密实截面组合梁的竖向抗剪强度Ⅱ:受负弯矩作用的组合梁

在负弯矩区段,虽存在严重的混凝土开裂,但组合梁的竖向抗剪承载力仍远大于钢梁腹板抗剪名义值.采用通用有限元程序ABAQUS 6.5,对密实截面组合梁负弯矩区的弯剪强度问题进行研究.分析结果表明,提出的有限元分析方法可以准确预测组合梁的弯剪强度,同时对组合梁的变形刚度也可以较准确地模拟.在此基础上,利用有限元方法,对剪力连接程度、混凝土强度、力比、混凝土翼板截面尺寸、剪跨长度等参数进行计算分析,回归得到组合梁负弯矩区截面考虑力比影响的竖向抗剪强度公式.研究发现,在负弯矩区段,组合梁竖向抗剪强度的提高,只来源于混凝土翼板的抗剪作用,组合作用的贡献可以忽略;采用建议的抗剪强度公式可以不考虑组合梁负弯矩区截面弯矩与剪力的相互影响.     

钢-砼组合梁竖向抗剪承载力研究

在6根钢-火山渣砼简支组合梁和6根钢-火山渣砼连续组合梁试验的基础上，探讨影响组合梁竖向抗剪承载力的主要因素：混凝土翼板、名义剪跨比和力比等。试验与计算结果表明，在计算组合梁竖向抗剪承载力时，如果不考虑混凝土翼板的作用，计算结果将趋于保守，对于连续组合粱还应该考虑弯矩比的影响。     

钢砼组合梁竖向抗剪承载力的试验研究

在６根钢－火山渣砼简支组合梁和６根钢－火山渣砼连续组合梁试验的基础上,探讨影响组合梁竖向抗剪承载力的主要因素：混凝土翼板、名义剪跨比和力比等．试验与计算结果表明,在计算组合梁竖向抗剪承载力时,如果不考虑混凝土翼板的作用计算结果将趋于保守,对于连续组合梁还应该考虑弯矩比的影响。     

钢-砼组合梁竖向抗剪承载力研究

在6根钢-火山渣砼简支组合梁和6根钢-火山渣砼连续组合梁试验的基础上,探讨影响组合梁竖向抗剪承载力的主要因素:混凝土翼板、名义剪跨比和力比等。试验与计算结果表明,在计算组合梁竖向抗剪承载力时,如果不考虑混凝土翼板的作用,计算结果将趋于保守,对于连续组合梁还应该考虑弯矩比的影响。     

部分外包简支组合梁竖向抗剪设计研究

考虑了钢梁腹部钢筋混凝土对组合梁抗剪性能的影响,给出了部分外包简支组合梁弹性理论计算时的剪应力分析方法,对塑性抗剪承载力的计算引入了钢骨混凝土梁的抗剪承载力计算公式,结合试验进行对比,给出了部分外包简支组合梁的塑性抗剪承载力公式,可以为实际工程应用提供参考。     

钢-混凝土组合梁在负弯矩作用下抗剪性能的试验研究

通过3根钢-混凝土组合梁在负弯矩作用下的试验,研究了其变形发展及破坏过程,得到了组合梁的跨中剪力-挠度曲线、交界面滑移曲线和沿截面高度分布的应变变化曲线,分析了剪切连接程度、截面尺寸、剪跨比、材料强度、钢筋配置等因素对组合梁承载力和延性的影响。对钢梁进行了塑性分析,得出在负弯矩作用下钢-混凝土组合梁抗剪承载力的提高不是由于钢梁腹板的硬化效应所致,而是由于混凝土翼板的贡献,并提出了考虑混凝土翼板影响的组合梁在负弯矩作用下抗剪承载力计算公式。将计算结果与实测结果进行了比较,二者吻合良好。     

钢-混凝土组合梁截面组合抗剪性能的试验研究

对4根密实截面钢-混凝土组合梁的组合抗剪性能进行了试验研究。试件全部采用简支,跨中两点对称单调静力加载,考虑抗剪连接程度及正负弯矩的影响。试验结果表明,组合梁负弯矩区的界面滑移规律与正弯矩区的不同,其大小对组合梁的抗剪承载能力影响较小。不论混凝土翼板是处于组合梁截面的受压区还是受拉区,其对组合梁截面的抗剪承载能力均有明显的贡献,目前规范仅计算钢梁腹板的抗剪作用偏于保守。按叠加法建立了计算组合梁抗剪承载能力的计算式,计算值与实测值吻合良好。     

