对组合钢梁-预制空心板中栓钉连接件的性能分析

在钢-混凝土组合梁中,剪切连接件的机械作用使得纵向剪力转移到钢翼缘/混凝土板的接合处。这种转移能力取决于剪切连接件的强度和混凝土板抵抗由剪力高度集中所导致的纵向开裂的能力。大多数对组合结构的分析都集中在传统的钢筋混凝土和金属面板结构,而对预制空心板中栓钉的剪切能力研究很少。本文对带栓钉的预制空心板组合梁结构提出标准的推力试验方法。一共进行7组测试性试验,试验结果显示新方法符合钢筋混凝土楼板规范要求。在确定这个新的标准方法后,对栓钉进行了72个足尺推力试验,确定了该类型连接件的性能,通过分析试验结果,还指出了各类参数对连接件强度和延性的作用。本文还提出了这种剪力连接件的设计公式。     

Bolted shear connectors vs. headed studs behaviour in push-out tests

Prefabrication of concrete slabs reduces construction time for composite steel–concrete buildings and bridges. Different alternatives for shear connectors (bolts and headed studs) are analysed here to gain better insight in failure modes of shear connector in order to improve competiveness of prefabricated composite structures. Casting of high strength bolted shear connectors in prefabricated concrete slabs offers the higher level of prefabrication comparing to a standard method of grouting welded headed studs in envisaged pockets of concrete slabs. In addition, bolted shear connectors can easily be dismantled together with the concrete slab thus allowing the improved sustainability of the construction, simpler maintenance, and development of modular structural systems. Bolted shear connectors have been rarely used in construction, actually just for rehabilitation works, because there is a lack of design recommendation. The first step towards the design recommendation is to understand the difference between the headed shear studs and the bolted shear connectors in a push-out test. Push-out tests, according to EN1994-1-1, using 4 M16 — grade 8.8 bolts with embedded nut in the same layout and test set-up as for previously investigated headed studs were performed. Finite element models for both shear connectors were created, and good match with experimental data was obtained. Basic shear connector properties such as: shear resistance, stiffness, ductility and failure modes have been compared and discussed in detail by using experimental and FE results. Parametric FE analyses of shear connector's height are carried out and shear resistance reduction factor has been proposed for bolted shear connectors.     

Experimental study on semi-rigid composite joints with steel beams and precast hollowcore slabs

The concept of semi-rigid composite connection has been widely researched in the past; however, most of the researches are limited to composite joints with metal deck flooring and solid concrete slabs. Composite construction incorporating precast concrete hollowcore slabs (HCU) is a recently developed composite floor system for buildings. The research on the structural behaviour of the semi-rigid composite joints with HCU is new and without any previous experimental database. In this paper, eight full-scale tests of beam-to-column semi-rigid composite joints with steel beams and precast hollowcore slabs are reported. The variables are stud spacing, degree of the shear connections, area of the longitudinal reinforcement and slab thickness. The test set-up and instrumentation is described in detail. The experimental behaviour is analysed and based on the test data the structural behaviour of these semi-rigid composite joints is discussed. Based on the experimental data, a simplified method to predict rotation and moment capacity for this type of composite connection is proposed.     

陶粒混凝土-开孔薄壁钢梁组合楼板的受力性能研究

由腹板开孔且翼缘卷边的H形薄壁钢梁和陶粒混凝土预制板经后浇砂浆和抗剪键组装而成的组合楼板,具有轻质、高强、无需支模、装配化程度高等优势。为研究该类组合楼板的受力性能,对6组不同构造的两边简支组合楼板试件开展静载试验,分析抗剪键分布及薄壁钢壁厚的变化对组合楼板整体受力性能的影响。结果表明：对应等效均布荷载2kN/m2的组合楼板,中心挠度远小于L/500,能够承担的最大荷载值为13.25kN/m2;当混凝土严重开裂且板跨中最大挠度达到L/45时,组合楼板试件并未出现整体塌落;主钢梁上抗剪栓钉的增加,对提高组合楼板的极限荷载和整体刚度均不明显;边梁增设抗剪栓钉对组合楼板的屈服荷载及整体刚度均产生显著影响,当边梁设置与主梁同样的抗剪栓钉时,屈服荷载和整体刚度增幅分别为82.1%和35.6%。     

Stahl‐Beton‐Haftverbindungen für Verbundbrücken – Versuche und Bemessung

Connections by adherence for steel‐concrete composite bridges – tests and design. This paper presents experimental and analytical research that was conducted on new connections “by adherence” for steel‐concrete composite bridges. Their resistance is due to the frictional shear resistance of different interfaces positioned in a judicious manner. These connections makes it possible to erect the structure quickly with full‐depth precast concrete slabs, while the concreting works on site are as much as possible limited. Experimental results show that these connections exhibit a high resistance to horizontal shear forces and are very stiff compared to traditional connectors (headed studs). However, their ductility is limited. Based on the experimental results, a calculation model, taking into account the deformation observed during the tests and behavior laws for interfaces, was then developed and used in a parametric study. Some results are presented and discussed. A simplified method for determining the resistance of these connections, based on these results, some design rules as well as some recommendations for construction are finally proposed. The behavior of steel‐concrete composite beams with connections by adherence is also shortly discussed.     

