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。     

T形肋GFRP抗剪连接件的静载推出试验

为改善玻璃纤维增强塑料（GFRP）与混凝土的界面粘结性能,进行了3组共计9个T形肋GFRP抗剪连接件的静载推出试验,主要考虑了T形肋内开孔及横向穿孔钢筋2个参数对其抗剪性能的影响,得到了破坏形态、裂缝分布规律及荷载 相对滑移关系,分析了T形肋对GFRP抗剪连接件粘结滑移性能、极限承载力以及破坏机理的影响。基于试验得到的破坏机理建立了T形肋GFRP抗剪连接件的极限承载力计算公式。结果表明:T形肋增加了GFRP抗剪连接件与混凝土的接触面积,提高了界面的粘结力;界面出现滑移后,T形肋孔内的混凝土榫或钢筋混凝土榫能提供更好的抗剪性能;孔内是否配置横向穿孔钢筋将导致试件出现2种不同的破坏形态。     

Experimental shear resistance evaluation of Y-type perfobond rib shear connector

Recently due to the increase in the construction of the steel–concrete composite structures, researches on shear connector which is capable of composite behavior of two members have been widely studied. This study evaluated the behavior of Y-type perfobond rib shear connector which is superior in shear resistance and ductility than conventional perfobond rib shear connector. Also, it suggested a shear resistance equation based on the push-out test. Firstly, various types of the proposed Y-type perfobond rib shear connectors have been examined to evaluate the effect on design variables such as strength of concrete, transverse rebar, thickness of rib, and Y-shape angle. As a result, the experiment showed that the higher the concrete strength, the shear resistance increased, while ductility decreased. In addition, transverse rebar significantly impacted both shear resistance and ductility to increase. Moreover, as thickness of ribs increased, shear resistance increased and ductility decreased. It was also proven that Y-shape angle has an effect on shear resistance and ductility to grow. Furthermore, it was indicated that Y-type perfobond rib shear connector has higher shear resistance and ductility than the conventional perfobond rib shear connector by comparing and estimating the experimental results. Lastly, the effect of bearing resistance, transverse rebar, dowel resistance by holes, and dowel resistance by Y-shape ribs on shear resistance was estimated by regression analysis. Through the result, the shear resistance equation was suggested to predict shear resistance of Y-type perfobond shear connector.     

GFRP肋式剪力连接件受力性能对比试验研究

剪力连接件是保证GFRP混凝土组合梁/板中两种不同材料共同工作的重要构造,设计了矩形肋和T形肋两类GFRP肋式剪力连接件,进行了3组共8个GFRP肋式剪力连接件的推出试验,包括:矩形肋开孔、T形肋开孔、T形肋不开孔3组GFRP肋式剪力连接件,得到了其破坏形态、极限承载力、荷载滑移曲线及荷载应变变化规律,重点研究肋内开孔及肋的截面形式对GFRP肋式剪力连接件受力性能的影响。试验结果表明:GFRP肋式剪力连接件的破坏形态均为混凝土劈裂破坏;对比矩形肋开孔试件,T形肋开孔试件强度高、延性好;对比T形肋不开孔试件,T形肋开孔试件强度与延性均能提高。基于试验结果,建立了考虑肋内开孔及肋截面形式影响的GFRP肋式剪力连接件极限承载力计算公式,拟合得到了GFRP肋式剪力连接件的荷载滑移曲线上升段的理论模型,建立了其抗剪刚度计算公式。     

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.     

钢-混凝土组合梁开孔波折板连接件受剪性能试验研究

通过12组不同参数的开孔波折板连接件试件进行单调加载受剪试验,研究了不同构造参数的连接件试件的破坏形态、荷载-滑移特性、构造参数对受剪承载力的影响,以及贯穿钢筋的应变、开孔波折板的von Mises应力随荷载的变化规律。研究结果表明：开孔波折板连接件的荷载-滑移曲线基本可分为无滑移阶段、弹性阶段、塑性阶段及破坏阶段;波高和混凝土强度对连接件的承载能力、抗剪刚度、滑移特性等影响显著;开孔波折板焊接边的von Mises应力大于自由边,折板段的von Mises应力大于平板段,开孔周边板的von Mises应力随荷载增加而增加;结构参数相同的试件,贯穿钢筋直径越小,其承担的剪力越大,连接件波高越大,贯穿钢筋承担剪力越小;与开孔板连接件相比,无贯穿钢筋的开孔波折板连接件的受剪承载力提高了300%,设置贯穿钢筋的开孔波折板连接件的受剪承载力提高了约200%。     

