Perforated Shear Connector Research Articles

A Study on the Mechanical Behavior of a Wind Turbine Foundation with a Constrained Structural Shear Connector

Aiming to solve the problems that a wind turbine foundation with a foundation pipe may suffer from grouting, where the concrete around the interface collapses and the interface disintegrates under a long-term wind load, a kind of wind turbine foundation with a constrained structural shear connector is proposed. In this article, the scaling model tests and a finite element simulation of a traditional stud foundation pipe, perforated steel shear connector foundation pipe, and three groups of constrained structural shear connector foundation pipes with different anchored depths are presented. The force transmission mechanism and damage mechanism of constrained structural shear connector wind turbine foundations are revealed, and the shear resistance of a constrained structural shear connector is analyzed. The influences of buried depth and other parameters on the mechanical properties of the shear connector are also investigated. The results show that the constrained structural shear connector has the advantages of stronger interfacial stiffness and significant force transfer and diffusion, and can more effectively connect the foundation pipe and concrete foundation to work together. It can give full play to the material advantages of concrete and reinforcements, and effectively improve the embedded stiffness and durability of concrete foundations. It can solve the problem of cracks in concrete caused by local pressure. At the same time, it is suggested that the diameter of the surrounding concrete should be in the range of 3 to 4 D, and the embedment depth of the stud should not be less than 0.4 D to give full play to the performance of the constrained structural shear connector.

EXPERIMENTAL INVESTIGATION ON THE SHEAR RESISTANCE OF I-SHAPED PERFORATED CONNECTORS IN COMPOSITE BEAMS

Introduction: Steel-concrete composite girders have been widely used in bridges, with the stability of the interface being crucial. Shear connectors and reinforced concrete slabs play a key role as interfaces. Understanding the interaction between the composite beam and slab is essential for predicting the overall system response. It is necessary to optimize the connection between steel beams and reinforced concrete slabs in steel-concrete composite girders and facilitate their assembly and installation on-site, emphasizing their pivotal role in upholding the structural integrity of composite systems. The purpose of the study was to conduct an experimental investigation and a numerical simulation using the finite element method. During the study, the following methods were used: examining the behavior of IPE and IPN perforated shear connectors using push-out tests. The main objective was to analyze how the I-shaped perforated connector, concrete slab, steel beam, and rebar affect the measured slip between the steel beam and concrete slab. To achieve that, specimens with IPE80 or IPN80 shear connectors having circular or long cut holes containing 8 mm or 6 mm diameter steel bars were used to enhance the connector’s resistance against uplift forces. The test setup follows Eurocode 4 guidelines, focusing on hole shape and anti-lift rebar diameter parameters. The predominant failure modes were mainly dictated by the crushing of the concrete slab. As a result, it was found that the hole geometry of IPE and IPN perforated shear connectors significantly impacts shear load capacity and ductility. The long cut hole shape in IPE and IPN perforated shear connectors exhibits superior ultimate load capacity but less interfacial slip compared to the circular hole. The IPE and IPN perforated shear connectors demonstrated satisfactory ductility for all tested hole shapes, and the 3D finite element models are consistent with the test results.

Fatigue performance and optimal design of corrugated steel–concrete composite bridge deck

Orthotropic steel bridge deck (OSD) has been widely used in long and medium span bridges. However, traditional OSD with U-ribs is prone to fatigue cracking at the deck-to-rib welded joint. Corrugated steel–concrete composite bridge deck (CSCCBD) composed of corrugated steel plate, concrete layer and perforated plate shear connectors was proposed recently to improve the fatigue performance of the bridge deck. In this paper, comparing of the fatigue performance of OSD and CSCCBD was conducted through finite element (FE) analysis. The results showed that the stress amplitude of deck-to-rib welded joint of CSCCBD was reduced by more than 90 % compared with OSD. The fatigue problem of deck-to-rib welded joints can be solved fundamentally. It is further studied that distribution of fatigue vulnerability details of CSCCBD. The most unfavorable fatigue vulnerability details are located around the diaphragm-to-rib weld. The fatigue life of CSCCBD was evaluated based on the linear cumulative damage theory. Consequently, the effect of diaphragm cut-out on the fatigue performance of CSCCBD was studied. It was found that the diaphragm without cut-out can effectively reduce the stress amplitude caused by vehicles, and increase the earliest fatigue cracking life of details around the diaphragm-to-rib weld from 2.16 years to 43.4 years compared with OSD. Finally, the section form of CSCCBD without cut-out was optimized by response surface method (RSM). It was proved that RSM was adequate for the optimization design of CSCCBD.

