开孔钢板连接件承载力计算公式研究

研究分析了国内外学者提出的开孔钢板连接件极限承载力计算公式,由于其考虑了不同的影响因素和采用了不同的试验试件,现有的连接件承载力计算公式差异较大.本文设计、制作了7组不同的孔内不设贯通钢筋的开孔钢板连接件试件共21个,完成了极限承载力试验.基于连接件承载力的主要影响因素,提出了连接件承载力计算公式.通过与非线性有限元以及现有公式的计算结果比较,本文公式、非线性有限元、Hosain及胡建华公式与本文试验结果较为吻合,可供连接件设计时参考.     

低温下栓钉连接件抗剪承载力的数值模拟研究

为研究低温下栓钉连接件的抗剪承载力,通过有限元软件ABAQUS建立低温推出试验模型,并进行低温推出试验验证有限元模型的准确性。通过56个模型参数化分析,得出研究结论:栓钉连接件的抗剪承载力随温度降低而提高,在-20,-40,-60℃时相较于常温下分别提高12. 1%、18. 6%和24. 2%;低温环境下,混凝土强度是栓钉连接件抗剪承载力的主要影响因素,而栓钉自身强度对连接件整体抗剪承载力的影响较小。在严寒地区组合结构的设计中,建议在已有的承载力设计公式基础上,引入混凝土低温影响系数。     

贯穿钢筋对开孔板连接件抗剪承载力影响的非线性分析

采用ABAQUS软件建立有限元模型,模拟开孔板连接件推出试验,研究贯穿钢筋对开孔板连接件抗剪承载力的影响。研究结果表明:模拟的推出试验结果与实际试验结果吻合较好,能够反映开孔板连接件的真实受力情况,贯穿钢筋的屈服强度和直径对开孔板连接件极限抗剪承载力有显著的影响,开孔板连接件的极限抗剪承载力随着贯穿钢筋屈服强度和直径的增加而线性增加;贯穿钢筋长度对开孔板连接件极限抗剪承载力影响不大,贯穿钢筋在开孔中不同位置对开孔板连接件抗剪承载力影响较小。根据研究结果给出了开孔板连接件的极限抗剪承载力与钢筋屈服强度、直径和长度的关系表达式。     

腹板嵌入式外包U形钢-混凝土组合梁正弯矩区受弯性能研究

传统钢-混凝土组合梁需要焊接不同形式的抗剪连接件,为避免繁琐的焊接工序及焊接对钢材产生的不良影响,提出了腹板嵌入式外包U形钢-混凝土组合梁。在冷弯成型的U形钢腹板上部开槽,并嵌入到混凝土翼板,与板底横向钢筋共同组成带有混凝土榫连接件的腹板嵌入式外包U形钢-混凝土组合梁(WUCSB)。设计了8个WUSCB的正弯矩区受弯性能试验,考虑U形钢板厚度、连接件间距、混凝土翼缘板宽等参数的影响,分析组合梁的破坏模式,并基于荷载-挠度曲线和荷载-滑移曲线等试验结果对其刚度、承载力和延性等受力性能指标进行评价;建立了有限元模型,进行U形钢板厚度、混凝土翼缘板宽和梁底纵筋直径等3个参数的影响规律分析。试验结果表明：该组合梁满足完全抗剪连接,组合作用良好,U形钢可以达到全截面塑性,具有良好的整体受弯性能;增加U形钢板厚度和梁底纵筋直径可以提高组合梁的承载力;连接件间距、栓钉及箍筋对组合梁的承载力影响较小。基于试验结果和连接件的传力机理,给出了WUSCB抗剪连接度的计算方法;基于全截面塑性假定,给出了WUSCB受弯承载力设计方法,该承载力设计方法具有一定的安全储备。基于换算截面法,给出了受弯刚度计算方法,出...     