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。     

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。     

π形开孔板连接件受剪性能试验研究

高性能组合结构中抗剪连接件的研究受到广泛关注,通过6组10个π形开孔板抗剪连接件试件在单调及重复荷载作用下的推出试验,研究其破坏模态、荷载-滑移曲线以及应力发展规律等。分析了贯穿钢筋、腹板间距、翼缘板的布置方向、连接件数量以及加载方式对π形开孔板连接件初始刚度和受剪承载力等力学性能的影响。结果表明：π形开孔板抗剪连接件的初始刚度较大,翼缘板的存在承担了大部分剪力,阻止了纵向贯穿裂缝的发展,提高了承载力;布置贯穿钢筋连接件的荷载-滑移曲线下降平缓,表现出较好的延性;随着腹板间距的减小,腹板间混凝土的套箍作用增加,提高了连接件的承载力;在重复荷载作用下,连接件表现出良好的受力和耗能能力。根据试验结果,提出了连接件承载力计算式,承载力计算值与试验结果吻合较好。     

Behavior and strength of headed stud shear connectors in ultra-high performance concrete of composite bridges

This study presents an experimental and numerical investigation on the static behavior of headed stud shear connectors in ultra-high performance concrete (UHPC) of composite bridges. Four push-out specimens were tested. It was found that no cracking, crushing or splitting was observed on the concrete slab, indicating that UHPC slab exhibited good performance and could resist the high force transferred from the headed studs. The numerical and experimental results indicated that the shear capacity is supposed to be composed of two parts stud shank shear contribution and concrete wedge block shear contribution. The stiffness increment of a stud in UHPC was at least 60% higher than that in normal strength concrete. Even if the stud height was reduced from 6d to 2d, there was no reduction in the shear strength of a stud. Short stud shear connectors with an aspect ratio as small as 2 could develop full strength in UHPC slabs. An empirical load-slip equation taking into account stud diameter was proposed to predict the load-slip response of a stud. The reliability and accuracy of the proposed load-slip equation was verified by the experimental and numerical load-slip curves.     

Evaluation on the behavior of abutment-pile connection in integral abutment bridge

Integral abutment bridges can reduce the amount and cost of construction and maintenance work since they do not have expansion joints and shoes in order to increase stability and durability of the bridges’ system. Integral abutment bridges normally have single-row H-pile systems to resist the behaviors under service loading conditions such as thermal loading. In order to transfer member forces between abutments and H-pile, the abutment-pile connection in the integral abutment bridge should have rigid behavior. Therefore, the installation of reinforcing bars and minimum installed length of the piles in the concrete abutment are required to resist bearing force and deformation caused by shear forces and bending moments. This study examines the abutment-pile connections in the integral abutment bridge to improve the shear and bearing resistance of concrete abutment and constructability of abutment-pile connections for the single-row H-pile system with weak axis. Three types of new abutment-pile connections are proposed in this study. They feature transverse reinforcing bars perforated in H-pile, stud connectors, and perfobond rib connectors on the flange of H-pile, respectively. They are intended to increase the stiffness and strength so that they will better resist the bearing force caused by deformations and rotations at abutment H-pile concrete. Loading tests and FE analysis were conducted to evaluate the stiffness and behaviors of proposed connections for half scale abutment-H-pile connection specimens. From the test results, proposed abutment-H-pile connections were evaluated to secure sufficient stiffness, rotational stiffness, and bearing strength.     

