Mechanical performance of shear studs and application in steel-concrete composite beams

This work experimentally investigates the effects of shear stud characteristics on the interface slippage of steel-concrete composite push-out specimens. ABAQUS is used to establish a detailed 3D finite element(FE) model and analyze the behavior of push-out specimens. The modeling results are in good agreement with the experimental results. Based on parametrical analysis using the validated FE approaches, the effects of important design parameters, such as the diameter, number, length to diameter ratio, and yield strength of studs, concrete strength and steel transverse reinforcement ratio, on the load-slip relationship at the interface of composite beams are discussed. In addition, a simplified approach to model studs is developed using virtual springs with an equivalent stiffness. This approach is demonstrated to be able to predict the load-displacement response and ultimate bearing capacity of steel-concrete composite beams. The predicted results show satisfactory agreement with experimental results from the literature.

Bending Stiffness of Truss-Reinforced Steel-Concrete Composite Beams

This paper is concerned with a special steel-concrete composite beam in which the resisting system is a truss structure whose bottom chord is made of a steel plate supporting the precast floor system. This system works in two distinct phases with two different resisting mechanisms: during the construction phase, the truss structure bears the precast floor system and the resisting system is that of a simply supported steel truss;once the concrete has hardened, the truss structure becomes the reinforcing element of a steel-concrete composite beam, where it is also in a pre-stressed condition due to the loads carried before the hardening of concrete. Within this framework, the effects of the diagonal bars on the bending stiffness of this composite beam are investigated. First, a closed-form solution for the evaluation of the equivalent bending stiffness is derived. Subsequently, the influence of geometrical and mechanical characteristics of shear reinforcement is studied. Finally, results obtained from parametric and numerical analyses are discussed.

Experimental study on seismic behaviors of steel-concrete composite frames

Steel-concrete composite frames are seeing increased use in earthquake region because of their excellent structural characteristics, including high strength, stiffness, and good ductility. However, there exist gaps in the knowledge of seismic behavior and the design provisions for these structures. In order to better understand the seismic behaviors of composite frame systems, eight steel-concrete composite frames were designed. These composite frames were composed of steel-concrete composite beams and concrete filled steel tube columns. The axial compression ratio of column, slenderness ratio and linear stiffness ratio of beam to column were selected as main design parameters. The low reversed cyclic loading tests of composite frame system were carried out. Based on test results, the seismic behaviors of composite frames such as failure mode, hysteresis curve, strength degradation, rigidity degradation, ductility and energy dissipation were studied. Known from the test phenomenon, the main cause of damage is the out-of-plane deformation of steel beam and the yielding destruction of column heel. The hysteretic loops of composite frame appear a spindle shape and no obvious pinch phenomenon. The results demonstrate that this type of composite frame has favorable seismic behaviors. Furthermore, the effects of design parameters on seismic behaviors were also discussed. The results of the experiment show that the different design parameter has different influence rule on seismic behaviors of composite frame.

The Study of Force and the Mechanical Characteristic of Incremental Launching Construction Method on a Steel-Concrete Continuous Beam Bridge

The usage of steel-mixed composite beams is quite extensive today.During an event of constructing steel-mixed composite bridges,the incremental launching construction method is generally adopted.This paper mainly analyzes the force of incremental launching construction on a steel-concrete continuous beam bridge,the classification of incremental launching construction,the application of incremental launching construction in steel-mixed composite beams,the temporary facilities existing in incremental launching construction as well as their existing problems.Lastly,the analysis of the stress of composite beams in incremental launching construction is described by using the reference for the construction of mixed composite continuous beam bridges provided.

Field validation of UHPC layer in negative moment region of steel-concrete composite continuous girder bridge

Improving the cracking resistance of steel-normal concrete(NC)composite beams in the negative moment region is one of the main tasks in designing continuous composite beam(CCB)bridges due to the low tensile strength of the NC deck at pier supports.This study proposed an innovative structural configuration for the negative bending moment region in a steel-concrete CCB bridge with the aid of ultrahigh performance concrete(UHPC)layer.In order to investigate the feasibility and effectiveness of this new UHPC jointed structure in the negative bending moment region,field load testing was conducted on a newly built full-scale bridge.The newly designed structural configuration was described in detail regarding the structural characteristics(cracking resistance,economy,durability,and constructability).In the field investigation,strains on the surface of the concrete bridge deck,rebar,and steel beam in the negative bending moment region,as well as mid-span deflection,were measured under different load cases.Also,a finite element model for the four-span superstructure of the full-scale bridge was established and validated by the field test results.The simulated results in terms of strains and mid-span deflection showed moderate consistency with the test results.This field test and the finite element model results demonstrated that the new configuration with the UHPC layer provided an effective alternative for the negative bending moment region of the composite beam.

