奥氏体型S30408不锈钢角焊缝连接拉伸试验研究

为研究奥氏体型S30408不锈钢角焊缝连接接头的承载性能,对6个正面角焊缝连接试件和5个侧面角焊缝连接试件进行了拉伸试验,测得焊缝连接试件在拉伸作用下的极限荷载,以及焊缝强度、焊缝随荷载的变形情况,并对焊缝的破坏状态进行了观察。试验结果表明：正面角焊缝连接接头焊缝断裂面呈底部垂直于芯板表面而上部接近30°斜截面的不规则撕裂状,其抗拉强度平均值742 MPa,焊缝平均变形量为2 875 mm。侧面角焊缝连接接头焊缝断裂面较为平整,接近45°理论值,其剪切强度平均为506 MPa,焊缝平均变形量为4 387 mm。正面角焊缝连接试件焊缝抗拉强度为侧面角焊缝连接试件剪切强度的1.47倍。正面角焊缝和侧面角焊缝连接试件承载力试验值均高于CECS 410:2015《不锈钢结构技术规程》和欧洲规范Eurocode 3的设计值,CECS 410:2015规程中对于正面角焊缝和侧面角焊缝连接试件承载力设计值的规定过于保守;欧洲规范Eurocode 3对正面角焊缝连接试件承载力设计值的规定也较为保守,而对侧面角焊缝连接试件承载力设计值的规定较为合理。     

双相型S22053不锈钢角焊缝连接拉伸试验研究

焊缝连接广泛应用于不锈钢结构生产和装配领域,但目前国内外专门关于不锈钢焊缝连接承载性能的研究较少。为研究国产双相型S22053不锈钢角焊缝搭接接头的承载性能,对6个正面角焊缝连接试件和5个侧面角焊缝连接试件进行了拉伸试验,测得了焊缝连接在拉伸作用下的极限荷载、极限强度等,并对焊缝随荷载的变形情况进行了测量。试验结果表明：正面角焊缝连接试件破坏截面平均角度约29°,并非45°理论值,其极限强度平均值973MPa,焊缝平均变形量为1.139mm。侧面角焊缝连接试件破坏截面平均角度约46°,比较接近45°理论值,其极限强度平均为637MPa,焊缝平均变形量为1.792mm。正面角焊缝连接试件焊缝极限强度为侧面角焊缝连接试件的1.53倍。     

Tragfähigkeit von Lochleibungsverbindungen vorgespannter Glasscheiben zur Ausbildung von Anschlüssen im Konstruktiven Glasbau

Strength of bearing connections in toughened glass plates for the structural use. In steel structures due to their “infinite'” ductility the bearing connections are standard components of joints. Their design rules are based on simple engineering models. However if analogous bearing connections are subject of glazing structures the requirements on the materials' ductility cannot be met. Therefore interlayers out of mortar etc. in the hole surrounding the bolt have to be introduced such that a ductile load deformation behaviour can be reached reducing stress peaks and avoiding steel‐glass‐contact. On this basis design rules are to be established to predict the load carrying capacity of bolts in glass bearings. The following investigations describe the experimental and theoretical works to derive an engineering model for this purpose.     

Tragverhalten von textilbewehrtem Beton

Load‐bearing Behaviour of Textile Reinforced Concrete. Bond Cracking Behaviour and Load‐bearing Behaviour The load‐bearing behaviour of Textile Reinforced Concrete (TRC) is similar to concrete reinforced by steel, however, it is more influenced by the bond of the technical textile in the fine concrete. Thus the cracking behaviour, loading capacity, the deformation behaviour and the durability are investigated besides the material properties. Based on the results of these investigations, design models have been developed and first applications have been realized. The article summarizes the recent results in the field of load‐bearing behaviour of TRC.     

钢结构角焊缝的极限强度及抗力分项系数

本文根据国内不同地区的试验,分析角焊缝强度及其可靠性,导出了过去角焊缝连接设计隐含的安全系数。进而定出其按概率极限状态方法设计的目标可靠指标β值及抗力分项系数,与新修订的钢结构设计规范(GBJ 17—88)规定的角焊缝计算方法大致相符。从理论上证明角焊缝连接的折算方法满足概率极限状态设计要求。     

Laser welded built-up cold-formed steel beams: Experimental investigations

The results of a research project aimed at designing and development a built-up cold-formed steel beam assembled by laser welding are described in this paper. The research activity was concerned with the evaluation of the applicability of laser welded connections to cold-formed members and with the assessment of the load bearing capacity of the assembled beams. With this aim, both lap-shear and U-tension tests were carried out on laser welds in order to assess the influence on connection strength of different parameters such as the gap between the steel sheets and the zinc coating. Finally, the load bearing capacity of laser welded built-up cold-formed members was investigated by four-point bending tests. Four full-scale prototypes were manufactured with different spacings of connections along the flanges in order to evaluate the effects of weld configuration on the load bearing capacity.     

