钢框架梁柱节点恢复力模型的研究

为了研究高层钢结构梁柱节点的抗震性能 ,对钢框架节点在低周反复荷载作用下的性能进行了足尺模型试验研究。在试验研究的基础上 ,考虑了节点延性、耗能性能和强度、刚度退化等影响 ,建立了钢框架梁柱节点的恢复力模型 ,计算结果与试验结果吻合良好。建立的模型对高层钢结构的抗震设计具有较好的参考价值     

钢框架梁柱节点恢复力模型的研究

为了研究高层钢结构梁柱节点的抗震性能,对钢框架节点在低周反复荷载作用下的性能进行了足尺模型试验研究.在试验研究的基础上,考虑了节点延性、耗能性能和强度、刚度退化等影响,建立了钢框架梁柱节点的恢复力模型,计算结果与试验结果吻合良好.建立的模型对高层钢结构的抗震设计具有较好的参考价值.     

混合高强钢框架节点抗震性能试验研究

混合高强钢框架是一种钢梁采用低强钢材、钢柱采用高强钢材的新型抗弯钢框架结构体系。为研究这一新型框架体系梁柱刚性节点的抗震性能,对两个钢框架节点进行了低周循环加载试验。研究结果表明:混合高强钢框架节点的滞回曲线饱满,其破坏形态、承载性能、耗能能力与普通钢框架相近,并没有因柱截面尺寸的减小导致抗震性能变差。但由于柱截面尺寸变小,节点整体刚度降低导致初始刚度有所下降。     

基于等效结构应力的钢框架焊接梁柱节点低周疲劳评估

在地震作用下钢框架梁柱焊接节点会发生低周疲劳现象,进而导致结构发生破坏。本文基于等效结构应力法提出一种高层钢框架梁柱焊接节点低周疲劳评估方法。首先,结合有限元多尺度模拟方法,建立包含翼缘及腹板焊缝细节的钢框架梁柱焊接节点多尺度模型。其次,利用不同单元尺寸多尺度模型,验证结构应力的网格不敏感特性,进而通过等效结构应力法评估钢框架梁柱焊接节点的疲劳寿命。结果表明,采用等效结构应力法可消除网格的敏感性,在往复荷载作用下,靠近工艺孔焊缝应力水平高于远离工艺孔焊缝,翼缘中心焊缝寿命最低,裂纹最先产生于翼缘焊缝中心处,评估方法为实际工程提供技术支持。     

多、高层钢结构的抗震性能研究

由梁柱节点形式、钢框架–支撑布置方式,钢结构体系入手展开对多、高层钢结构抗震性能的讨论和研究。对比不同形式梁柱节点对抗震性能的影响,利用试验方式通过有限元法探明不同支撑配置方式下钢框架–支撑结构的抗震性能优劣,对比不同结构体系抗震性能优缺点并分析在实际工程中的适用情况。     

钢框架栓焊梁柱连接节点的抗震设计

节点设计是整个钢结构设计的重要环节,提高钢框架梁柱连接节点的抗震性能是整个钢结构抗震设计的重要内容.本文主要介绍了提高钢框架栓焊梁柱连接节点的抗震设计的主要措施,主要方法包括:通过加腋和加盖板对节点进行加强,提高节点承载力;对梁局部削弱,使塑性铰从节点区外移至梁上;改进节点区焊接孔构造形式,缓解局部应力集中;妥善处理弧板和垫板,减少焊缝缺陷.     

高强度钢材钢结构抗震研究进展综述

随着屈服强度的提高,高强度结构钢材的屈强比增大,断后伸长率减小,由于缺少相应规范条文,其在抗震设防地区的应用受到限制。从材料、构件和结构三个层面出发,总结了近年来国内外学者针对高强度钢材钢结构抗震性能的研究成果。重点包括:材料的静力拉伸力学性能、循环本构和极低周疲劳性能;柱、梁和连接节点的抗震性能;高强钢结构框架的抗震性能等内容。最后,对高强钢钢结构抗震性能的进一步研究工作进行了展望。     

