【作者】 刘君平；

【导师】 刘永健；

【作者基本信息】 长安大学 ， 桥梁与隧道工程， 2009， 博士

【摘要】 主管内填混凝土矩形钢管桁架结构由矩形钢管混凝土主管和矩形钢管支管组成,支管和主管采用焊缝直接相贯连接,是一种新型结构形式,具有良好的应用前景。本文在国家西部交通建设科技项目(2006318812112)和交通部应用基础研究项目(2006319812130)的资助下,对该新型结构的受力机理和设计方法进行了研究,为其在桥梁结构中的应用提供了理论依据。论文主要研究内容、方法和结论如下：1.完成了主管内填混凝土带竖杆warren形式和warren形式矩形钢管桁架的试验研究。主管内填混凝土矩形钢管桁架比空钢管桁架具有更高的整体承载力和节点承载力,但桁架整体变形能力减小。在受剪效应比较明显时,结构均发生节点破坏,但节点破坏模式并不相同,主管内填混凝土改变了节点的失效位置和失效模式。2.完成了主管内填混凝土warren形式矩形截面钢管桁架与圆形截面钢管桁架的对比试验研究。在几何尺寸及杆件材料性能相近情况下,两种截面形式的空钢管桁架在承载力及变形方面没多大差异；主管内填混凝土后,圆形截面桁架的整体和节点承载力比相应的矩形截面桁架承载力要高。矩形截面桁架能取得更大抗弯刚度,但延性相比较差,而且节点变形占桁架整体变形比例要大。3.基于试验结果,得到了主管内填混凝土对支主管应力、节点应力和桁架整体刚度的影响。受压主管内填混凝土能很好地协助钢管受力、减小钢管应变；受拉主管内填混凝土初期作用不明显,在受力后期能够阻止钢管的紧缩变形,提高桁架后期承载力；主管内填混凝土对支管影响不明显；主管内填混凝土能很好地提高受压节点的抗压刚度和强度,减小受拉节点的变形并提高强度。4.利用ANSYS通用程序建立了主管内填混凝土矩形钢管桁架结构的数值分析模型,得到了有限元分析参数,有限元分析结果与试验结果吻合较好。利用有限元分析参数进行了支主管等宽桁架受力性能的研究,分析结果表明,节点间隙处主管是桁架的薄弱部位,往往发生此处主管的剪切失效,主管内填混凝土能够提高主管的抗剪切能力。5.分析了主管内填混凝土矩形钢管桁架结构的刚度组成及受压主管内填混凝土抗压刚度和抗弯刚度取值对桁架静力性能的影响,抗压刚度取值对桁架的受力性能有较大影响,而抗弯刚度影响较小。在计算受压主管应力时,建议受压主管抗压刚度取作EA=EsAs+EcAc；在计算桁架的整体变形时,需要考虑节点变形的影响,建议对受压主管的抗弯刚度和抗压刚度进行折减。6.分析了节点的受力特点,得到了支主管等宽桁架主管的剪切破坏模式并提出了相应的承载力计算方法。探讨了主管内填混凝土矩形钢管桁架受压杆件的计算长度系数取值,建议受压主管取1.0,受压支管取0.75；在考虑节点变形影响基础上,提出了桁架整体变形的放大系数计算方法,建议对空钢管桁架和仅受压主管内填充混凝土桁架的变形放大系数取为1.15,拉压主管内均填充混凝土桁架取为1.20。更多还原

【Abstract】 The rectangular hollow section (RHS) steel tubular truss with the concrete-filled in chord is a kind of novel structural system, which chord members are concrete-filled rectangular section steel tube and its web members with rectangular section steel tube are welded on the surface of chords. Supported by the Program for West Transport Construction Science and Technology(2006319812112), and Applied Basic Research Programs of ministry of transport of China (2006319812130), the mechanical behaviors and design method of the trusses were studied in this paper, provided a theoretical basis for its application in bridge structure. The main achievements are summarized as follows:1. Test on two types RHS steel tubular trusses under static point loading at middle span were carried. The failure mode of trusses was due to the joints failure, but the failure modes were different, the concrete-filled in chord changed the failure mode.2. Test on trusses made with RHS and circular hollow section (CHS) steel tube were carried. The trusses of RHS and CHS have not much difference in the bearing capacity and deformation, but with chord concrete-filled, the CHS trusses have the higher bearing capacity of the overall truss and joints, better deformability than the corresponding RHS trusses, and the less proportion of joints deformation in the total deformation.3. Based on experimental results, the influence from concrete-filled in chords on chords members, branch members, joints stress and the overall stiffness of truss were obtained. The concrete-filled in compression chord can help compression chord members very well, and reduce the steel tube strain; The concrete-filled in tension chord do not effect the tension chord members obviously at start state, but can prevent the contraction deformation of tension steel tube at late stage, so increse the bearing capacity; The concrete-filled in chords do not effect the branchs obviously; The concrete-filled in chords can greatly enhanced the strength and rigidities of compression joints, reduce the deformation and increase the strength of tension joints,4. The nonlinear finite element model according to ANSYS program of RHS steel tubular trusses with concrete-filled chord was also built up, the calculating results of nonlinear finite element method kept in with those from tests. The mechanism of trusses with branch and chord section width equal were studied by FEA, the joints gap is the weak positon, the trusses failure were due to the chord shear failure, the concrete-filled chord can improve the shear capacity.5. The rigidity of concrete-filled in compression chord effect on trusses mechanical behavior was analyzed. The compressive stiffness of concrete-filled in compression chord does a greater effect than the bending rigidity. When in the calculation of compression chord stress, the suggestion value of compression stiffness is EA=EsAs+EcAc, as to the trusses deformation calculation, for the effect of joints deformation, the bending rigidity and compression rigidity should be reduced, but reduce method and reduce coefficient should be further discussed.6. The mechanical behavior and failure mode of joints were analyzed, the failure mode of trusses with branch and chord section width equal were provided, and the corresponding formula to calculate ultimate bearing capacity. The mechanism and failure path of overall trusses were studied, the effective length coefficient of compressive member were provided, as to compressive chord, it is 1.0, as to compressive branch, it is 0.75. the amplification factor method of calculation the overall deformation were provided, the amplification factor for RHS truss and RHS truss with concrete-filled in the compression chord is 1.15, and amplification factor for RHS truss with concrete-filled in both compression and tension chords is 1.2.更多还原