Predicting the capacity of perfobond rib shear connector using an ANN model and GSA method

Due to recent advances in the field of artificial neural networks (ANN) and the global sensitivity analysis (GSA) method, the application of these techniques in structural analysis has become feasible. A connector is an important part of a composite beam, and its shear strength can have a significant impact on structural design. In this paper, the shear performance of perfobond rib shear connectors (PRSCs) is predicted based on the back propagation (BP) ANN model, the Genetic Algorithm (GA) method and GSA method. A database was created using push-out test test and related references, where the input variables were based on different empirical formulas and the output variables were the corresponding shear strengths. The results predicted by the ANN models and empirical equations were compared, and the factors affecting shear strength were examined by the GSA method. The results show that the use of ANN model optimization by GA method has fewer errors compared to the empirical equations. Furthermore, penetrating reinforcement has the greatest sensitivity to shear performance, while the bonding force between steel plate and concrete has the least sensitivity to shear strength.     

开孔板连接件受剪承载力研究

为研究开孔板（PBL）连接件的受剪承载力,在已有试验和理论研究的基础上,分析了单孔PBL连接件的破坏模式及受剪承载力的主要影响因素,并建立开孔钢板厚度不小于9mm时,单孔PBL连接件考虑侧向约束力的受剪承载力模型。该模型考虑了开孔钢板周围的混凝土包裹、贯通钢筋和试件底面摩擦对PBL连接件提供的较强约束作用,以及由此导致的单孔PBL连接件受剪承载力的提高。通过大量的单孔PBL连接件的受剪试验数据拟合得到单孔PBL连接件的受剪承载力计算公式。该计算公式和已有计算公式的计算值与试验值的对比分析表明,未设置贯通钢筋的试件受剪承载力的离散性较大,而设置贯通钢筋的试件受剪承载力的离散性相对较小;该计算公式能合理考虑混凝土包裹、贯通钢筋和试件底面摩擦对PBL连接件受剪承载力的影响,其计算结果与试验值总体吻合得较好。     

Experimental study on shear performance of twin perfobond rib shear connectors under monotonic and repeated loading

通过4个抗剪连接件试件的单调加载和重复加载推出试验,研究双开孔钢板连接件的承载能力、荷载-位移关系、延性、初始刚度、刚度退化及耗能等力学性能。结果表明：双开孔钢板连接件初始刚度大,且具有较好的延性及耗能能力;加载初期荷载-位移曲线呈线性关系,该阶段承载力主要由贯穿孔内混凝土榫提供,随着荷载的增加,试件荷载-位移曲线出现第一个明显拐点,混凝土榫压碎后,荷载-位移曲线出现峰值点,该阶段承载力主要由贯穿钢筋提供;重复荷载下各试件初始刚度值与单调荷载下相差不大;随着加载循环次数的增加,试件刚度不断减小,试件耗能能力逐渐降低。目前国内外已有计算式所考虑因素和计算方法不尽相同,通过国内外87个开孔钢板模型试验结果与各公式计算值的对比发现,日本JSCE公式计算值与试验值吻合度最好。     

Shear resistance of the perfobond-rib shear connector depending on concrete strength and rib arrangement

In this study, a perfobond-rib shear connector between steel and concrete mixed girder bridge components is described. Push-out tests were conducted and the results were compared with established shear-capacity equations for perfobond shear connectors. Modified shear-capacity equations that consider the perfobond-rib arrangement, including rib height and spacing, are proposed. The test results were compared with studies of the concrete end-bearing zone, of transverse rebars in the rib holes, and of the shear-capacity equations of perfobond ribs. From the push-out tests, the shear capacity of the perfobond-rib shear connector varies in proportion to concrete strength, as indicated by the increase in the contribution to the shear resistance of the concrete. The ductility of the conductor is related to the flexibility limit of the transverse rebar in the rib hole. The shear capacity of a twin perfobond-rib shear connector was reduced to about 80% that of a single perfobond rib by reducing the shear capacity contributed by the concrete end-bearing zone, the concrete dowel, and the transverse rebar in the rib hole. The perfobond rib can be used as a shear connector in composite or mixed structures since it has sufficient ductility as well as high shear capacity.     

