缀板连接的内核分离式屈曲约束构件的承载力设计方法

屈曲约束构件可分为延迟屈曲构件和不屈曲构件，延迟屈曲构件在内核屈服前失稳破坏，当满足承载力设计要求时有更好的经济性。目前已有研究多针对不屈曲构件。针对缀板连接的内核分离式屈曲约束构件，利用平衡法研究了单个分肢的计算长度系数；推导了绕两个主轴的整体弹性屈曲荷载，利用有限元方法研究其弹性空间失稳特性；基于大量有限元弹塑性数值算例，拟合得到正则化长细比 稳定系数设计曲线。研究结果表明：分肢计算长度系数仅与缀板和分肢线刚度比有关，通过比较绕两个主轴方向的长细比可判断构件空间弹性失稳的形式；采用拟合设计曲线可较好预测延迟屈曲构件弹塑性承载力，且比有限元结果偏于安全，区分不屈曲构件和延迟屈曲构件的临界正则化长细比可取为0.75；最后给出了保证分肢弹塑性失稳不先于整体破坏的设计建议。建立的涵盖不屈曲构件和延迟屈曲构件的缀板连接的内核分离式屈曲约束构件承载力设计方法可为设计提供参考。

Design method of ultimate bearing capacity for battened core-separated buckling-restrained members

Buckling-restrained members (BRMs) can be classified as the buckling-prevented BRMs and the buckling-delayed BRMs. Buckling-delayed BRMs buckle before the yielding of the core, so it is more economic when it meets the bearing requirements. But most of previous studies focused on the buckling-delayed BRMs. A kind of new members named as the battened core-separated buckling-restrained member (battened CSBRM) was investigated. The effective length coefficient of a chord was obtained firstly based on the equilibrium method. Then elastic buckling loads bending about x and y axis were introduced and the buckling performance was investigated by finite element (FE) buckling analysis. Finally, based on the results of numerical analysis, an interaction formula between normalized slenderness ratio and stability factor was proposed to predict the ultimate bearing capacity. The research shows that the effective length coefficient of a chord is only related to the linear flexural rigidity ratio between a batten and a chord. The buckling mode of a specific member can be predicted by simply comparing the slenderness about two axes. Comparison with FE results show that the proposed interaction formula for calculating the ultimate resistance is effective and conservative. Furthermore, it is recommended that the critical value of normalized slenderness should be taken as 0.75. At last, design recommendations are proposed to prevent the failure of a chord before the overall failure of a battened CSBRM. The above research establishes a unified design method for both types of battened CSBRMs.