楼板系统对去柱后钢框架梁的轴向约束刚度研究

钢梁两端约束刚度对其悬链线效应影响很大,因此钢梁悬链线效应中约束刚度的研究是一个重要的内容。该文研究“双跨钢梁”两端的钢梁、楼板以及栓钉连接件对钢梁的轴向约束作用。首先,提出提供约束的钢梁、楼板以及栓钉连接件的非线性位移和变形函数。其次,利用最小势能原理,推导楼板系统对去柱钢框架梁轴向约束刚度的计算公式。考虑提供约束的楼板总是局限在一定范围内,提出并使用楼板“临界长度”对理论公式进行了修正。最后,采用20 个有限元算例对理论公式进行算例验证,证明了该文研究结论的可靠性。

RESEARCH ON CONTRIBUTION OF SLABS TO AXIAL RESTRAIN STIFFNESS OF BEAMS IN A STEEL FRAME AFTER THE REMOVAL OF A COLUMN

An accurate evaluation of boundary axial stiffness is crucial in predicting the actual response of affected frame beams.Consequently,the influence of the planar stiffness of surrounding concrete slabs,a significant aspect affecting the value of boundary axial stiffness of the beam,is an important part of catenary action research.This paper sheds a considerable light on the stiffness evaluation of the boundary axial restraints provided by adjacent slab systems to the beam considered.Firstly,three components that contribute to the axial stiffness of the restraint are identified,namely,slabs,steel beams and studs.Then the nonlinear deformation functions of the components were proposed,from which the axial restraining stiffness formulas were derived.Due to the fact that only a part of slab length is attributed to the resisting external force if a sufficient slab length is allowed,an ’effective length’ has to be considered.The axial stiffness formulas are then modified on the base of the effective length.Subsequently,the reliability of the proposed formulas was validated against a case study of 20 examples,and good correlations are observed.