螺栓端板连接节点加固后承载性能有限元分析

已有试验表明,螺栓端板连接梁柱节点具有良好的受力性能,但节点刚度较小,循环荷载作用下破坏模式以螺栓拉断为主。当建成的结构由于各种因素螺栓端板节点承载性能不能满足要求时,需要进行加固以提高节点刚度和承载力。改：善其抗震性能,本文提出了在柱腹板加斜向加劲肋,并对端板进行焊接的加固方案。有限元分析表明加固后节点的刚度、延性和承载力都得到提高。静力加载时,荷载一位移曲线在达到峰值后出现平缓的下降段;循环加载时,节点破坏模式是梁翼缘发生局部屈曲形成塑性较,滞回曲线饱满。由于使用了焊缝,节点有可能发生脆性破坏,加固中应尽量使用较小尺寸的焊缝,施工中也应保证焊缝的质量,减小残余应力。     

高强度螺栓与焊缝并用接头抗剪承载力的有限元分析

通过对不同焊脚尺寸的侧面角焊缝与不同直径高强度螺栓之间并用连接的有限元模型研究,并考虑到不同螺栓数目或布置方式对并用连接承载力的影响,确定了高强度螺栓和侧面角焊缝之间合理的构造匹配方式。通过分析,绘出各连接情况下并用连接节点的荷载-变形曲线,研究探索高强度螺栓和焊缝的协同工作能力,以及影响栓焊并用连接承载力的因素。确定高强度螺栓和侧面角焊缝分别对并用连接节点承载力的贡献,给出承载力的计算公式,提出设计建议。     

钢梁-方钢管钢骨聚丙烯纤维增强水泥基复合材料柱节点的静力有限元分析

采用有限元分析软件ANSYS,对钢梁-方钢管内置C60混凝土和聚丙烯纤维增强水泥基复合材料(PP ECC)梁柱节点进行了三维非线性有限元分析。分析结果表明:由于PP ECC的作用,钢梁-方钢管钢骨PP ECC梁柱节点的极限承载力远大于钢梁-方钢管钢骨混凝土梁柱节点的极限承载力,充分体现出PP ECC具有良好的刚度及承载力。PP ECC比混凝土能更好地与钢管、钢骨进行协同工作,更能充分发挥钢管、钢骨的受力性能。     

Bemessungsvorschlag für Holz/Beton‐Verbundbalken unter Beachtung abgestufter Verbindungsmittelabstände

Design proposal for timber/concrete composite beams with graded connnector distances. The distance of connections of timber/concrete composite beams is often graded for economical reasons according the shear force distribution. The load‐carrying capacity of composite beams according to DIN 1052 respectively E DIN 1052 with internal forces, which are linearly determined, (γ‐procedure) are clearly reduced compared to beams without graded distances of connectors. The actual load‐bearing behaviour distinctly shows non‐linearities. The influence of the gradations of the connectors on the load‐bearing behaviour of composite beams is investigated, because the influence of the stiffness of connections on the load‐bearing capacity of composite beams is small. The paper presents a comparison between failure loads determined by FE‐analysis and the working loads according to the current design rule. It is shown that the decrease of load‐bearing capacity is smaller than assumed by current code of practice. Structures with several different distances of connections have the largest safety‐factor. These systems can more economically be designed. As the result of the investigations, a new design proposal is presented, which takes non‐linearities into account and guarantees a constant safety‐zone between failure load and working load. These proposal permits an economic design of timber/concrete composite beams.     

Tragverhalten von Stahlgussbauteilen in Offshore‐Windenergie‐Anlagen unter vorwiegend ruhender und nicht ruhender Beanspruchung

Load bearing behaviour of cast steel components in offshore wind turbines under fatigue and static loads. The installation of offshore wind turbines of the 5‐megawatt class in deep water of the North Sea makes it economically necessary to build foundations in high quantities. Constructions of this kind are a major technical challenge in terms of design, manufacturing and operation. In this paper the dynamic behaviour of jacket constructions in the North Sea are investigated. Currently jacket structures are constructed with steel pipes that are welded at the connecting nodes. This procedure implies several disadvantages. In contrast cast steel elements are universally applicable and designable. To verify the load bearing behaviour numerical simulations and laboratory tests are done. Laboratory tests include the testing of the ultimate load bearing capacity. In a large scale setup and fatigue tests at small cast steel specimen.     