开孔板连接件受剪性能试验研究

开孔板连接件是钢-混凝土组合梁中常用的一种抗剪连接件。通过21个开孔板连接件试件在单调静力荷载作用下的推出试验,研究了开孔板的开孔直径、混凝土强度等级、孔中横向贯通钢筋的直径和数量等对开孔板连接件的破坏形态、荷载-滑移特性和受剪承载力等的影响。研究表明:开孔板连接件的荷载-滑移曲线(P-S曲线)大致可分为弹性阶段、塑性发展阶段和下降段;提高混凝土强度等级、增大开孔直径可提高开孔板连接件的受剪承载力,横向贯通钢筋直径由16mm增大至20mm时,试件的受剪承载力提高了21.8%,配置横向贯通钢筋2 16的试件受剪承载力比相应的未配置横向贯通钢筋的试件高19.1%;随着混凝土强度等级的提高,试件抗剪刚度增大,而开孔直径及横向贯通钢筋直径则对抗剪刚度无明显影响。最后,基于试验结果提出了开孔板连接件受剪承载力的计算方法。研究成果可为编制《钢-混凝土组合桥梁设计规范》提供依据和参考。     

斜板PBL剪力键受剪性能试验研究

为缓解间隔式PBL剪力键端部受力集中的问题,提出一种斜板PBL剪力键.通过四组共16个推出试件的加载试验,研究了直板与斜板PBL剪力键的受剪承载力、刚度及变形性能.研究结果表明:直板剪力键与斜板剪力键受剪承载力相当,斜板剪力键具有较高的抗剪刚度和较好的变形能力.当考虑端部承压作用时,斜板剪力键的受剪承载力随肋板角度变化...     

Shear resistance mechanism and load-slip curve features of perfobond rib connectors during plastic stage

为保证单孔PBL连接件在塑性阶段仍具备较高的残余受剪承载力和较好的延性,对22组未设置贯通钢筋和21组设置贯通钢筋的单孔PBL连接件的荷载-滑移曲线进行了统计分析,研究了板厚不小于9mm的单孔PBL连接件进入塑性阶段后的受剪机理。在此基础上,根据荷载-滑移曲线的延性特征将其进行分类,并给出了判别条件。研究表明：单孔PBL连接件塑性阶段的残余受剪承载力由混凝土榫沿剪切破坏面的黏结力、侧向约束力提供的受剪承载力以及贯通钢筋的销栓作用组成。根据塑性阶段的侧向约束力情况,将单孔PBL连接件荷载-滑移曲线分为Ⅰ类、Ⅱ类与Ⅲ类曲线。可通过控制约束强度比,避免未设置贯通钢筋和设置贯通钢筋的单孔PBL连接件的荷载-滑移曲线出现延性较差的第Ⅲ类曲线,并可通过控制贯通钢筋比,避免设置贯通钢筋的单孔PBL连接件的荷载-滑移曲线出现经济性较差的第Ⅱ类曲线;可通过联合控制约束强度比和构造钢筋比,避免荷载-滑移曲线出现峰值点处荷载突变。     

单孔PBL剪力连接件疲劳性能试验研究

为研究PBL剪力连接件在疲劳荷载作用下的力学性能,完成了2组10个单孔PBL剪力连接件的等幅疲劳推出试验。分析PBL连接件在有、无贯通钢筋两种形式下的疲劳破坏模式,及受剪承载力、剪力-滑移关系受疲劳荷载的影响。通过建立单孔PBL连接件的损伤指标考察其疲劳损伤规律。试验结果表明：无贯通钢筋的PBL剪力连接件的疲劳损伤指标随循环加卸载逐渐趋于稳定,难以发生疲劳破坏;设置贯通钢筋的PBL剪力连接件的疲劳损伤表现为贯通钢筋断裂,PBL剪力连接件的疲劳损伤速度先慢后快,平均残余变形随疲劳荷载循环单调递增,其变化规律符合二次抛物线形式。     

钢纤维混凝土焊钉-橡胶连接件受剪承载力试验研究

为建立钢-混凝土组合结构桥梁使用的钢纤维混凝土(SFRC)焊钉-橡胶连接件受剪承载力设计计算方法,设计并制作了18组54个SFRC焊钉-橡胶连接件,通过单调加载与循环加载推出试验,研究了混凝土强度、焊钉直径、钢纤维体积掺量、橡胶套筒高度及厚度、加载模式等对其受剪承载力的影响规律.基于准牛顿法进行非线性拟合,提出了SFR...     

