规则钢筋混凝土框架中考虑双向随机偏心距的柱承载力抗震可靠度分析

地震作用下RC框架柱大多处于双偏压受力状态。为考虑双向偏心距随机特性的影响，采用Monte Carlo方法分析了RC框架柱的承载力抗震可靠度。基于已有的试验数据，分析了GB 50010—2010《混凝土结构设计规范》中双偏压构件抗力计算模式的不确定性及其对极限状态方程的影响。以按规范设计的典型RC框架角柱、边柱和中柱为例，结合已有荷载和抗力变量的统计概率参数，通过对荷载效应以及抗力进行抽样，分别按单偏压和双偏压情形计算了RC柱的承载力抗震可靠度。结果表明：对于规则框架结构，双偏压情形下使柱具有较低可靠度的地震作用方向(沿结构主轴)与单偏压情形并不相同；考虑双向随机偏心距后，RC柱的承载力抗震可靠度会较单向随机偏心距下的可靠度有较大程度的降低。

Reliability analysis of seismic bearing capacity for columns in regular RC frame with biaxial random eccentricity

The reinforced concrete (RC) frame columns are often subjected to biaxial bending and axial compression under earthquakes. To study effects of random properties of biaxial eccentricity, seismic bearing capacity reliability is analyzed for RC frame columns with Monte Carlo simulation. Based on the database of tested column results, the uncertainty of resistance computation model in Code for design of concrete structures (GB 50010—2010) is analyzed for biaxial bending and axial compression members, and its effects on limit state equation are also discussed. Taking several typical corner columns, exterior columns, and interior columns in code-based designed frames as examples, the seismic bearing capacity reliability is analyzed，not only in both uniaxial bending and axial compression case, but also in biaxial bending and axial compression case, by sampling load effects and resistance with the prescribed statistics of random variables. It shows that for regular frames the earthquake direction along the principal axis of structure leading to a low reliability of column in the biaxial bending and the axial compression case is different from that in the uniaxial bending and axial compression case, and the column reliability with biaxial random eccentricity is much less than that with uniaxial random eccentricity.