装配整体式钢-混凝土组合梁栓钉抗剪连接件受力性能试验研究

为研究装配整体式钢-混凝土组合梁中栓钉抗剪连接件的受力性能,设计了10个栓钉抗剪连接件,对其进行推出试验,得到了现浇混凝土板和预制混凝土板中栓钉抗剪连接件在单调和重复荷载作用下的界面剪力-滑移曲线以及破坏形态。结果表明:预制混凝土板中栓钉受剪承载力比现浇混凝土中栓钉受剪承载力略低,均为栓杆剪断和栓钉根部焊缝破坏;重复荷载作用下峰值界面剪力对应的界面滑移明显大于单调荷载作用下峰值界面剪力对应的界面滑移;重复荷载作用下的峰值界面剪力与单调荷载下的峰值界面剪力相当,其界面剪力-滑移曲线基本一致。     

Experimental study on mechanical behavior of shear studs in assembled monolithic steel-concrete composite beam

为研究装配整体式钢-混凝土组合梁中栓钉抗剪连接件的受力性能,设计了10个栓钉抗剪连接件,对其进行推出试验,得到了现浇混凝土板和预制混凝土板中栓钉抗剪连接件在单调和重复荷载作用下的界面剪力-滑移曲线以及破坏形态。结果表明：预制混凝土板中栓钉受剪承载力比现浇混凝土中栓钉受剪承载力略低,均为栓杆剪断和栓钉根部焊缝破坏;重复荷载作用下峰值界面剪力对应的界面滑移明显大于单调荷载作用下峰值界面剪力对应的界面滑移;重复荷载作用下的峰值界面剪力与单调荷载下的峰值界面剪力相当,其界面剪力-滑移曲线基本一致。     

纤维高强混凝土抗剪性能的试验研究

通过84根尺寸为100mm×100mm×400mm的高强混凝土、钢纤维高强混凝土、聚丙烯纤维高强混凝土试件在剪切荷载作用下的抗剪试验,研究了纤维类型和纤维体积率(掺量)对高强混凝土抗剪强度及在剪切荷载作用下变形性能的影响。结果表明,纤维的加入有效地改善了高强混凝土的抗剪强度及变形性能。初裂抗剪强度和变形、极限抗剪强度和变形以及抗剪韧性均随纤维体积率(掺量)的增加而增大,试件破坏时能保持完整性。根据试验结果,建立了钢纤维高强混凝土及聚丙烯纤维高强混凝土抗剪性能的剪力传递模型和数学表达式。     

开孔波形板剪力连接件推出试验研究

通过对设有双开孔波形板剪力连接件的试件进行推出试验,探讨了这种连接件在外荷载作用下的钢板和混凝土应变分布及荷载滑移变化规律,分析了混凝土板与钢板交界面的界面特性及贯穿钢筋的受力情况、混凝土板的掀起作用等,结果表明:开孔波形板剪力连接件具有较高的抗剪能力和连接性能,混凝土与钢梁交界面相对滑移量小。     

π形开孔板连接件受剪性能试验研究

高性能组合结构中抗剪连接件的研究受到广泛关注,通过6组10个π形开孔板抗剪连接件试件在单调及重复荷载作用下的推出试验,研究其破坏模态、荷载-滑移曲线以及应力发展规律等。分析了贯穿钢筋、腹板间距、翼缘板的布置方向、连接件数量以及加载方式对π形开孔板连接件初始刚度和受剪承载力等力学性能的影响。结果表明：π形开孔板抗剪连接件的初始刚度较大,翼缘板的存在承担了大部分剪力,阻止了纵向贯穿裂缝的发展,提高了承载力;布置贯穿钢筋连接件的荷载-滑移曲线下降平缓,表现出较好的延性;随着腹板间距的减小,腹板间混凝土的套箍作用增加,提高了连接件的承载力;在重复荷载作用下,连接件表现出良好的受力和耗能能力。根据试验结果,提出了连接件承载力计算式,承载力计算值与试验结果吻合较好。     

开孔板连接件受剪性能试验研究

开孔板连接件是钢-混凝土组合梁中常用的一种抗剪连接件。通过21个开孔板连接件试件在单调静力荷载作用下的推出试验,研究了开孔板的开孔直径、混凝土强度等级、孔中横向贯通钢筋的直径和数量等对开孔板连接件的破坏形态、荷载-滑移特性和受剪承载力等的影响。研究表明:开孔板连接件的荷载-滑移曲线(P-S曲线)大致可分为弹性阶段、塑性发展阶段和下降段;提高混凝土强度等级、增大开孔直径可提高开孔板连接件的受剪承载力,横向贯通钢筋直径由16mm增大至20mm时,试件的受剪承载力提高了21.8%,配置横向贯通钢筋2 16的试件受剪承载力比相应的未配置横向贯通钢筋的试件高19.1%;随着混凝土强度等级的提高,试件抗剪刚度增大,而开孔直径及横向贯通钢筋直径则对抗剪刚度无明显影响。最后,基于试验结果提出了开孔板连接件受剪承载力的计算方法。研究成果可为编制《钢-混凝土组合桥梁设计规范》提供依据和参考。     

