The effects of partial shear connection in composite flush end plate joints Part II—Analytical study and design appraisal

The behaviour of composite beams under hogging bending has been successfully simulated using an analytical model derived previously. This paper describes the extension of the work to study the behaviour of composite joints incorporating semi-rigid flush end plate connections. With proper inclusion of the joint characteristics, the model was found to be equally capable of modelling the structural behaviour including the effects of partial shear connection. Experimental results of a novel series of composite joint tests detailed in the accompanying companion paper were compared, in addition to those published in the literature. The analysis results provided close agreement with the various test behaviour. Using the model that has been properly calibrated against experimental results, a systematic parametric study was also undertaken. The outcomes are described herein. In addition, existing design models to predict the strength, stiffness, and ductility of composite joints were also reviewed and compared against the test results. The results emanating from this paper contribute as a total package apart from experimental undertakings to further understand the complex behaviour of the composite joints. This is very beneficial in a design perspective.     

Behaviour of flush end plate joints to concrete-filled steel tubular columns

This paper presents the results of an experimental program for bolted moment connection joints of circular or square concrete filled steel tubular (CFST) columns, and H-shaped steel beams using high-strength blind bolts. In order to investigate the static performance and failure modes of the blind bolted connection, an experimental program was conducted involving four sub-assemblages of cruciform beam-to-column joints subjected to monotonic loading. Moment-rotation relationships of the tested connections were obtained and their performance was evaluated in terms of their stiffness, moment capacities and ductility. The test parameters varied were the column section type and the thickness of the end plate. The results showed that the proposed blind bolted connection, which behaves in a semi-rigid and partial strength manner according to the EC3 specification, displays reasonable strength and stiffness. The rotation capacity of this type of connection to square or circular CFST columns exceeds 70 mrad and this satisfies the ductility requirements for earthquake-resistance in most aseismic regions. The blind bolted connection is shown to be a reliable and effective solution for moment-resisting composite frame structures.     

Non-linear analysis of steel-concrete composite frames with full and partial shear connection subjected to seismic loads

The seismic performance of moment-resisting frames consisting of steel-concrete composite beams with full and partial shear connection is investigated. To this end, six full scale composite substructures with headed stud shear connectors have been tested and the corresponding inelastic response to both monotonic and variable reversed displacements have been investigated. Three-dimensional finite element models of the substructures set with the ABAQUS code and based on shell elements are established in order to evaluate different modelling assumptions and local effects; and to calibrate a one-dimensional model conceived with the Drain-3DX code relying on layered beam-column elements. The one-dimensional model is then exploited for a parametric study on two four-storey frames by means of non-linear dynamic analyses. The analyses have revealed that composite frames with a low shear connection degree of about 0.4 perform as well as their companion frames with full shear connection under severe seismic loads. Nonetheless, the shear connection degree should be high enough in order to protect shear connectors in the central part of beams from failure. Although their equivalent damping is not very high, shear connectors could reduce the ductility demand on other parts of a composite frame, such as beam ends or partial strength beam-to-column joints. This design option could provide a further means to achieve a favourable performance of a composite moment-resisting frame, in addition to the benefit of cost reduction.     

Shrinkage effects on the flexural stiffness of composite beams with solid concrete slabs: An experimental study

This paper describes the testing of three full-scale simply-supported composite steel-concrete beams. The specimens were representative of a typical secondary beam used in composite flooring systems and were designed in accordance with Australian guidelines with a degree of shear connection equal to 0.5. Two beams were cast unpropped while the third was prepared under propped conditions. The beams were loaded to failure 18 months from concrete casting by a point load applied at mid-span. During this period the specimens were monitored to collect information on their time-dependent behaviour. Extensive data was measured during the ultimate tests, i.e. deflection at quarter points, slip and strain readings. Standard coupon and cylinder tests provided the instantaneous material properties of the materials. Push-out tests were performed to obtain information on the response of the shear connectors. The measured ultimate strengths of the beams were greater than those calculated based on rigid-plastic analysis using the actual properties obtained from standard material tests. Although this information is very useful for the calibration of theoretical models and design recommendations, the main contribution of this paper is the recognition of the detrimental effects at service conditions of shrinkage in composite members incorporating a solid slab. This shrinkage was observed to cause the composite flexural stiffness to degenerate to the value calculated with no shear interaction for a certain range of loading.     

Experimental study on shear connection in unfilled composite steel grid bridge deck

This paper describes the results of experimental tests on the shear connection of the unfilled composite steel grid deck. To investigate the slip behavior and the shear strength of the connection, a total of 14 push-out specimens with variables for the number of holes, the area of reinforcements through holes, and the reinforcement diameter, were fabricated and push-out tests were performed. From the test results, each contribution affecting the shear resistance of the connection such as the friction force between the steel beam and the concrete, the concrete dowels, and the shear force due to reinforcement bars, was evaluated experimentally. An analytical expression was developed based on an existing formula used to predict the shear resistance of the connection. The equation predicts the shear strength to within 10% of the experimental results for the connection with reinforcing bars.     

