Ultimate load analysis of pretensioned inverted T-beams with circular web openings

The provision of transverse openings in floor beams to facilitate the passage of utility pipes and service ducts not only results in a more systematic layout of pipes and ducts, it also translates into substantial economic savings in the construction of a multi-storey building. In this paper, ultimate load analysis of statically loaded simply supported pretensioned inverted T-beams with circular web openings is presented. Major findings relevant to ultimate load analysis of pretensioned beams with circular web openings are summarized. An attempt has been made to answer the frequently asked questions related to ultimate load analysis on multiple circular web openings. It has been shown that the analysis method for pretensioned beams with multiple large circular web openings can be further simplified without sacrificing rationality.     

Finite element analysis and structural design of pretensioned inverted T-beams with web openings

This paper presents the results of a research project aimed at providing standard circular web openings to the popular precast pretensioned inverted T-beam. Opening size and placement and required materials strengths were investigated. In this paper the nonlinear analysis and design of simply supported pretensioned inverted T-beam with circular web openings are presented. Two design parameters are varied: opening location and number of openings. The results from nonlinear finite element analysis were substantiated by test results from five pretensioned inverted T-beams with web opening and one solid beam. Good agreement is shown between the theoretical and the experimental results. The test results obtained from this investigation show that the performance of the specimens with web openings is almost identical to that of the specimen without web openings. A simple design method for pretensioned inverted T-beam with circular web openings is proposed.     

Web buckling study of the behaviour and strength of perforated steel beams with different novel web opening shapes

This paper presents an experimental and analytical study on the behaviour of perforated steel beams with closely spaced web openings. Seven specimens including two typical cellular beams (i.e. circular web openings) and five perforated beams with novel web opening shapes were tested to investigate the failure mode and load strength of the web-post between two adjacent web openings. Fourteen numerical test specimens were developed and analysed by the finite element method and the results were compared with the full scale experiments. The effect of web opening spacing/web opening depth of web-posts was studied to investigate the effective ‘strut’ action of the web-post buckling. The effect of the web opening depth/web thickness was also studied to investigate the stability (slenderness) of the web-post subjected to vertical shear load. Two hundred and twenty-fine elastic-plastic finite element analyses were then employed in a comprehensive parametric study to propose an empirical formula which predicts the ultimate vertical shear load strength of web-posts formed from the particular web opening shapes.Perforated beams with standard circular, hexagonal and elongated web openings are mostly used nowadays. Various non-standard web opening shapes are introduced through this paper for first time. These new pioneering web opening shapes improve the structural performance of the perforated beams when examined under the web-post buckling failure mode. In addition, the manufacturing procedure of these non-standard web openings show great advantage in comparison with the manufacturing way of the more popular cellular beams.     

Web openings in horizontally curved composite plate girders

The paper is concerned with the effects of circular or square web openings on the ultimate strength of horizontally curved composite plate girders. Finite element analysis using the computer package LUSAS has been employed to investigate the behavior and ultimate strength capacity of the girders with web openings of different proportions. The opening sizes and their locations within the web panels have been studied in detail, and the results are presented in the form of load–deflection and load–opening size plots. An approximate method to determine the ultimate strength capacity of horizontally curved composite plate girders accounting for the presence of web openings and composite action between the steel girder and concrete slab is presented. The accuracy of the method is established by comparing the predicted strength with the corresponding values predicted by the finite element method.     

腹板开洞钢拱的平面内稳定极限承载力设计理论及方法

腹板开洞钢拱组合了拱和开洞构件的特性,目前在轻轨列车站篷及航站楼等的钢结构中有广泛应用。本文首先用有限壳单元分析了以工形截面腹板开洞圆弧钢拱为代表的拱的平面内弹性屈曲性能,考察了腹板孔洞的几何参数和拱本身的几何参数对屈曲荷载的影响;按照整体屈曲荷载的等效原则,把腹板开洞拱等效为由两个T形截面和缀板组成的格构式构件,并给出了格构式构件的等效截面尺寸。然后研究了各参数下的腹板开洞钢拱的弹塑性屈曲性能,定量考察了孔洞对稳定极限承载力的削弱作用,提出了腹板开洞钢拱特有的单边塑性铰的破坏机理。利用已经建立的拱的稳定系数与拱的正则化长细比的关系,根据等效构件的换算长细比,提出了受静水压力及其它荷载分布形式的腹板开洞拱的平面内稳定极限承载力设计方法。     

开圆孔波纹腹板钢梁弹塑性抗剪屈曲试验及设计方法研究

为研究波纹腹板H型钢梁开孔后的受剪性能,设计完成4个试件的受剪承载力试验。试验设计为两端简支梁的跨中单调加载,试验中监测试件跨中位移,得到试件的荷载-位移曲线、极限荷载和破坏形态等。采用ABAQUS对其进行数值模拟,将模拟结果与试验对比得到,有限元模型能较好地模拟各试件的受载变形过程。参考现有未开孔波纹腹板的弹塑性屈曲计算方法,根据试验结果及有限元参数分析结果,提出波纹腹板开孔后的弹塑性承载力的计算式。研究表明,开圆孔后的波纹腹板均发生整体剪切屈曲破坏,现有的未开孔波纹腹板弹塑性屈曲计算公式对于开孔后的波纹腹板偏于不安全,文中提出的公式与试验及参数分析的结果相比具有较好的安全性,且形式简单、便于采用。     

