梁柱组合节点受弯承载力统计分布

在钢-混凝土组合抗弯框架的抗震设计中,梁柱组合节点转动响应的随机性会影响能量耗散区域的位置。事实上,在节点的强度作用全部发挥的情况下,地震能量的耗散发生在梁端,相反地,在节点的强度作用部分发挥的情况下,则耗散也会发生在梁柱连接节点的连接部件上。在结构框架中,节点构件的材料随机性变化扮演了重要的角色,因为它影响了节点的弯曲强度,从而也影响了其塑性转角。因此,框架的研究项目旨在评估包括材料随机变化在内的钢-混凝土组合框架的地震可靠性,并着重分析了材料随机变化对梁柱节点转动响应的影响。特别是通过蒙特卡罗模拟法从整体来对梁柱节点转动性能描述参数的统计分布法则进行评估。这种分布法则提出了关于钢-混凝土组合抗弯框架的一个完整的概率地震需求分析的重要输入数据,而其节点建模所使用的转动弹簧的随机值参数也满足之前推断出的分布法则。     

半刚性连接梁柱组合节点低周反复荷载试验研究

为研究半刚性连接梁柱组合节点的抗震性能,开展了1个纯钢框架梁柱中节点、2个组合框架梁柱中节点的低周反复荷载试验。梁柱采用平齐式高强螺栓端板连接,试验采用柱顶加载模式。对试件的试验现象、变形、应变和耗能能力等进行了分析和比较。试验结果表明,组合节点相对于纯钢节点而言,由于负弯矩作用下钢筋的抗拉作用和正弯矩作用下混凝土板的抗压作用,其受弯承载力和转动刚度均有较大程度地提高;连接弯矩-转角关系的滞回曲线饱满、稳定,具有良好的耗能能力;平端板连接梁柱组合节点在反复荷载作用下具有较高的承载力和良好的延性,抗震性能良好。     

Random material variability effects on full-strength end-plate beam-to-column joints

In the seismic design of steel frames, beam-to-column joints are generally designed as full strength joints in order to avoid their engagement in the plastic range promoting the location of plastic hinges at the ends of the connected beams. In this paper, the reliability of the criteria to design full strength beam-to-column joints is investigated. In particular, in the first part of the work, starting from probabilistic analyses accounting for random material variability of connecting elements, the reliability of the design criteria suggested by codes is analyzed. Successively, on the basis of the obtained results, a new design criterion able to account for both the random material variability and the overstrength exhibited by the beam before the occurrence of local buckling is proposed.     

Experimental investigation of dry mechanical beam–column joints for precast concrete based frames

This paper proposes dry mechanical beam–column joints for fully restrained moment connections of concrete components. This novel joint can be used for reinforced concrete precast frames and steel–concrete composite precast frames. The new dry mechanical joint consists of extended steel plates with bolts designed to transfer tension and compression forces, providing fully restrained moment connections at the beam–column joint. The extended end plate with bolts introduced for column‐beam joint assembly was originally used in the steel moment frame, as introduced in AISC 358. This study developed similar but unique mechanical joint details for concrete frames in order to provide fully restrained moment connections for both steel–concrete composite precast frames and reinforced concrete precast frames. Experimental and analytical investigations were performed to verify the structural behavior of fully restrained moment connections for concrete components in order to identify the parameters that influence the structural behavior of dry mechanical moment concrete connections. These connections are expected to be used in modular offsite construction for buildings and heavy industrial plants. Copyright © 2016 John Wiley & Sons, Ltd.     

Dynamic response of composite frames with different shear connection degree

The influence of partial composite action between concrete slab and steel beam and of partial-strength connections on the seismic response of composite frames is evaluated. To this end, experimental tests were carried out at the Laboratory of the National Technical University of Athens. The specimens, one-story one-bay moment-resisting frames with steel–concrete composite beams, were tested under base acceleration on the shaking table. Experimental results demonstrated that for different degrees of partial interaction between the slab and the beam the response of the specimens varied significantly. Specimens with intermediate and low shear connection degree showed the most favourable performance, in terms of ductile behavior and energy dissipation. The slip between the slab and the beam interface contributed to the energy dissipated by the system and the ductility demands decreased on other parts like the beam ends and the joints. Then, finite element models simulating the behavior of the tested specimens were developed and, after validation, extended parametric studies were carried out. The main objective is to investigate the influence of the partial interaction and the employment of partially restrained beam-to-column joints on the dissipative capacities of composite frames under strong ground motions. Numerical results confirmed the experimental conclusions and revealed that the use of intermediate and low shear connection degrees with partial-strength joints results in an advantageous seismic design.     