部分剪力连接预应力组合箱梁受弯性能试验研究

为研究剪力连接程度对预应力钢与混凝土组合箱梁的界面相对滑移、挠度及受弯承载力的影响,设计制作了4根不同剪力连接程度预应力钢与混凝土组合箱梁模型试件,采用三分点对称加载,对其进行了受弯性能试验研究。研究表明,随着剪力连接程度的降低,变形及界面滑移明显增大,承载能力有所降低,但并不与剪力连接程度成正比关系,连接程度为0.5的组合箱梁承载力较完全连接组合箱梁降低不到30%。结合国内外7根部分剪力连接组合梁试验资料, 运用最小二乘法,对欧洲规范EC4中关于部分剪力连接组合梁承载力计算公式进行了修正。结果表明,修正值与实测值吻合良好,满足工程精度要求。     

Finite element modelling of composite beams with full and partial shear connection

The present investigation focuses on the evaluation of full and partial shear connection in composite beams using the commercial finite element (FE) software ANSYS. The proposed three-dimensional FE model is able to simulate the overall flexural behaviour of simply supported composite beams subjected to either concentrated or uniformly distributed loads. This covers: load deflection behaviour, longitudinal slip at the steel-concrete interface, distribution of stud shear force and failure modes. The reliability of the model is demonstrated by comparisons with experiments and with alternative numerical analyses. This is followed by an extensive parametric study using the calibrated FE model. The paper also discusses in detail several numerical modelling issues related to potential convergence problems, loading strategies and computer efficiency. The accuracy and simplicity of the proposed model make it suitable to predict and/or complement experimental investigations.     

不同构造特征的H形钢梁-柱半刚性连接节点抗震性能试验研究及有限元分析

通过对6个具有不同构造特征和几何尺寸的H形钢梁-柱半刚性连接试件进行拟静力试验和有限元分析,得到节点弯矩-转角（M-θ）滞回曲线及M-θ骨架曲线,分析了试件的极限弯矩、连接初始刚度、延性、耗能性等性能。研究结果表明：对于几何尺寸相近的梁柱端板连接,柱强轴方向翼缘-端板连接的极限弯矩及初始连接刚度远高于柱弱轴方向的腹板-端板连接,且后者的延性也比较差;采用弱轴方向的端板连接,应在腹板的两个方向同时设置加劲板,以保证有足够的连接强度和延性;在柱翼缘设置抗剪托板对于梁柱外伸端板连接性能无明显影响,而且延性还有降低趋势。     

各国半刚性梁柱节点端板厚度计算方法的比较

对半刚性钢框架梁柱连接的常见形式———外伸端板高强螺栓节点端板厚度的计算方法进行了探讨 ,比较了各国算法的优缺点 ,提出了螺栓分布位置对端板厚度的影响     

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。     

平端板连接半刚性梁柱组合节点的抗弯承载力Ⅰ:负弯矩作用

基于现有试验数据以及组合节点抗弯承载力的研究成果,利用塑性分析方法和组件法,提出一种平端板连接组合节点承受负弯矩作用时,其塑性抗弯承载力的计算方法。探讨组合节点的实效模式,给出其各组件承载力的计算方法,组件包括钢筋、螺栓、柱腹板、梁翼缘、混凝土楼板等。考虑中和轴出现的6种位置:混凝土楼板内;钢梁上翼缘内;钢梁腹板内,所有螺栓受压;前m-1排螺栓受拉,第m排部分受拉,其余受压;1～m排完全受拉;只有钢梁下翼缘受压。该方法可以考虑节点承受非对称荷载作用的情况以及作用在连接上的剪力、高强度螺栓撬力等因素的影响。如果将组合连接的配筋率取为零,不考虑组合楼板的影响,使用该方法同样可以计算平端板连接梁柱纯钢节点在承受负弯矩作用时的抗弯承载力。     

按部分剪力连接计算压型钢板-混凝土组合板承载力的简化方法

提出多种荷载作用下,简支压型钢板-混凝土组合板承载力的部分剪力连接简化计算方法。分析组合板纵向剪切破坏的部分剪力连接理论模型,阐明组合板纵向剪切破坏的机理,以及控制截面位置和极限荷载的求解思路。通过公式推导,分别得到了组合板在两点对称荷载和均布荷载作用下的承载力计算公式。在此基础上,提出点荷载和均布荷载共同作用下的组合板承载力计算方法,通过参数分析,对该方法进行简化,得到多个荷载作用下组合板承载力的简化计算公式。结合12个简支组合板的静力试验结果,进行公式验证,计算结果与试验值吻合良好。通过小比例滑块试验得到压型钢板与混凝土的界面强度参数,即可用该方法计算组合板的承载力。     

Performance of shear connection in composite beams with profiled steel sheeting

This paper describes the structural performance of shear connection in composite beams with profiled steel sheeting. An accurate and efficient nonlinear finite element model was developed to study the behaviour of headed stud shear connectors welded through-deck. The profiled steel sheeting had transverse ribs perpendicular to the steel beam. The material nonlinearities of concrete, headed stud, profiled steel sheeting, reinforcement and steel beam were included in the finite element model. The capacity of shear connection, load-slip behaviour of the headed stud, and failure modes were predicted. The results obtained from the finite element analysis were verified against experimental results. An extensive parametric study was conducted to study the effects on the capacity and behaviour of shear connection by changing the profiled steel sheeting geometries, the diameter and height of the headed stud, as well as the strength of concrete. The capacities of shear connection obtained from the finite element analysis were compared with the design strengths calculated using the American Specification, British Standard and European Code for headed stud shear connectors in composite slabs with profiled steel sheeting perpendicular to the steel beam. It is found that the design rules specified in the American and British specifications overestimated the capacity of shear connection, but the design rules specified in the European Code were generally conservative.     