Preliminary Design of a Steel–UHPFRC Composite Truss Arch Bridge and Model Tests of K-Joints

The preliminary design and comparisons of major technical and economic indicators between a steel-ultrahigh-performance fiber-reinforced concrete (UHPFRC) composite truss (SUCT) arch bridge and a concrete-filled steel tubular (CFST) arch bridge with both spans of 375 m are carried out in this study. Compared with the CFST arch bridge, the SUCT arch bridge can improve the durability of the bridge and has advantages in terms of steel consumption, self-weight, carbon emission, and other indicators due to the use of UHPFRC with high compressive strength as the arch ribs to bear the large axial forces. Adoption of the cyclic construction method for the SUCT arch bridge with two closure processes results in a total cost basically equivalent to that of the CFST arch bridge. For the K-joints in the connection area of the UHPFRC arch ribs and steel web members, a new hybrid connection form of “perforated shear connectors (PBL) + headed studs” is proposed. Loading tests in three directions in plane, pull-out tests, and parameter analysis are carried out. The experimental results show that the new hybrid connector is reasonable for the K-joints, which has advantages of large stiffness, short force transmission path, and high efficiency, and can ensure the continuity of steel fibers. Moreover, the new hybrid connector displays good shear performance, pull-out performance, and high bearing capacity. Based on the results of parameter analysis, the sensitivity of the pull-out bearing capacity to the three variables is compressive stress in the arch rib, followed by the tensile and compressive strengths of UHPFRC.

Push-out tests on adhesively bonded perfobond shear connectors for timber-concrete composite beams

In this paper, perforated shear connectors (perfobond), used extensively in steel-concrete composite (SCC) beams, are implemented in timber-concrete composite beams (TCC) and experimentally investigated. In contrast to its original use, the perfobond connector is connected with an adhesive to the timber beam while welded in the SCC solution. On the concrete slab side, connection is achieved using the original concept, a combination of dowel action with bearing between concrete and connector. In this paper the mechanical behaviour of the shear connection using the perfobond connector in TCC beams is investigated by means of push-out tests. Concrete type, concrete strength and surface roughness of the connecter were the testing variables. The results are compared with the common shear connections for TCC in terms of strength, stiffness and ultimate slip. From this work, it can be concluded that perfobond connections give promising strength and stiffness results, however, for the geometries covered in the experimental program, the ultimate slip is limited. Nevertheless, the high stiffness and load capacity presented by this connection demonstrates a significant potential for its implementation in TCC, as high composite action can be achieved.

Evaluation of formulations for predicting the shear strength of concrete filled circular holes in steel plates

Abstract Since the development of perforated plate shear connectors, different formulations have been proposed to predict their shear strength. Most of these formulations were derived from standard push-tests on multiple concrete filled holes (CFH) specimens simulating specific steel-concrete composite beam applications. Aiming at a more general application of these connectors in composite structures and the understanding of the physical and geometric parameters that influence their shear strength, the present work evaluated the use of 12 different formulations to predict 92 test results of single-hole specimens extracted from the literature. Such tests were chosen because the single-hole configuration allows better isolation of the connection behavior which facilitates comparative analysis. The predictions were statistically evaluated, and it was considered that the best formulations were those that showed lower scatter of data and a correction factor closer to one. Also, it was investigated if the individual terms that constitute the formulations adequately describe or show relation to the mechanics that govern the connection. It was verified that the best statistically rated formulations were also the ones showing clearer relation to the connector mechanical behavior. Among the evaluated formulations, three were significantly better than the others for strength prediction, however, it was noted that they can be further improved by considering the influence of concrete confinement and plate thickness on the hole’s strength.

Innovative composite deck slab for railway bridges: Experimental investigations on the fatigue resistance of the dowel strips

ABSTRACTAt TU Wien, Institute of Structural Engineering, Research Centre of Steel Structures, a new, extremely slender steel‐concrete‐steel composite (SCSC) plate is under investigation to meet the requirements of today's standards related to the geometric conditions and noise emission in the substitution of old railway bridges. The multi‐layer structure of the plate consists of two steel cover plates with an unreinforced concrete core, hence the name sandwich plate. Perforated shear connectors, welded alternately to only one of the outer steel plates, work together to ensure the transmission of the shear flow between the outer plates, by the activation of diagonal concrete compression struts between neighboring dowel bars. After the examination of the static load‐bearing capacity in former research programs (1), the current investigations are focussed on the fatigue behaviour of the SCSC plate, whereby the main focus lies on the investigation of the relation between the amplitude of the traffic load and the bearable number of load cycles of the SCSC plate till crack initiation in the shear connectors.A detailed description of the numerical modelling of the SCSC plate using the Abaqus/Explicit (2) software and the calculation of the fatigue life of the dowel strips using the notch strain concept are described in (3; 4; 5). This paper gives an overview of the planning, execution and evaluation of the experimental investigations and compares the experimental and the numerical results regarding the fatigue life of the dowel strip.

