Tests on block shear of coped beams with a welded end connection

An experimental study of block shear of coped beams with a welded clip angle connection is presented in this paper. Twelve full-scale coped steel I-beam tests were conducted. The test parameters included the web block aspect ratio (height to width ratio of the web block connected to the clip angle) and the connection rotational stiffness. Out of the 12 test specimens, eight test specimens failed in block shear of the connection, namely, tensile fracture of the block width (the web underneath the clip angle) and shear yielding of the block height (the web along the vertical side of the clip angle). Two test specimens failed by local web buckling at the cope, one test specimen failed in the welds and the remaining one did not fail due to the limited capacity of the loading jack.The test results showed that in general the block shear capacity of the test specimens increased with increasing web block aspect ratio and increasing connection rotational stiffness. The current design specifications (AISC-LRFD, CAN/CSA-S16-09, CAN/CSA-S16-01, BS EN 1993-1-8-2005, BS5950-1:2000, and AIJ-1990) provide conservative estimates of the block shear capacity of the test specimens except for the specimen that had the smallest connection rotational stiffness. It should be noted that none of the design equations evaluated in this programme consider the influence of the web block aspect ratio and the connection rotational stiffness.     

An investigation of the block shear strength of coped beams with a welded clip angle connection — Part I: Experimental study

The ends of a coped beam are commonly connected to the web of a girder by double clip angles. The clip angles may either be bolted or welded to the web of the beam. One of the potential modes for the failure of the clip angle connection is the block shear of the beam web material. To investigate the strength and the behavior of the block shear of coped beams with welded end connections, ten full-scale coped beam tests were conducted. The test parameters included the aspect ratio of the clip angles, the web shear and tension area around the clip angles, the web thickness, beam section depth, cope length, and connection position. The test results indicated that the specimens failed, developing either tension fractures of the web near the bottom of the clip angles or local web buckling near the end of the cope. Although the final failure mode of the six specimens was local web buckling, it was observed during the tests that these specimens exhibited a significant deformation of the block shear type prior to reaching their final failure mode. No shear fracture was observed in all of the tests. A comparison between the ultimate loads in the test and the predictions using the current design equations indicates that the current design standards such as the AISC-LRFD, CSA-S16-01, Eurocode 3, BS5950-1:2000, AIJ and GB50017, are inconsistent in predicting the block shear strength of coped beams with welded end connections. The analytical study of the strength of the test specimens using the finite element method, a parametric study, and a proposed design model for designing block shears for coped beams with welded clip angles are included in a companion paper.     

An investigation of the block shear strength of coped beams with a welded clip angle connection — Part II: Numerical study

An experimental study of the block shear capacity of ten full-scale coped beams with a welded clip angle connection was presented in Part I. The test results were compared with predictions using block shear design equations in several current design standards. In general, the results showed that the existing design standards did not provide consistent predictions of the block shear capacity of coped beams with welded clip angles. In addition, the equations provided by the standards cannot accurately reflect the failure mode of the specimens observed in the tests. In order to gain a better understanding of the connection behavior, such as the stress distribution in the web near the periphery of the clip angles and the failure mechanism of the connection, an analytical study of the block shear capacity of coped beams with welded clip angles was carried out using the finite element method. Based on the limited test data and the results of the finite element analysis (FEA), a strength model was established and a design equation was proposed to evaluate the block shear strength of coped beams with welded clip angles. It was shown that the proposed design equation gave better predictions of the block shear capacity of the specimens.     

Numerical investigation of the effects of connection rotational stiffness on block shear capacity of coped beams with a welded end connection

In order to investigate the effects of connection rotational stiffness on the block shear capacity of coped beams with welded end connections, a numerical investigation was conducted. Parametric study is conducted based on the validated finite element model. Based on the mechanical model of double angle connection, the pitch and the beam element length-to-angle thickness (L/t) ratio of the outstanding leg are selected as two important parameters to consider the effects of the connection rotational stiffness. The results of parametric study show that the connection rotational stiffness has a great influence on the block shear capacity of coped beams with double welded clip angle connection. The results of parametric study also show the pitch has no significant effect on the block shear capacity. Based on the results of finite element analysis, the design equation proposed by Yam et al. (2007) was modified to account for the effects of the connection rotational stiffness.     