基于梁式试验与推出试验的栓钉连接件荷载-滑移关系对比研究

为比较基于梁式试验与推出试验得到的栓钉连接件荷载-滑移关系,在定性理论分析的基础上,建立两种试验的精细化有限元模型并进行了试验验证,运用有限元模型分析两种试验中栓钉连接件的受力状态,比较栓钉连接件的抗剪承载力和剪切刚度。结果表明,在弹性阶段,梁式试验中栓钉连接件处于双向受压状态,栓钉连接件所受掀起力较小,剪切刚度比推出试验高;在极限状态下,梁式试验中栓钉连接件所受掀起力大,栓钉连接件的抗剪承载力较推出试验低。建议当采用推出试验获得栓钉连接件的荷载-滑移关系时,应考虑将栓钉连接件的抗剪承载力进行适当折减,而剪切刚度不予折减。     

ECC混凝土应用于开孔钢板连接件试验研究

基于6个孔内不设贯通钢筋的普通混凝土和ECC混凝土开孔钢板连接件试件的极限承载力试验,研究分析了ECC混凝土对连接件极限承载力和滑移的影响,提出了连接件极限承载力和滑移的计算公式。结果表明,采用ECC混凝土可明显提高混凝土的开裂荷载以及增大钢与混凝土间的相对滑移。通过与非线性有限元以及现有公式的计算结果比较,研究的公式、非线性有限元、Hosain及胡建华公式与试验结果吻合较好。     

集中荷载作用下拱形双钢板混凝土组合墙板的有限元分析

通过ANSYS/LS-DYNA平台对9个拱形双钢板混凝土组合墙板在集中荷载下的试验进行了有限元分析,对试件进行了精细化建模,有限元模型由锤头、上下钢板、混凝土、连接件和底板等部分组成。通过对比试验和有限元分析的力-位移曲线以及破坏特征,验证了有限元模型的准确性。通过该有限元模型分析了影响试件承载力的参数,主要包括混凝土厚度、钢板厚度、连接件间距、连接件直径和矢跨比,结果表明,钢板厚度为影响承载力的主要因素,连接件间距的减小和直径的增加可以提升试件的组合性能,合理的矢跨比应在1/4～1/3之间。     

集簇式栓钉抗剪承载力折减系数计算方法

为给装配式钢-混组合结构梁桥集簇式栓钉抗剪连接件的设计提供参考,深入研究了集簇式栓钉抗剪连接件的受力特性。采用ABAQUS有限元软件建立推出试验有限元模型,对群钉效应及其主要影响因素进行了有限元参数化分析,并给出综合考虑混凝土强度、栓钉排数、栓钉纵向间距影响的集簇式栓钉连接件抗剪承载力折减系数计算公式。结果表明:受到群钉效应的影响,集簇式栓钉连接件的单钉平均抗剪承载力有较大程度的折减并且钉群受力呈现明显的不均匀性; 随着混凝土强度的提高,φ22×200栓钉连接件抗剪承载力、抗剪刚度逐渐增大; 当栓钉排数从3排增加至7排时,群钉的单钉平均抗剪承载力以及栓钉抗剪承载力折减系数逐渐降低,同时钉群受力的不均匀程度大幅提升; 当栓钉纵向间距由4d(d为栓钉直径)增加至8d时,群钉的单钉平均抗剪承载力以及栓钉抗剪承载力折减系数呈现增大趋势; 提出的集簇式栓钉连接件抗剪承载力折减系数计算公式计算值与有限元值吻合良好,可以为装配式钢-混组合结构梁桥集簇式栓钉抗剪连接件的设计提供理论依据。     

点支式玻璃建筑中铸铝支承件的简化设计方法

在点支式玻璃建筑中可以采用自重轻,比强度高的铸铝支承件代替不锈钢支承件。通过对铸铝支承件的承载性能试验研究和弹塑性有限元分析,得到了铸铝支承件的肢端屈服荷载和承载性能,但仍没有承载力的简化设计公式提出。利用经过试验研究验证可靠的有限元模型进行弹性有限元分析,研究支承件在不同受力状态下的应力分布,与由材料力学提出的理论方法比较。分析给出了各支承件的应力集中系数与简化的承载力设计方法。简化计算公式与试验研究、有限元分析结果比较表明,简化公式具有良好的适用性,而且考虑到铸铝支承件的脆性破坏形式而预留了一定的安全储备,能够为铸铝支承件的合理设计提供依据。     

