圆形钢管弯扭构件承载力实用计算方法研究

利用通用有限元软件ABAQUS对圆形钢管弯扭构件的荷载-变形关系曲线进行了计算,将计算曲线与实验曲线进行了比较,基本吻合。在此基础上,考虑不同加载路径的影响,对圆形钢管弯扭构件的工作性能进行了分析,最后在参数分析结果的基础上,提出了圆形钢管弯扭构件承载力相关方程的实用计算方法。本文的研究成果可为相关研究提供参考。     

Performance of concrete-filled thin-walled steel tubes under pure torsion

In practice, concrete-filled steel tubes (CFST) are often subjected to torsion. To date, such a problem however has not been addressed satisfactorily by design codes. The present study is thus an attempt to study the torsional behaviours of concrete-filled thin-walled steel tubes. ABAQUS software is used in this paper for the finite element analysis (FEA) of CFST subjected to pure torsion. A comparison of results calculated using this modelling shows good agreement with test results. The FEA modelling was used to investigate the influence of important parameters that determine the ultimate torsional strength of the composite sections. The parametric studies provide information for the development of formulae to calculate the ultimate torsional strength, as well as the torsional moment versus torsional strain curves of the composite sections.     

矩形钢管弯扭构件的工作性能研究

利用通用有限元软件ABAQUS对矩形钢管弯扭构件的荷载一变形关系进行计算,计算结果与试验结果基本吻合。在此基础上,考虑不同加载路径的影响,对矩形钢管弯扭构件的工作性能进行分析,最后在参数分析结果的基础上,提出矩形钢管弯扭构件承载力相关方程的实用简化计算方法,该方法所得计算结果得到试验结果的验证。     

钢筋混凝土和预应力混凝土构件的拉弯扭和压弯扭强度

托架下弦处于预压力、强大的轴拉力、弯矩、剪力和扭矩的共同作用下工作;而托架上弦则处于轴压力、弯矩、剪力和扭矩的共同作用下工作。本文经过5榀下承式托架和2榀上承式托架以及10个压弯扭模型梁的试验分析说明:用我国钢筋混凝土结构设计规范TJ 10-14中弯扭构件的抗扭强度计算公式和迭加原理计算这些构件是不合适的,而且编于过分安仝。在分析这些试验资料的基础上,提出了一个考虑拉、弯、剪、扭和压、弯、扭共同作用的实用强度计算方法,计算结果与试验结果符合较好。     

钢管混凝土压弯扭构件工作机理及性能研究

本文考虑不同加载路径对钢管混凝土压弯扭构件进行了有限元全过程分析，对钢管混凝土压弯扭构件的工作机理及性能进行了深入系统的研究。为了验证理论分析方法的正确性，进行了十二个压弯扭构件的试验，分析表明，理论结果与试验结果吻合良好。     

新型冷弯箱形组合构件力学性能研究

基于箱形截面具有双轴对称、抗弯扭刚度大的特点,提出将冷弯∑形截面两两翼缘相对,并将其卷边焊接形成一种新型冷弯箱形组合截面——DS。应用非线性有限元方法分析新型截面构件在轴压、弯矩及压弯荷载作用时的诸如屈曲模式、承载力、刚度、延性及相关曲线等方面力学性能。同时,还对相同参数的新型截面构件与C形截面构件的单位承载力耗钢量进行比较。分析表明:新型截面构件在承受轴压力时具有高承载力及较高的截面模量,截面加劲充分而使子板件局部屈曲不易出现等力学性能优势。特别适宜承受轴压荷载,同时也适宜承受弯矩和压弯荷载的作用。轴压构件的单位承载力耗钢量一般仅为相同参数C形构件的50%左右,经济效益明显。新型箱形组合构件适于深入试验研究并合理应用于实际工程。     

Mechanistic Approach to Structural Fire Modeling of Composites

In this paper, a framework is presented for the modeling of the response of structural composites subjected to combined mechanical loading and fire. An emphasis is placed on the response of composites at temperatures below the decomposition temperature, where the viscoelastic response of the composite material becomes important. Material property characterization results are presented for an E-glass reinforced vinyl ester composite typical of that used for naval ship applications. Time-temperature equivalence is used in a compression strength model to predict the time to failure of composites subjected to isothermal compression loading (compression creep rupture failure). These predictions are compared with experimentally determined times to failure with good agreement. In particular, shift factors obtained from shear compliance testing are able to collapse the compression creep rupture data at different temperatures, indicating that viscolelasticity is the dominant mechanism driving the failure. This model is combined with a standard diffusion model for heat transfer in the composite to predict the time-dependent failure of composites subjected to simultaneous one-sided heat flux and compression loading. Predicted times to failure are compared with experimental results with good agreement.     