Finite element modeling of block shear failure in coped steel beams

Block shear is a potential failure mode that is encountered in the connection regions of coped steel beams. Limited experimental studies completed so far have shown that the block shear failure in coped steel beams is a complex phenomenon, which is highly dependent on the number of bolt lines. In this paper, the use of the finite element method in predicting the block shear failure load was studied by making comparisons with experimental findings. The effects of numerical modeling details on load capacity predictions were investigated. In light of these investigations, a finite element analysis methodology has been developed and used to conduct a parametric study. Simplified load capacity prediction equations were developed based on the results of the parametric study and are presented herein.     

Experimental study of the strength and behaviour of reinforced coped beams

A total of 10 full-scale tests were conducted to investigate the strength and behaviour of reinforced coped steel I-beams. The test parameters included the length of longitudinal stiffeners, length of transverse stiffeners, combined longitudinal and transverse stiffeners, double transverse stiffeners, cope depth and cope length. For the coped beam specimens without stiffeners, local web buckling failure occurred in the cope. For the specimens with longitudinal stiffeners only, the general failure mode was flexural yielding of the full beam section at the location of maximum bending moment followed by web crippling at the end of the cope between the longitudinal stiffeners and the top flange of the full beam section. In contrast, the general failure mode for the specimens with combined longitudinal and transverse stiffeners consisted of flexural yielding of the full beam section at the location of maximum bending moment followed by flange local buckling near the loading position.The test results show that the reinforcements were able to increase the capacity of the coped beam specimens significantly and the results also illustrate that in addition to cope depth, cope length also affects the behaviour and strength of the reinforced coped beam specimens. Based on the limited test data, a modification to the current reinforcement details for coped beams was proposed. The proposed reinforcement details accounted for the effects of various cope details. To increase the range of applicability of the proposed reinforcement details, a numerical study is currently underway to consider a wider range of cope details.     

A numerical study of the strength and behaviour of reinforced coped beams

A numerical study of the strength and behaviour of reinforced coped beams is presented in this paper. Nonlinear finite element analysis was conducted to predict the structural behaviour and strength of the test specimens examined in a different research study by the authors. The finite element analytical results generally agreed well with the test results. Subsequently, a parametric study using the validated FE models was conducted to further examine the effects of various parameters on the strength and behaviour of reinforced coped beams. For all cases examined in the study, none of the reinforced coped beams experienced flexural failure at the coped section. The parametric results show that for the same beam section, the strength of the reinforced coped beams decreases with increasing cope depth to beam depth ratio (d_c/D), irrespective of the cope length to beam depth ratio (c/D) and types of stiffener. In addition, the strength of the beams generally decreases with increasing c/D ratio. It was also found that for the cope details examined in the study, coped beam sections with a web depth-to-thickness ratio (d/t_w) less than or equal to 52.7 and reinforced by a pair of longitudinal stiffeners are able to develop either the plastic moment capacity of the full beam section near the loading position or the shear yield capacity of the coped section. For a coped beam section with a larger d/t_w ratio, a stiffener arrangement consisting of longitudinal and transverse stiffeners is recommended.     

Lateral-torsional buckling resistance of coped beams

The lateral-torsional buckling resistance of beams depends on the support conditions. In floor structures for buildings coped beams are often used. A numerical model was developed to investigate the influence of copes on the lateral buckling resistance. This model is described in a companion paper [Maljaars J, Stark JWB, Steenbergen HMGM, Abspoel R. Development and validation of a numerical model for buckling of coped beams. Journal of Constructional Steel Research 2005;61(11):1576-93]. In this paper results of a parameter study carried out with the numerical model are presented. Based on these results recommendations for design rules are given. The study is restricted to (coped) beams with end plates.     

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.     

A parametric study on ultimate strength of single shear bolted connections with curling

Recommended procedures of finite element modeling for predicting the structural behaviors of single shear bolted connections in cold-formed austenitic stainless steel are presented in this paper. It was shown that predictions by FE analysis method were in a good correspondence with test results for ultimate behaviors such as failure mode, ultimate strength and out-of-plane curling. A parametric study on four-bolted connections with extended variables; plate thickness, end distance and edge distance is performed in order to consider the influence of curling on ultimate strength for practical design and ultimate strengths obtained from FE analysis results are also compared with those calculated by current design standards and recently modified equations by Kuwamura. It is found that Kuwamura's equations, which are specified by SSBA design manual are more valid for predicting ultimate strength of bolted connection without curling compared to other design specifications, while for specimens curled in FE analysis, Kuwamura's equations overestimated the ultimate strength due to strength reduction caused by curling and current other design standards showed a tendency to underestimate the ultimate strength of block shear fracture regardless of curling occurrence. Consequently, revised design formula for considering the effect of curling on bolted connection is proposed in this paper using correlations between strength reduction ratio and plate thickness. Furthermore, the validation of proposed design equations in predicting the ultimate strength is verified through comparisons with existing test results and additional FE analysis results.     