过焊孔衬板焊缝对钢框架梁柱节点断裂性能的影响研究

设计了5个高强钢T型节点试件,采用拉卸循环加载试验和有限元数值分析方法,研究其过焊孔衬板焊缝对节点断裂性能的影响;基于T型连接件研究基础,设计了3个钢框架梁柱节点试件,采用低周循环往复加载试验方法研究过焊孔衬板焊缝对梁柱节点断裂性能的影响。结果表明:高强钢T型连接件中过焊孔衬板焊缝对试件断裂性能影响显著,当过焊孔衬板采用双边或四边焊缝时,在极限荷载下可将试件焊缝处的应力峰值移至腹板区域,与传统过焊孔衬板单边焊缝试件相比,其塑性变形能力得到显著提高;将钢框架梁柱节点传统过焊孔衬板焊缝改为双边或四边焊缝后,其节点延性、极限承载能力均得到有效改善,与传统过焊孔衬板单边焊缝试件相比,采用双边焊缝节点试件的延性系数、极限承载力分别提高约29%、23%;采用四边焊缝节点试件的延性系数、极限承载力分别提高约70%、33%。     

不同焊接孔形式梁柱节点的抗震性能分析

梁柱节点局部构造对钢框架结构抗震性能影响显著,为了全面地对比分析不同焊接孔形式及尺寸对焊接节点抗震性能的影响,采用通用有限元软件ANSYS建立节点的非线性有限元模型。通过建立的5种不同焊接孔形式及尺寸的梁柱节点模型,与标准焊接孔节点模型对承载力、滞回性能和塑性损伤指数进行分析对比,探讨焊接孔形式及尺寸对节点抗震性能的影响。分析结果表明:焊接孔的形式及尺寸对节点滞回性能有较大影响,焊接孔的局部形式会造成节点不同的累计损伤效果。结论对于工程应用有重要的参考意义。     

无工艺孔钢梁与H型钢柱焊接节点受力性能分析

以无工艺孔钢梁与H型钢柱焊接节点作为研究对象,基于ABAQUS有限元分析与拟静力试验,对无工艺孔节点与普通工艺孔节点受力性能进行比较,并阐述无工艺孔节点的性能优势及在我国应用的可行性。结果表明,无工艺孔法应用于钢结构梁柱节点,可以有效地提高节点的抗震性能,在我国现阶段钢结构加工技术条件下应用具有可行性。     

未补强焊接梁柱接头之应用于箱形柱

探讨钢结构特殊弯矩构架梁柱接头的耐震行为,梁柱接头采用未补强焊接梁柱接头,特点在于厚梁翼板、箱形柱断面、且焊接扇形孔采用美国AWS的建议,以盼能提供良好的韧性行为。以试验方法进行两组实尺寸试体的试验,梁柱子结构承受反复载重。试验结果显示,两组试体皆可达4%弧度层间变位角,梁发展塑性弯矩强度;破坏肇因于梁翼全渗透焊道裂缝造成的撕裂。研究成果提供预审合格梁柱接头更广泛的实务应用。     

焊接及螺栓连接钢框架的循环加载试验研究

为了探讨、比较焊接和螺栓连接钢框架的极限承载能力、滞回性能及动力特性,本文进行了6榀1∶2比例的单跨双层钢框架循环加载试验和动力特性测试,其中焊接、端板螺栓连接、角钢螺栓连接钢框架各两榀。试验过程中每层框架都铺设了混凝土楼板和配重,水平循环荷载按三角形分布施加。循环加载试验表明:当焊接连接框架的焊缝质量较高时,钢框架具有良好的承载能力和滞回性能,其最终破坏模式是构件形成塑性铰而发生强度破坏,属于典型的延性破坏,框架侧向层间塑性变形可以达到层高的1/25,塑性变形主要来自梁柱连接节点域的剪切变形和柱、梁的弯曲变形;端板螺栓连接框架的承载能力和滞回性能也较好,耗能能力略低于焊接框架,框架侧向层间塑性变形可以达到层高的1/30,但端板焊缝容易发生断裂;角钢螺栓连接框架的承载能力和耗能能力相对较低,塑性变形主要发生在连接角钢和柱脚部位,且翼缘连接角钢容易发生低周疲劳破坏。动力特性测试结果表明:随着节点转动刚度的减小,框架自振     