Behaviour of concrete-filled steel tubular members subjected to shear and constant axial compression

Concrete-filled steel tubes (CFST) are used extensively in modern civil engineering. In many cases, they are often subjected to shear and constant axial compression, particularly when being used in high-rise buildings. ABAQUS Programming is used in this paper for the analysis of CFST subjected to shear and constant axial compression. A comparison of results calculated using this model shows good agreement with test results in general. The theoretical model was used to investigate the influence of important parameters that determine the ultimate shearing strength of the composite members. The parametric studies provide information for the development of formulae to calculate the ultimate strength of CFST members subjected to shear and constant axial compression.     

箱形钢-混凝土组合梁的复合弯扭试验研究

为研究钢-混凝土组合梁的弯扭性能,完成了6根箱形组合梁的纯扭和弯扭试验,详述了在不同扭弯比下箱形组合梁的受力性能及破坏形态,对裂缝发展和应力的变化情况进行了分析,揭示了箱形组合梁在弯扭复合作用下,极限扭矩和极限弯矩会相应提高的机理。对组合梁扭型破坏和弯型破坏进行了对比分析,指出了根据传统的弯剪扭相关方程而得到的相关公式的不合理性,并给出了在复合弯扭和弯剪扭下的相关公式,得到的结论能为组合梁计算和分析设计提供参考。     

钢筋砼偏压扭构件非线性全过程分析

本文根据空间变角桁架模型及软化砼的本构关系,对于承受以扭矩为主的钢筋砼偏心受压构件的性能进行了全过程分析,对总数为25个试件(其中15个属于本文作者)所进行的分析,表明计算结果与试验结果符合良好。文中根据作者试验研究结果,简要介绍了压弯扭构件的扭转性能,初步讨论了软化变角桁架理论的适用范围,并对压弯扭构件的性能提出了分析方法。     

椭圆形钢管混凝土构件纯弯力学性能分析

利用有限元软件ABAQUS建立椭圆形钢管混凝土构件纯弯力学性能分析的有限元计算模型,并通过6个椭圆形钢管混凝土构件纯弯试验验证有限元计算模型的准确性。在此基础上对其受力全过程中钢管及混凝土应力分布情况进行分析,同时给出钢管与核心混凝土之间的相互作用,并对剪跨比、钢管强度、混凝土强度、短轴长和长轴长等参数对纯弯时构件极限承载力及荷载-位移曲线的影响进行比较。结果表明:椭圆形钢管混凝土构件在跨中发生倾向弯曲破坏,钢管屈服强度、混凝土强度、长轴长、短轴长及钢管壁厚等参数对其力学性能影响显著,剪跨比对其力学性能影响不明显。     

组合荷载作用下钢管混凝土构件的性能分析

研究了薄壁钢管混凝土构件在组合荷载如压扭,弯扭,压力、弯曲和扭转作用下的性能。采用ABAQUS软件进行有限元分析,对比发现,模型的计算结果与试验一致。采用该模型对在如压扭、弯扭、压弯扭等组合荷载下影响构件极限强度的重要参数进行研究分析。参数研究有利于今后推导计算复合构件在组合荷载作用下极限强度的公式。     

高强钢筋混凝土复合受扭构件的延性分析

对压弯剪扭复合受力下,23根高强钢筋混凝土柱模型进行了试验研究,并结合9根普通强度钢筋混凝土柱的复合受扭试验数据,对压弯剪复合受扭构件的延性性能进行了综合分析。探讨了轴压比、相对偏心距、混凝土强度、加载方式及纵筋与箍筋配筋强度比等参数对复合受扭构件延性的影响。分析了以上各参数对构件的初始刚度、开裂刚度和极限刚度的影响及其变化规律。为钢筋混凝土柱的抗震设计提供了理论依据。     

钢管混凝土柱轴压力-弯矩-扭矩空间复合受力拟静力试验研究

采用自行设计的压力-弯矩-扭矩复合受力加载装置,基于力-位移混合控制加载方法,完成了8个钢管混凝土柱试件在压-弯-扭等复合荷载作用下的拟静力试验,变化了截面形式、加载方式和弯扭比等参数。试验结果表明：圆钢管混凝土柱和矩形钢管混凝土柱在压-弯-扭等复合受力往复荷载作用下的滞回曲线较为饱满,没有“捏拢”现象产生,具有较好的耗能能力;弯扭比较大的矩形钢管混凝土试件在扭转角较大时由于钢管底部局部屈曲较为明显,存在承载力退化现象;钢管混凝土截面轴向应变基本满足平截面假定;弯矩的存在将削弱钢管混凝土柱的受扭能力;在压-弯-扭等复合受力往复荷载作用下,钢管剪应变与扭转角之间存在较好的线性关系。对试验实测结果和已有文献分析表明：在弯扭比较大时由主压应力导致钢管表面发生局部鼓曲而破坏,弯扭比较小时,主拉应变将导致钢管混凝土柱表面在低周往复荷载作用下开裂。研究成果可为进一步开发考虑扭转作用的钢管混凝土纤维梁单元提供基础性依据。     

