Shear Strength Of Connections Research Articles

The effect of staged process parameters for flow drill screws on the strength of the connection between carbon fiber-reinforced plastic and aluminum alloy

This article applies flow drill screws (FDS) technology to the connection of dissimilar materials, carbon fiber-reinforced plastic (CFRP) and 6061-T6 aluminum alloy (AA6061-T6), and proposes a method to study the influence of FDS process parameters on the strength of the connection in stages. Based on this method, the optimal process parameters for the connection of this type of plate are explored. Firstly, the mathematical analysis of the process in each stage is conducted, and then the different process parameters in different stages are grouped and tested for the strength of the joint. The optimal process parameters obtained from the previous stage are input into the next stage for further testing, resulting in the highest shear connection strength of 5.98 kN for the FDS connection of CFRP and AA6061-T6 plates. The experimental results show that the influence of different process parameters on the strength of the joint varies in different stages. To improve the connection strength, high speed and low feed force should be selected in the second stage, low speed and low feed force should be selected in the third stage, and the tightening torque should be reasonably selected in the fourth stage.

Investigation of cyclic behavior of partially concrete-filled steel tubular columns

A partially concrete-filled steel tubular (CFST) member is formed by partially filling concrete into a steel hollow section (SHS). Partially CFST members are mainly used as bridge piers and frame columns due to the improved structural performance, since the potential plastic hinge is expected to occur at the composite section when subjected to an earthquake. In practice, the shear transfer between the upper SHS and the lower CFST part of a partially CFST column needs careful consideration, sometimes leading to complex details. In this study, two types of shear connectors, namely bolted shear connectors and diagonal-rib shear connectors were proposed and arranged below the concrete-filling interface. Five square partially CFST specimens and a reference steel tubular column were designed and tested under combined constant axial compression and cyclic lateral loading. The test variables included the concrete-filling ratio, types of shear connectors, and strength of shear connectors. The results demonstrated the effectiveness of the two types of shear connectors, and the specimens with diagonal-rib shear connectors showed excellent performance. The method and corresponding formulas about the full shear connection were proposed to calculate the resistance of square partially CFST columns under combined compression and flexure.

Data-Driven Prediction Model for High-Strength Bolts in Composite Beams

In recent years, the application of artificial intelligence-based methods to engineering problems has received consistent praise for their high predictive accuracy. This paper utilizes a BP neural network to predict the strength of steel–concrete composite beam shear connectors with high-strength friction-grip bolts (HSFGBs). These connectors are widely used in bridge and building construction due to their superior strength and stiffness compared to traditional beams. A validated finite element model was used to predict the strength of HSFGB shear connectors. A reliable database was created by analyzing 208 models with different characteristics for machine learning modeling. Previous studies have identified issues with result variation and overestimation or underestimation of shear connection strength. Among the machine learning methods evaluated, the backpropagation neural network model performed the best. It achieved a goodness of fit of over 93% in both the training and testing sets, with a low coefficient of variation of 6.50%. Concrete strength, bolt diameter, and bolt tensile strength were found to be important variables influencing the strength of shear connectors. Other variables showed a proportional or inverse relationship with compressive strength, except for concrete strength and bolt pretension. This study presents an accurate machine learning approach for predicting the strength of HSFGB shear connectors in steel–concrete composite beams. The study offers valuable insights into the effects of various variables on the performance of shear connection strength, providing support for structural design and analysis.

Development of novel concave shear connector to enhance the composite behavior

In recent decades, the use of composite structures has increased in favor of their quick, simple, and cost-effective construction and shear connectors are the key to attaining this composite behavior by transferring horizontal shear from concrete to steel girder and avoiding vertical separation. The efficiency of the composite connection depends on the stiffness and strength of the shear connector. The current study proposes an innovative concave type shear connector for the composite steel beams-RCC slab structure in buildings and bridges, which is economical and easier to install compared to conventional headed studs. The push-out tests were simulated in ABAQUS software using finite element analysis to assess the connection's ductility, stiffness, and shear strength as well as the connection's ultimate slip. The numerical analysis observed an enhanced strength and stiffness of the concave shear connectors compared to conventional headed shear studs, achieving a material saving of 20% and satisfying the Eurocode ductility criteria.

Efficient beam element model for analysis of composite beam with partial shear connectivity

A two-node beam element formulation with eight degrees of freedom was developed and implemented into MATLAB to simulate the nonlinear behavior of the composite. The beam element includes the reinforced concrete slab, the concrete reinforcement, the steel beam, and the shear connectors. One dimension-softening model was used to simulate the concrete, the bilinear isotropic plastic model was used to simulate the steel, and a multi-linear spring was used to simulate the partial shear connectivity. Experimental results were used to validate the numerical model, which was able to closely predict the experimental response by a 2% difference. The model was able to simulate several material nonlinearities such as the plasticity of the steel beam and cracking and crushing of concrete slab. A parametric study was performed to investigate the effects of strength of shear connector, concrete slab thickness, steel beam depth, and the concrete compressive strength on the overall response of steel–concrete composite beams. It was found that the variation in shear connector strength significantly affects the response of the composite beams. In addition, the composite beam stiffness and strength increased with the increase of the steel beam depth, significantly.