钢结构住宅墙体(板)连接节点应用与研究现状

墙体(板)与钢框架结构的连接节点对提高钢框架的抗震性能有重要影响,节点的承载力、刚度是保证墙体(板)与钢框架共同作用的关键因素。对砌块墙体、钢筋混凝土墙体、轻钢龙骨墙板、蒸压加气混凝土墙板和复合墙板与钢框架的连接节点以及节点的破坏形式和作用机制进行概述,提出节点对钢框架抗震性能的影响程度,并对新型连接节点进行展望,为以后的工程应用提供理论与试验依据。     

Seismic-induced fire resistance of composite welded beam-to-column joints with concrete-filled tubes

Major earthquakes in urban areas have often been followed by significant fires that cause extensive damage to property. Therefore, a seismic-induced fire is a scenario that should be addressed properly in performance-based engineering. In this paper, numerical and experimental results of welded steel-concrete composite full-strength beam-to-column joints under post-earthquake fires are described. This was part of a European project aimed at developing fundamental data and prequalification design guidelines of ductile and fire-resistant composite beam-to-column joints with concrete-filled tubes. In detail, seismic and fire analyses were used to design moment-resisting frames endowed with the proposed joint typology. A total of six specimens were designed and subjected to both monotonic and cyclic lateral loads. The specimens were subassemblages of beam-to-column joints, and performed well. Since the scope of the project was to promote joint typologies able to survive a seismic-induced fire, some specimens were pre-damaged before being subjected to fire loadings by imposing monotonic loads equivalent to damage levels induced by seismic loadings. Thus, after fire testing, valuable information about the performance of the proposed joint typology was obtained, and the adequacy of the concurrent seismic and fire design was demonstrated.     

Seismic behaviour of beam-to-column partial-strength joints for steel-concrete composite frames

The paper presents a large experimental campaign carried out on ten steel-concrete composite beam-to-column sub-assemblages employing monotonic and cyclic loading test protocols. Structural members (beams, columns and slabs) were defined through the design of a full-scale 3D prototype frame subjected to PSD testing campaign; main design hypothesis was to dissipate seismic energy in the joints designed as partial-strength. Testing programme on beam-to-column sub-assemblages was executed in order to assess seismic performance varying structural details at beam-to-column connection level and material qualities. Different mechanical connecting systems between concrete slab and column, two end-plate configurations, weak and strong column web panel, two steel qualities and different concrete strengths.The analysis of sub-assemblages performance was realized in two steps: a first step in which the joints behaviour was assessed, characterizing response at local level (e.g. moment-rotation curves); a second step in which the response was assessed at global level (e.g. force-displacement curves). The structural behaviour (i.e. resistance, plastic deformation and stiffness) was evaluated at three stages-identified as initial, service and maximum load-in order to monitor the evolution of sub-assemblage response increasing solicitation level. Moreover, seismic behaviour of specimens-in terms of dissipated energy, ductility, over-strength and equivalent viscous damping-was also executed. Comparison between experimental results was made in order to identify those parameter suitable for improved and reliable seismic behaviour of steel-concrete composite partial-strength joints.     

Experimental investigation of the influence of steel joints upon the flexural capacity of precast concrete columns

In previous studies, the authors have shown that successful modular construction depends on using the correct types of joint connections. In this experimental study, steel beam–column joint connections were shown to be very efficient in facilitating the construction of modular frames while ensuring sufficient flexural moment capacity at the joints to resist lateral loads. This research also included an investigation of the behavior, the crack pattern, and the flexural moment capacity of concrete columns with hybrid composite joints by means of structural experiments on three specimens. Three column specimens were subjected to cyclic loading under displacement control using an oil jack. The influence of including steel sections at the beam–column joint upon the flexural moment capacity of the column was studied, and the use of concrete–steel hybrid composite joints was found to increase the flexural structural performance of the concrete columns. The flexural moment capacity in the maximum load limit state of a concrete column with steel joints was 43.2% greater than that of a conventional reinforced concrete column without steel joints. The steel section in the joint was found to greatly contribute to the flexural moment capacity and to the modular construction technologies.     

Post-earthquake fire and seismic performance of welded steel-concrete composite beam-to-column joints

The performance of steel-concrete composite full strength joints endowed with concrete filled tubes, designed with a multi-objective methodology dealing with seismic actions followed by fire is presented in this paper. In detail, instead of a traditional single-objective design where fire safety and seismic safety are independently achieved and the sequence of seismic and fire loading are not taken into account, the proposed design approach guarantees: (i) both seismic safety and fire safety with regard to accidental actions; (ii) fire safety for at least 15 min fire exposure on a joint characterised by stiffness deterioration and strength degradation due to seismic loading.In order to achieve the multi-objective design, full strength beam-to-composite tubular column joints were designed by means of the component method of Eurocode 4 Part 1-1 and Eurocode 3 Part 1-8, while Eurocode 4 Part 1-2 was considered for fire design. Moreover, to face a seismic-induced fire, they were enhanced with specific joint components which will be detailed.Both the experimental programme and the results provided by seismic tests, pre-damaged tests and fire tests carried out on beam-to-column joints are presented and discussed. The results demonstrate their adequacy in terms of design and performance. Moreover, non-linear numerical simulations clearly show that these joints can be deemed adequate for moment resisting frames of medium ductility class characterised by a behaviour factor of about 4.     