Long-term deflection of cracked composite beams with nonlinear partial shear interaction: I — Finite element modeling

In this paper, a uniaxial nonlinear finite element procedure for modeling the long-term behavior of composite beams at the serviceability limit state is presented. The finite element procedure follows a displacement-based approach. The nonlinear load-slip relationship of shear connectors as well as the creep, shrinkage, and cracking of concrete slab are accounted for in the proposed finite element procedure. The effects of creep and shrinkage of the concrete slab are considered only for uncracked concrete. The nonlinear iterative procedure adopted for tracking the nonlinear behavior of the composite beam implemented the total nodal deformations, not the incremental deformations, as the independent variables of any iteration. The results of the proposed finite element procedure were compared with the experimental results of four composite beams reported in the literature. The proposed finite element procedure was capable of predicting the deflections and stresses of the four beams with an acceptable degree of accuracy. A parametric study was conducted to study the effect of the nonlinearity of load-slip relationship of shear connectors and the cracking of the concrete deck on the long-term behavior of simply-supported composite beams.     

剪切连接度对组合梁工作性能的影响

为探讨剪切连接度对组合梁工作性能的影响,采用有限元软件ANSYS建立模型,并通过组合梁模型计算分析了剪切连接度对滑移、截面应变分布、挠度及极限承载力的影响,得到了一些有意义的结论。     

预制墙体钢板抗剪键连接数值模拟研究

通过对预制装配式剪力墙钢板抗剪键连接形式进行试验和数值模拟研究,分析了该种连接形式受力性能,包括承载力、抗震性能和延性性质,试验共设计了五组尺寸相同试件,采用ABAQUS有限元软件对其模拟,将得出数值结果与试验结果作了对比,结果表明:该种连接形式具有一定的承载力,在轴压为正时试件具有很好的延性,试验和数值结果较好吻合。     

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。     

关于板柱结构的适用高度

在美国及其他一些国家,板柱结构是最常被采用的结构形式之一。它的使用灵活,建筑净空较高,易于施工。但它的抗震性能究竟如何,令人怀疑,而震害又屡有发生,板柱节点的脆性破坏,如何防止?本文介绍了国外一些板柱结构的震害情况以及其原因的分析,并介绍国外规范对板柱结构的要求,结合新的抗震规范,作者提出一些设计建议供参考,使板柱-抗震墙结构可以建造得较高,以满足使用上的要求。     

三边约束组合钢板剪力墙单元抗震性能试验研究

提出一种适用于钢框架结构体系的新型组合钢板剪力墙单元,它由三边固接一边弹性约束的钢板和预制水泥基覆板组合而成。通过三种钢板宽厚比的纯钢板剪力墙和组合钢板剪力墙共6个试件的静力加载试验,考察宽厚比对三边约束钢板受剪承载力的影响,同时考察分析预制水泥基覆板对内嵌钢板的屈曲承载力和受剪承载力的影响。试验结果表明：宽厚比决定了钢板初始抗侧性能和屈曲模态;预制水泥基覆板对提高剪力墙单元受剪承载力和钢板屈曲承载力有一定帮助;通过有效抑制内嵌墙板的面外屈曲,可以提高组合钢板剪力墙单元的抗震性能。     

An investigation of the block shear strength of coped beams with a welded clip angle connection — Part I: Experimental study

The ends of a coped beam are commonly connected to the web of a girder by double clip angles. The clip angles may either be bolted or welded to the web of the beam. One of the potential modes for the failure of the clip angle connection is the block shear of the beam web material. To investigate the strength and the behavior of the block shear of coped beams with welded end connections, ten full-scale coped beam tests were conducted. The test parameters included the aspect ratio of the clip angles, the web shear and tension area around the clip angles, the web thickness, beam section depth, cope length, and connection position. The test results indicated that the specimens failed, developing either tension fractures of the web near the bottom of the clip angles or local web buckling near the end of the cope. Although the final failure mode of the six specimens was local web buckling, it was observed during the tests that these specimens exhibited a significant deformation of the block shear type prior to reaching their final failure mode. No shear fracture was observed in all of the tests. A comparison between the ultimate loads in the test and the predictions using the current design equations indicates that the current design standards such as the AISC-LRFD, CSA-S16-01, Eurocode 3, BS5950-1:2000, AIJ and GB50017, are inconsistent in predicting the block shear strength of coped beams with welded end connections. The analytical study of the strength of the test specimens using the finite element method, a parametric study, and a proposed design model for designing block shears for coped beams with welded clip angles are included in a companion paper.