组合效应对高层钢框架梁柱节点脆性破坏的影响分析

美国北领地震中,不少钢框架梁柱连接出现了意想不到的脆性破坏。观察表明,大部分破坏发生在节点区的梁下翼缘与柱翼缘之间的全熔透焊缝以及相邻板件的焊缝热影响区。由此可知,焊缝质量不良是节点断裂的主要因素。此外,连接缺乏有效的延性也是破坏的一个原因。节点抗震性能试验中多数采用的是钢节点,没有考虑钢梁上的混凝土板。实际结构中,混凝土楼板的存在提高了节点连接的强度和刚度,这也就加剧了下翼缘发生脆性破坏。通过有限元方法,分析了混凝土板组合效应对梁柱节点脆性破坏的影响。     

Ductile moment connections used in steel column-tree moment-resisting frames

This paper presents analytical and experimental studies on the cyclic behavior of beam-to-column moment connections used in steel column-tree moment-resisting frames. The column-tree system is joining the column-trees and link beams in the field while the column-trees are fabricated in the shop by welding stub beams to the column. The proposed ductile column-tree connections have two distinctively improved connection details which are no weld access hole detail and a widened flange of the stub beam. Nonlinear finite element analysis demonstrated the effectiveness of the improved connection details which significantly reduce the stress concentration and plastic strain demands at the beam flange groove weld. Cyclic testing of three full-scale specimens was conducted to verify the proposed connection details. All the specimens successfully developed ductile behavior with no brittle fracture by forming the plastic hinging of the beam away from the beam-column interface. The widened flange and no weld access hole details are effective in reducing the potential of brittle fracture.     

Failure criteria and cumulative damage models for steel components under cyclic loading

In this paper the behaviour of welded beam-to-column connections under low-cycle fatigue is investigated in terms of failure criteria. A damage index and a failure criterion for steel components under cyclic loading, based on the capacity of the structural details to dissipate energy, are presented and discussed.After a review of some cyclic test results obtained for steel beam-to-column connections, a comparison is presented between the cumulative damage model based on the damage index and failure criterion previously introduced, and other models and failure criteria available in the literature.     

Seismic response of multi-storey steel buildings with flexible connections

In the limit states design of steel building frames, usually simplifying assumptions are made with regard to the behaviour of beam-to-column connections. The Canadian standard for steel buildings recognizes three such sets of assumptions. One of them is the ‘special simple construction’ in which the beam-to-column connections are assumed to be completely free (pinned) to resist gravity loads and are assumed to be ‘rigid’ to resist the lateral loads due to earthquake or wind. Such connections are then designed for moments due to lateral loads only, and thus they are usually flexible. This paper is concerned with the influence of the connection flexibility and the strength on the overall strength and stiffness of steel building frames. The study considers 10 storey and 20 storey office buildings. The first part of the paper illustrates the analysis and design of the 10 storey building on the basis of ‘special simple construction’. By using realistic connection behaviour, the frames were subjected to equivalent static loads due to wind or earthquake and El Centro, 1940 earthquake excitation. In the nonlinear static analysis the building frames were subjected to specified gravity loads and incremental lateral loads until failure. In the nonlinear dynamic analysis the buildings were subjected to specified gravity loads and 70% of El Centro, 1940 earthquake excitation. For comparison purposes the frames were analysed twice, first assuming rigid connections and then with flexible connections. The static analyses results show that the connection flexibility increases the building deflections at specified loads, but the strength is only marginally affected. The dynamic analyses results show an increase in deflections and also generally an increase in column bending moments due to connection flexibility and the associated strength.     

