【作者】 王振山；

【导师】 苏明周；

【作者基本信息】 西安建筑科技大学 ， 结构工程， 2013， 博士

【摘要】 轻型门式刚架结构具有良好的经济效益和抗震性能，在低层建筑中应用广泛。由于自重较轻，地震作用力较小，人们对于该结构的抗震研究较少。但在后来的一些强烈地震中，结构局部仍然会发生一定程度的破坏，严重的局部变形甚至会引起整体结构的倒塌，这引起了人们对其抗震性能研究的重视。本文对1/2缩尺模型端板竖放、平放、斜放螺栓连接节点进行滞回试验研究，每种节点形式3个试件。试验得到了节点的荷载-位移曲线、骨架曲线、刚度退化和螺栓内力分布情况。研究表明：三种形式节点的破坏模式基本相似，均为距梁端约1.5倍梁大头截面高度位置翼缘发生局部屈曲，构件承载力达到峰值后迅速下降，呈脆性破坏形式。试件的荷载-位移滞回曲线饱满程度不高，说明其塑性发展较小，耗能能力较差，地震作用下不能利用其塑性耗能能力，结构设计应按弹性阶段考虑。端板厚度和螺栓强度对节点刚度影响较大，端板越厚，螺栓强度越高，节点刚度越大。但进入弹塑性阶段，端板越厚其刚度退化速度越快。综合考虑三种节点的抗震性能，建议设计时优先考虑使用端板竖放形式。总之，按“规程”设计的节点可满足了“强节点，弱构件”的抗震设计理念要求。本文同时对1/3缩尺模型柱脚铰接端板竖放节点的整体门式刚架结构进行拟静力试验研究，刚架的破坏模式为形成3个“屈曲铰”的机构：2个铰位于梁的两个端部，1个位于梁跨中截面薄弱处；试验得到了结构的滞回曲线、骨架曲线、刚度、刚度退化及水平位移情况，并利用底部剪力法对其地震承载力进行验算。结果表明：虽然该结构延性、耗能能力较低，难以利用其塑性变形提高抗震性能；但由于结构自重轻，地震作用力小，仍可较好满足抗震设防要求。通过应变数据的分析，发现塑性阶段，近、远端梁应变差异较大，并分析了影响结构整体性能的因素，如局部屈曲、蒙皮效应、楔率、翼缘宽厚比及腹板高厚比等。本文通过有限元软件对试验模型进行验证，并分析了试验模型原型结构的抗震性能，在此基础上进行参数分析，包括翼缘宽厚比、腹板高厚比和楔率对结构抗震性能的影响。研究发现：梁翼缘宽厚比、腹板高厚比及楔率主要影响结构的承载力和耗能情况；柱翼缘宽厚比、腹板高厚比及楔率主要影响结构初始刚度、退化刚度和位移情况。在有限元参数分析结果上，拟合得到结构屈服荷载、峰值荷载与破坏荷载之间的计算公式以及退化刚度、负刚度与初始刚度之间的计算公式。同时，本文提出了一种提高门式刚架整体抗震性能的支撑形式，有限元分析表明：带支撑结构比未设置支撑结构承载力提高10%以上，耗能能力提高1.8倍。在强化双线性模型以及端板竖放节点滞回试验的基础上，建立了该节点的M-θ简化模型，与整体拟静力试验及有限元模型对比发现，该简化模型对结构的屈服荷载与最大荷载计算较准确，具有较高的工程意义。最后，本文提出了考虑翼缘宽厚比、腹板高比及楔率影响的门式刚架退化三线型恢复力模型，与试验结果吻合较好，为该结构的抗震性能分析提供了一种简化方法。根据上述研究结果，对轻型门式刚架节点及整体结构的抗震性能有了较全面认识，可为相关规范修订提供一定依据，并为日后展开更深入的研究奠定基础。更多还原

【Abstract】 Light portal frame structure was widely adopted in low-rise buildings for goodeconomic benefit and aseismic performance, but there ware less anti-seismicresearches on the structure due to light dead-weight and small seismic force. However,the structure partial of portal frame was some extent damaged under severeearthquakes; the structural integer collapse could be caused by the serious localdeformation, which arose of people’s stress on its anti-seismic research.The paper conducted hysteretic tests for vertical, flat and bevel endplate boltjoints of1/2scale model and three specimens were prepared for each joint form. Theload-displacement curve, skeleton curve, and distribution of stiffness degradation andinternal forces of bolt were obtained by the tests. It was showed that the failure modesof the three joint forms were similar, which the local buckling occurred on the flangeabout1.5times of the height of large end of beam to the beam end, the memberbearing capacity declined quickly after peak value, and brittle failure modes wereformed. The load-displacement curves of all specimens were not plump, which showedsmall plastic development and poor energy-dissipating capacity of the light portalframe structure, so the structure should be designed with elastic theory. The jointstiffness was influenced by the thickness of endplate and the strength of bolt, which thejoint stiffness would be higher with thicker endplate and higher strength bolt,meanwhile, the stiffness would degenerate more quickly. The form of vertical endplateis recommended in design by the comprehension of the aseismic performance of three joint forms. In conclusion, the requirements for aseismatic design concept of “strongerjoint and weaker member” would be obtained according to the “portal frameregulation”.Through the quasi-static anti-seismic test of the entire portal frame structure onsingle-layer and single-span heel hinged endplate of1/3scale model, three “bucklinghinges” were formed: two hinges were located at the two ends of the beam and one atthe weak cross-section of beam span; and the situation of the hysteretic curve, skeletoncurve, stiffness, stiffness degradation and horizontal displacement of the structure wasobtained; and equivalent base shear method was adopted to calculate and check theearthquake bearing capacity. It was concluded that the aseismic performance of lightportal frame structure could not be improved by its plastic deformation for the lowductility and energy-dissipating capacity, but the structure could satisfy the requirementof seismic fortification criterion for light dead weight and small seismic action. Throughthe analysis of strain data, it was found that the strains of close and far ends of beamwere different in plastic stage, and the factors which affect overall structuralperformance was analyzed, such as local buckling, skin effect, taper, flange width-thickness ratio and web width-tapering ratio.The test model was verified by the finite element software and the aseismicperformance of the prototype structure was analyzed, by which the parameter analysiswas done, including the influence of flange width-thickness ratio, web width-taperingratio and taper on the aseismic performance of the structure. It was concluded that thebearing capacity and hysteretic behavior were influenced by the flange width-thicknessratio, web height-thickness ratio and tapering ratio of beam; and the initial stiffness,degradation stiffness and displacement were influenced by the flange width-thicknessratio, web height-thickness ratio and tapering ratio of column. Based on the parameteranalysis, the computation formula of yield load, ultimate load and peak load, as well asthat of stiffness degradation, negative stiffness and initial stiffness was obtained. Asupporting form specific to portal frame was presented, which would rise10%ofstructural bearing capacity and1.8times of energy-dissipating capacity compared tofinite element verified model.Based on strengthening bilinear model and the test, M-θ simplified model of vertical endplate joint was established, comparison with the overall quasi-static testsand finite element model, which could well calculate the yield load and maximum loadof the structure and had a high practical engineering significance. Finally, trilinearrestoring force model was established according to flange width-thickness ratio, webwidth-tapering ratio and taper, which was fitted with results of test, and could provide asimplified analysis method for seismic performance analysis of light portal framestructure.According to the above study, an all-round knowledge on the aseismic performanceof the joint of and entire portal frame structure was showed, which provided certainbasis for revising the relevant specifications and lays solid foundation for future study.更多还原