【作者】 汪洋；

【导师】 李天；

【作者基本信息】 郑州大学 ， 防灾减灾工程及防护工程， 2014， 博士

【摘要】 钢-混凝土组合桁架梁是由钢桁架与混凝土板组合而成的受弯构件，这种组合梁具有优越的空间利用性能和显著的工程经济效益。钢-混凝土组合桁架梁目前在我国的研究还处于起步阶段，相关的理论和试验研究尚欠不足，尤其是缺乏适合我国工程设计需要的组合桁架结构承载性能及设计方法的研究。由于钢-混凝土组合桁架梁类型多样，受力性能亦较复杂，论文选取结构形式相对典型，在我国部分地区已开始初步使用的圆钢管组合桁架梁为研究对象，通过试验研究、有限元数值模拟、参数分析以及理论推导，研究钢-混凝土组合桁架梁的抗弯承载性能及其影响因素。论文首先采用试验方法研究了钢-混凝土组合桁架梁的抗弯承载能力。设计了4根编号为CB1、CB2a、CB2b和CB3的钢-混凝土组合桁架梁试件进行抗弯试验，详细介绍了试件单调加载静力试验的全过程情况，包括组合梁的破坏形态、变形性能、控制截面应变、滑移等。以CB2b试件为例，分析了混凝土受压翼缘板的应变及应力分布、荷载-挠度曲线以及抗弯极限承载力的变化特点。试验结果表明：钢-混凝土组合桁架梁的整个截面应变基本符合平截面假定；钢-混凝土组合梁的混凝土受压翼缘存在较明显的剪力滞后效应；钢-混凝土组合桁架梁具有较高的受弯承载能力和一定的延性性能。在试验研究的基础上，论文以4个试件为例分别建立了符合工程实际的钢-混凝土组合桁架梁的有限元模型。通过计算分析，了解了组合桁架梁的应力变化特点、组合梁的荷载-位移关系、荷载-滑移关系以及组合桁架梁的极限承载力，并与试验结果进行了对比。分析表明：从弹性刚度来看，4个试件有限元计算的弹性刚度均大于试验弹性刚度；从承载力来看，有限元得到的构件极限承载力与试验结果较接近，变形性能与试验结果基本吻合。为了便于设计应用，论文对钢-混凝土组合桁架梁受压混凝土翼板的有效宽度进行了大量的计算分析，并将分析结果与我国现行钢结构设计规范有关组合梁有效宽度的规定做了比较。论文对上述4个组合桁架梁试件混凝土翼板的应力分布情况分析表明：组合桁架梁在荷载作用下，随着作用荷载的增加，有效宽度系数变化较为复杂，但总体上呈增大的趋势。当其他条件不变时，组合梁的宽跨比（b/l）越大，有效宽度系数e越小。增大组合梁混凝土翼板宽度时，混凝土板上的应力分布不均匀程度会增大，剪力滞后效应加剧。因此，设计计算时应适当限制组合梁的宽跨比（b/l），使混凝土翼板充分发挥承载能力。设计计算时，如对梁的宽跨比不加区分，完全按照钢结构设计规范的规定取值，则有可能高估宽跨比较小的组合梁的极限承载力，导致偏于不安全的结果。在极限承载力状态下，组合桁架梁有效宽度的计算结果不低于现行钢结构规范的取值，对于不同高跨比的钢-混凝土组合桁架梁，设计计算时，可以完全按照钢结构设计规范的规定取值，计算组合梁的极限承载力。为了便于设计应用，论文最后还给出了便于工程应用的有效宽度简化计算公式。论文对组合梁的混凝土板厚度和宽度、腹杆截面尺寸、桁架梁上弦托板宽度以及栓钉抗剪连接程度等参数进行了分析，研究这些设计参数对组合桁架梁抗弯性能的影响特点。研究表明：当其他参数不变时，组合梁腹杆截面径厚比增加时，组合梁的初期刚度、后期刚度以及极限承载力均无明显变化。因此设计时适当考虑采用较厚且较宽阔的混凝土翼板，既可以提高组合梁承载力又能改善组合梁的变形性能。另外，上弦托板的宽度和栓钉抗剪连接程度都会在一定范围内提高组合梁的承载能力。为能从理论上更好地把握组合桁架梁的抗弯性能，论文推导了钢-混凝土组合桁架梁受弯承载力理论分析的基本假定和计算公式，总结组合桁架梁极限承载力的实用计算方法并与试验研究和有限元分析得到的数据结果进行了对比。研究表明：对于部分抗剪连接的桁架组合梁（CB1），有限元计算值和理论值几乎一致，而试验值比理论值偏小5%。对于完全抗剪连接的桁架组合梁（CB2a、CB2b和CB3），试验值比理论值平均偏大7%，有限元计算值比理论值偏大约19%。可见设计时采用理论推导的实用公式是偏于安全的。论文提出了一种新型双钉头型栓钉剪力连接件形式，并进行了推出试验有限元模拟分析，在此基础上讨论了影响新型栓钉连接件抗剪承载力的主要因素，并结合有关规范公式提出了设计建议，最后还分析了采用新型栓钉的钢-混凝土组合桁架梁的抗弯承载力。研究表明：当其他参数不变时，采用新型栓钉的组合梁极限承载力明显提高，后期刚度有所提高，变形能力显著增强。更多还原