钢筋砼偏压扭构件抗扭强度的研究

本文根据作者对偏压扭构件的试验研究结果,集中地讨论了在单调扭矩和低周反复扭矩作用下,钢筋砼偏心受压构件抗扭强度的实用计算方法。文中提出了抗扭强度计算公式及其适用条件,公式简便易用,可用于计算纯扭构件和轴压扭构件的抗扭强度,可供设计偏压扭构件参考。     

Flexural performance of rectangular CFST members

This paper presents a finite element analysis (FEA) modeling to study the flexural performance of rectangular concrete filled steel tubular (CFST) members with compact, non-compact or slender element sections. Seventy test results are used to verify the FEA modeling. Generally good agreements were achieved in the ultimate bending capacity and the curvilinear trends of the moment versus mid-span deflection relations of the composite member between the experimental results and the FEA results. The FEA modeling is then used to investigate the residual failure patterns of the core concrete, the typical residual deformations of outer steel tube and the stress and strain distributions across the composite section in the whole loading procedure. Analysis results show that interaction of steel and concrete in the composite beam offers stress redistribution in steel and concrete which makes the rectangular CFST beam have high flexural capacity and ductility. Finally, the reliability analysis method is used to calibrate the existing design formulae on composite beam in EC4 (2004), AISC (2010) and DBJ/T13-51-2010 (2010). It was found that all the design formulae achieved adequate reliability index.     

双向压弯作用下槽钢的正常使用及承载力极限状态

随着对轻钢结构的要求越来越高,设计的有效性和准确性也越来越重要。为此,需很好地了解结构的性能,故对双向压弯作用下槽钢杆件的性能进行研究,提出了几种模拟方法,进行槽钢的非线性分析。突出了正常使用极限状态和承载力极限状态之间的联系。提出了双向压弯作用下槽钢的经济、有效设计,以达到经济、轻质的效果。提出几种方法,解决实际中普遍遇到的设计难题。给钢结构设计人员介绍分析程序,可用于优化双向压弯作用下的槽钢尺寸。     

箱形型钢混凝土梁复合受扭性能试验

通过5根箱形型钢混凝土梁的复合受扭性能试验,详细描述了试件在不同扭弯比作用下的加载过程。试验表明,箱形型钢混凝土梁在复合受力情况下,出现扭转型或弯曲型两种破坏形态;扭弯比是影响弯、扭破坏形态的重要因素;适当的弯矩存在能显著提高型钢混凝土梁的抗扭强度。通过对试验数据分析得到的箱形型钢混凝土梁的弯扭相关方程,可为其设计提供参考和依据。     

钢-混凝土组合梁扭转的组合作用分析

在试验及理论分析的基础上,对开口截面钢-混凝土组合梁在扭转中的组合作用进行研究。组合梁在扭转中,即使是纯扭作用下,截面上仍存在组合作用,分析时不能忽略混凝土翼板和钢梁间的相互约束作用,否则会低估组合梁的抗扭能力。钢梁自身的抗扭作用很小,钢梁对组合梁扭转的贡献在于,它向混凝土翼板提供了纵向约束。在钢筋混凝土变角软化桁架模型(RA-STM)的基础上,通过引入平截面假定,以考虑组合梁扭转中的组合作用,建立适于分析开口截面钢-混凝土组合弯扭性能的三维桁架模型:在弯扭作用下,组合梁截面各单元分别处于一维应力状态(体系1)和二维应力状态(体系2),体系1用来抵抗由弯矩和扭矩引起的截面纵向应力,体系2用来抵抗由扭矩引起的截面剪应力,两者通过截面的纵向应变协调和内力平衡条件联系起来。所分析内容充分满足平衡条件、变形协调条件和材料本构方程。计算结果与试验结果吻合良好。此外还简要评价了现有的组合梁极限扭矩计算公式的不足。     

In-plane strength of concrete-filled steel tubular circular arches

More than 400 concrete-filled steel tubular (CFST) arch bridges have been constructed worldwide so far. However, design codes or guidance for the in-plane strength design of CFST arches are yet to be developed. In current design practice, the philosophy for the in-plane strength design of reinforced and prestressed concrete arches is widely adopted for CFST arches. For this, the CFST arches are considered under central or eccentric axial compression and are treated similarly to CFST columns, and the classical buckling load of CFST columns is used as the reference elastic buckling load of CFST arches. However, under transverse loading, the in-plane elastic buckling behaviour of CFST arches, particularly shallow CFST arches, is very different from that of CFST columns under axial compression. In addition, different from CFST columns under central or eccentric axial compression, CFST arches are subjected to significant nonlinear bending actions and transverse deformations prior to buckling and these will influence the strength of CFST arches greatly. Therefore, it is doubtful if the current method for in-plane strength design of CFST arches can provide correct strength predictions. In this paper, a method for the in-plane strength design of CFST circular arches, which is consistent with the current major design codes for steel structures, is developed by considering both geometric and material nonlinearities. A design equation for the in-plane strength capacity of CFST arches under uniform compression, and a lower-bound design equation for the in-plane strength check of CFST arches under combined actions of bending and compression are proposed.