开孔钢板连接件承载力试验研究

本次试验设计、制作了7组不同的孔内不设贯通钢筋的开孔钢板连接件试件共21个,完成了其极限承载力试验。在此基础上,研究分析了钢板孔径大小、圆孔间距、钢板厚度及混凝土强度等对连接件极限承载力的影响,提出了连接件极限承载力和滑移的计算公式,供连接件设计时参考。     

夹板式夹层玻璃抗风压性能试验研究

夹板式夹层玻璃具有良好的安全性能,已得到了越来越广泛的应用。现有关于夹板式夹层玻璃的研究还比较有限,国内现行规范尚未规定夹板式夹层玻璃的设计。本文从夹板式夹层玻璃的抗风压性能出发,以某夹板式玻璃幕墙工程抗风压性能试验为基础,研究了不同压力差对夹板式夹层玻璃作用下的挠度分布规律,并将试验结果与规范JGJ102—2003的点式玻璃计算方式的结果进行对比,并对夹板式夹层玻璃的挠度计算进行了探讨,为今后规范的进一步完善、修订及夹板式夹层玻璃在玻璃幕墙工程中的应用提供了试验依据。     

Response of pre-cast reinforced composite sandwich panels to axial loading

This paper summarises the results of an experimental and numerical study of precast reinforced composite sandwich panels. Full-scale tests were carried out to determine their axial strength capacity. Load–deformation response, strains variation across the insulation layer, strains in shear connectors, crack appearance and propagation under increasing load were recorded and analysed. A brief review of previous research works undertaken on the load bearing capacity of reinforced concrete solid walls is presented. Test results and finite element analysis (FEA) results were compared with calculated values based on current ACI design practice and other available design formulations developed for solid walls to determine if these empirical formulae are also applicable for sandwich panels. A semi-empirical formula was proposed to better fit the experimental and the FEA results.     

Structural behaviour of eccentrically loaded precast sandwich panels

Results of an experimental investigation to study the ultimate strength behaviour of precast concrete sandwich panels (PCSP) with steel truss shear connectors are reported. Six full-scale sandwich panels with variable slenderness ratio were cast and tested under eccentric loads. Deflection characteristics, variations of strains across the insulation layer, strains in shear connectors, crack appearance and propagation under increasing load were recorded and analysed. The role of the shear truss connectors in transferring load from the outer wythe (layer) to the inner and ensuring composite behaviour was also observed. Results obtained showed that all panels behaved in a fully composite manner under eccentric load till failure. The ultimate strength of the PCSPs was found to decrease non-linearly with the increase in the slenderness ratio. Because of the complex behaviour of PCSP due to its material non-linearity and the interaction between its various components, finite element analysis (FEA) was conducted. Comparison with test results indicated that the FEA closely estimate the wall strength and formulae based on reinforced concrete principles underestimate the wall strength.     

Study of the flexural performance and a novel calculation formula for the degree of composite action for precast concrete sandwich panels

This study investigates the flexural performance and degree of composite action (DCA) of precast concrete sandwich panels (PCSPs) with four types of connectors. Five full-scale specimens were designed, and 4-point bending tests were performed. The specimens included four PCSPs utilizing glass fiber reinforced polymer (GFRP) truss connectors, steel truss connectors, concrete rib connectors, and GFRP pin connectors, respectively, along with a solid panel (SP). The results indicated that the flexural performance and DCA provided by the four types of connectors followed an ascending order as follows: GFRP pin-type connectors, GFRP truss connectors, steel truss connectors, and concrete rib-type connectors. Moreover, the study presented a novel method for calculating DCA, namely, the neutral axis method, which was compared with the displacement and strain methods. The reasonableness and accuracy of the neutral axis method in calculating DCA during the linear elastic stage were verified. Results indicated that the neutral axis method provided more precise and reasonable DCA that closely matched the experimental results compared with the displacement and strain methods. Additionally, the neutral axis method was simpler to calculate DCA and had a broader range of applications. Finally, the study provided recommendations for the optimal application scenarios of each calculation method.     