Experimental study on shear behavior of bolt connectors in steel-concrete composite beams

为研究螺栓抗剪连接件在钢-混凝土组合梁中的受剪性能,对24个采用螺栓连接件的钢-混凝土组合试件进行了推出试验,分析了螺栓直径、螺栓强度、螺栓埋置长细比和混凝土强度等参数对螺栓连接件的破坏模式、荷载-滑移特性和受剪承载力的影响。研究结果表明：螺栓抗剪连接件的破坏模式主要为螺栓周围混凝土受压破坏和螺栓栓杆的剪断破坏;当发生混凝土受压破坏时,增大混凝土强度、螺栓直径、螺栓埋置长细比可以提高螺栓连接件的受剪承载力;当发生螺栓的栓杆剪断破坏时,提高螺栓强度可以提高螺栓连接件的受剪承载力。在试验研究的基础上,给出了不同破坏模式下钢-混凝土组合梁螺栓连接件的受剪承载力的计算方法,建议公式的计算结果与试验结果吻合较好。     

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.     

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.     

带Perfobond和T形肋连接的半刚性组合结构 第二部分:设计模型评估

针对半刚性组合框架提出一种新的设计和施工体系,主要采用Perfobond剪力连接和考虑T形肋连接构件的共同作用。试验表明,这种连接的结构性能可以满足作者在前面研究工作中提出的结构设计模型(Ferreira LTS,de Andrade SAL,da SVellasco PCG,用于半刚性螺栓连接的设计模型,Stability and ductility of steel structures,Elsevier;1998;Ferreira LTS,de Andrade SAL,da S Vellasco PCG.边柱和角柱中的半刚性组合连接,Eurosteel,2nd European conference on steel structures,1999)。基于这些结论,针对简支受力的半刚性组合螺栓连接提出两种设计模型。通过对比分析试验结果的弯矩-转角曲线、初始刚度和转动能力,归纳模型的性能(da S Vellasco PCG,de Andrade SAL,Ferreira LTS,deLima LRO.带Perfobond和T形肋连接的半刚性组合结构,第一部分:全尺寸试验.Journal of Constructional Steel Research 2005)。最后基于连接和组合截面的几个关键点处的试验压应变数值,对试验中的组合框架和设计模型所受到的实际压力进行评测。     

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.     

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。     

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.     

带施工缝钢筋混凝土柱剪切恢复力模型试验研究

考虑轴压比、剪跨比、配筋率等不同参数的变化,设计一组端部带施工缝的钢筋混凝土柱进行低周反复荷载试验。观察试件的破坏形态并与无缝柱对比,发现施工缝对柱端传力机制和破坏机理均有影响,会造成应力集中,使塑性铰长度变小,沿施工缝的滑移使塑性铰区剪切变形增大。试验中测量了施工缝周围的剪切变形,得到剪力-剪切变形滞回曲线。分析各个参数对剪切滞回曲线的影响,发现轴压比增大使受剪承载力提高而使延性降低;剪跨比减小使剪切变形分量增大,同时使滞回曲线由梭形变为反S形。回归得出二折线骨架曲线的分段计算式,并在综合现有剪切恢复力模型研究成果基础上确定加卸载规则,给出了带施工缝钢筋混凝土柱截面剪切恢复力模型。对带施工缝试件进行数值计算,力-位移滞回曲线的计算结果与试验吻合良好,验证了模型的有效性。     

Finite element modeling of push-out tests for large stud shear connectors

An accurate nonlinear finite element model of the push-out specimen has been developed to investigate the capacity of large stud shear connectors embedded in a solid slab. The material nonlinearities of concrete, headed stud, steel beam and rebar were included in the finite element model. The damage and failure were included in the material model for the headed stud to accurately obtain the ultimate strength of the stud connector. The capacity and ductility of the connection, the load–slip behaviour and failure mode of the headed stud were predicted. The results obtained from the finite element analysis were verified against experimental results of other researches. An extensive parametric study was conducted to study the effect of the changes in stud diameter and concrete strength on the capacity and behaviour of the shear connection. The capacity and ductility of the shear connection obtained from the finite analysis were compared with those specified in EC4 and AASHTO LRFD. It is observed that the AASHTO LRFD specifications overestimated the capacity of the large stud shear connectors, whereas the design rules specified in Eurocode-4 were generally conservative for stud diameters of 22, 25 and 27 mm, and unconservative for diameter of 30 mm. The ductility of the large stud shear connectors is sufficient for practical application in composite bridges.