Finite element modelling of composite beams with full and partial shear connection

The present investigation focuses on the evaluation of full and partial shear connection in composite beams using the commercial finite element (FE) software ANSYS. The proposed three-dimensional FE model is able to simulate the overall flexural behaviour of simply supported composite beams subjected to either concentrated or uniformly distributed loads. This covers: load deflection behaviour, longitudinal slip at the steel-concrete interface, distribution of stud shear force and failure modes. The reliability of the model is demonstrated by comparisons with experiments and with alternative numerical analyses. This is followed by an extensive parametric study using the calibrated FE model. The paper also discusses in detail several numerical modelling issues related to potential convergence problems, loading strategies and computer efficiency. The accuracy and simplicity of the proposed model make it suitable to predict and/or complement experimental investigations.     

螺栓连接曲梁的弯曲应力及螺栓剪力计算

由于螺栓连接曲梁变形是静不定问题,不能简单把螺栓连接曲梁的弯曲变形作为静定问题处理,否则会导致曲梁的弯曲应力及螺栓剪力存在较大的计算误差.因此,按静不定问题研究螺栓连接曲梁的弯曲变形,推导出了曲梁弯曲应力及螺栓剪力的计算公式.算例分析表明,该方法计算结果与有限元方法求解结果非常接近,两种方法计算结果的误差很小;对于螺栓连接曲梁截面弯曲应力及螺栓剪力的计算,应把梁弯曲变形按静不定问题处理更为合理.     

高强轻骨料混凝土梁抗剪承载力的试验分析与计算

通过集中荷载作用下的8根高强轻骨料混凝土简支梁的抗剪试验研究,分析了高强轻骨料混凝土梁的抗剪破坏形态和抗剪性能。结合国外大量砂轻混凝土简支梁抗剪试验结果的分析,提出了砂轻混凝土无腹筋梁斜向开裂荷载和抗剪极限荷载的计算公式,与试验结果符合较好。在此基础上,建议了砂轻混凝土无腹筋梁和有腹筋梁的简化抗剪计算公式。     

集中荷载作用下超高强砼有腹筋 约束梁抗剪强度的试验研究

通过集中荷载作用下的１８ 根高强砼有腹筋约束梁的斜裂缝特点、破坏形态和抗剪性能,若重研究了砼强度、配箍特征值、剪跨比对试件抗剪强度的影响．依据实验结果,将几个抗剪公式对超高强砼有腹筋约束抗剪强度的适用性进行了比较．通过对试验数据的回归分析,提出了超高强砼有腹筋约束梁抗剪强度的建议计算公式并给出了其适用条件     

体外预应力混凝土梁受剪承载力计算方法研究

为研究体外预应力对混凝土梁受剪承载力提高的作用机理和体外预应力混凝土梁受剪承载力计算方法,分析钢筋混凝土梁和体外预应力混凝土梁微元体受力特点的区别,探讨体外预应力对受剪性能影响的机理,求解体外预应力对混凝土和箍筋抗剪贡献的提高系数,得到体外预应力混凝土梁受剪承载力理论计算式。采用已有体外预应力混凝土梁剪切破坏的试验数据对理论计算式进行验证,并与各国规范计算结果进行对比。结果表明,理论计算式得到的受剪承载力计算值与试验值的比值均值为0.950,标准差为0.125,提出的计算式可较好地预测体外预应力混凝土梁的受剪承载力,并可以考虑梁的几何尺寸、剪跨比、预应力筋弯起角度、纵筋率、配箍率、纵筋及腹筋屈服强度、混凝土强度等影响因素。     

Effects of partial shear connection on the behavior of semi-continuous composite beams

In this paper, the effects of partial shear connection on the behavior of semi-continuous composite beams were studied numerically using two-dimensional finite element model with plane stress elements. The finite element model takes into account the nonlinearity of the different materials involved. For the shear connectors, a non-linear (shear-slip) relation, drawn from the push-out tests, was used. The accuracy of the proposed finite element model was verified against test results available in the literature. A simplified method to predict load capacity and deflection of the semi-continuous composite beams was also proposed. Based on the results obtained from the finite element analysis, the concept of partial shear connection in the hogging moment regions can be accepted provided that the shear connectors are sufficiently ductile.     

