Perfobond Rib Shear Connectors Research Articles

Shear Behavior of Y-Shaped Perfobond Rib Shear Connector with UHPC Grout

Shear Behavior of Y-Shaped Perfobond Rib Shear Connector with UHPC Grout

Shear behavior on PBL shear connector with a relatively thin perforated steel plate in steel-UHPC composite bridge deck system

Recently, a new steel-UHPC composite deck system is used for long-span bridges, which uses the perfobond rib (PBL) shear connectors with a thinner steel perforated plate. Because the steel perforated plate is thinner, its failure mode may be different from that of thicker steel perforated plate. To explore the shear behavior of PBL shear connectors in this new composite deck system, five sets of ten specimens are tested in this study. The parameters of the hole diameter, D, the traverse rebar diameter, ds, and the perforated steel plate thickness, ts are considered. The failure modes, strain development versus loading, and some mechanical indexes are discussed. The experiments show that the PBL shear connector with a thinner perforated steel plate causes a shear failure, while the thicker one results in bending or bending-shear failure. According to FE (finite element) analysis, the orthogonal analysis is conducted to investigate the effect of each parameter and their interaction on the mechanical behavior. It is found that the ultimate capacity and stiffness are the most sensitive to the diameter of the traverse rebar, ds, and the perforated steel plate thickness, ts. In addition, a theoretical formula is proposed to predict the bearing capacity of PBL shear connectors. The proposed formula considers the relationship between shear strain and the dilation angle for the first time. The results show a good agreement with the experiments. The study in this paper provides a good reference for the application and optimization of PBLs with a thinner steel perforated plate in new steel-UHPC composite deck system.

Summary of the Calculation of the Shear Capacity of Perfobond Rib Shear Connectors

The analysis of longitudinal shear resistance based on shear capacity is the basis for assessing the reliability of steel-concrete joint structures. It is of great significance for the longitudinal shear of bridge structures and even for the establishment of a shear-resistant design code for steel-concrete bridge structures based on reliability theory. In this article, a more comprehensive overview of the test methods, the current state of research, and the remaining problems in the field of connectors for perfobond rib shear connectors (PBL) are presented. Firstly, the test methods for PBL connectors are categorized. The applicable characteristics of each test method and their advantages and disadvantages are summarized, and the research progress on the calculation of shear load-capacity in this structure is discussed in detail. Finally, it is concluded that the international research on the shear capacity of PBL connectors is still at a stage where the scope of their adaptation is small. Reasonable and accurate quantification of the sensitivity parameters of the PBL connectors was studied. The normality of the test form and other relevant factors should be taken into account to establish a set of more effective shear capacity calculation methods. This can be used to guide the shear capacity design of the structure more directly.

Tensile resistance and shear-tension interaction relationship of T-type perfobond rid shear connectors

This study aims to investigate the mechanical performance of T-type perfobond rib (T-type PBL) shear connectors under complex load cases. Initially, the experimental tests were conducted and finite element analyses (FEA) were performed. Subsequently, a parametric study was carried out to assess the impact of geometric parameters on tensile resistance and the effect of tension ratio on the shear-tension interaction resistance of T-type PBL connectors. Finally, based on the test and FEA results, prediction methods were developed for evaluating the tensile resistance and shear-tension interaction relationship of T-type PBL connectors. The test results showed that the pull-out of the concrete below the flange led to the failure of T-type PBL shear connectors under tension. The concrete failure angles were approximately 33°. The failure under shear was manifested as concrete collapse and connector yielding. The ultimate capacity decreased with the increase in tension ratio. The specimens with tension ratios of 25%, 45%, and 65% decreased 7.9%, 16.3%, and 24.2%, respectively, compared to the specimen under pure shear. The parametric study suggested that the rib height and perforated rebars were the main factors impacting the tensile resistance of T-type PBL shear connectors. When the tension ratio reached 55% of the ultimate, the failure mode of the shear connectors was dominated by the pull-out of the concrete. The tensile resistance evaluation formula was verified by the test and FEA results, demonstrating an average calculated-to-FE-results ratio of 0.99 with a standard deviation of 0.04. The suggested shear and tension interaction relationship for T-type PBL connectors had reliable predictive outcomes, with a coefficient of variation of 0.02. This study could provide guidance for the design of T-type PBL shear connectors and promote the application in long-span composite structures.