竹木复合板水平剪切强度的研究

采用短梁法研究了竹木复合板的水平剪切强度。研究结果表明，竹木复合板试件的跨距是影响水平剪切强度测定的主要因素，水平剪切强度随跨距的增加而明显降低，合理的跨距为板厚的4倍；竹木复合板水平剪切强度的范围为3．2～11．1MPa。

装配式建筑地下室吊装工程施工

文章以张家界蓝色港湾一期酒店为例,介绍了装配式建筑地下室的吊装工程施工方法。

纤维增强整体木梁受弯试验研究

玄武岩纤维板-木拼接整体木梁是在合理利用资源、生态环保、方便施工等理念的指导下进行研究的,其特点在于将多段/多层木拼接同时与玄武岩纤维板复合为一体,既发挥了新型材料玄武岩纤维板轻质高强的优点,同时也使得对木材的使用更加充分合理,有效地节约了资源.该种组合木梁承载力高、跨度大、制作方便,既适用于既有建筑改造更换木构架,也适用于新建木结构.在经济技术分析基础上,经建筑市场调查,有可观的经济效益,同时具有良好的环保效益、社会效益.

钢—混凝土组合板梁技术及经济优势分析

解决城市小跨径桥梁施工造成长时间道路交通拥堵的良方是选择快速化施工的桥型,最大限度地缩短工期,通常快的不一定是好的,好的不一定是省的,本文突破常规推荐一种全新的桥梁方案:钢—混凝土组合板梁,从结构耐久性、景观效果、工期、造价、养护各方面分析,该桥型具有"功能适用、结构安全、造价经济、结构耐久、造型美观、环境协调、技术先进"等特点,并充分吸取国内外桥梁设计和建设的新理念、新材料、新工艺和先进经验,体现"以人为本""实用美观"的设计理念,无疑该桥梁集快、好、省于一体,为同行提供参考和借鉴。

中小跨径双主梁形式钢板组合梁截面优化设计

为提出结构安全,经济适宜的中小跨径钢板组合梁桥,提升公路桥梁的建设品质,以辽宁省内两座跨径分别为5×30 m和5×35 m的双主梁钢板组合连续梁桥为依托工程,采用有限元建模对这两种跨径的双主梁组合梁桥进行参数分析,以主梁跨中挠度及单位面积用钢量为评价指标,提出以上两种跨径组合梁桥的推荐梁高及合理板件配置。结果表明:在关键截面应力保持相同水平的条件下,跨中挠度及用钢量均随主梁高度的增加而减小,综合考虑视觉效果,经济性和城市空间限制等因素,最终分别选择1.9 m和2.1 m作为5×30 m和5×35 m两种跨径的双主梁钢板组合梁桥的推荐梁高。

铝-木组合梁受弯性能研究

提出一种以T型带肋定向结构刨花板(oriented strand board,OSB)为骨架,梁腹板下表面与铝板通过螺钉连接组成的铝-OSB板T形截面带肋组合梁(简称为铝-OSB板组合梁)。以组合梁的腹板高度和铝板厚度为参数,设计了4根铝-OSB板T形截面带肋组合梁试件,对各个试件进行抗弯性能的试验,观察在各级荷载作用下试件的破坏过程和破坏形态、OSB板和铝板的应变变化以及组合梁跨中挠度的变化规律。建立ABAQUS有限元模型,对比有限元模拟与试验的结果,并且分析不同螺钉间距对组合梁受弯性能的影响。试验结果表明:在达到极限承载力时,各组合梁的铝板均达到屈服应变;组合梁中OSB板和铝板能够同时参与工作,整体工作性能好,组合效应显著;提高组合梁的腹板高度和铝板厚度可以不同程度地提高组合梁的受弯承载力,且腹板高度对组合梁的受弯性能影响远大于铝板厚度对其的影响;有限元分析结果与试验结果吻合良好;基于有限元模拟的分析表明,随着螺钉间距的减小,组合梁的承载力会有所提高。

大跨度组合式叠合箱网梁楼盖施工技术

潍坊医学院新校区图书馆工程,成功地应用了大跨度组合式叠合箱网梁楼盖施工技术。该技术通过叠合箱底盒外伸拉接筋与肋梁主筋的钩锚、叠合箱上盒外伸拉接筋与肋梁纵筋牢固连接等关键工序,将预制叠合构件"叠合箱"与后浇肋梁连接成梁板合一的整体,形成工字形断面的网梁楼盖,连接可靠,整体性好,既实现了大跨度大空间,又降低了工程成本,节约了工程投资,并形成了一套先进的大跨度组合式叠合箱网梁楼盖施工技术。

木工字梁悬臂模板施工技术在云龙湾大桥的运用与创新

结合云龙湾大桥塔柱的施工,介绍了木工字梁悬臂模板施工技术,针对施工过程中遇到的问题,创新了一种在木模板表面覆彩涂板的复合面板技术,确保了混凝土外观质量,节约了施工成本。