钢-压型钢板混凝土组合梁的极限负弯矩强度

组合梁的抗剪连接程度是影响组合梁极限承载能力的重要因素。为此 ,推导了压型钢板混凝土组合梁负弯矩强度计算公式 ,讨论了采用线性内插法的简化计算方法 ,分析了影响负弯矩强度计算的剪力连接程度     

组合梁负弯矩区“抗拔不抗剪”滑移计算

为改善组合梁负弯矩区受力性能,聂建国提出一种新的抗拔不抗剪剪力连接件技术,能使混凝土不受拉力作用。但这样必然导致组合梁的滑移增大,且组合梁抗滑刚度分布的变化使原有滑移计算方法都不再适用。本文从滑移微分控制方程出发,得到了负弯矩区采用抗拔不抗剪连接件技术的组合梁滑移计算的解析表达式,经过算例分析与比较,结果表明采用抗拔不抗剪新技术将会使滑移增大,使用时应充分考虑其影响。该滑移计算方法可以为新技术的应用和推广提供参考。     

负弯矩作用下钢筋混凝土U型叠合梁受力性能研究

针对一种由预制U型梁、预制板和现浇板组成的新型钢筋混凝土叠合梁,开展了负弯矩作用下钢筋混凝土U型叠合梁与现浇对比梁的足尺模型试验,对其破坏形态、截面承载力、位移延性和滑移等进行了较为系统的研究。研究表明:负弯矩作用下叠合梁和现浇梁均发生了受弯破坏;达到峰值荷载时叠合梁中预制板与现浇层之间、预制梁与预制板之间和预制梁与现浇层之间的最大滑移值均不大于0.5 mm;叠合梁的负弯矩截面抗弯承载力较现浇梁约低1%;叠合梁的位移延性系数为8.16,较现浇梁的位移延性系数高17%。本文研究成果可为这种新型钢筋混凝土U型叠合梁的工程应用提供技术依据和参考。     

Ultimate shear strength of composite welded steel-aluminium beam subjected to shear load

This paper describes a computationally designed process to determine the Ultimate Shear Resistance (USR) of composite steel-aluminium beams subjected to shear load. Aluminium alloys are used in a variety of structural engineering applications due to their high strength/weight ratio and durability. However, the strength of aluminium alloys is reduced near the weld due to the heat of the welding process. The USR of several different cross-sectional shapes of composite beams were initially computed using a proposed design equation. A consistent nonlinear 3-D finite element model using the ANSYS software package was used to fulfil the performance criteria. The value of the USR obtained from the proposed design equation was compared with the corresponding ultimate shear stress in the web panel obtained from the F.E. model. The outcome of the proposed equation encouraged its use as a new design equation. This equation could accurately predict the USR.     

Exact solutions for thin-walled open-section composite beams with arbitrary lamination subjected to torsional moment

The exact solutions for torsional analysis of thin-walled open-section composite beams with arbitrary lamination subjected to torsional moment are presented for the first time. For this, a general thin-walled composite beam theory with arbitrary lamination is developed by introducing Vlasov's assumption and the equilibrium equations and the force–deformation relations are derived from the energy principle. Applying the displacement state vector consisting of 14 displacement parameters and the nodal displacements at both ends of the beam, the displacement functions are derived exactly. Then, the exact stiffness matrix for torsional analysis is determined using the force–deformation relations. As a special case, the closed-form solutions for symmetrically laminated composite beams with various boundary conditions are derived. Finally, the finite element procedure based on Hermitian interpolation polynomial is developed. To demonstrate the validity and the accuracy of this study, the numerical solutions are presented and compared with the closed-form solutions and the finite element results using the Hermitian beam elements and ABAQUS's shell elements.     

Numerical study on horizontally curved steel-concrete composite beams subjected to hogging moment

The horizontally curved continuous composite steel-concrete beams, for instance, curved continuous composite bridges, have excellent qualities, such as quick construction, good seismic performance, saving construction formwork and convenience in spatial arrangement etc. At present, the application research of this kind of structures is becoming more of a concern, but very few studies have been conducted to study the mechanical performance of composite beams subjected to combined hogging (negative) bending and torsion. The purpose of the present study is to investigate the effects of curvatures on both elastic and inelastic behaviours of curved continuous steel-concrete composite beams in the interior support regions. Based on the experimental observations in a straight composite beam, a three-dimensional FE model capable of analysing the composite beams subjected to negative bending moment is built. Further numerical studies on curved composite beams with different curvatures are performed in this study. Strength and load carrying capacity, sectional strain distribution and movement of composite neutral axis before and after cracking, as well as the strain results of longitudinal reinforcing bars are investigated. Besides, the interaction equation for ultimate bending and torsional moments is proposed.     