Structural Design and Mechanical Behavior Investigation of Steel–Concrete Composite Decks of Narrow-Width Steel Box Composite Bridge

Steel–concrete composite decks are commonly employed in narrow-width steel box composite girder bridges to augment their lateral spanning capabilities, while the concurrent omission of longitudinal stiffeners leads to a substantial reduction in the number of components, thereby yielding a structurally optimized bridge configuration. This paper delineates the structural design parameters of a narrow-profile steel box composite girder bridge and assess the mechanical behavior of its incorporated steel–concrete composite deck under static and fatigue loading conditions. To this end, two full-scale segment specimens from the composite bridge decks were subjected to equal amplitude cyclic fatigue tests. The investigation specifically concentrated on the impacts of two types of shear connectors—namely, perforated steel plates combined with shear studs and perfobond rib shear connectors (PBL connectors)—on the static and fatigue performance, including fatigue stiffness, of the steel–concrete composite bridge decks. The results indicate that, under the static bending condition, the composite deck specimen equipped with stud connectors demonstrates superior overall flexural stiffness in comparison to the specimen featuring PBL connectors. Furthermore, the flexural stiffness of the steel–concrete composite specimens experiences a negligible alteration across two million fatigue loading cycles. Upon the completion of two million fatigue loading cycles, the composite deck specimens incorporating the shear connectors composed of perforated steel plates and shear studs exhibit relatively wider crack widths under the static peak load. Both configurations of the steel–concrete composite bridge deck specimens manifest evident interfacial detachment, signifying insufficient tensile pull-out stiffness of the shear connectors. It is recommended to increase the quantity of the shear connectors or select the pertinent types in order to enhance the interface shear resistance.

Shear Resistance of Perfobond Rib Shear Connectors under Cyclic Loading

Shear Resistance of Perfobond Rib Shear Connectors under Cyclic Loading

Study on shear performance of discontinuous PBL connectors with double holes

Discontinuous perfobond rib shear (PBL) connectors can be applied to fabricated steel-concrete composite beams. In this paper, six push-out specimens were designed to explore the shear performance of PBL under static and repeated loads. Four specimens were used for static push-out test. The remaining two were used for fatigue push-out test. The static load test mainly considers the influence of concrete at steel plate end and post-cast strip on the shear bearing capacity, initial shear stiffness and load-slip curve of discontinuous PBL shear connectors. On the basis of the test results, the calculating formulas of the shear capacity and shear stiffness of discontinuous PBL connectors considering the influence of end bearing, bond group effect and post-cast strip are proposed. The predicted results of the formula are close to the experiment. From the fatigue test results, it is found that the fatigue performance of above specimens with C50 and UHPC is better than that with studs, but the fatigue resistance of discontinuous PBL connectors with UHPC is not increased in proportion to the shear capacity. In addition, the residual slip and shear stiffness of PBL specimens after cyclic loading are related to fatigue load amplitude.

Flexural behavior of novel profiled steel-UHTCC assembled composite bridge decks

Ultra-high toughness cementitious composite (UHTCC) has been noticed in the application of composite bridge deck (CBD) structures to avoid tensile cracks, benefiting from its excellent crack resistance behavior and characteristic of tensile strain hardening. In this study, a novel profiled steel-UHTCC assembled CBDs was proposed by adopting duplicate profiled steel parts that integrated the Perfobond rib (PBL) shear connector onto their top flange plates, which will improve fabrication convenience and economic efficiency. The flexural behavior of the assembled CBDs was investigated. Four specimens assembled respectively with T-shaped, Z-shaped, B-shaped, and H-shaped profiled steel parts were designed and fabricated. The failure modes, load-deflection curves, strain distributions, and slippage situations of four specimens were monitored and discussed. Then, the theoretical analyses on the shear connection degrees and ultimate flexural capacities of the assembled CBDs were performed, and a theoretical formula was proposed for calculating the ultimate flexural capacity. Finite element (FE) models of the assembled CBDs were established via ABAQUS software and validated against the test results. Ten groups of FE examples were designed for the detailed study of several key design parameters including shear span length, PBL hole diameter, thickness of UHTCC slab, thickness of steel web, and normalized PBL hole numbers. Finally, the proposed theoretical formula was validated using experimental and simulated results, demonstrating the validity of the proposed formula.

