连接墙板内置支撑的钢框架节点加强构造分析

Analysis on reinforced measures of steel frame in connection regions with unbonded steel brace encased in panel

摘要:

为确保墙板内置无黏结支撑钢框架结构大侧移下利用内置支撑大幅屈服耗能,而钢框架在支撑连接区域处于弹性,通过有限元分析重点考察了支撑形式、支撑连接位置等对连接区域传力机制的影响,以及框架在连接处的加强构造.分析表明,1/50侧移角范围内时,梁端贴板加强后加强段基本处于弹性,非加强梁段的塑性铰位置与加强段端部间水平距离约为梁高的一半,塑性铰处翼缘轻微屈曲或无屈曲时钢梁截面的最大弯矩均接近塑性弯矩.据此,再结合支撑的连接位置和轴力便可确定出梁端内力,并进行节点域抗剪验算.分析还表明,节点域两侧的梁端弯矩按翼缘和腹板的抗弯刚度比例分配后传给节点域,而不是按现行设计规范中仅通过两翼缘的方式进行传递.节点域的柱腹板在剪切屈服后剪切变形大幅增加,增大了结构层间侧移.基于分析结果,给出了钢梁翼缘和腹板以及节点域柱腹板的贴板厚度等设计建议.

Abstract:

To ensure that steel frames with unbonded steel plate brace encased in panel, which is also called as panel buckling restrained brace (panel BRB), can use yielding of panel BRBs to dissipate energy under large drifts while keeping regions of the frames connected with panel BRBs in elastic state, finite element analysis was conducted to investigate effects of factors, such as the type and connection location of panel BRBs, on force transfer mechanics of connection regions and corresponding reinforced measures. The analysis reveals that reinforced plates fixed on beam let yielding of beam occur near the ends of unreinforced segments. The distance between the plastic hinge of unreinforced segment and the end of reinforced plate was about half of the height of the beam, and the maximum bending moment at the plastic hinge, with small local buckling or without buckling for flange plates, was close to the plastic moment of beam within drifts of 1/50. Based on the conditions above, together with connection locations and axial forces of panel BRB, the internal forces at the ends of beam can be acquired, hence the shear resistance of panel zone of column can be checked. The analysis also shows that bending moments at ends of beam transferred to the panel zone according to the proportion of flexural rigidity for flange and wed of beam rather than according to only two flanges required by design codes. The shear deformation of panel zone greatly increased after shear yielding, inducing the increase of inter-story drifts. Based on the analysis results, design suggestions on the determination of the thickness of reinforced plates on flange and web of beam and panel zone of column were provided.