Experimental evaluation of joints consisting of parallel perfobond ribs in steel-PSC hybrid beams

The objective of this paper is to estimate the structural capacity and application feasibility of joints with parallel perfobond ribs in steel-PSC (prestressed concrete) hybrid beams. In order to investigate the joints, two steel-PSC hybrid beams of 8 m length are fabricated, and experimental tests are performed. The hybrid beams consist of a steel beam in the center, PSC beams at both ends, and joints connecting the steel beam and the PSC beams. In the joints, perfobond ribs are used as shear connectors in place of studs which are generally used. The parallel perfobond ribs are attached to the steel plates horizontally and vertically to assess joint performance under both flexural moments and shear forces. The test results reveal that the failure of hybrid beams occurs at the PSC region near the interface between the PSC component and the joint. No joint failure is observed in the test beams up to the fracture load stage. In addition, the test beams show sufficient ductility by virtue of the arrangement of adequate reinforcements, even though perfobond ribs are considered to be stiff shear connectors. Therefore, it is concluded that the joint with parallel perfobond ribs is an applicable system to utilize in steel-PSC hybrid beams. In addition, the perfobond ribs can be an alternative to stud shear connectors in joints of hybrid beams.     

Effect of shear connector spacing and layout on the shear connector capacity in composite beams

A three dimensional nonlinear finite element model has been developed to study the behaviour of composite beams with profiled sheeting oriented perpendicular to its axis. The analysis of the push test was carried out using ABAQUS/Explicit with slow load application to ensure a quasi-static solution. Both material and geometric nonlinearities were taken into account. Elastic-plastic material models were used for all steel components and the Concrete Damaged Plasticity model was used for the concrete slab. The post-failure behaviour of the push test was accurately predicted, which is crucial for realistic determination of shear capacity, slip and failure mode. The results obtained from finite element analysis were verified against the experimental push tests conducted in this research and also from other studies. After validation, the model was used to carry out an extensive parametric study to investigate the effect of transverse spacing in push tests with double studs placed in favourable and staggered positions with various concrete strengths. The results were also compared with the capacity of a single shear stud. It was found that shear connector resistance of pairs of shear connectors placed in favourable position was 94% of the strength of a single shear stud on average, when the transverse spacing between studs was 200 mm or more. For the same spacing, the resistance of staggered pairs of studs was only 86% of the strength of a single stud. The strength of double shear studs in favourable position was higher than that of the staggered pairs of shear connectors.     

浅析栓钉剪力连接件受剪承载力的影响因素

探讨和总结了压型钢板肋与钢梁组合结构的栓钉连接件的受力性能，从焊接方法、混凝土强度压型钢板的厚度等多方面，分析了各种影响因素对栓钉连接件受力性能的影响。     

腹板嵌入式组合梁局部受压试验研究

基于传统钢-混凝土组合梁提出了一种节省钢材且具有较高抗剪承载力的新型组合梁——腹板嵌入式钢-混凝土组合梁,由倒T形钢梁腹板上部开槽,嵌入到混凝土翼板中形成。通过4个局部受压试件的试验得出,腹板嵌入式组合梁局部受压承载力随混凝土强度等级和局部荷载作用下扩散应力分布面积的增加而提高。综合各影响因素推导出了腹板嵌入式组合梁中连接件的局部受压承载力计算公式,并提出进行局部受压设计时对横向配筋率和应力扩散深度的构造要求。通过理论计算值与试验结果的对比,验证了公式的适用性。     

Experimental study on ultimate strength of concrete filled double tubular steel with shear connector

Concrete Filled Tubular steel (CFT) member, which represents a superb deformability due to well-known confined effect between steel tube and concrete, has been used mainly as bridge pier. As a progressive composite member, Concrete Filled Double tubular steel (CFDT), which is consist of double skin steel tubes and filled concrete between them, has been proposed. Although a lot of reports on mechanical characteristics of the CFDT member are presently published, the necessity of shear connector for the CFDT member has not been addressed. In this research, the shear connector was installed at the interface between tubes and concrete in the CFDT member. To investigate the effect of the shear connector on the bending characteristics, the four points bending test were carried out. The results show that integrating the steel tubes and concrete enhances its bearing capacity. Furthermore, the strains of outer and inner tubes were also discussed in this paper.     

