P-M-φ分析对RC高墩的转动变形能力计算的适用性研究

Applicability of P-M-φ Analysis on Estimating Rotational Deformation Capacity of RC Tall Column

为了研究RC高墩的抗震性能和试验方法,通过对4根RC高墩模型进行了拟静力试验,观察到墩底附近在加载后期均出现剪切斜裂缝,随着保护层混凝土逐渐脱落,主筋在断裂前发生明显的屈曲现象。这些现象说明RC高墩的实际破坏形态、破坏机理与P-M-φ分析的前提假设是不一致的。试件的实测极限曲率值,比P-M-φ分析计算值,小约50%,本文结论是P-M-φ分析会严重高估RC高墩的曲率能力,偏于不安全。

In order to study the seismic capacity and design method of RC tall column,the pseudo-static test was carried out on four RC tall column models. The shearing diagonal cracks were observed near the bottom of the pieces at the late phase of loading.With the fall of the protecting cement,the main reinforcement bucked prior to breaking. These appearances indicated that the actual failure pattern and mechanism of tall column were different from the presupposition of P- M- φ analysis. The actual curvature values of the pieces measured at their ultimate state were nearly 50% less than the theoretical value which was obtained from P- M- φ analysis. The main conclusion is that P- M- φ analysis is inapplicable to estimate the curvature capacity of tall RC column. The result would be seriously overestimated,which is probably unsafe for the bridge.