高韧性钢骨梁柱接头

钢骨结构一向被认为具有良好的耐震韧性．因此广为使用于世界各地的建筑结构中，高层建筑更是大量采用钢骨结构。但美国北岭（Northridge）地震首次曝露钢骨建筑结构梁柱接头大量破坏之现象，引起各界震惊，甚至造成社会恐慌。日本阪神地震亦发现大量钢骨梁柱接头脆性断裂。由实际发生之地震显示，梁柱接头无论是采用工地焊接或是于工厂内焊接均无法保证其梁端之塑性转角能达到结构抗震之需求，且美式之腹板栓接－翼板焊接之梁柱接头，或日式之工厂焊接－工地栓接之托梁式设计皆已不符现行设计法规之规定。本文除介绍钢骨梁柱接头断裂之原因外．并说明高韧性钢骨梁柱接头的设计原理，此种高韧性接头不仅设计简单施工容易且造价低廉，而其塑性转角更可达4％以上，有助于确保钢骨结构的耐震韧性。     

半刚性连接钢框架-非加劲钢板剪力墙结构性能研究

半刚性连接钢框架-非加劲钢板剪力墙结构弥补了传统抗弯钢框架侧向刚度不足的缺点,为采用更加经济的半刚性节点提供了可能。为研究不同梁柱连接刚度对双体系结构抗震性能的影响,完成了3个单跨两层不同梁柱连接刚度试件的水平低周往复加载试验研究,系统分析了三者的整体性能和破坏模态,拟从承载力、刚度、延性、耗能、整体性能和节点性能六个方面对双体系的节点刚度与墙体的匹配效果进行评价。结果表明:在半刚性框架内设置钢板墙能较大程度提高结构的极限承载力与侧向刚度;结构具有理想的屈服顺序,内填板在加载初期非常有效。屈服区域延伸至整个墙体时,附加荷载将基本上由边缘构件承担,试件破坏主要由内填板的屈服和框架柱的弯扭失稳控制;节点刚度退化小,且内填板的设置缓解了节点区自身的延性要求,梁柱连接形式对试件的抗侧刚度和整体强度的影响不大,降低连接刚度有利于提高试件延性和耗能能力。     

Cyclic flexural analysis and behavior of beam-column connections with gusset plates

This research investigates the cyclic flexural behavior of double-angle concentrically braced frame beam-column connections using three-dimensional nonlinear finite element analysis. Prior experimental research demonstrated that such connections possess appreciable flexural stiffness, strength, and ductility. The reserve capacity provided by these connections plays a significant role in the seismic behavior of low-ductility concentrically braced frames, so knowledge about the impact of connection parameters on local limit states and global connection performance is needed for employing reserve capacity to design and assess concentrically braced frames. Finite element models were developed and validated against prior experiments with focus on the limit states of failure of the fillet weld between the gusset plate and beam, low-cycle fatigue fracture of the steel angles joining the beam and gusset plate to the column, and bolt fracture. The models were used to evaluate the flexural stiffness, strength, and ductility of braced frame connections with primary attention on the effects of beam depth, angle thickness, and a supplemental seat angle. The finite element analysis demonstrated that increasing beam depth and angle thickness and adding a supplemental seat angle all increased the stiffness and strength of the connection while maintaining deformation capacity. A procedure to estimate the flexural behavior of beam-column connections with gusset plates was developed based on the results of the numerical simulations.     

A study to enhance the deformation capacity of beam-to-column connections using high strength steel having high yield ratio

As structures are becoming bigger and more having long span, construction materials are also becoming higher performance materials. In response to this trend, 800MPa tensile strength class structural steel was developed in South Korea. Currently, many experiments applied high strength steel about flexural members, compression members, and connections are continuously conducted, but the design guideline for high strength steel has yet to be established. From among these, it is more difficult that planning of ductile beam-to-column connections because of the high yield ratio, which is the characteristic of high strength steel and related studies are not sufficient. Therefore, This study proposed connection details for the purpose of enhancing the deformation capacity of high strength steel beam-to-column connections and it conducted full-scale experiment and FEM analysis using the connection detail as the variable. As the connection detail, it applied non-scallop welding method and improved horizontal stiffener construction method. Especially, it suggests the stress balance design formula for the improved horizontal stiffener construction method, in order to improve the efficacy of strain distribution. Through the results of experiment and FEM analysis, it was analyzed structural performance of connections with proposed details, and it suggested the design scope of the improved horizontal stiffener.