钢结构柱脚抗剪键抗剪承载力计算

为了确定钢结构柱脚抗剪键的抗剪承载力,分别以混凝土应变达到应力峰值应变和极限应变为抗剪屈服承载力和极限承载力的两种极限状态,选取混凝土应力-应变关系接近实际受力情况的非线性弹塑性模型,建立了考虑抗剪键剪切变形的Timoshenko梁平衡微分方程,采用Galerkin法求得抗剪键的变形曲线,进而推导了两种抗剪承载力的理论计算公式,提出了确定抗剪键埋深和截面规格的方法。研究表明：抗剪键的抗剪承载力和理论埋深取决于其材料截面特性及基础混凝土强度。研究同时表明,抗剪键埋深范围内混凝土压力方向不改变,对柱脚底板产生附加弯矩。采用有限元方法对比分析,算例结果验证了理论计算公式的正确性。图7表1参13     

单肋型装配式钢牛腿抗火性能试验研究

考虑肋板厚度、偏心距、承载、保护套类型等参数,进行了6个不同形式的单肋型装配式钢牛腿的抗火性能试验.测试了升温过程中节点的变形、温度场分布和耐火极限,观察了试件的破坏形式.试验结果表明:对于无保护外套的单肋型装配式钢牛腿,肋板厚度、偏心距和承载是影响其抗火性能的主要因素,耐火极限随肋板厚度增大而增加,随荷载和偏心距增大...     

刚性剪力键力学性能分析

通过有限元分析了组合梁刚性剪力键在极限荷载下的位移、应力,得出荷载一滑移曲线及应力分布规律,并对其构造尺寸进行了参数化分析,最后根据经验公式及有限元计算结果推出了其极限承载力简化公式。分析表明,刚性剪力键能够有效的传递混凝土与钢粱间的纵向剪力。     

Push-out tests on a new shear connector of I-shape

In steel-concrete composite beams, the shear connectors are commonly used to transfer the longitudinal shear forces across the steel-concrete interface. This paper summarizes the results of 24 push-out test specimens with a new type of shear connector called “I-shape connector”. The test specimens were designed to study the effect of the following parameters on the ultimate load capacity: the height of I-shape connector, the length of I-shape connector, the compressive strength of concrete and the number of transverse reinforcing bars. The experimental results are presented and discussed, focusing on the failure modes and load-slip behaviour. Finally, the experimental results are compared to the existing design equations to predict the ultimate load capacity of I-shape shear connectors.     

Experimental and analytical investigations on the hat shaped shear connector in the steel-concrete composite flexural member

Over the last decade, there are many research results on the new type shear connectors to solve the problems associated with the headed stud shear connector. It was revealed that the new type shear connector has better structural safety, welding quality, constructability, cost-effectiveness, etc. Especially, perforated shear connector (perfobond shear connector) which has superior fatigue resistance and constructability is receiving attention among various types of shear connectors. In this study, we suggest the new type shear connector which improved the perfobond shear connector. Newly suggested hat shaped shear connector can be used instead of headed stud shear connector commonly used in the concrete-steel composite beam. To evaluate the load carrying capacity of this hat shaped shear connector, push-out tests are carried out and test results are analyzed. In addition, the finite element analysis is conducted on the concrete slab having shear connector to investigate the stress distribution pattern affected by the presence of hat shaped shear connector. The existing design equations for the perfobond shear connectors are reviewed briefly and the equation for the prediction of load carrying capacity of new type hat shaped shear connector is suggested based on the experimental results, finite element analysis results, and existing equations suggested in the previous studies.     

Experimental investigation on behaviour of steel-concrete composite bridge decks with perfobond ribs

This paper introduces a test program conducted for steel-concrete composite bridge decks with perfobond rib shear connectors. The composite deck consists of profiled steel sheeting, perfobond ribs, steel reinforcements, and concrete. To provide longitudinal shear resistance between the profiled sheeting and the concrete, perfobond ribs were used. For a prototype steel-box girder bridge, two types of deck profiles with deck-to-girder connections were designed. To validate the effectiveness of the proposed deck system for bridge application, push-out, full-scale flexural, and deck-to-girder connection tests for each deck profile have been conducted. The results of tests have shown that the perfobond ribs can be effectively used for shear connection in the steel-concrete composite decks.