Distribution of shear force in perforated shear connectors

A perforated shear connector group is commonly used to transfer shear in steel–concrete composite structures when the traditional shear stud connection is not strong enough. The multi-hole perforated shear connector demonstrates a more complicated behavior than the single connector. The internal force distribution in a specific multi-hole perforated shear connector group has not been thoroughly studied. This study focuses on the load-carrying capacity and shear force distribution of multi-hole perforated shear connectors in steel.concrete composite structures. ANSYS is used to develop a three-dimensional finite element model to simulate the behavior of multi-hole perforated connectors. Material and geometric nonlinearities are considered in the model to identify the failure modes, ultimate strength, and load–slip behavior of the connection. A three-layer model is introduced and a closed-form solution for the shear force distribution is developed to facilitate design calculations. The shear force distribution curve of the multi-hole shear connector is catenary, and the efficiency coefficient must be considered in different limit states.

09.18: Innovative composite deck slab for railway bridges: Analysis of the fatigue behaviour of the shear connectors using the strain‐life method

ABSTRACTAt Vienna University of Technology, Institute of Structural Engineering, a new, extremely slender steel‐concrete‐steel composite (SCSC) plate is under investigation to meet the requirements of today's standards related to the geometric conditions and noise emission in the substitution of old railway bridges. The layered construction consists of two steel cover plates with an unreinforced concrete core. Perforated shear connectors, welded alternately to the outer steel plates, work together to ensure the transmission of the shear flow between the outer plates. In addition to the distribution of the traffic load in cross direction, the SCSC deck slab also acts as main girder bottom flanges in longitudinal direction of the bridge construction. After the examination of the static load bearing capacity in former research programs [1, 2], the current investigations are focussed on the fatigue behaviour of the shear connector of the SCSC plate.In the course of research a nonlinear, three‐dimensional finite element model served as the basis for a lifetime calculation using the local strain‐life method. The aim was to investigate the relation between the range of traffic load and the bearable number of load cycles of the SCSC plate till crack initiation in the shear connectors. This paper provides an overview of the approaches used to calculate fatigue life and gives a brief summary of the results.

Experiment study on fatigue performance of perforated shear connectors

In order to investigate the fatigue behavior of perforated shear connection in steel-concrete composite bridges, 24 connection specimens with different geometric configurations were subjected to static and fatigue testing protocols. Using the design shear resistance of perforated shear connectors obtained from static push-out tests as a reference load level, numbers of fatigue cycles under different cyclic load levels were determined. Accumulated relative slip between steel and concrete components was used to characterize and track fatigue damage accumulation. The relationship between cycle numbers and accumulated relative slip between steel and concrete was established. Test results revealed that the fatigue damage of perforated shear connectors can be divided into three stages, and fatigue life of perforated shear connectors can be evaluated by the accumulated slip, which depends on the maximum shear stress and stress range.

Behavior of Perforated Shear Connectors in Steel–Concrete Composite Joints of Hybrid Bridges

AbstractPerforated shear connectors (PSCs) in steel–concrete composite joints are usually deeply embedded in concrete, and the perforated plate thickness varies significantly, which is different from those in a steel–concrete composite beam. In this study, two types of push-out tests (24 specimens in total) were conducted to compare the mechanical behavior of PSCs used in steel–concrete composite joints with that in composite beams. The testing variables include the push-out test arrangement, plate thickness, and concrete compressive strength. The experimental results are presented and discussed, focusing on the shear resistance, load-slip behavior, and failure modes. Finally, the experimental results were compared with existing shear resistance equations to evaluate their applicability for PSCs in composite joints.

Flexural performance of innovative hybrid sandwich panels with special focus on the shear connection behavior

The present study intends to evaluate the flexural performance of hybrid sandwich panels through the execution of four point bending tests. The proposed hybrid sandwich panel uses Deflection Hardening Cementitious Composites (DHCC) on the top layer, a GFRP bottom layer and perforated shear connectors in the GFRP ribs to transfer shear stresses between top and bottom layers.The tested hybrid slabs use two types of shear connectors, which include indented and perforated shapes. The tests were performed to study the behavior of a novel shear connection between the GFRP ribs and the DHCC layer that is here proposed. A comparison on the obtained experimental results was executed to clarify the influence of the shear connectors’ geometries on the flexural performance of the developed hybrid slabs.The results show that the shear connection mechanical behavior strongly influences the peak load, the deflection at peak load, the post-peak load carrying capacity and the degree of composite action of the hybrid slabs.

