不同加强方式下主方支圆K型搭接节点关键参数分析

KEY PARAMETRIC ANALYSIS FOR UNSTIFFENED OVERLAPPED K-JOINT WITH THE SQUARE CHORDS AND CIRCULAR BRACES STRENGTHENED IN DIFFERENT WAYS

通过主管外壁加套管和主管内灌混凝土的加强方式可以改善K型搭接节点的力学性能。为探讨两种加强方式的优劣,通过ANSYS建立有限元模型,首先对有限元模型进行了验证,基于验证的有限元模型进行了参数分析,得到两种加强节点在关键参数影响下的滞回曲线和骨架曲线,对比分析其承载力和滞回性能,其中,K-1节点为主管外壁加套管加强,K-2节点为主管内灌混凝土加强。结果表明:随支、主管夹角θ增加,两种加强节点的滞回性能和承载力均减弱;随支、主管径宽比β增加,两种加强节点滞回性能均减弱,但承载力提高;支、主管厚度比λ对K-1的滞回性能和承载力有一定影响,对K-2的影响不明显;随主管宽厚比η增加,K-1的滞回性能和承载力变化不明显,K-2的滞回性能和承载力均有提高;搭接率O_v的变化对两种加强节点的滞回性能和承载力影响不显著。K-2的承载力和滞回性能总体优于K-1,进一步对K-2延性和耗能进行分析,其延性随参数θ、λ和η的增大均有提高,而随参数β和O_v的增大均有所降低;节点的能量耗散能力与参数β和λ均呈正相关,而与参数θ、η和O_v呈负相关。

The mechanical properties of overlapped K-joint can be improved by the strengthening ways of adding corresponding casing outside the chord and pouring into concrete inside the chord. In order to discuss the advantages and disadvantages of the two kinds of strengthening models, the finite element model was established by ANSYS. Firstly, the finite element model was validated, and the parameters of the finite element model were analyzed based on the validation, obtaining the hysteresis curves and skeleton curves of two kinds of reinforced joints under the influence of the key parameters, compared and analyzed their bearing capacity and hysteretic behavior. Among them, the joint of K-1 was strengthened by adding corresponding casing outside the chord and the joint of K-2 was strengthened by pouring into concrete inside the chord. The results showed that the hysteretic behavior and bearing capacity of the two reinforced joints were all weakened with the increase of θ, and the hysteretic behavior of the two kinds of reinforced joints were all weakened with the increase of β, but the bearing capacity increased;the effect of λ on the hysteresis and bearing capacity of K-1 was limited, and the effect on the K-2 was not obvious;with the increase of η, the alteration of hysteretic behavior and bearing capacity of K-1 was unconspicuous and the hysteresis behavior and bearing capacity of K-2 obviously increased;the change of overlapped ratio O_v had little effect on the hysteresis behavior and bearing capacity of the two reinforced joints. In general, the bearing capacity and hysteresis behavior of K-2 were better than that of K-1. The ductility and energy dissipation of K-2 were further analyzed. The ductility increased with the increase of parameter θ,λ,O_v, and decreased with the increase of parameter β and O_v;the energy dissipation capacity of the joints was positively correlated with the parameters of β and λ, but was negatively correlated with the parameter θ,η and O_v.