钢筋混凝土柱-钢梁组合框架节点研究进展

钢筋混凝土柱-钢梁(RCS)组合框架是一种新型组合结构体系,它充分地利用和发挥了钢和钢筋混凝土构件各自的优点,是一种低成本、高效率的结构形式.系统地介绍了RCS组合节点和组合框架的研究和应用背景,阐述了RCS组合节点和组合框架的国内外研究现状,重点评述了RCS组合节点的试验研究和数值模拟研究两个方面的进展情况,介绍了RCS组合节点的抗震性能.最后,指出了RCS组合框架结构研究存在的问题和今后的发展趋势.     

A theoretical model for predicting the rotational capacity of steel base joints

The last version of Eurocode 8 has opened the door to the design of Moment Resisting steel Frames (MRFs) promoting the dissipation of the seismic input energy in the joints. Within this framework, in order to provide the basic tools for the prediction of the main parameters characterizing the monotonic and cyclic behaviour of joints, in the last two decades, many experimental and theoretical studies have been carried out. As a result of this effort, in EC3 the formulations for predicting stiffness and resistance of common joint typologies have been codified. Despite this, dealing with the rotation capacity of base joints, there is still a lack of knowledge. In order to overcome the knowledge gap surrounding the evaluation of the plastic rotation capacity of base joints, in this paper the development of a mathematical model able to evaluate the ductility supply of exposed base plate joints is presented. Within the framework of the component method, a mechanical approach for predicting the rotational capacity of base plate joints is set up starting from the definition of the ductility supply of the single joint components. Furthermore, the proposed mechanical model is validated by means of the comparison with three full scale experimental tests carried out at the University of Salerno.     

圆钢管混凝土柱-多向斜交钢梁内隔板式节点数值分析

常州润华环球中心结构复杂,存在大量多向斜交钢梁与圆钢管混凝土柱相连的节点,为研究此类节点的受力性能,利用有限元软件ABAQUS6.10在考虑材料、几何及接触等三重非线性因素的基础上对节点进行了数值分析。结果表明:内隔板式圆钢管混凝土柱-多向斜交钢梁节点能够满足"强节点、弱构件"的抗震设防要求,节点具有较高的承载能力;内隔板能有效地与钢管共同工作,提高节点的承载能力;钢梁之间的夹角对承载力的影响较小。     

设置悬臂梁段拼接耗能的钢框架抗震性能试验研究

为了检验设置悬臂梁段拼接的钢框架抗震性能,对3榀1/2缩尺的一层半单跨钢框架进行了低周往复加载试验,研究拼接节点对整个钢框架抗震性能影响.拼接处翼缘和腹板拼接板均采用8.8级高强度摩擦型螺栓连接,研究了3种钢梁拼接设计方法对结构抗震性能的影响,得到了钢框架的滞回曲线、骨架曲线、耗能能力、刚度退化、层间侧移角、拼接梁段竖...     

木-混凝土梁柱组合节点的受力性能试验研究与理论分析

为探索木-混凝土组合梁在框架结构中运用的可行性,借鉴钢结构顶底翼缘角钢连接,提出了角钢混合连接木-混凝土梁柱组合节点形式,并就其受力性能展开了试验与理论研究.试验中共设计了3个节点试件,即木梁-木柱节点、木-混凝土组合梁与木柱组合节点和木-混凝土组合梁与钢柱组合节点,并对其进行低周反复荷载试验.结果表明:提出的角钢混合...     

钢管混凝土柱与钢梁组合节点的抗震试验

研究了由带钢筋混凝土板的钢管混凝土柱与钢梁组成的组合节点的抗震性能。进行了4个内部节点和2个外部节点的试验,柱顶承受恒定轴力,梁端承受循环荷载。主要参数有:节点形式,柱顶轴力大小及梁截面构造形式。对能反映组合节点韧性、强度退化、耗能能力等抗震性能的几个指标进行分析,结果证明组合节点的抗震性能非常好。     

Seismic performance of CFST column to steel beam joint with RC slab: Experiments

The objective of this research is to investigate the seismic behaviour of the composite joint consisting of circular concrete filled steel tubular (CFST) column and steel beam with reinforced concrete (RC) slab. Six specimens, including four interior and two exterior joints, were tested under constant axially compressive load on the top of the columns and cyclic loads at the ends of the beams. The main experimental parameters were the type of the joint, the axial load level on the CFST column and the section configuration of the beam. Several indexes that could reflect the seismic behaviour of the composite joint, such as the ductility, the strength degradation, and the energy dissipation capacity were analyzed. It was found that the composite joints exhibited favorable seismic performance.     

Analytical behavior of frames with steel beams to concrete-filled steel tubular column

This paper reports the mechanism of composite frames with steel beams connected to concrete-filled square hollow section (SHS) columns. Detailed analysis was carried out on longitudinal stress in steel beams, axial stress distribution in concrete, and concrete stress along the column height and at the connection panel. Parametric studies were conducted to investigate the influence of axial load level, beam-to-column linear stiffness ratio on the structural behavior of composite frames. Simplified hysteretic lateral load (P) versus lateral displacement (Δ) models are proposed for such composite frames.     

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。