钢框架焊接梁柱节点子结构抗倒塌性能试验研究

设计了2种过焊孔构造（扇形和扩大型过焊孔）的3个钢框架梁柱节点子结构试件,采用落锤冲击的加载试验方法模拟结构的动态倒塌过程。通过试验获得节点试件的破坏形态及其冲击荷载和变形时程曲线,分析试件冲击荷载和位移时程响应规律以及子结构动态转角和耗能变化趋势。结果表明：过焊孔构造对节点在冲击荷载作用下的破坏形态和力学性能有显著影响,补强焊缝可有效改善扩大过焊孔节点的上翼缘压曲;与扇形过焊孔相比,扩大型过焊孔节点试件具有更好的抗冲击转动能力,其极限转角满足FEMA 350中的转角限值（θ=0.064 rad）要求;通过分析冲击过程中试件截面内力发展规律可知,由于节点过早破坏限制悬链线效应的形成,该类型节点子结构由于节点转动能力不足不能充分发挥悬链线效应。     

Untersuchungen zum Ermüdungsverhalten von hochfesten Stählen im Rahmen von LIFTHIGH

Investigations on the fatigue behaviour of high‐strength steels in the scope of LIFTHIGH. In the research project P 512 of FOSTA, different kinds of longitudinal attachments and five variants of butt welded plates made of high strength steel have been already investigated to enlarge the available recommendations. The obtained results provide a basis for further going investigations within the European ECSC‐project LIFTHIGH – “Efficient Lifting Equipment With Extra High Strength Steel”. In this project longitudinal attachments made of fine grain high strength steel with post weld treatment such as TIG‐dressed welds and ground welds have been investigated. For a more precise evaluation of the different variants of butt welded plates made of S 960 QL, these details have been also produced and tested made of S 690 M an S 1100 QL. In addition transverse attachments have been incorporated in the experimental programme.     

Zum Tragverhalten von Verbunddübeln – Teil 1: Tragverhalten unter statischer Belastung

Verbunddübel stellen eine sehr tragfähige und robuste Verbindung auch bei hochfesten Betonen zwischen Stahlbauteilen und Betonquerschnitten dar. Die Herstellung des Stahldübels ist dabei einfach und wirtschaftlich. Mittels Verbunddübelleisten lassen sich neue Querschnitte für den konstruktiven Ingenieurbau entwickeln. Halbierte Walzprofile, die mit der speziellen Geometrie der Verbunddübel geschnitten wurden, werden als außenliegende Bewehrung im Verbundbau eingesetzt. In zwei Teilaufsätzen wird die Bemessung der Verbunddübel für unterschiedliche Randbedingungen und Belastungsarten erläutert. Der erste Beitrag befasst sich mit der Technologie der Verbunddübel, deren Tragverhalten und der Bemessung der Verbindung unter ruhender Belastung. Das Ermüdungsverhalten ist Schwerpunkt in einem zweiten Aufsatz. Die Problemstellung wird ausführlich erläutert und ein Bemessungsvorschlag auf Grundlage des Strukturspannungskonzeptes vorgestellt. Load bearing behaviour of composite dowels – Static loads (part I). Composite dowels realise a high load bearing capacity for connections between concrete and steel. The technology establishes a short time and cost‐effective production process. Using composite dowels for shear transmission new and innovative cross‐sections can be designed. Halved rolled sections which have been cut along with a specific dowel geometry are applied as external reinforcement. The publication is divided into two parts describing design of composite dowels for different boundary conditions and load cases. Foremost the technology, their load bearing behaviour, the design concepts for composite dowels for static loads are highlighted. The behaviour under cyclic load, will be introduced in a second part. The fatigue behaviour will be explained in detail and design concepts based upon the hot spot stress will be given.     

Experimental study of lateral load behavior of H‐shaped precast reinforced concrete shear walls with bolted steel connections

This paper presents an experimental study of H‐shaped precast reinforced concrete shear walls involving vertical connections under combined vertical and lateral loading. The H‐wall is composed of two prefabricated flange wall panels: one prefabricated web wall panel and vertical bolted steel connections between the flange and web panels. The assembling of the H‐wall is completely dry without any in situ casting. Three H‐wall specimens were constructed and tested to investigate the mechanical behavior and seismic performance of them. The lateral load‐bearing capacity, ductility, energy dissipation, lateral stiffness, strain in the connecting steel frame, and sliding within the bolted steel connections are presented and discussed to evaluate the effectiveness of the vertical connections. The ultimate shear‐resistance mechanism of the precast H‐wall assembly is also analyzed. The H‐wall assemblies generally possess high load‐bearing capacity, favorable ductility, and good energy‐dissipating capacity. The thickness of the steel plates in the connecting steel frame affects the lateral stiffness and the ultimate load‐bearing capacity of the H‐walls. Furthermore, the encasing steel plates for the web wall panel not only helps transfer the stress in the wall steel bars but also confines the concrete resulting in improved ductility.     

