一种四角钢组合约束型防屈曲支撑的外围约束机理及刚度取值研究

Study on restraint stiffness of a four-angle assembled steel buckling-restrained brace

对一种四角钢组合约束型防屈曲支撑的外围约束刚度的取值进行研究。这种防屈曲支撑的外围约束构件由四个角钢通过螺栓连接,由于螺栓数目有限,所以与外围整体式防屈曲支撑相比,其外围约束刚度应进行一定程度的折减。根据外围约束构件的受力特点,提出一个简化的桁架模型,基于该模型给出一种确定外围约束刚度的方法。其中,四个角钢间的连系刚度是决定整体约束刚度的重要参数,其受到角钢分肢板件的面内刚度与面外刚度的共同控制。通过理论与数值分析相结合的手段,在参数分析的基础上,提出角钢间连系刚度的拟合计算公式。数值分析表明,该方法可用于精确确定这种四角钢组合约束型防屈曲支撑的外围约束刚度。

An investigation was conducted to evaluate the restraint stiffness of a four-angle assembled steel buckling- restrained brace （ABRB）. The restraining components of this type of ABRB are composed by four angle steels with bolt connections spaced longitudinally and regularly. As the number of bolts that connect the angle steels as a whole is limited, the restraint stiffness of ABRBs should be reduced compared to that of the braces with fully integrated restraining components. A simplified truss model is proposed to reflect the mechanism of the restraining components, and accordingly a method to determine the restraint stiffness is given. Link stiffness between the restraining angle steels is mainly affected by the in-plane and out-of-plane stiffness of the angle plate. Based on theoretical and numerical results obtained, a formula is put forward to determine the link stiffness. The accuracy of the proposed restraint stiffness is also verified by FE numerical analysis.