Vierendeel joints in the circular hollow sections of high strength steel subjected to brace moment and chord compressive loadings

The Vierendeel joints used in buildings and highway bridges as well as offshore platforms are investigated by both the experimental approach and finite element method. A number of full scale specimens using new high strength steel (i.e., tensile strength of 600 MPa) are tested under cyclic quasi-static loadings to understand their strengths, rotational stiffness characteristics, and failure modes. The nonlinear three-dimensional finite element models are also constructed to verify the experimental results. The present experimental results are seen to closely agree with those from finite element analysis as well as theoretical predictions such as AISC and CIDEC equations.     

Performance of shear connection in composite beams with profiled steel sheeting

This paper describes the structural performance of shear connection in composite beams with profiled steel sheeting. An accurate and efficient nonlinear finite element model was developed to study the behaviour of headed stud shear connectors welded through-deck. The profiled steel sheeting had transverse ribs perpendicular to the steel beam. The material nonlinearities of concrete, headed stud, profiled steel sheeting, reinforcement and steel beam were included in the finite element model. The capacity of shear connection, load-slip behaviour of the headed stud, and failure modes were predicted. The results obtained from the finite element analysis were verified against experimental results. An extensive parametric study was conducted to study the effects on the capacity and behaviour of shear connection by changing the profiled steel sheeting geometries, the diameter and height of the headed stud, as well as the strength of concrete. The capacities of shear connection obtained from the finite element analysis were compared with the design strengths calculated using the American Specification, British Standard and European Code for headed stud shear connectors in composite slabs with profiled steel sheeting perpendicular to the steel beam. It is found that the design rules specified in the American and British specifications overestimated the capacity of shear connection, but the design rules specified in the European Code were generally conservative.     

高强钢组合梁研究概述

近年来,钢—混凝土组合梁结构发展很快,在建筑和桥梁领域已经得到了越来越多的应用.在材料科学取得长足进步以及组合梁理论不断完善的背景下,把高强高性能材料引入到普通的钢—混凝土组合梁中,将取得显著的经济效益和社会效益.高强材料组合梁是新材料和新结构的有机结合.本文主要介绍了高强钢组合梁在国内以及在澳大利亚、欧洲、美国等发达地区的研究现状,并指出其优点和在设计中存在的问题.文中对高强钢与高强混凝土相结合的组合梁亦有所提及.     

Nominal moment capacity of hybrid composite sections using HSB600 high-performance steel

This paper contains a parametric study to develop provisions for predicting the nominal moment capacity of hybrid composite girders using HSB600 high-performance steel in the positive bending region. The ultimate moment capacity and the ductility of a wide range of hybrid composite sections are calculated using moment-curvature analysis, and the plastic moment of each section is obtained using simple plastic theory. The obtained moment capacity and the ductility of hybrid composite sections are compared to the previous research work and the current AASHTO LRFD’s design equations. The comparison results show that there are considerable differences in moment capacity distribution between the hybrid composite sections and the conventional composite sections. It was also observed that the hybrid composite sections have sufficient rotation capacity similar to the conventional composite sections. Based on the results of the parametric study, new design equations are proposed for predicting the nominal moment capacity of hybrid composite sections. It is expected that the new design equations can be applied to simple supported or continuous hybrid composite beams in plastic design.     

Capacities of headed stud shear connectors in composite steel beams with precast hollowcore slabs

In steel-concrete composite beams, the longitudinal shear force is transferred across the steel flange/concrete slab interface by the mechanical action of the shear connectors. The ability of the shear connectors to transfer these longitudinal shear forces depends on their strength, and also on the resistance of the concrete slab against longitudinal cracking induced by the high concentration of shear force. Most of the research in composite construction has concentrated on the more traditional reinforced concrete and metal deck construction, and little information is given on shear capacity of the headed studs in precast hollowcore slabs. In this paper, a standard push test procedure for use with composite beams with precast hollowcore slabs is proposed. Seven exploratory push tests were carried out on headed studs in solid RC slabs to validate the testing procedures, and the results showed that the new test is compatible with the results specified in the codes of practice for solid RC slabs. Once a standard procedure is established, 72 full-scale push tests on headed studs in hollowcore slabs were performed to determine the capacities of the headed stud connectors in precast hollowcore slabs and the results of the experimental study are analysed and findings on the effect of all the parameters on connectors’ strength and ductility are presented. Newly proposed design equations for calculating the shear connectors’ capacity for this form of composite construction are also be given.