Design of horizontally curved plate girder webs containing circular openings

A simple design method to predict the ultimate shear capacity of horizontally curved plate girder webs containing centrally placed circular openings, and subjected to shear is presented in this paper. The solution is obtained by incorporating the effects of curvature and opening size to an equilibrium equation for straight girders containing web openings. It is observed from a parametric study that ultimate load carrying capacity drops linearly with increasing degree of curvature for curved girders having smaller web openings. No significant drop in ultimate capacity is, however, observed when the web opening size exceeds half of the web depth. Accuracy of the proposed equation is assessed by comparing the results with the corresponding finite element values as well as with available experimental results. A satisfactorily correlation has been observed.     

钢筋混凝土圆孔梁的抗震性能及其设计方法

采用钢筋混凝土圆孔梁是一种降低高层建筑层高的有效途径。由于梁腹开孔后破坏了钢筋混凝土梁的受剪机理，尤其当孔洞设置在框架梁端附近时，在地震作用下，使高层建筑框架梁端塑性铰区域的受力性能更为复杂。为解决这类框架梁的设计问题，本文通过２４根圆孔梁及２根对比实腹梁的低周反复荷载试验和静力荷载试验，结合对国内外有关试验的研究，基本摸清了圆孔梁的静力性能及抗震性能。根据受力特征和破坏形态的机理分析，提出了圆孔梁的实用强度计算方法及有效的配筋构造措施。     

腹部开孔钢筋混凝土简支梁受剪承载力计算

基于29个腹部开圆孔和42个腹部开矩形孔的钢筋混凝土简支梁的试验结果,针对不同受剪破坏形态,提出了腹部开孔的钢筋混凝土简支梁孔侧剪切破坏下的受剪承载力下限值计算公式以及上下弦杆剪切破坏下的受剪承载力计算公式,计算公式中反映了孔洞尺寸、加强腹筋、梁纵筋面积、弦杆高度、剪跨比等参数的影响。通过和国内外共计122个钢筋混凝土开孔简支梁试件试验数据的对比表明,建议公式的计算结果与试验结果吻合较好,且具有适当的安全储备。并给出了建议公式的推荐适用范围,可供实际工程设计参考。     

Openings in horizontally curved plate girder webs

Ultimate strength tests on plate girders curved in plan containing centrally placed circular web openings are reported. Girders, built up of Grade 43A rolled steel plates, were tested to failure and parameters studied include opening size and degree of curvature. Test results show that the ultimate load capacity of the girders dropped linearly with the increasing opening size. Decrease in ultimate load carrying capacity with increasing degree of curvature is also observed for curved girders having smaller web openings. The failure mechanism observed in the tests was similar to that observed in plate girders without web openings, the only difference being the position of plastic hinges on the flange plates. The girders were analysed using the elasto-plastic finite element package, ABAQUS. Comparison of analytical predictions with the experimental results for deflected profiles, ultimate load values and load-deflection relationships show good agreement.     

腹板开孔钢梁的极限承载力有限元分析

应用有限元法对腹板中心开圆孔钢梁的性能和极限承载力进行了研究,并用其它学者所做的试验加以验证。由有限元计算所得的极限荷载、破坏特征以及荷载变形关系与试验结果比较接近。研究表明,在孔洞周边设置加劲肋对孔进行加强可以显著改善这类梁的承载性能。     

Behavior of steel-concrete composite cantilever beams with web openings under negative moment

The effect of web openings on the mechanical behavior of composite beams under negative moment was studied through monotonically loading tests. Nonlinear finite element method based analysis was also conducted for cantilever composite beams. The test and the finite element analysis results indicated that the initial cracking loads of composite beams with web opening are lower than that without web opening. The first crack initiated from the concrete slab on the top of the opening. The beams with web opening failed due to shear failure of concrete slab upon the opening. It was also found that the load carrying capacity of beam decreases with the increase of the moment-to-shear ratio at the central line of the opening and the mechanical behavior of beam can be improved significantly by applying stiffening steel plates around the opening. To quantify the reduction of load carrying capacity, a method for calculating the load carrying capacity of beams with web openings under negative moment was derived with consideration of the interaction between moment and shear. Good consistency was obtained between the proposed method, the finite element method and the test results.     

Deflection of castellated beams subjected to uniformly distributed transverse loading

This paper presents an analytical solution for determining the deflection of castellated/cellular beams with hexagonal/circular web openings, subjected to a uniformly distributed transverse load. The solution is derived using the principle of minimum potential energy. To validate the derived analytical solution, three-dimensional linear finite element analysis is performed using four-node shell elements built-in ANSYS software. Good agreement between the finite element result and the present analytical solution is demonstrated.     

