方钢管混凝土柱节点抗剪受力性能的研究

为研究方钢管混凝土柱与钢-混凝土组合梁连接节点的破坏特征和抗震性能,进行了3个内隔板式节点、2个外隔板式节点和1个栓钉内锚固式节点的低周反复荷载试验。在此基础上,对方钢管混凝土柱节点的抗剪受力性能进行了分析,将节点域抗剪贡献分为三部分进行研究,包括:节点域钢管腹板的抗剪贡献、节点域钢管翼缘与内隔板或外隔板组成的钢板框架的抗剪贡献以及节点域混凝土的抗剪贡献,由此得到了相应各部分剪力-剪切变形曲线的计算方法。根据剪切变形协调的条件将上述三部分曲线进行叠加,就可以得到节点的剪力-剪切变形骨架线。此后,提出了卸载线和再加载线的简化确定方法,从而得到了方钢管混凝土柱节点剪力-剪切变形曲线的恢复力模型。理论模型与多组试验结果相比,基本吻合,虽然在再加载刚度和耗能性能方面存在一定的误差,但是整体而言仍然具有参考意义。在此基础上,提出了方钢管混凝土柱节点屈服抗剪承载力和极限抗剪承载力的计算公式,从而为工程设计提供了实际依据。     

半刚性钢框架梁柱弱轴端板连接的试验研究和有限元分析

空间钢框架结构的高等分析必须考虑梁柱弱轴连接的抗弯性能。为研究钢框架梁柱节点弱轴端板连接的性能,进行2个边柱弱轴端板连接试件和2个中柱弱轴端板连接试件的单调加载试验,并建立有限元分析模型。为与试验结果对比,有限元分析采用的构件几何尺寸、材料特性等参数和加载过程均与试验相同,对比显示有限元分析结果和试验结果吻合较好。明确了弱轴端板连接的应力分布、塑性发展、变形特点和破坏模式。研究表明:①梁柱弱轴端板连接具备一定的转动变形能力和良好的弯矩承载能力,在端板受拉区可能形成塑性铰;②梁端弯矩较小时弯矩-转角曲线就体现出非线性的性质,弱轴端板连接属于典型的半刚性连接;③中柱节点和边柱节点弱轴端板连接的承载力基本一样,但半刚性特性差别很大。     

The seismic performance of new detailing for RCS connections

Over the past few decades considerable experimental and numerical studies have been conducted on the Reinforced Concrete columns to Steel beams (RCS) connections. Most of those researches have focused on studying the joint failure modes and ultimate joint strength of specimens utilizing strong beams and columns with weak joints. In this paper, two interior RCS connections were designed based on the Strong Column–Weak Beam (SCWB) criterion. Both specimens were tested under quasi-static reversed cyclic loading. The tested specimens were modeled by a finite element method, which verified with experimental results. Several models with different joint details were investigated using the verified FEM. Lateral load–story drift response, vertical bearing stresses, joint shear forces, shear strains at the joints, and axial stresses of the joint stirrups were studied in those models. The results indicated that the performance of models directly depends on joint detailing, effectiveness of shear keys, and the amount of confinement provided for a joint region.     

现浇柱叠合梁框架节点抗震性能试验研究

以一幢六层现浇柱叠合梁框架实际工程为背景,按照强柱弱梁、强节点弱构件等原则进行设计,取4个不同位置的现浇柱叠合梁框架节点进行低周反复荷载下的足尺模型试验,对现浇柱叠合梁框架节点的破坏形态、滞回曲线、位移延性、刚度退化、耗能能力、预制梁与预制板之间和预制板与现浇板之间的滑移等进行了较系统的研究。结果表明:4个现浇柱叠合梁框架节点均实现了强柱弱梁、强节点弱构件的设计目标,破坏形态均为梁端受弯破坏形式,节点核心区仅有少量细小裂缝;边节点、中节点和平节点的初裂位置为梁中新旧混凝土界面处,而角节点的初裂发生在柱上;与其他2个节点相比,中节点和边节点的滞回曲线饱满;中节点、边节点和平节点的位移延性高于角节点;4个节点的刚度退化规律基本一致。研究成果可为现浇柱叠合梁框架在地震区的推广应用提供技术依据和基础数据。     