Bearing capacity analysis of perfobond rib shear connectors in steel-concrete composite structures

Perfobond rib shear connectors (PBL shear connectors) are a commonly used method for connecting steel beams to concrete slabs. However, the varying factors of material strength, geometric parameters, and testing methods lead to notable differences in theoretical models, thereby requiring further research for accurate prediction of bearing capacity. In this paper, the load transfer process and damage evolution mechanism during loading of PBL shear connectors are reviewed. Twenty-five sets of single-ribbed plate test data, consisting of both conventional type and deep-buried type tests, have been selected for analysis. The effects of concrete strength, hole area, transverse rebar area, and steel plate thickness on the bearing capacity have been quantitatively analyzed using linear regression. The analysis results demonstrate that an increase in concrete strength, hole area, transverse rebar area, and steel plate thickness by one unit results in a corresponding increase in bearing capacity by 1.034%, 0.011%, 0.102%, and 0.214% for the conventional type of PBL shear connectors, respectively. An increase in concrete strength, hole area and transverse rebar area by one unit results in a corresponding increase in bearing capacity by 0.511%, 0.015% and 0.094% for the deep-buried type of PBL shear connectors, respectively. Additionally, taking theoretical analysis into account, a predictive equation for the bearing capacity of both conventional type and deep-buried type specimens is proposed. The accuracy and reliability of the proposed equation are verified through comparison with experimental results.

Experimental investigation on mechanical behavior of T-type perfobond rid shear connectors under combined shear and tension

The stress of shear connectors becomes more complicated as the span length of steel-concrete composite bridges increases. To bear the great shear and uplift forces, a T-type perfobond rib (T-type PBL) shear connector with sufficient stiffness and ductility is proposed. While the shear behavior of T-type PBL connectors has been evaluated in previous studies, its mechanical performance under combined shear and tension is not well understood due to the particular shape and numerous impact factors. Therefore, one pull-out test considering pure tension and seven modified push-out tests considering combined shear and tension were carried out to investigate the failure mode, bearing capacity, and load-slip behavior of T-type PBL connectors under combined actions. The pull-out test was performed to determine the tensile resistance, followed by a series of modified push-out tests with constant horizontal tension to investigate the structural behaviors. Additionally, the effects of the rib height, flange width, and hole numbers were evaluated. Based on the test results, conical failure surfaces formed from the flange of the T-type PBL to the concrete surface for all specimens, and the concrete failure angle was approximately 32°. The bearing capacity of the specimen improved by 26% when the perfobond rib height increased from 100 mm to 120 mm, but the flange width barely had any effect. The capacity of 1-hole specimen dropped by 20% while 2-hole specimen increased by 8% compared to the standard specimen, which may relate to the distance between adjacent holes. Increasing the rib height by 25% and 50% reduced the initial relative slip (S90) by 30% and 32%, respectively, indicating the improvement in initial stiffness. Generally, the pull-out resistance of the T-type PBL shear connector was enhanced by increasing the flange width, rib height, and number of holes. An evaluation equation considering the hole number and hole spacing was suggested for the bearing capacity of T-type PBL shear connectors under the combined actions. The validity was verified by test results, with a calculated-to-test-result ratio of 1.12 and standard deviation of 0.15. This study could enhance the understanding of the behavior of T-type PBL connectors under the combined actions, and promote the potential application in long-span composite bridge decks.

Residual mechanical properties of composite beams with PBL connectors under fatigue loads

Experimental and theoretical calculation approaches were used to explore the residual mechanical properties of steel–concrete composite beams with Perfobond rib shear (PBL) connectors after fatigue loading. Six test beams were designed and fabricated including four PBL connector beams and two stud shear connector beams. The static performance, fatigue life, and failure mode under static and fatigue action were compared among the beam samples. The fatigue properties and residual mechanical properties of the beams with PBL connectors were then investigated under different fatigue load amplitudes. A calculation model for the post-fatigue residual bearing capacity of the PBL connector beam was established based on the test results and the theory of material residual strength. Compared with the stud composite beam, the PBL connector composite beam shows better static strength and fatigue resistance under the same loading conditions. The fatigue load amplitude has a greater impact on the fatigue performance of the PBL connector composite beam than the stud composite beam; when the fatigue load amplitude is 28% of the ultimate bearing capacity, the fatigue life of the composite beam is only 1.2 million loading times. The proposed calculation model of residual bearing capacity of composite beams with PBL connector yields results in accordance with experimental values, indicating that it has strong applicability. The results presented here may provide a workable reference for improving the design of steel–concrete composite beams with PBL shear connectors.