Trag‐ und Ermüdungsverhalten liegender Kopfbolzendübel unter Quer‐ und Längsschub

Structural and fatigue behaviour of horizontally lying shear studs subjected to vertical and longitudinal shear. In consideration of structural, manufacturing and economic aspects new interesting composite cross sections for buildings and bridges consisting of reinforced concrete and structural steel lead to a horizontally lying arrangement of headed shear studs influenced by edge proximity. Compared to common vertical shear studs the relatively small distance of horizontally lying shear studs from the edge of the slab leads to different bedding conditions of the connectors within the surrounding reinforced concrete material, which results in differing structural and fatigue behaviour of this type of shear connection. For future applications of horizontally lying shear studs on the basis of experimental and theoretical investigations design rules for the shear connection subjected to monotonic vertical shear, monotonic vertical and longitudinal shear and cyclic longitudinal shear are presented.     

Neue Untersuchungen zum Ermüdungsverhalten von Verbundträgern aus hochfesten Werkstoffen mit Kopfbolzendübeln und Puzzleleiste

New investigations on the fatigue behavior of composite beams made of high strength materials with two different kinds of shear connection. Scope of the research project [1] was the investigation of the fatigue behaviour of different shear connectors (headed studs ∅︁ 22 mm and puzzle‐strip) together with high strength materials (steel S 460 and concrete C 80/95). For both types of shear connectors cyclic push‐out‐tests as well as large scale experiments with composite beams under cyclic loading have been carried out. The headed studs failed after a mean lifetime of 2,3 million cycles, the residual strength after 1 million cycles was reduced by about 25% compared to the static push‐out strength. In the puzzle‐strip cracks were visible, however, the residual strength was not reduced at all. Further, the push‐out tests with headed studs show a slight improvement of the fatigue behaviour using high strongth concrete (HSC). The cyclic beam tests show that the prediction of the fatigue according to EC 4 – as for specimens with normal strength materials – is not satisfactory. A good prediction of the crack propagation (and fatigue) can rather be achieved by using a crack‐slip‐relationship [6]. Also for shear joints with continuous puzzle‐strips a threshold value can be determined by fracture mechanics to which no further crack propagation (theoretically) occurs. However, this depends on the state of the cutting‐induced heat treatment of the surface material and on the surface roughness.     

Behavior and strength of headed stud shear connectors in ultra-high performance concrete of composite bridges

This study presents an experimental and numerical investigation on the static behavior of headed stud shear connectors in ultra-high performance concrete (UHPC) of composite bridges. Four push-out specimens were tested. It was found that no cracking, crushing or splitting was observed on the concrete slab, indicating that UHPC slab exhibited good performance and could resist the high force transferred from the headed studs. The numerical and experimental results indicated that the shear capacity is supposed to be composed of two parts stud shank shear contribution and concrete wedge block shear contribution. The stiffness increment of a stud in UHPC was at least 60% higher than that in normal strength concrete. Even if the stud height was reduced from 6d to 2d, there was no reduction in the shear strength of a stud. Short stud shear connectors with an aspect ratio as small as 2 could develop full strength in UHPC slabs. An empirical load-slip equation taking into account stud diameter was proposed to predict the load-slip response of a stud. The reliability and accuracy of the proposed load-slip equation was verified by the experimental and numerical load-slip curves.     

高温下钢筋桁架楼承板中栓钉抗剪性能研究

对15个试件进行常温和高温下推出试验,研究钢筋桁架楼承板中栓钉的抗剪性能,得到混凝土楼板和栓钉不同位置处的温度分布以及栓钉受剪承载力随温度的退化规律。试验结果表明,钢筋桁架楼承板中栓钉在常温和高温下的破坏均为栓钉剪断破坏,栓钉根部混凝土局部压碎,但是与平板混凝土板中栓钉的破坏位置不同,所研究的栓钉剪断破坏的位置在钢梁上翼缘处,而不是在栓钉根部焊缝处,这也在很大程度上导致了钢筋桁架楼承板中栓钉受剪承载力比平板混凝土板中栓钉低。钢筋桁架楼承板中栓钉的受剪承载力和刚度均随温度的升高而降低。通过对试验数据的分析,提出了钢筋桁架楼承板中栓钉高温下受剪承载力和荷载-滑移曲线的计算方法。     