Design for openings in cold-formed steel channel stub columns

This paper is concerned with the ultimate load capacity of perforated cold-formed steel channel stub columns. A design equation has been developed to determine the ultimate load capacity of perforated channel short columns containing either single or multiple openings of square, circular and manufacturer's opening shape. The equation is based on extensive parametric studies carried out using finite element modelling on plain and lipped channel sections containing openings. A wide range of parameters such as plate slenderness, opening shapes and sizes have been considered in the study. Web plate slenderness and opening area ratio are the two main variables used to derive the design equations. The accuracy of the proposed design equation is established by comparison with a number of experimental and finite element results reported by other researchers.     

钢筋混凝土开洞梁的试验分析及传力模式

通过对开洞深梁、开洞短梁以及开洞浅梁试验结果的分析 ,根据其受力特性进行了分类 ,并分别阐述了破坏形态、影响因素及传力模式 ,供开洞梁设计参考     

腹板开洞压型钢板组合梁的非线性分析

钢-混凝土组合梁下通过的管道会导致建筑层高的增加而减小组合结构的优势。腹板开洞的钢-混凝土组合梁有效的减小了梁下所需的空间,从而在工程上解决了该问题。但是,洞口的存在影响了钢-混凝土组合梁的受力性能。文章利用ANSYS有限元软件对腹板开洞压型钢板组合梁进行了非线性分析,探讨了洞口处弯剪比对腹板开洞组合梁受力性能的影响。分析结果表明,洞口位置靠近加载点或者支座处都会削弱组合梁的承载力,而组合板对腹板开洞组合梁的抗剪承载力贡献很大,在计算中忽略的话是偏于保守的。     

腹板开洞钢-混凝土组合梁极限承载力的影响因素分析

腹板开洞组合梁在国外工程中已广泛应用。在钢梁腹板上开矩形洞的钢-混凝土组合梁可减少管道对建筑空间的占用,降低工程成本。但腹板洞口的存在影响了组合梁开洞截面的抗弯和抗剪承载力。介绍目前开洞组合梁承载力的计算方法,并利用ANSYS软件对影响腹板开洞组合梁极限承载力的主要因素进行计算分析。结果表明:洞口弯剪比、洞口尺寸、栓钉连接件数量、洞口上方组合板的宽度与厚度、洞口偏心距、混凝土板的横向配筋率对开洞组合梁的承载力均有一定影响,在结构设计时应予以考虑。     

梁腹板开有圆孔时的稳定问题研究

钢梁腹板开孔的局部稳定问题非常重要。本文作者研究了开有圆孔的腹板在剪切、弯矩单独作用下的屈曲应力以及相应的腹板高厚比限值。此外，分析了腹板在剪切、弯矩共同作用下的屈曲问题，得出了用相关公式表示的屈曲条件。     

矩形开孔钢筋混凝土伸臂梁受剪性能试验研究

为方便设备管线通过,采用腹部开孔梁可有效降低楼层高度,但开孔会削弱梁的整体刚度,导致孔洞附近的应力及内力重分布十分复杂。为研究腹部矩形开孔的钢筋混凝土伸臂梁的受力性能,以正反弯矩比、孔洞位置、剪跨比及孔侧斜筋作为主要变量,对12根钢筋混凝土开孔伸臂梁和1根钢筋混凝土实腹伸臂梁试件进行了两点加载下的受剪性能试验。研究了各种参数对开孔伸臂梁的裂缝开展及破坏形态、应变分布、变形和受剪承载力等受力性能的影响。试验结果表明：正反弯矩比和孔心剪跨比改变了伸臂梁在孔洞附近的受力状态,导致破坏时孔侧呈现出不同的裂缝形态。配置孔侧斜筋后,孔侧混凝土和箍筋更好地发挥协同抗剪作用,试件的受剪承载力显著提高,裂缝开展和变形均得到有效的控制。利用混凝土开孔简支梁发生孔侧剪压破坏的受剪承载力公式对开孔伸臂梁的受剪承载力进行计算,并和试验数据进行对比可知,按开孔简支梁的算式对开孔伸臂梁的受剪承载力进行计算,计算结果与试验结果的平均比值为0.96,方差为0.07,结果偏于安全。     

Nonlinear FE analysis of the ultimate behavior of steel castellated beams

A numerical model is developed to predict the behavior of castellated beams with hexagonal and octagonal openings up to failure. The numerical model takes into account both material and geometric nonlinearities. To initiate buckling, an initial small out-of-plane geometric imperfection, obtained from an eigenvalues buckling analysis, was imposed to the model. Results of experimental data obtained from previous works have shown that the model is able to predict, with good accuracy, the ultimate load and to some extent the mode of failure. A parametric study is then realized to assess the cross-section classification given in the Annex N and to compare between the ultimate load behavior of castellated beams with hexagonal and octagonal openings when subjected to flexure and shear force. The numerical results have been compared with those obtained with the design method presented in ENV1993-1-1 Annex N.