New design rules for the shear strength of LiteSteel beams

The LiteSteel Beam (LSB) is a new cold-formed hollow flange channel section produced using dual electric resistance welding and automated continuous roll-forming technologies. The innovative LSB sections have many beneficial characteristics and are commonly used as flexural members in building construction. However, limited research has been undertaken on the shear behaviour of LSBs. Therefore a detailed investigation, including both numerical and experimental studies, was undertaken to investigate the shear behaviour of LSBs. Finite element models of LSBs in shear were developed to simulate the nonlinear ultimate strength behaviour of LSBs, including their elastic buckling characteristics, and were validated by comparing their results with experimental test results. Validated finite element models were then used in a detailed parametric study into the shear behaviour of LSBs. The parametric study results showed that the current design rules in cold-formed steel structures design codes are very conservative for the shear design of LSBs. Significant improvements to web shear buckling occurred due to the presence of torsionally rigid rectangular hollow flanges, while considerable post-buckling strength was also observed. This paper therefore proposes improved shear strength design rules for LSBs within the current cold-formed steel code guidelines. It presents the details of the parametric study and the new shear strength equations. The new equations were also developed based on the direct strength method. The proposed shear strength equations have the potential to be used with other conventional cold-formed steel sections such as lipped channel sections.     

剪切连接度对组合梁工作性能的影响

为探讨剪切连接度对组合梁工作性能的影响,采用有限元软件ANSYS建立模型,并通过组合梁模型计算分析了剪切连接度对滑移、截面应变分布、挠度及极限承载力的影响,得到了一些有意义的结论。     

High strength steel bolted connections with filler plates

The effects of undeveloped filler plates were experimentally evaluated for high strength steel bolted connections using standard size holes, oversize holes and multiple fillers. Filler plates up to 51 mm (2 in.) thick were utilized in connecting high performance A709 HPS 480W (HPS 70W) grade steel plates using 22 mm (0.88 in.) A490 bolts. With increasing filler thickness, the connection strength was found to decrease up to a limit and then recover for thicker fillers in standard and oversized hole connections. Multiple filler connections experienced the greatest strength decrease as the bolt failure shifted to the threads located outside the shear planes. Deformations also exhibited a limit, however the use of oversize holes resulted in 1.7 times larger deformations than standard or multiple fillers. Recommendations were developed for strength reduction and deformation amplification as function of filler thickness and bolt diameter.     

波纹钢板纵向接缝环槽铆钉连接与高强度螺栓连接受剪性能试验研究

与高强度螺栓连接相比,环槽铆钉连接具有预紧力不易损失、耐久性好等优势,具有替代高强度螺栓用于波纹钢板纵向接缝的可行性。为便于实际工程应用,需要对其受剪性能进行研究。以波形、板厚与连接件个数为参数设计了6组36个波纹钢板纵向接缝的轴压试验,包括两组单波波纹钢板环槽铆钉连接接缝、两组四波波纹钢板环槽铆钉连接接缝以及两组四波波纹钢板高强度螺栓连接接缝。波纹钢板波形尺寸分别为150 mm×50 mm、380 mm×140 mm,板厚分别为6、7 mm和8 mm。同时考虑波形和铆钉直径的影响,对四种连接形式的32个环槽铆钉进行了预紧力试验。主要从预紧力和受剪承载力两方面对两种连接形式进行了对比,并研究了钉群效应对于环槽铆钉连接纵向接缝承载力的影响。结果表明：强度等级相同的环槽铆钉预紧力明显高于高强度螺栓预紧力,环槽铆钉接缝在试验加载过程中未出现类似于高强度螺栓接缝的预紧力损失、连接松动现象,前者具有更大的受剪承载力和更好的延性。按JGJ 99—2015《高层民用建筑钢结构技术规程》计算波纹钢板环槽铆钉连接纵向接缝承载力偏于保守。考虑钉群效应的影响,建议采用JGJ 99—2015计算孔壁承压承载力...