九堡大桥引桥组合梁焊钉受力性能研究

九堡大桥引桥为多跨连续组合箱梁桥,截面为开口梯形钢梁与混凝土桥面板组合形式,钢梁与混凝土板间设置了大量的圆柱体焊钉连接件,连接件受力形式与传统钢板梁组合桥不同。文中结合该工程,采用ANSYS有限元程序建立其空间实体模型,采用弹簧单元详细模拟了焊钉,计算了焊钉连接件的受力,分析了焊钉连接件的受力特点。结果表明:焊钉连接件不仅承受沿纵桥向的剪力,还承受沿横桥向的剪力及沿竖向的拉拔力,连接件所受的剪力和拉拔力在全桥范围分布规律复杂。     

Full-scale tests on composite steel-concrete beams with steel trapezoidal decking

This paper describes the detailed testing of two full-scale steel-concrete composite beams comprised of composite slabs with deep trapezoidal decking connected to universal beams by welded stud shear connectors. The ribs of the decking were orthogonal to the longitudinal axes of the steel beams. This situation exists in secondary beams in flooring systems of steel framed buildings, and beams with deep trapezoidal slabs of this type are economic since they are able to span large distances, with or without propping. Despite the popularity of these decks and many useful research contributions over several decades, there are some concerns related to the strength and ductility of the shear connection because of the large voids in the slab and the need to place the studs off-centre to circumvent welding them through the longitudinal stiffener in the rib. There is also significant disquiet as to the applicability of push test results on much smaller specimens to the design of full-scale beams. The experimental work in this paper therefore intends to provide benchmark data for the calibration of theoretical models and of design recommendations. The beams were 8 m long with low degrees of shear connection. The tests showed that both beams behaved in a very ductile fashion with the ultimate moment capacities being above those predicted from the Eurocode 4 guidelines.     

群钉钢-混凝土组合件栓钉受力状态研究

芜湖公铁两用长江大桥上层公路桥采用混凝土桥面系与钢桁组合梁，连接件为栓钉，节点附近栓钉的布置为密集型大吨位．为确定芜湖桥栓钉承载力设计值，完成了3000～5000kN栓钉群钢-混凝土组合件的极限承载力试验和有限元分析．该成果已用于芜湖桥的设计．     

Zur praktischen Ermittlung der Verformungen von Verbundträgern und Flachdeckensystemen unter Berücksichtigung der Nachgiebigkeit der Verbundfuge

Simplified method for the determination of the influence of flexibility of shear connection on deflections of composite beams and slim‐floor systems. For composite beams and slim‐floor systems normally ductile shear connectors like headed studs are used. The flexibility of the shear connection influences the deformation behaviour of the structure especially where partial shear connection and/or ribbed concrete slabs with ribs transverse to the beam are used. For slim‐floor systems the special geometry of the cross section leads to a significant influence of the deformation behaviour of the shear connection on the deflections. Because the exact calculation of deformations under consideration of the flexibility needs a quite complicate theoretical model, for practical applications a simplified model based on a modified modular ratio method is presented.     

焊钉连接件时变抗剪性能的试验研究

对于无支架施工的长跨连续组合梁,在施工期间进行分阶段浇筑混凝土时,需考虑不同混凝土龄期的组合梁结合面上连接件的早期组合作用。为此,进行了混凝土不同龄期下焊钉连接件的推出试验,分析了焊钉连接件极限抗剪强度、极限滑移、设计抗剪强度和剪切刚度随时间的变化规律,并给出了相应的时变计算公式。研究发现,混凝土龄期小于3 d时推出试件主要为混凝土板劈裂破坏;在不同混凝土龄期时推出试件的剪力-滑移规律基本相同,但抗剪强度和刚度均随混凝土龄期的增长而增大,且早期增长较快,后期较慢,说明组合梁结合面的早期组合效应不能忽略。     

木-混凝土组合梁剪力连接件的研究现状

木-混凝土组合梁是利用各种不同的剪力连接件把木和混凝土这两种材料结合而成的一种新型整体受力构件。木梁与混凝土板的交界面上存在着纵向剪力,由混凝土与木梁之间的抗剪连接件承受。文章总结了国内外木—混凝土组合结构的相关研究内容,详细地介绍了国外木—混凝土组合梁剪力连接件的研究现状,并提出现阶段我国在木结构相关领域的研究方向。     