纤维增强混凝土剪力墙压弯剪耦合作用变形能力分析

采用具有受拉应变硬化性能的新型纤维增强混凝土(FRC)能改善受力钢筋的变形能力,对提高剪力墙抗震性能有显著作用。为了建立更为合理的FRC剪力墙试件荷载-变形能力分析方法,用以分析平面复杂应力状态下,轴力、弯矩和剪力之间的相互作用机理,基于单轴弯剪模型,提出一个修正的纤维模型,其模拟结果与试验结果吻合较好。研究表明,建议模型能较为准确地预测单调荷载作用下纤维增强混凝土剪力墙的变形能力,其显著特点为变形分量计算明确,耦合作用机理清晰;并且可通过受压软化系数,较为直观地反映出混凝土性能差别对墙体变形能力的影响,同时展示出FRC优良的受剪和受压性能。     

方钢管梁与钢筋混凝土现浇板嵌入式连接方式试验研究

为了研究方钢管梁与钢筋混凝土现浇板的一种新型连接方式,即方钢管梁采用嵌入混凝土板中一部分的连接方式,对嵌入混凝土板中方钢管上部侧面布置不同剪力连接件的11个新型方钢管梁-钢筋混凝土现浇板组合试件的抗剪性能进行了推出试验,对其中7个试件进行单调静力加载推出试验,对另外4个试件进行低周反复加载推出试验。获得了不同连接方式试件的破坏模式、承载能力及变形能力。试验结果表明,相对于常规连接方式组合梁,除了在方钢管梁侧向布置小钢板连接件的试件取得了较好的承载能力以外,其余剪力连接件组合梁的承载能力及变形能力均有所下降。     

槽钢剪力连接件的性能研究第二部分:分析研究

建立了一个有效的数值模型,主要是利用有限元方法模拟槽钢剪力连接件的试验。重点测试单调加载下钢筋混凝土板的槽钢剪力连接件的抗剪能力。通过第一部分的试验研究中的试验数据证实,本文的数值模型是有效的,而且与北美设计规范中给出的数据进行了对比。利用这个非线性模型进行的参数研究主要涉及混凝土强度、开槽尺寸和开槽方向等变量。结果显示:混凝土强度、开槽腹板和翼缘厚度以及开槽的长度都对槽钢剪力连接件的极限强度影响很大,但是开槽截面高度的影响很有限。同样,改变开槽的方向也会对剪力连接件的刚度和极限强度产生影响。     

钢筋混凝土/ECC组合梁-柱节点抗震性能的试验研究

高延性纤维增强水泥基复合材料(ECC)是一种具有应变硬化特性和多裂缝开展机制的新型建筑材料。对于钢筋混凝土构件,用ECC材料代替混凝土能够有效提高构件的强度和延性性能。文章对普通钢筋混凝土梁-柱节点和钢筋混凝土/ECC组合梁-柱节点构件进行了低周反复加载试验研究。结果表明:对于节点区未配箍筋的节点构件,在节点区用ECC材料代替混凝土能够显著提高构件的承载力、变形及延性性能;钢筋混凝土/ECC组合梁-柱节点构件的抗震性能比在节点区配置箍筋的钢筋混凝土节点也要更优越。     

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.     

Experimental study on shear behavior of bolt connectors in steel-concrete composite beams

为研究螺栓抗剪连接件在钢-混凝土组合梁中的受剪性能,对24个采用螺栓连接件的钢-混凝土组合试件进行了推出试验,分析了螺栓直径、螺栓强度、螺栓埋置长细比和混凝土强度等参数对螺栓连接件的破坏模式、荷载-滑移特性和受剪承载力的影响。研究结果表明：螺栓抗剪连接件的破坏模式主要为螺栓周围混凝土受压破坏和螺栓栓杆的剪断破坏;当发生混凝土受压破坏时,增大混凝土强度、螺栓直径、螺栓埋置长细比可以提高螺栓连接件的受剪承载力;当发生螺栓的栓杆剪断破坏时,提高螺栓强度可以提高螺栓连接件的受剪承载力。在试验研究的基础上,给出了不同破坏模式下钢-混凝土组合梁螺栓连接件的受剪承载力的计算方法,建议公式的计算结果与试验结果吻合较好。     

