Search Results (10)

To enhance the bearing capacity of cable–pylon anchorage zones in cable-stayed bridges, this paper proposes the integral steel wall plate (IWP) structure and investigates the structural performance of its application in anchorage zones with a steel anchor beam and with a steel anchor box. The proposed structure contains an end plate, a surface plate, and several perforated side plates, forming steel cabins that encase the concrete pylon wall, where the steel and concrete are connected by perfobond connectors on side plates. A half-scaled experiment and a finite element analysis were first conducted on the IWP with the steel anchor beam to study the deformation at the steel–concrete interface, as well as the stress distribution in steel plates and rebars. The results were compared with experimental data of a conventional type of anchorage zone. Then, finite element models of anchorages with steel anchor boxes were established based on the geometries of an as-built bridge, and the performance of the IWP structure was compared with conventional details. Finally, the effects of plate thickness and connector arrangement were investigated. Results show that the proposed IWP structure offers excellent performance when applied with an anchor beam or anchor box, and it can effectively reduce principal tensile stress on the concrete pylon wall compared with conventional anchorage details. Full article

Current research on the stress mechanisms of composite connectors within steel–concrete structures of bridge towers is sparse, and there is a lack of established experimental methods and finite element modeling techniques for studying these mechanisms. This study focuses on a specific type of composite shear connector within the steel–concrete section of the Shunde Bridge tower. By employing proposed experimental methods and finite element model analysis, this research examines the load–slip curves and stress distribution of these shear connectors. It aims to elucidate the stress mechanisms and mechanical relationships between the composite connectors and the individual perforated plate connectors and shear stud connectors that comprise them. The results demonstrate that the proposed experimental methods and finite element modeling approaches effectively analyze the stress mechanisms of composite connectors, revealing that the ultimate load-bearing capacity and elastic stiffness of the composite connectors are approximately the sum of those of the individual connectors configured in parallel; The mechanical performance of the composite connectors in the steel–concrete section of the bridge tower is approximately the additive sum of the mechanical performances of the individual connectors comprising them. By comparing the experimentally measured load–slip curves with those calculated from the finite element models, it validates the modeling approach of the finite element model, and the material parameters established through material characteristic tests and literature review are reasonable. Full article

To reduce the cast in place work of concrete and realize the industrial production of a bamboo–concrete composite (BCC), innovative connection systems composed of an assembled bamboo–lightweight concrete composite (ABLCC) structure featuring perforated steel plate connectors are presented for use in engineering structures. This study examined the shear performance of connection systems composed of an assembled BCC structure featuring perforated steel plate connectors based on the design and fabrication of three groups of shear connectors with nine different parameters using bamboo scrimber, lightweight concrete, perforated steel plates, and grout. Push-out tests were conducted on these shear connectors. A linear variable differential transformer (LVDT) and digital image correlation (DIC) were utilized for measurements. The test parameters comprised fabrication techniques (assembled and cast-in-place/CIP) and connector size (steel plate thickness). This study investigated mechanical performance indicators, including the failure mode, load–slip relationship, shear stiffness, and shear capacity of the shear connectors. The experimental results showed that the shear connector failure modes involved concrete spalling near the connectors and deformation of the perforated steel plates. The load–slip curves generally included three stages: high slope linear increase, low slope nonlinear increase, and rapid decrease. The shear capacity and stiffness of the assembled shear connectors were 0.84 times and 2.46 times those of the CIP connectors, respectively. The stiffness of the 4 mm steel plate connectors increased by 42% compared to the 2 mm steel plate connectors. Analysis showed that the shear capacity of the BBC primarily consisted of four aspects: the end bearing force of the steel plate, contact friction, and forces due to the influence of tenon columns and the reinforcing impact of through-rebars. This study proposes a simple and suitable formula for obtaining the shear capacity of perforated steel plate connectors in the BCC structure, with the analytical values being in good agreement with the test results. Full article

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. Full article

In order to improve the shear resistance and structural ductility of the perfobond rib (PBL) connector, a new PBL connector with steel–rubber tenon is proposed in this study, which aims to increase the shear load capacity of the connector while improving the ductility of the connector. First, models of new PBLs are established based on the validated finite element method, and their mechanical properties are compared with other shear connectors. The results show that the stiffness and shear load capacity of the proposed connector can be effectively improved when the steel ring is added, where the shear stiffness can be reduced, and the deformation capacity of the specimen can be improved when the rubber ring is added. When a steel ring with a thickness of 5 mm and a rubber ring with a thickness of 5 mm are involved, the shear load capacity of the connector with steel–rubber tenon is increased by 13.7%, and the shear stiffness is reduced by 37.3% compared to the conventional concrete tenon connector, while the ductility is increased by 75.1% compared to the connector with steel ring tenon. Subsequently, as for the connectors with steel–rubber tenon, the effects of the thickness of the steel ring, the thickness of the rubber ring, the diameter of perforated rebar, the strength of concrete and the strength of perforated steel plate are analyzed based on the finite element model of a PBL. The results show that an increase in the thickness of the steel ring, the diameter of the perforated rebar and the strength of the concrete will cause an increase in the shear stiffness and shear load capacity of the connector; however, an increase in the thickness of the rubber ring can cause a decrease in the shear stiffness and shear load capacity of the connector, while a change in the strength of perforated steel plate has little effect on the shear stiffness and shear load-carrying capacity. Finally, based on the finite element parametric analysis results and the damage mechanism of the proposed connector, a calculation equation applicable to the PBL connector with steel–rubber tenon is presented to predict the shear load capacity of the connector. Full article