Behavior of channel shear connectors, Part I: Experimental study

In composite beams, shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface. This paper presents an experimental study on the behavior of channel shear connectors embedded in a solid concrete material slab under monotonic and low-cycle fatigue loading. The latter would be applicable to composite structures subjected to seismic events. Of specific interest are the behavior and effects of different concrete materials. A series of push-out specimens made of plain concrete, reinforced concrete (RC), fiber reinforced concrete (FRC) and engineered cementitious composite (ECC) were tested for this evaluation. The results show that the reversed cyclic shear strength of most specimens is 10%-23% lower than their monotonic strength. Also, using the polypropylene fibers (FRC specimens) has a slight effect on the shear strength and load-displacement behavior of the specimens; however, using the polyvinyl alcohol fibers (ECC specimens) causes considerable increase in ultimate strength and ductility of channel shear connectors. Finally, the experimental load capacities are compared with that suggested by North American design codes.     

压型钢板-混凝土组合楼板纵向受剪承载力试验研究

针对组合楼板主要的破坏模式——纵向剪切破坏进行分析,对8块U76型压型钢板-混凝土组合楼板进行了静力试验。试验结果表明:组合板越厚、剪跨越小、剪力横向钢筋越多,组合板纵向受剪承载力就越高。通过与无栓钉组合板的试验结果比较分析,表明组合板中剪跨区的栓钉,能极大地提高受剪承载力;并通过试验得到组合板的荷载-纵向相对滑移关系曲线图,采用欧洲规范4的建议公式,以试验数据为依据,回归得出组合楼板的剪力粘结系数m、k,为该种楼板的工程设计提供参考依据。     

Effect of shear connector spacing and layout on the shear connector capacity in composite beams

A three dimensional nonlinear finite element model has been developed to study the behaviour of composite beams with profiled sheeting oriented perpendicular to its axis. The analysis of the push test was carried out using ABAQUS/Explicit with slow load application to ensure a quasi-static solution. Both material and geometric nonlinearities were taken into account. Elastic-plastic material models were used for all steel components and the Concrete Damaged Plasticity model was used for the concrete slab. The post-failure behaviour of the push test was accurately predicted, which is crucial for realistic determination of shear capacity, slip and failure mode. The results obtained from finite element analysis were verified against the experimental push tests conducted in this research and also from other studies. After validation, the model was used to carry out an extensive parametric study to investigate the effect of transverse spacing in push tests with double studs placed in favourable and staggered positions with various concrete strengths. The results were also compared with the capacity of a single shear stud. It was found that shear connector resistance of pairs of shear connectors placed in favourable position was 94% of the strength of a single shear stud on average, when the transverse spacing between studs was 200 mm or more. For the same spacing, the resistance of staggered pairs of studs was only 86% of the strength of a single stud. The strength of double shear studs in favourable position was higher than that of the staggered pairs of shear connectors.     

槽钢剪力连接件的性能研究第一部分:试验研究

在组合梁的设计中,剪力连接件一般用于将纵向剪力转移到钢-混凝土的连接界面。对单调低周疲劳荷载作用下混凝土板中的槽钢剪力连接件的性能进行了试验研究。这种混凝土板将应用于地震作用下的组合结构,其中不同混凝土材料的性能和作用成为了研究重点。对一系列由素混凝土、钢筋混凝土(RC)、纤维钢筋混凝土(FRC)和水泥基复合材料(ECC)组成的构件进行推出测试。结果显示:大部分构件的循环抗剪强度要比它们在单调加载条件下的抗剪强度低10%~23%。同时,聚丙烯纤维(FRC构件)的采用对构件的抗剪强度和荷载-位移曲线也产生影响。然而,聚乙烯醇(ECC构件)的采用在剪力连接件的极限强度和延性上引起了显著的增加。最后,对比了试验构件的承载能力与北美设计规范建议的数值。     

Longitudinal shear test on steel-concrete composite beam with two rows of shear studs

为研究带双排栓钉的组合梁的纵向受剪性能,进行了7个带双排栓钉的钢-混凝土组合梁试件和1个带单排栓钉的钢-混凝土组合梁对比试件的纵向受剪试验。研究栓钉横向或纵向间距、横向配筋率、混凝土强度、栓钉排布方式等因素对带双排栓钉的钢-混凝土组合梁纵向受剪性能和混凝土板破坏形态的影响,并分析了各研究参数对峰值荷载和极限滑移量的影响。结果表明：带双排栓钉的钢-混凝土组合梁试件破坏模式主要表现为“八”字形裂缝的剪切破坏;栓钉横向、纵向间距、混凝土强度以及混凝土板配筋率是影响钢-混凝土组合梁受剪承载力的主要因素;受剪承载力均随着栓钉横向间距、纵向间距、混凝土强度以及混凝土板的横向配筋率的增加而增大。