams, the preload effect of the lagged strain of material on ultimate capacity of unstrengthened RC beams should be taken into account. Based on the plane cross-section assumption and the lagged strain of steel wire ropes, the formula of ultimate capacity of strengthened RC beams under preload is proposed, and the calculation results conform well with the numerical ones.