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。     

单调荷载下栓钉连接件受剪性能试验研究

栓钉是钢-混凝土组合梁中常用的柔性受剪连接件。通过18个栓钉受剪试件在单调荷载下的推出试验,较系统地研究了混凝土强度等级、栓钉直径以及钢梁类型等参数对栓钉的破坏形态、破坏机理、荷载-滑移规律和极限受剪承载力的影响。研究表明:栓钉的受剪承载力随着混凝土强度等级的提高以及栓钉直径的增大而增加;轧制工字钢试件中栓钉的受剪承载力比焊接工字钢试件中的高10%~30%。在试验的基础上提出了栓钉受剪承载力的计算方法。     

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.     

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。     

波纹钢腹板组合箱梁桥力学性能研究现状及发展

波纹钢腹板组合箱梁桥以波纹钢代替普通混凝土作为腹板,可有效减轻桥梁自重,提高跨越能力,近几十年来得到广泛关注和深入研究。对国内外关于该组合结构的波纹钢腹板力学性能、整体静力学性能、动力学性能、疲劳性能及剪力连接件和转向块等方面的研究现状及成果进行总结、分析。指出:波纹钢腹板组合箱梁体外预应力筋的应力增量、组合箱梁几何参数对其力学性能影响的综合分析、剪力连接件几何参数对其力学性能的影响及剪力连接件在重复荷载下的力学行为规律等方面是需要进一步研究的课题。     

An experimental study on channel type shear connectors

This paper describes an experimental study on European channel shear connectors. While shear studs are widely used in steel–concrete composite elements, the channel connectors are also gaining popularity due to their certain advantages. The channel connectors do not require special equipment and standard welding procedures are adequate for attachment purposes. In addition, this type of connector offers higher amounts of shear resistance due to its high contact area with surrounding concrete. Although first studies date back to 1950s, little work has been done in the past to investigate their behavior. Majority of the work done to date was on channel connectors used in North America with a very limited parameter range. An experimental study consisting of 15 push-out tests was carried out to investigate the behavior of European type channel connectors with various heights and lengths. The ultimate resistance of the connectors obtained from experiments was compared against those predicted by North American steel design specifications. It was observed that the equations presented in American and Canadian specifications are too conservative. Based on a model that represents the typical failure mechanism in push-out tests, a new equation was developed for the ultimate resistance of channel shear connectors. It is shown that the developed equation is capable of predicting the ultimate resistance of channel connectors with reasonable accuracy.     

Lightweight steel–concrete–steel sandwich system with J-hook connectors

This paper investigates a new concept for designing composite structures comprising a lightweight concrete core sandwiched in between two steel plates which are interconnected by J-hook connectors. Specifically, lightweight concrete (density less than 1450 kg/m³) and novel J-hook connectors have been developed for this purpose. The hook connectors are capable of resisting tension and shear, and their uses are not restricted by the core thickness. Push-out tests confirms that the shear transfer capability of J-hook connector is superior to the conventional headed stud connector in achieving composite action between steel plate and concrete core. Twelve sandwich beam specimens have been tested to evaluate the flexural and shear performance subjected to static point load. Parameters investigated include degree of partial composite, concrete with and without fibres and concrete strength. Using Eurocodes as a basis of design, theoretical model is developed to predict the flexural and shear capacity considering partial composite and enable construction of sandwich structures with J-hook connectors. Compared with test results, the predicted capacity is generally conservative if brittle failure of connectors can be avoided. Test evidence also shows that inclusion of 1% volume fraction of fibres in the concrete core significantly increases the beam flexural capacity as well as its post-peak ductility.     

Experiment study on fatigue performance of perforated shear connectors

In order to investigate the fatigue behavior of perforated shear connection in steel-concrete composite bridges, 24 connection specimens with different geometric configurations were subjected to static and fatigue testing protocols. Using the design shear resistance of perforated shear connectors obtained from static push-out tests as a reference load level, numbers of fatigue cycles under different cyclic load levels were determined. Accumulated relative slip between steel and concrete components was used to characterize and track fatigue damage accumulation. The relationship between cycle numbers and accumulated relative slip between steel and concrete was established. Test results revealed that the fatigue damage of perforated shear connectors can be divided into three stages, and fatigue life of perforated shear connectors can be evaluated by the accumulated slip, which depends on the maximum shear stress and stress range.