A strength degradation model of PBL shear connectors under fatigue load

Perfobond rib shear connectors (PBL shear connectors) have been widely used in steel and reinforced concrete composite bridge. To investigate the degeneration law of the bearing capacity of PBL shear connectors after a number of fatigue loading times, both static test on one specimen and fatigue test on six specimens were performed. The failure mode, ultimate bearing capacity and load-slippage curves were emphatically focused in static test, while residual performances, including the residual strength, residual slip and shear stiffness of PBL shear connectors after a certain number of fatigue loading were also studied. Furthermore, influence of number of cycles on the residual strength and residual slip of PBL shear connector specimen within the lifetime was analyzed. Test results showed that residual strength of PBL connector decreased nonlinearly with increasing loading times, and residual slip development showed a three phrase trend of “fast, slow and then fast”, but the shear stiffness was basically constant during whole loading process. Based on the residual strength theory and elastic foundation theory, residual static bearing capacity of PBL shear connectors after a number of fatigue loading times was proposed. By comparison, it was found that the residual shear bearing capacity determined by proposed model agreed well with the experimental results, which would have a great significance to guarantee the safety of a structure and prevent secondary damages to a composite bridge during the service period.

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

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

Research on the Shear Behaviour of Composite Shear Connectors

In order to make full use of the advantages of welded stud and perfobond rib shear connectors, a new type of composite shear connector is proposed. Studs are welded to the perforated steel plate of the PBL connectors. Six specimens were designed and tested to investigate the shear behaviour of the composite connectors. The effects of the hole number, welded stud number, and end-bearing modes on the shear behaviour of the composite connectors were discussed. In addition, the composite connectors were compared with the conventional welded stud and perfobond rib connectors to analyse the difference in shear performance. The composite connectors’ shear behaviours are significantly better than those of welded stud connectors and PBL connectors. The experimental results show that increasing the number of welded studs and perforated holes and end-bearing concrete can significantly improve the shear performance of composite connectors. Secondly, a finite element model was established considering the nonlinearity of the structure and was validated based on the experimental results. Finally, the effects of reinforcement diameter, welded stud diameter, and concrete strength on the shear performance of composite connectors were analysed. The shear resistance increases as the penetrating rebar diameter, welded stud diameter, and concrete strength increase. Moreover, the overall damage level of the concrete can be significantly affected.

Experimental and numerical investigation on mechanical performance of continuous steel-UHPC composite slabs

Ultra-high-performance concrete (UHPC) has recently gained popularity for use in bridge constructions. Innovative steel-UHPC composite slabs (SUCS) with perfobond rib shear connectors were utilized as the deck slabs of the Fulong Xijiang Bridge (a composite cable-stayed bridge with span length of 580 m) in Foshan, China. The SUCS functions as multi-span continuous slabs supported on the transverse diaphragms of the girder. Two full-scale experiments were conducted to explore key mechanical performance aspects of continuous SUCS, including the load-deflection response, strain development, cracking behavior, moment redistribution and interface slipping behavior. The specimens experienced ductile flexural failure, and significant moment redistribution occurred with the formation of three plastic hinges. A detailed finite element model (FEM) was established to simulate the tested continuous slabs and also simply supported SUCS reported in the literature. A new constitutive model is proposed to describe the strain-hardening behavior of UHPC. Fasteners based on the shear stiffness formula and load-slip relationship reported in the literature modeled perfobond rib shear connectors and studs, respectively. The predicted results of deflection, interface slip and failure mode correspond well with experimental results, indicating that the FEM accurately simulates SUCS. In addition, comprehensive parametric studies performed using the validated FEM revealed the influences of different parameters on mechanical performance of continuous SUCS.

Investigation on shear behavior of studs and PBL shear connectors in steel-concrete hybrid bridge girder

Due to the excellent properties of concrete and steel, steel–concrete composite structures have a wide range of applications in civil engineering. The most common shear connectors are the stud and perfobond rib (PBL) shear connectors, and there are a lot of studies on the shear behavior of stud and PBL shear connectors, respectively. But fewer studies were conducted on the combined shear behavior of both. This research presents experimental and numerical studies on the shear behavior of stud and PBL shear connectors. Test results show that the primary failure of the specimens is that the studs were sheared off, accompanied by concrete damage. The number of rows of shear connectors and the diameter of the transverse rebar can significantly affect the shear capacity. In contrast, the concrete dowel diameter has a limited impact on the shear capacity. Based on the validated finite element (FE) analysis, the effects of concrete strength, perforated plate thickness, and stud diameter on the shear capacity were parametrically investigated. The test and FE analysis results are compared with the existing equations of stud and PBL shear connectors. A combination most consistent with test and FE analysis results with discrepancies less than 5% is suggested for predicting the shear capacity of stud and PBL shear connectors.