The shear lag effects on welded steel single angle tension members

This paper presents a study of the shear lag effects on the behaviour and strength of welded steel single angle tension members. A total of thirteen single angles with welded end connections were tested in tension. The test parameters included long and short leg connections, balanced and unbalanced weld arrangements and longitudinal fillet weld lengths. Out of the thirteen specimens, nine failed by fracture of the gross section and four failed in the welds. The efficiency of the specimens, which is defined as the ratio of the test ultimate load () to the tensile capacity (a product of the gross sectional area and the tensile strength of the material) of the specimens varied from 0.82 to 1.02. It can be observed from the test results that both the ultimate loads sustained by the short leg connected angles and the ductility of all the angle specimens were greater when the balanced weld arrangement was used in the connections than when the specimens were connected using the unbalanced welded arrangement. Finite element analyses of the specimens were conducted and the analysis results compared well with the test results. The capacities of the test specimens were also evaluated using various design approaches. In general the design specifications (AISC-LRFD, BS5950-1:2000, and CSA-S16-01) provided good predictions of the tensile capacity of the single angle specimens with a reasonable degree of conservatism. However, the design specifications underestimated the tensile capacity of specimens which were connected by the short leg and with a balanced weld arrangement.     

The strength of planar fillet weld groups subjected to an eccentric shearing force in their planes

The method developed previously for estimating the strength of fillet welded connections subjected to a shearing force only and of planar fillet weld groups subjected to an eccentric force applied outside their planes is used to analyse some planar fillet weld groups (Fig. 3) subjected to an eccentric shearing force in their planes. The welds are assumed to have equal leg lengths which are the same for all the welds belonging to a group. The line of action of the applied force is either parallel or perpendicular to the directions of the welds in a group. The strength is predicted as a function of the weld group geometry, the load eccentricity and the weld metal UTS. The effect of the longitudinal residual stress locked into the welds during the fabrication is allowed for. The theoretical predictions are compared with experimental results and it is concluded that the theory will provide lower bounds on the strengths of the connections investigated if the weld metal UTS obtained from tension tests on specimens cut from deposited weld metal is used in the calculations.     

Aussteifung von Gebäudehüllen durch randverklebte Glasscheiben

Stabilisation of building envelopes by the use of circumferential glued glass panels. The pursuit of maximum transparency with increasingly filigree bearing structures fuels the possibility of using the glazing as a load bearing element that is able to transmit both lateral and in plane forces. Space grid structures with rectangular glass panes seem to be very capable for this purpose. In this case the linear bars are normally pin‐joint at nodes to minimise both cross sections and erection cost. It is common to triangulate space grid structures with rods or prestressed steel cables. These bracings could be omitted if the stiffening forces would be transmitted by the glazing. In the here considered system the glass panes are used as shear panels to stabilize the envelope. Therefore, the panes are glued to the space grid members along their perimeter. Details were designed and the load bearing behaviour of the connections and the glass elements were investigated and design rules developed. These rules consider the shear interaction in laminated glass elements, and the interaction of in plane and out of plane loads.     

Cyclic response characteristics of retrofitted moment resisting connections

Experimental studies were conducted in order to investigate the behavior of the weld in steel moment resisting connections. A total of forty seven reduced-scale subassembly model specimens were tested that represent welded moment resisting connections of the beam to box column. These specimens were used to study the following aspects in fabrication and retrofitting of moment resisting connections: Complete joint penetration (CJP) groove weld behavior, transversely loaded fillet weld behavior, grinding and rewelding influence on weld behavior, reinforcing of connection with T-stiffener and rib plates, strain rate effect on weld and material characteristics and electrode toughness effect on weld behavior. Following test result interpretations, five full-scale moment resisting connections of beam to box column were fabricated and tested. These models included one specimen fabricated with details of an outdated connection, two specimens with an improved CJP groove weld detail, and two specimens retrofitted by T-stiffeners. Each specimen was subjected to a standard quasi-static cyclic load pattern. Overall, the improved and retrofitted specimens performed well, achieving total (elastic plus plastic) story drift ratios of at least 4% radians in magnitude before experiencing 20% strength degradation.