方钢管混凝土柱与钢-混凝土组合梁连接的内隔板式节点的抗震性能试验研究

为研究方钢管混凝土柱与钢-混凝土组合梁连接的内隔板式节点的抗震性能,本文对3个节点试件进行了低周反复荷载试验,在此基础上对节点的受力过程、破坏形态、滞回曲线、骨架曲线、变形恢复能力、延性、刚度退化和耗能能力等抗震性能进行了较为深入的研究与分析。试验结果表明:内隔板式节点能够有效地传递梁端弯矩及剪力,其滞回曲线呈明显的梭形,单周耗能能力较强;节点在梁端塑性铰破坏模式下具有较好的承载力、耗能性能及滞回特征,而在剪切破坏及局部焊接破坏模式下则延性较低,抗震性能相对较差;节点在整个加载过程中刚度退化明显,持续均匀,同时表现出一定的变形恢复能力;楼板组合作用对于节点的抗震性能具有一定程度的影响。     

预应力混凝土中柱节点在剪力和弯矩作用下的分析研究

本文采用塑性极限分析方法并利用节点的对称性，建立了预应力混凝土板柱中节点在剪力和不平衡弯矩作用下抗冲切和抗弯的相关方程。与国内外有关的试验数据的比较表明，该计算公式具有较好的精度，可以在实际工程中应用。     

方钢管混凝土边柱节点抗震性能试验研究

通过柱端加载的3个内隔板三面焊接的方钢管混凝土柱-H形钢梁节点的低周反复荷载试验,研究其不同轴压比情况下节点的破坏模式、延性、耗能性能等。试验结果表明,内隔板与柱壁未焊一侧受力约为内隔板与柱壁焊接一侧的1/3,内隔板未焊一端梁翼缘侧面柱壁间焊缝被撕裂,内隔板与柱壁板焊接一侧梁翼缘在柱顶位移约70mm时发生局部屈曲。研究结果表明,节点具有很好的延性和耗能能力,层间转角位移延性系数μ=3.40~3.45,弹性和弹塑性层间位移角分别为φy=0.0075~0.0083 rad、φu=0.0279~0.0286 rad,等效粘滞阻尼系数he=0.247~0.462。满足现行抗震规范的要求。三面焊接的内隔板式节点可以用于方钢管混凝土边柱节点。     

Seismic behavior of connections composed of CFSSTCs and steel-concrete composite beams — finite element analysis

Based on the experimental results of connections composed of concrete-filled square steel tubular columns (CFSSTCs) and steel-concrete composite beams with interior diaphragms, exterior diaphragms, or anchored studs, 3-D nonlinear finite element models were established to analyze the mechanical properties of these three types of connection using ANSYS. Finite element analyses were conducted under both monotonic loading and cyclic loading. The load-displacement and shear force-deformation curves of the finite element analyses are in agreement with those of the tests in terms of strength and unloading stiffness. Parametric analyses were conducted on the connections with exterior diaphragms under monotonic loading to investigate the influences of axial load ratio, width to thickness ratio, and dimensions of exterior diaphragms on the connection behavior. It was found that the strength and stiffness are less influenced by the axial load ratio and the dimensions of the exterior diaphragms, but more influenced by the width to thickness ratio of the steel tube under shear failure mode.     

A simplified numerical model for post-tensioned steel connections with bolted angles

Post-tensioned (PT) self-centering beam–column connections has been developed for its good seismic performance. Many researchers have investigated its mechanical behavior by numerical or experimental method. Prior researches have indicated that the analysis by elaborate FE models is very time consuming. To overcome this disadvantage, a simplified numerical model was established in this paper. The accuracy of results derived by this model was validated against prior investigations on interior PT connections with top-and-seat angles. Influence of initial PT force on mechanical behavior of PT connection was investigated. The Geometric and material nonlinearities, and strands can be considered in the modeling. A planar steel frame structure was established and hysteretic analysis was conducted. Results indicated that the computational cost can be greatly reduced by this model.     