【Abstract】 Steel truss-concrete composite girder is a new type of composite beam structurewith superior space-using performance and significant project economic benefits.As apromising structural system of application, the research of steel truss-concretecomposite girder in China is still at the starting stage, related theoretical andexperimental research is still insufficient, especially the lack of research on bearingperformance and the design method suitable for needs.Because of the complex mechanical performance of steel truss-concretecomposite girder and the extensive experimental study is not realistic.A relativelysimple circular steel tube composite truss girder has been used as the research objectin this paper.The theoretical analysis, finite element numerical simulation andexperiments are adopted to study the properties and the influence factors of bendingbearing capaticy of the steel truss-concrete composite girder.Firstly, this thesis uses the experimental method to study the steel truss-concretecomposite beam flexural capacity.The CB1, CB2a, CB2b and CB3specimen aretaken for example.The test results show that: the whole section strain of the steel-trussconcrete composite girder of obeys the plain section assumption.Therefore, thetheoretical calculation with the plane section assumption is reasonable. It is alsofound that the concrete composite beams shear compression flange exist obvioushysteresis effect, therefore, the shear lag effect should be considered during thedesigns.The results show that: the bearing capacity and deformation performance ofcomposite truss beam is good.On the basis of experimental researches, the elastic and plastic stress analysis ofthe solid-web steel-concrete composite beams is put out, the circular steel tube trusstype steel concrete composite beams are analyzed and the stress and the effectivesection width is discussed, the formulas of the ultimate bending bearing capacity ofthe composite beams are derived. Theoretical analysis shows that: the compressiveconcrete flange effective width is an important factor which affects the bending bearing capacity.The accurate effective width should be calculated in design.For thesteel truss-concrete composite girder, there are only two basic failure modes offlexural failure, namely the lower chord tension yield failure or upper concrete plateis pressed.Designers should choose the failure mode and calculate the bearingcapacity of the corresponding limit. Analysis shows that:the4specimens of finiteelement calculation of elastic stiffness are larger than the test of elastic stiffness; frombearing capacity, bearing capacity and the test results are close to the ultimate finiteelement, the deformation performance is consistent with the test results. This providesa basis for the further study of parameter analysis.In order to facilitate the design application,a simplified calculation formula forthe effective width of steel-truss concrete composite girder is put out,which isconvenient for engineering application. In order to understand furtherly of the factorswhich have influence on the bearing capacity of the steel-truss concrete compositegirder, this paper also analyses the ventral rod thickness, width of concrete slab,girder truss chord plate width and spacing of studs and other parameters.On this basis,this paper presents a method to design a steel-truss concrete composite girderpreliminarily.In order to further understand the influence factors of the bending bearingcapacity of composite beams, the ventral bar section, concrete slab thickness andwidth, upper plate truss beam width and stud shear connection degree and otherparameters are analyzed.The characteristics of these design parameters haveimportmant influences on the flexural performance of composite truss girder.Research results show that: when the other parameters are fixed, composite beam webrod diameter thickness ratio increases, the initial stiffness of the composite beam, postyield stiffness and ultimate bearing capacity had no obvious change. So the designappropriate to consider the use of concrete wing plate is thick and broad, not only canimprove the bearing capacity of composite beams and can improve the deformationproperties of composite beams. In addition, the degree of shear connection upperplate width and studs are combined to improve the bearing capacity of beam in acertain range.The theoretical analysis is put out in order to understand better of the theory of flexural performance of composite truss girder. Comparison of solid web steel-concrete composite beam from the two levels of elasticity and plasticity, and the fullshear connection composite beams with partial shear connection composite beamplastic analysis results were put out. Research shows that: for non full shear trusscomposite beam (CB1), finite element calculation and theoretical values are almostthe same, while the test is smaller than the theoretical value of5%. For the completeshear truss composite beams (CB2a, CB2b and CB3), average7%greater than thetheoretical value of the test value, finite element calculation value is about19%higher than theoretical value.Therefore, the theoretical calculation formulas of theultimate bending bearing capacity of the composite beams are suitable for use,and itcan ensure enough strength and ductility reserve.At present, the traditional stud connectors are widely used in most steel-concretecomposite structures in China, the connection pieces root is relatively weak, the shearability is poor, the connection is easily failure.These disadvantages cause great wastein steel-concrete composite structures in China.Aiming at this problem, this paperproposes a novel double screw form head stud shear connection, and put out thepush-out test and finite element simulation analysis. On this basis, the main factorsinfluencing the new stud shear connectors carrying capacity are discussed and somedesign suggestions are put forward. Finally, the bending bearing capacity of asteel-truss concrete composite girder with the new style double-nut stud shearconnectors is discussed. The results show that: when the other parameters areconstant, the higher bearing capacity and better deformation ability should beobtained in the composite beams with new style double-nut stud shearconnectors.And the new stud shear connector has a good application prospects in thesteel-concrete composite structures.更多还原