Structural behaviour of perforated shear connectors with flange heads in composite girders: an experimental approach

Perforated shear connector with flange head (PSCFH) as a new type of connector behaves high bearing capacity and excellent ductility in steel-concrete composite girders. In this paper 15 groups, totally 45 push-out test specimens, were conducted to investigate the effects of plate thickness, connector height, flange length, flange number, hole diameter on the web, diameter of reinforcing bars and concrete strength on structural behaviour of PSCFH. In the push-out tests, failure mode, load versus slip curve and bearing capacity of all the specimens were obtained. Based on the results of push-out tests, bearing mechanism was analyzed and a calculation model of the shear bearing capacity was proposed with respect to the failure modes. Calculation results based on the proposed model agree well with the experimental values.

Consideration on load transfer mechanism of perforated rib shear connectors

Consideration on load transfer mechanism of perforated rib shear connectors

Perforated shear connectors on composite girders under monotonic loading: An experimental approach

This paper presents the results of sixteen push-out tests performed at the Civil Engineering Department of the University of Coimbra, Portugal, on perforated steel shear connectors with varying geometries. Eight tests using the previously studied Perfobond and T-Perfobond geometries were initially performed and were followed by another eight tests on two innovative geometries, the I-Perfobond and 2T-Perfobond. The investigated variables included the shear connector geometry and the provision of transverse reinforcement within a shear connector’s holes. The results are presented and discussed with a focus on the shear connectors’ structural responses in terms of their shear transfer capacity, ductility, stress distribution and collapse modes. Finally, a comparison of the experimental results with existing analytical models of the Perfobond and T shear connectors is also presented to establish their accuracy and applicability.

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.

개방형 유공강판 전단연결재로 보강된 강관말뚝머리의 휨거동에 관한 유한요소 해석

Various kinds of shear connector such as headed stud, channel, perforated steel plate and others are commonly used to transfer stress and present composite performance in composite structures, and many researches have been conducted to improve the characteristics of different types of shear connectors. It is focused in this study on the bending performance of steel pipe pile cap with the open type perforated shear connector for the composite connection to the spread footing. Nonlinear analysis was conducted, using ABAQUS, a finite element analysis program, to obtain information for determining the characteristics of the structure and to allow various parametric analysis for bending performance of steel pipe pile cap with the open perforated shear connector.

Longitudinal shear in composite steel and concrete trusses

The distribution of longitudinal shear along an interface between steel and concrete of composite trusses is generally highly non-uniform, exhibiting peaks above truss nodes (unless after plastic redistribution). The investigation presented here examines experimentally the behaviour of two steel and concrete composite truss girders, using perforated shear connector to reach full shear connection. Experimental results have served to calibrate the non-linear 3D numerical FE model formulated using ANSYS software package. More than 30 variants of shear connections of a simple truss with Vierendeel panel at midspan have been studied, having various load–slip relationships obtained from previous research. Distinctive peaks of shear flow in the connection above truss nodes have been found within elastic behaviour–especially important for connectors loaded in fatigue–followed by plastic redistribution in plastic region. Comparison of the numerical results with proposals given in Eurocode 4 and influence of shear connection densification above truss nodes are discussed in a detail. Finally, some recommendations for practical design are presented.

Perforated FRP Shear Connector for the FRP-Concrete Composite Bridge Deck

In recent years, the FRP-concrete composite bridge deck system has been introduced because of its light-weight and durability. The FRP-concrete composite bridge deck is composed of FRP module and concrete, and they are connected with shear connectors. In order to insure the composite action between FRP module and concrete, appropriate types of shear connector need to be installed. In this study, new type of FRP shear connector was suggested and the experimental investigations are conducted based on the studies of Perfobond. In the experimental study, the push-out test was conducted and the load carrying mechanism was analyzed including the friction effect of sand coating. Considering the load carrying mechanism of perforated shear connector under shear force, the empirical equation for the prediction of shear strength of perforated FRP shear connector was suggested.

Evaluation of Load Carrying Capacity of the Perforated Shear Connector with Flange Heads

In the construction of composite bridge structures, various types of shear connectors are usually used to provide an efficient load transfer and the composite action of two or more different materials. In the previous work conducted by authors, a new type of the shear connector was introduced, which is the perforated shear connector with flange heads (T-shaped perforated shear connector), and the structural behavior of the shear connector was discussed based on the results of push-out tests. For the practical design of new shear connector, it is necessary to develop the equation for the prediction of the load carrying capacity of the shear connector. In this study, the existing design equations for the Perfobond shear connector were briefly analyzed and the equation for the prediction of the shear capacity of T-shaped perforated shear connector was suggested empirically. By comparing the results obtained by the suggested equation, the existing equations for the Perfobond shear connector, and the experiment, the applicability and effectiveness of the suggested equation was estimated.