钢筋砼板柱结点冲剪强度计算

本文回顾了前人的钢筋砼板柱结点冲剪试验结果,分析了其所显示的裂缝开展过程和破坏形式。以这些分析为基础,分别对高、低配筋率的板柱节点,用屈服线和板梁模型,推导出中柱结点的强度计算公式。计算结果与试验对比,符合较好,并能解释各种试验中所观测到的强度影响因素。     

无粘结预应力混凝土平板-T形中柱节点抗震性能试验研究

在6个1:1.5缩尺无粘结预应力混凝土平板-T形中柱节点试件的试验基础上,本文对各试件在低周反复荷载作用下的受力过程和破坏特性进行描述,分析了无粘结预应力钢筋应力增量变化特点、板暗梁面筋和节点区附近板暗梁箍筋的应力变化特点,对比了T形柱不同截面参数和不平衡弯矩不同加载方向对该节点抗震性能和不平衡弯矩分配的影响,对该节点的抗震性能进行了评价。试验结果表明,节点的不平衡弯矩主要靠板的弯曲作用来传递,T形柱腹板长度c1对节点的抗震性能和不平衡弯矩分配系数等方面具有决定作用。文中采用隔离体方法对板柱节点进行受力分析,推导了节点剪力传递弯矩系数的计算公式,提出了节点理论抗弯承载力的计算方法。试验结果对工程设计有一定的参考价值。     

Joint behavior and design procedure of a through plate connection for steel beam to hollow or concrete‐filled tubular columns

The through plate connection has a practical reliable configuration for fully restrained connections for a steel I‐beam to hollow or concrete‐filled tubular columns in seismic areas. Based on experimental programs of authors on interior planar moment connections via through plate technique, this paper presents the outcome of the studies focusing on the joint behavior and the shear transfer in the panel zone of through plate connection. Based on the conducted approved three full‐scale tests, the behavior of connection components and panel zone shear force were investigated accurately in order to provide useful information and key parameters to facilitate design calculations and proportioning the connection. The contribution of each component in the total shear capacity of the panel zone region was determined. Load transfer mechanisms were explained and by quantifying the portion of load transfer paths, the calculation approach was described for design purpose. The proposed design procedure was validated for a wide range of beam to column connections using finite element models. Verified numerical models were used to conduct parametric studies. The numerical results revealed that the proposed analysis method can predict well the induced demand in the connection components and also the design procedure is suitable and secure for all cases.     

Seismic behavior of connections composed of CFSSTCs and steel-concrete composite beams—experimental study

In order to investigate the seismic behavior of connections composed of concrete-filled square steel tubular columns and steel-concrete composite beams, fourteen cruciform connection specimens were tested. The strength, deformation, and energy dissipation capacity of these composite connections were analyzed. The test results showed that the strength of connections with interior diaphragms is adequate, but their ductility is low. Also, the deformation capacity of connections with anchored studs is good, but their strength is low. In comparison, the connections with exterior diaphragms have adequate strength, good ductility, and high-energy dissipation capacity, and as a result, it can be concluded that they are more suitable for applications in moment resisting frames in seismic regions.     

方钢管混凝土柱和钢-混凝土组合梁连接节点的抗震性能试验研究

为研究方钢管混凝土柱和钢-混凝土组合梁的抗震性能,对14个十字型连接构件进行试验。分析了这些构件的强度、变形和耗能能力。试验结果显示:内隔板式节点的强度是足够的,但延性较差。同时,螺栓节点具有较强的变形能力但其强度较低。相比之下,外隔板式节点具有足够的强度、良好的延性和高耗能能力,因此这类节点更适用于地震区抗弯结构的设计。     

Behavior of semi‐rigid connections and semi‐rigid frames

Semi‐rigid connections are widely used in different countries. These connections are usually used in semi‐rigid frames with bracing system. Considering the frequent use of these connections, studying their behavior as an individual connection or as a frame with a semi‐rigid connection is of great importance. In this paper, moment–rotation behavior of bolted angle connection as a usual semi‐rigid connection is studied, and the affecting factors on there are investigated. Finite element connection models are developed. These models are verified by comparing the results of finite element analyses with the results of experimental test, and the verified models are used to investigate the behavior of the connections. The behavior of semi‐rigid frame with bolted angle connection is then studied conducting time‐history analyses. The results show that the increase in shear stiffness of angle bolted connections significantly decreases the lateral drift and increase the frame stability against lateral loading. Copyright © 2012 John Wiley & Sons, Ltd.     