Experimental Study of Perfobond Rib Shear Connector under Lateral Force

A series of full-scale pushed out tests were performed on the Perfobond rib shear connector. The tests were designed to examine the performance of the Perfobond rib shear connector under different rib hole sizes and shapes, reinforcing bar sizes, rib thicknesses, as well as the presence of lateral forces. It has been revealed from the test results that the rib hole size and reinforcement diameter may not act independently, and the influence of one’s size is actually dependent on the size of the other one. The lateral forces also affect the performance of the shear connector; for example, the capacity of the shear connector would be larger under compression than under tension. The existence of transverse pretension stress accelerated the cracking of concrete, leading to the strength and stiffness of concrete, perforated plate, and reinforcing rebars unable to fully exert their effect. In addition, the constraint effect of transverse stress improved the strength and stiffness of concrete and delayed the concrete cracking, bringing the strength and stiffness of concrete, perforated plate, and reinforcing rebars into full play, and resulting in a significant improvement in the shear capacity of Perfobond rib shear connectors.

Shear Resistance Assessment of the Y-Type Perfobond Rib Shear Connector under Repeated Loadings

The steel–concrete composite structures consist of two different material parts, which are connected with reliable shear connectors to enable the combined action of the steel and concrete members. The shear connectors may experience either one-directional repeated cyclic loadings or fully reversed cyclic loadings depending on the structural functions and acting loadings. It is essential for structural engineers to estimate the residual shear strength of the shear connectors after action of repeated loads. The characteristics of deteriorating shear capacities of Y-type perfobond rib shear connectors under repeated loads were investigated to estimate the energy dissipating capacity as well as the residual shear strength after repeated loads. To perform the repeated load experiments four different intensities of repeated loads were selected based on the monotonic push-out tests which were performed with 15 specimens with five different design variables. The selected load levels range from 35% to 65% of the representative ultimate shear strength under the monotonic load. In total, 12 specimens were tested under five different repeated load types which were applied to observe the energy dissipating characteristics under various load intensities. It was found that the dissipated energy per cycle becomes stable and converges with the increasing number of cycles. A design formula to estimate the residual shear strength after the repeated loads was proposed, which is based on the residual shear strength factor and the nominal ultimate shear strength of the fresh Y-type perfobond rib shear connectors. The design residual shear strength was computed from the number of repeated loads and the energy dissipation amount per cycle. The reduction factor for the design residual shear strength was also proposed considering the target reliability level. The various reduction factors for the design residual shear strength were derived based on the probabilistic characteristics of the residual shear strength as well as the energy dissipation due to repeated loads.

Flexural behavior of steel-UHPC composite slabs with perfobond rib shear connectors

Steel-concrete composite slabs are often used as bridge decks and floors in buildings. This study examines the mechanics of composite slabs that are composed of steel plates and UHPC. Full-scale experiments of three steel-UHPC composite slabs and one steel–concrete composite slab are carried out to investigate how the number and type of shear connectors can affect mechanical behavior. Experimental results showed steel-UHPC composite slabs experienced flexural failure while steel–concrete composite slab experienced punching failure. Experimental data also demonstrated that steel-UHPC composite slabs possess superior ductility, capacity and stiffness. Among the composite slabs, the specimen with sufficient perfobond rib shear connectors (i.e. PBL shear connectors) exhibited the best flexural performance. Subsequently, the experimental results are used to develop a method to predict the bending capacity for composite slabs while taking the tensile contribution of the UHPC and the location of the cross-sectional neutral axis into consideration. The method is applicable to the specimens in this study as well as other specimens described in literature. The proposed formulas for calculating the flexural stiffness of composite slabs can accurately reproduce the load–deflection behavior for specimens under service loads. Results from this paper can guide engineers in the practical application of steel-UHPC composite slabs.

EXPERIMENTAL AND NUMERICAL INVESTIGATIONS ON THE FLEXURAL BEHAVIOR OF STEEL-UHPC COMPOSITE SLABS WITH PERFOBOND RIB SHEAR CONNECTORS

A new type of steel-ultra-high performance concrete (UHPC) composite slab with perfobond rib shear connectors (PBL shear connectors) is studied, which can be used as large-span bridge decks and floors in buildings. According to the deck system of an ultra-long-span composite cable-stayed bridge, full-scale tests on three steel-UHPC composite slabs (SUCS) and a steel-C60 composite slab (SCCS) were conducted. The influence of the number and type of shear connectors were investigated. The experimental results demonstrate that, subjected to concentrated load, typical flexural failure of SUCS occurred while punching failure of SCCS occurred; that the SUCS possessed much higher ultimate capacity, rigidity and ductility than the SCCS with the same thickness did; that the specimen with sufficient perfobond rib shear connectors exhibited the best mechanical performance among the three SUCSs. Elaborate finite element models of the SUCSs were established in ABAQUS, which can reproduce the load-deflection curves obtained from the tests. Parametric study is conducted adopting the established finite element models.