【作者】 王悦；

【导师】 王燕；

【作者基本信息】 青岛理工大学 ， 结构工程， 2008， 硕士

【摘要】 针对钢框架刚性节点在地震荷载作用下出现大量的脆性破坏,梁上未出现明显的或没有发生塑性变形的问题,为了改善节点性能避免脆性断裂,本文从延性角度出发,使用有限元分析软件ANSYS,对新型延性节点进行有限元分析,结果显示狗骨式节点和扩翼式节点具有理论上的合理性和实际中的可行性。狗骨式节点塑性铰的形成位置移至梁翼缘削弱处,扩翼式节点的塑性铰形成位置移至扩翼圆弧段末端,两者均远离梁柱焊接处这一易发生脆性破坏的薄弱环节,而且两种节点在梁柱焊接处的应力值均有减小,应力集中程度也有减弱。根据钢框架强柱弱梁的抗震设计原则,新型延性节点满足使梁上塑性铰的位置远离节点区的设计思路,达到塑性铰外移和增加抗震性能的目的。狗骨式节点由于粱翼缘削弱,节点承载能力受损,扩翼式节点由于梁根部翼缘宽度的扩大,节点承载能力提高,可承受较普通刚性节点更大的荷载作用。综合分析这两种新型延性节点的受力性能,在钢框架梁柱节点设计中,为满足抗震要求,建议首选扩翼式节点。分别对狗骨式节点的削弱参数、扩翼式节点的设计参数变化时的不同节点进行弹性和弹塑性有限元分析,从应力发展和节点承载力等方面分析削弱参数、设计参数对节点性能的影响。狗骨式节点的削弱参数可适当取较大值,以满足塑性铰外移,但是参数值不宜过大,以防止节点削弱太大,使节点的承载能力受到较大的损失。扩翼式节点的扩翼段、扩翼圆弧段的长度、宽度适当加大,有助于节点的抗震性能增强和承载力的增加。通过以上研究分析,对狗骨式节点削弱参数和扩翼式节点设计参数的取值范围提出建议,确定狗骨式节点梁翼缘削弱的长度、深度以及与柱翼缘的距离,并确定扩翼式节点的扩翼段的长度、宽度以及扩翼圆弧段的长度,使其抗震性能满足延性要求,为工程设计提供可参考的设计依据。更多还原

【Abstract】 The rigid joints of steel frame appeared lots of brittle failure and the beams didn’t appear plastic deformation obviously or plastic deformation didn’t happen at all under the earthquake load. According to these problems, in order to improve joint properties to avoid brittle rupture, this paper performs the finite element analysis on the new ductile node from the view of ductility through ANSYS. There are two kinds of the new ductile node: reduced beam section(also called dog-bone section) and connection with widened beam flanges. The result showed that these two connections are feasible theoretically and practically. The position of plastic hinge in dog-bone section joint moves to the weakened department of beam flanges. And the position of plastic hinge in connection with widened beam flanges moves to the end of the arc segment of widened flanges. Both are far away from the weakness of beam-to-column connection, which is easy to appear brittle fracture. And in the beam-to-column connection, both stresses and degree of stress concentration decrease. According to the strong column weak beam principles of anti-seismic design of steel frames, it matches the idea of making plastic hinges of beams away from connection area and apply to make the plastic hinge away from the connection. The ultimate bearing capacity of dog-bone section joint reduces because of weakened beam flanges. But the ultimate bearing capacity of widened beam flanges joint is greater than the traditional rigid connection. As a result, it is suggested that connections with widened beam flanges are selected firstly in the design of beam-to-column connection in steel frames to meet anti-seismic requirements.Elastic and el-plastic finite element analysis is made on the joints on which weakening parameters of reduced beam section joint and designing parameters of connection with widened beam flanges change, and the effect of the changes of these weakening and designing parameters on joint properties has been analyzed from the aspect of stress and load-carrying of joints. It will satisfy the purpose of plastic hinge moving outside to select the bigger parameters of dog-bone section joint. But the value should not be too large, otherwise the load capacity of the joint will be damaged. Also the appreciate increase of the widened beam flanges dimension is useful to enhance the seismic behavior and the load capacity. Finally, the scale of the parameters is suggested based on the research result.The scale of the parameters of this two typical ductile connection is suggested from the above research result. It is determined that the length, depth and distance to column flange of dog-bone section joint and the length, width of widened flanges and arc segment of connection with widened beam flanges. These seismic behavior satisfies the ductility and provides a basis for engineering design.更多还原