混合框架可更换梁的抗震性能及设计方法

Seismic performance and design method for hybrid frame replaceable beams

针对端板-螺栓连接的RCS混合框架可更换梁,采用ABAQUS有限元软件对其在低周反复荷载作用下的受力性能进行分析。研究了长度系数对其破坏过程、破坏模式、滞回性能、抗剪承载力和塑性转动能力等性能的影响;在此基础上,分析了加劲肋间距对剪切型可更换梁抗震性能的影响。分析结果表明:长度系数可以作为可更换梁破坏模式的控制参数,当长度系数e≤1.45时可更换梁发生剪切破坏,当长度系数e>1.45时发生弯剪破坏;长度系数对试件抗剪承载力影响较大,而加劲肋间距对抗剪承载力的影响不明显。经综合分析,提出了剪切屈服型可更换梁长度系数的建议值,即0.9~1.2。分析结果还表明,该型式可更换钢梁具有良好的承载力和变形能力,其超强系数均大于AISC给出的超强系数建议值;此外,加劲肋加密可有效防止可更换梁腹板的屈曲,进而保证可更换梁的耗能能力与塑性转角,因此,不建议将剪切型可更换梁的加劲肋间距设置过大。基于参数分析结果,从截面尺寸、承载力计算、构造措施和连接设计四个方面,给出了可更换梁的设计方法,并通过试验予以验证,为类似的结构构件设计提供参考。

The mechanical behaviors of a replaceable beam with end-plate-bolt connections in the hybrid frame structure under low cycle repeated loading were analyzed with the finite element software ABAQUS.The effects of length ratio on the failure process,failure mode,hysteretic performance,shear bearing capacity and plastic rotation capability of the replaceable beam were studied.Based on the shear yielding property,the influence of the stiffener spacing on the seismic performance was analyzed.The results show that the length factor can be used as a control parameter for the failure mode of the replaceable beam.When the length ratio e is less than 1.45,the shear failure of the replaceable beam occurs.When the length ratio e is more than 1.45,the bending and shear failures of the replaceable beam occur.The length ratio has a great influence on the shear bearing capacity of specimens,but the stiffener spacing has little effect on the shear bearing capacity.A comprehensive analysis,shows that the length ratio of the shear yielding replaceable beam is recommended to be designed as from 0.9 to 1.2.The results also show that the shear yielding replaceable beam has good bearing capacity and deformation capacity,and its overstrength factor is higher than the recommended value of overstrength factors given by AISC341-10 provisions.In addition,reducing the stiffener spacing can effectively prevent the buckling of web of the replaceable beam,thus ensuring the energy dissipation capacity and plastic rotation angle of the replaceable beam.Therefore,it is not recommended to set the stiffener spacing of the shear yielding replaceable beam too large and based on the analysis results of parameters,the design method for replaceable beams should be given from four aspects:section size,bearing capacity calculation,structural measures and connection design.The conclusions were verified by experiment,providing a reference to similar structural designs.