中文摘要：

薄壁构件横截面不对称参数是计算弯扭屈曲临界弯矩的重要几何参数之一。该文推导了非形心主轴坐标系下不对称参数的积分公式，由不对称参数的积分公式推导了不对称参数的通用求和公式，进而化简得到单轴对称截面不对称参数的求和公式。采用不对称参数的通用求和公式推导了部分常用截面的及和（或）风的精确计算式或近似计算式，并对我国现行国标GB50017—2003和GB50018-2002、美国2013版AISI设计手册和SSRC协会的稳定设计指导、澳大利亚标准AS／NZS4600：2005等现有文献中βx和（或）βy计算式的精度进行了判定。研究表明，不对称参数通用求和公式的形式简单、计算可靠、便于应用。

英文摘要：

Monosymmetry section constants are key constants for calculating the critical moment of thin-walled members with flexural-torsiaonl buckling. The general integral formulae for monosymmetry section constants, βx and βy, are derived in the centroid axis coordinate system. The general summation formulae of fix and fly are derived based on the general integral formulae. Accurate and approximate formulae of βx and/or βy for some common cross-section are obtained from the general summation formula. The accuracy of those βx and/or βy formulae in China current code GB 50017-2003 and GB 50018-2002, 2013 AISI design manual and S SRC Guide and AS/NZS 4600：2005 etc., are judged according to the proposed accurate formulae. The results shown that the general summation formulae of βx and fly are simple, reliable and useful.