Static Experiment on Mechanical Behavior of Innovative Flat Steel Plate-Concrete Composite Slabs

A new type of composite slab is introduced in this paper, which is composed of normal flat steel plates and concrete slabs, connected and interacted by perfobond shear connectors (PBL shear connectors). Experiments on six specimens of this type of composite slab, loaded at two symmetric two-points, were described in this paper to get mechanical behaviors under bending moments. During the experiments, the crack patterns, failure modes, failure mechanism and ultimate bending capacity of specimens with composite slab were investigated, and the strains of concrete and flat steel plates were also measured and recorded in order to obtain the moment action. From the experimental results, it was found that composite interaction between the steel plate and the concrete fully developed, and such composite slab was verified to have good mechanical performance with high bending capacity, substantial flexural rigidity and good ductility. Plane section assumption was also verified and moreover, a design approach including calculation methods of bending capacity and flexural rigidity was established and proposed based on the experimental results, and the calculation methods were also verified and revised on the basis of comparisons of the calculated results and experimental results. Results from this paper provide references for the application of this new type composite slab.     

An experimental study on channel type shear connectors

This paper describes an experimental study on European channel shear connectors. While shear studs are widely used in steel–concrete composite elements, the channel connectors are also gaining popularity due to their certain advantages. The channel connectors do not require special equipment and standard welding procedures are adequate for attachment purposes. In addition, this type of connector offers higher amounts of shear resistance due to its high contact area with surrounding concrete. Although first studies date back to 1950s, little work has been done in the past to investigate their behavior. Majority of the work done to date was on channel connectors used in North America with a very limited parameter range. An experimental study consisting of 15 push-out tests was carried out to investigate the behavior of European type channel connectors with various heights and lengths. The ultimate resistance of the connectors obtained from experiments was compared against those predicted by North American steel design specifications. It was observed that the equations presented in American and Canadian specifications are too conservative. Based on a model that represents the typical failure mechanism in push-out tests, a new equation was developed for the ultimate resistance of channel shear connectors. It is shown that the developed equation is capable of predicting the ultimate resistance of channel connectors with reasonable accuracy.     

栓钉剪切连接件在SRHPC结构中的数值分析

探讨了型钢表面的栓钉与外包高强高性能混凝土之间的受力特性,基于既有的试验结果和理论计算,分析了栓钉的荷载—滑移曲线规律,研究了栓钉在三维有限元模拟中的影响因素,给出了三维受力状态下栓钉的刚度方程,建立了数值分析中每个方向的荷载—变形曲线。     

Design of composite asymmetric cellular beams and beams with large web openings

The design of composite asymmetric cellular beams is not fully covered by existing guidance but is an area of important practical application. Asymmetry in the shape of the cross-section of cellular beams causes development of additional bending moments in the web-posts between closely placed openings. Furthermore, the development of local composite action influences the distribution of forces in the web-flange Tees. The design method presented in this paper takes account of high degrees of asymmetry in the cross-section and also the influence of elongated or rectangular openings.Web-post moments also influence buckling of the web-post between openings, which is accentuated by adjacent long openings. Simplified equations are presented for web-post buckling based on a compression field or ‘strut’ model, which is calibrated against the results of Finite Element Analyses (FEA). The FEA are also extended to cover the case of highly asymmetric sections and ring-stiffened openings. Closed solutions are presented that enable the designer to calculate the maximum shear force acting on the beam when its load resistance is limited by web-post bending or buckling.For long openings, high pull-out forces may exist in the shear connectors at the edge of the opening. When combined with possible second-order effects due to shear deflection across the opening, it is necessary to limit the magnitude of local composite action due to Vierendeel bending that can be considered in 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.     

对组合钢梁-预制空心板中栓钉连接件的性能分析

在钢-混凝土组合梁中,剪切连接件的机械作用使得纵向剪力转移到钢翼缘/混凝土板的接合处。这种转移能力取决于剪切连接件的强度和混凝土板抵抗由剪力高度集中所导致的纵向开裂的能力。大多数对组合结构的分析都集中在传统的钢筋混凝土和金属面板结构,而对预制空心板中栓钉的剪切能力研究很少。本文对带栓钉的预制空心板组合梁结构提出标准的推力试验方法。一共进行7组测试性试验,试验结果显示新方法符合钢筋混凝土楼板规范要求。在确定这个新的标准方法后,对栓钉进行了72个足尺推力试验,确定了该类型连接件的性能,通过分析试验结果,还指出了各类参数对连接件强度和延性的作用。本文还提出了这种剪力连接件的设计公式。