浅谈钢与混凝土组合楼盖结构体系

通过对钢与混凝土组合楼盖结构体系的浅析,达到对组合楼盖结构在设计及施工中的更好应用。

碳纤维在Ⅰ字梁组合微弯板梁桥加固中的应用

分析了Ⅰ字梁组合微弯板桥开裂破损的主要原因 ,重点阐述了用粘贴碳纤维加固危桥的施工方法和程序 ,并结合某大桥整治加固实例及其试验结论和效益 。

热塑性复合材料防撞梁模压成型工艺研究

通过对某型号不锈钢防撞梁结构进行热塑性碳纤维/聚苯硫醚(CF/PPS)复合材料铺层和受力分析,利用热压罐成型工艺制备热塑性复合材料层合板,最后采用机械臂自动化转移和热模压成型工艺,研究了CF/PPS料片加热软化制备防撞梁零件的可行性。另外,对热塑性复合材料防撞梁零件进行了测试,结果表明:热塑性复合材料防撞梁外观质量良好,无明显缺陷以及纤维紊乱等现象;平均厚度为2.867 mm;单件防撞梁零件平均质量为462.4 g,比原来不锈钢零件质量减轻约51.3%;孔隙率平均值为1.20%;热塑性复合材料防撞梁零件耐环境性能良好;三点弯力学性能试验与仿真结果偏差为4%;热塑性复合材料防撞梁产品生产效率为10件/h。

竹木箱形组合梁力学性能试验研究

提出一种以竹集成材为翼缘,OSB板为腹板的竹木箱形组合梁。以组合梁的剪跨比和加劲肋为参数,对12根梁试件的力学性能进行四点弯曲试验研究。结果表明,当剪跨比小于2.0时,组合梁出现了明显的剪切破坏特征,随剪跨比增大,极限承载力呈显著下降趋势。加劲肋能显著提高组合梁的极限承载力,提高幅度为14.7%-18.3%,对极限位移的提高幅度为1.4%-7.5%。加劲肋增强后的组合梁的初始抗弯刚度亦有大幅提高,提高幅度为9.4%-16.9%。研究表明,以OSB板为腹板的竹木箱形组合梁在工程结构领域具有很好的应用前景。

竹质复合材料工字形梁的抗弯性能试验

为了探索竹质复合材料在桥梁建筑结构方向应用的可能性,对4根竹质复合材料工字形梁的抗弯力学特性进行了初步的四点抗弯模型试验研究,其中一根模型试验梁仅配置体外钢筋而不施加预应力,另一根模型试验梁施加体外预应力,并通过试验得到了模型试验梁的屈服承载力、极限承载能力、腹板与翼缘板的连接方式与结构抗弯刚度之间的相互关系。研究结果表明:该类竹质工字形梁的破坏模式有腹板撕裂破坏和腹板受压区局部屈曲破坏;梁的整体工作性能优良,能够提供较高的承载力和结构刚度,但是其后期结构变形较大,结构延性较好,工字形梁的承载力取决于结构变形量值;另外腹板与翼缘板之间采用螺栓连接和结构胶连接的连接方式也有待于进一步深化研究。

基于舒适度的钢桁架-混凝土组合楼板动力特性研究

大跨楼盖结构的振动舒适度问题在结构设计中不可忽视,钢桁架-混凝土组合楼板是大跨结构中常用的楼板形式。针对该类型楼板的振动舒适度问题,建立简化层合梁模型以及精细的层合板模型,分析结构动力特性的影响因素和影响机理,并建立某真实结构的参数化有限元模型,计算细部构件对楼板振动频率影响规律。研究表明:当混凝土板和钢桁架的弹性模量比、质量密度比满足一定条件时,存在"分界点"使得随着混凝土板厚增加,组合楼板基频先降低后增加。进行舒适度计算或减振设计时,应注意是否存在"分界点"以及"分界点"位置;增大混凝土板弹性模量或减小密度能提高楼板基频,但对基频改变不明显;工程上可通过适当提高下弦杆和腹杆截面惯性矩、提高桁架高度和减小楼板跨度等方法提高组合楼板频率。

有木隔板的木-混凝土组合梁斜交螺钉连接件抗剪承载力计算方法研究

为研究有木隔板的木-混凝土组合梁斜交螺钉连接件的抗剪承载力,分析了有木隔板的木-混凝土组合梁斜交螺钉连接件的受力机理,分别建立受压剪作用螺钉连接件单铰弯曲和双铰弯曲的受力模型,受拉剪作用螺钉木材受压破坏、单铰弯曲和双铰弯曲的受力模型,以及斜交螺钉连接件的受力模型,提出了有木隔板的木-混凝土组合梁斜交螺钉连接件抗剪承载力的计算方法,并与试验结果进行对比。结果表明,提出的算式能够较好地预测有木隔板的木-混凝土组合梁斜交螺钉连接件的抗剪承载力。