Performance of bolted angle connections in progressive collapse of steel frames

This paper is mainly focused on the behaviour of bolted top‐seat angle connections with double web angles, categorized as partially restrained connections, in progressive collapse of semi‐rigid steel frames due to sudden column loss. The main characteristics of this type of loading are declared and the effect of the imposed boundary conditions on the motivated elements is depicted. To study the performance of frame connections under these conditions, refined nonlinear finite element modelling technique is used. The models are created based on the previous experimental studies and their accuracy is examined through a comparison to the results of these tests. New models are created under conditions of the progressive collapse and the behaviour of the connections is studied. The study showed that due to the applied boundary conditions, the connections behave stiffer and show a higher moment capacity. Based on the results of the numerical models, equations are presented to estimate the moment‐rotation response of the studied connections under progressive collapse conditions based on the beam and connection mechanical and geometrical properties and the connection rotation. Copyright © 2009 John Wiley & Sons, Ltd.     

钢筋混凝土板柱节点的抗震性能研究

共进行了6个大比例尺板柱节点在竖向荷载和水平反复荷载作用下的试验,在对板柱节点试验结果分析研究的基础上,采用塑性极限方法,对钢筋混凝土板柱节点在冲切力和不平衡弯矩共同作用下的承载能力进行了研究,推导出板柱节点抗冲切和抗弯强度相关方程,并简化为实用计算公式。与本文作者和国内外有关试验数据的比较表明,本文提出的计算公式具有较高的精度。     

混凝土十字形中柱的板柱连接抗震性能试验研究

通过两个大比例十字形中柱的板柱连接试件(其中一个试件配置抗冲切锚栓),在竖向荷载和低周反复水平荷载作用下的试验,探讨了十字形中柱的板柱连接在模拟地震作用下的裂缝形态、破坏特征、混凝土以及钢筋的应变、滞回特性、位移延性等一系列受力特性。试验研究表明,十字形中柱的板柱连接与传统方形中柱的板柱连接受力性能类似,两个试件的极限侧移比都远超过了1.5%的侧移比限值要求,因此在板柱结构中引入十字形柱是可行的;配置抗冲切锚栓可以显著地提高板柱连接的承载能力和延性。此外,根据试验给出了十字形中柱的冲切临界面形式,并提出了其类似极惯性矩的计算公式,从而使十字形中柱的板柱连接可以应用现行规范的方法进行承载力分析计算,采用该方法的分析结果与试验结果符合较好。     

A new model to simulate joint shear behavior of poorly detailed beam-column connections in RC structures under seismic loads, Part I: Exterior joints

A new model that can simulate the shear behavior of reinforced concrete connections in structures subjected to seismic loads is proposed. The model uses limiting principal tensile stress in the joint as the failure criteria so that due consideration is given to the axial load on the column. The spring characteristics are based on the actual deformations taking place in the sub-assemblage due to joint shear distortion. The model can be easily implemented in any commercial nonlinear analysis package and does not need any special element or subroutine. The model is more rational than the rotational spring models and at the same time being easier to implement in analysis than the multiple spring models. The formulations to obtain the spring characteristics are given in the paper. Currently the model is used to perform nonlinear static analysis for the joints, however, the same can be utilized for the nonlinear dynamic analysis too with an associated hysteretic rule. Highly promising results are obtained using the proposed model for the cases against which the model is validated. This paper focuses on the modeling of exterior joints. An extension to interior joints will be presented later.     

密封养护混凝土内部湿度与收缩的一体化试验与模拟

对3种强度等级的混凝土进行了密封养护下内部相对湿度和自由变形的试验测定,获得了从混凝土浇注开始到77d龄期混凝土内部湿度和自由变形的发展数据,同时对混凝土因水泥水化引发的自干燥和自收缩问题进行了模拟.结果表明：混凝土内部相对湿度和收缩具有较好的同步性;混凝土内部湿度变化可以看作是其自收缩变化的驱动力;水灰比越小,自干燥引起的混凝土内部相对湿度下降幅度越大,密封条件下混凝土的收缩也越大;以水泥水化度和混凝土内部湿度为内因的自干燥与自收缩模型较好地模拟了密封条件下混凝土内部湿度变化与相应的自收缩发展.试验结果与模型预测值吻合良好,模型可用于不同养护环境下混凝土自干燥与自收缩的分析预测.