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. Full article

This paper proposes a new form of composite beam: a multi-cavity steel-concrete composite beam. This composite beam uses internal perforated steel plate to connect the concrete with the steel structure, and shear connectors are no longer required, which is more suitable for industrial production. The mechanical properties of a multi-cavity steel-concrete composite beam in industrial applications are studied to avoid failures. In this paper, two multi-cavity steel-concrete composite beams with a size of 2500 mm × 200 mm × 300 mm were prepared, in which the angle of internal porous steel plate was set as 60° and 75°, respectively. A full-scale static load test was conducted on the beams to research its deformation and failure modes. The finite element software ANSYS was used to perform finite element modeling of multi-cavity steel-concrete composite beams and to analyze the influence of concrete strength, steel strength, porosity, and the angle of internal porous steel plate on the mechanical properties of composite beams. The results are as follows: before the composite beam reaches its serviceability limit state, its deformation basically shows a linear change; with the increase of load, the plastic deformation is gradually obvious, which can still provide a certain bearing capacity in the failure stage; the bearing capacity of the composite beam is positively correlated with the strength of concrete and steel, while negatively correlated with the porosity and the angle of internal porous steel plate; composite beams have large bearing capacity, good ductility and integrity. Full article

For steel–concrete composite structure, a new type of stud–PBL composite shear connector can improve the shear resistance of steel–concrete interface, and polypropylene fiber ceramsite concrete can reduce the self-weight. Therefore, investigating the shear behavior of stud–PBL composite shear connectors for steel–ceramsite concrete composite structures bears significance. In this study, static testing and numerical simulation of the composite shear connector push-out specimen of polypropylene fiber ceramsite concrete were first conducted. The influencing factors of the shear bearing capacity were then analyzed. The formula for determining the shear bearing capacity of the steel–ceramsite concrete composite structure stud–PBL composite shear connectors was ultimately established. The results indicated that the new composite shear connector exhibited excellent shear resistance and good deformation ability. In addition, increasing concrete’s strength, stud’s diameter, and perforated plate’s thickness could significantly improve the shear bearing capacity of the composite shear connector. The calculated value of the shear bearing capacity of the composite shear connector was well correlated the measured value of the test. Overall, the stud–PBL composite shear connector could effectively improve the interfacial shear bearing performance of the steel–ceramsite concrete composite structure. Moreover, the established formula demonstrated broad applicability. Full article

Perfobond rib (PBL) shear connectors, made up of the perforated steel plates with the penetrating rebars passing through the holes, are extensively adopted in steel-concrete composite structures for their excellent performance. The adequate understanding of mechanical properties for PBL connectors is of great significance for their reasonable design. In this study, a push out experiment, including 12 specimens with the parameters of concrete strength, diameter of penetrating rebars and the number of holes on perforated steel plate, was performed to explore the mechanical behavior of PBL connectors with steel fiber high strength concrete (SFHSC). The experimental results showed that the shear capacity of the PBL connectors increased with the increase in concrete strength, diameter of the penetrating rebars and the number of holes. Furthermore, a general prediction formula for the shear capacity of PBL connectors was developed, which considers the shear contribution of concrete dowels, concrete end-bearing, interfacial bonding between the perforated steel plates and concrete and the penetrating rebars as well as the enhancement effect of steel fibers. The prediction results of the equation are in good agreement with the experimental data and could provide a reference for the design of PBL connectors. Full article

An analytical investigation focusing on the concrete damage progress of the PBL shear connector under the influence of various lateral pressures, employing a coupled RBSM and solid FEM model was carried out. The analytical model succeeded in simulating the test shear capacities and the failure modes adequately. The internal failure process was also clarified; the two horizontal cracks occurred near the top of the concrete dowels through the hole of the perforated steel plate, and afterward, the two vertical cracks also initiated and propagated along with the shear surface. In a low lateral pressure case, the shear strength was determined by the vertical cracks propagated along the shear surface. While as the amount of applied lateral pressure increased, the shear strength of the two vertical cracked surfaces was enhanced, and the shear strength of the PBL was characterized by the occurrence of the splitting cracks and caused the splitting failure into the side concrete blocks. Moreover, the combined effects of lateral pressure and hole diameters were also evaluated numerically, and it was found that the increase in shear strength was more in a large diameter case subjected to high lateral pressure because of the wide compressive regions generated around the concrete dowel. Full article