Parametric study on composite beam with various connections under mid-span impact scenarios

The falling-debris-impact scenario occurred in several severe collapse events. It is of great practical significance to investigate the resistance of structures subjected to falling-debris impact. Finite element (FE) simulation of composite beams subjected to drop-weight impact was conducted in this research. Parametric analyses were carried out based on the validated FE models. The results showed that increasing the impact velocity could enhance the strain rate effect and increase the structural resistance of composite beams. In terms of structural design, the composite slab can increase the energy absorption capacities of specimens compared to bare steel beams and beams with the solid concrete slab. The increase of the strength or thickness of concrete in the composite slab, the thickness of profiled steel plate, the ratio of longitudinal reinforcement, and the strength of shear connection of the composite structure were all conducive to the impact resistance. The increase of the span-to-depth ratio would increase the failure displacement and decrease the maximum structural resistance and energy absorption capacity. Moreover, compared with the static loading condition, the energy absorption capacities of welded unreinforced flange – bolted web (WUF-B) and fin plate (FP) specimens under impact loading increased while the energy absorption capacity of reversed channel connection (RCC) specimens decreased.

Longitudinal shear performance of lightweight steel-UHPC composite connections based on large-diameter high strength friction-grip bolts

In order to improve the construction efficiency and reduce the self-weight of composite bridges, prefabricated thin UHPC (ultra-high performance concrete) decks can be connected to steel girders by high-strength, large-diameter friction grip through-bolts. This paper presents a pilot experimental study into the shear performances of such composite connections. Thirty push-out tests were carried out to observe the influences of bolt diameter, slab thickness, bolt strength, pretension force and random asymmetric clearance of the bolt within the slab and joist. The observed failure modes include bolt fracture, pronounced permanent flexure of the bolts due to extensive yield, and crushing/splitting of the UHPC. 36% and 25% increases in diameter (from 22 to 30 mm) and tensile resistance (from 795 to 995 MPa) in 55 mm thick slabs led to 43% and 11% improvement respectively in connection shear resistance. Moreover, a bolt pretension force increase from 150 to 200 kN and a slab decrease in thickness from 55 to 35 mm respectively changed the failure mode from bolt bending to bolt fracture and reduced the shear resistance by 15%. Random asymmetric clearances of the bolts between 0.17 and 5.43 mm led to 88%-100% reduction of connection stiffness at the first slip stage and decreased shear resistance by up to 11%. Regression analysis shows that connection shear strength, stiffness and ductility are mixed polynomial and exponential functions of the key connection variables.

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.

Application of multi-hybrid metaheuristic algorithm on prediction of split-tensile strength of shear connectors

Shear connectors play a major role in the development of composite steel concrete systems. The behavior of shear connectors is usually calculated by push-out measurements. These experiments are expensive and take a lot of time. Soft Computation (SC) may be applied as an additional solution to remove the need for push-out testing. The objective of the research is to explore the implementation, as sub-branches of the SC approaches, of artificial intelligence (AI) techniques for the prediction of advanced C-shaped shear connectors. To this end, multiple push-out tests on these connectors will be carried out and the requisite data is obtained for the AI models. The Grey Wolf Optimizer algorithm (GWO) is built to define the parameters that influence the shear strength of angle connectors. Two regression metrics as determination coefficient (R2) and root mean square (RMSE) were used to measure the results of model. Furthermore, only four parameters in the predictive models are sufficient to provide an extremely precise prediction. It was found that GWO is a faster method and is able to achieve marginally higher output indices than in experiments.

Static Performances of Timber- and Bamboo-Concrete Composite Beams: A Critical Review of Experimental Results

The use of composite beams made with traditional concrete and bio-based materials (such as timber and bamboo) is a valuable solution to reduce the environmental impact of the building sector. Timber-Concrete Composite (TCC) beams have been used for decades in structural applications such as new buildings, refurbishment of old timber structures, and bridges. Recently, different researchers suggested composite beams based on engineered bamboo, commonly named Bamboo-Concrete Composite (BCC) beams. This study presents a systematic comparison of structural performances and connection behavior of TCC and BCC beams under short-term static load. TCCs beams are compared to BCC ones using similar shear connectors. The most important aspects of the two composite systems are compared: mechanical behavior of connectors and structural behaviors of full-scale composite beams (e.g., failure modes, connection stiffness, connection shear strength, ultimate load-carrying capacity, maximum deflection and composite efficiency). This comprehensive review indicates that BCC beams have similar or even better structural performances compared with TCC.

ОЦЕНКА РЕЗУЛЬТАТО В ИСПЫТАН ИЙ УГОЛКОВЫХ АНКЕРНЫХ УПОРОВ НА СДВИГОВОЕ ВОЗДЕЙСТВИЕ

The shear connector design should be executed according to the SP 266.1325800.2016. For the different typed of welded connectors are there analytic dependences, which could be used for shear connection strength estimation. The design code also allows to use powder-actuated Z-shape shear connectors. Their bearing capacity should be proved by tests according to the GOST R 58336-2018. Inasmuch the GOST doesn't consist the test estimation approach, the authors offer the method. For the test estimation methods the test results of 15 series specimen had been used. The results were compared with estimation according to the European standard for the verification.

Structural performance of steel-concrete composite bridges utilising innovative blind bolt shear connectors

The purpose of this research is to identify more efficient and reliable connection methods to design a composite steel/concrete structural system with a focus on sustainability. While using innovative blind bolt shear connectors into substitute for the welded stud brings several benefits regarding constructability and sustainability, research contributions on the high strength blind bolt shear connector are very limited. Therefore, in this study, several push-out test specimens were carried out, in accordance with the Eurocode 4 standards, for both the traditional welded stud and the blind bolt shear connector, to determine the ultimate capacity, ductility, stiffness, stress-strain and load versus slip performance. In addition, finite element analysis has been done on the two types of shear connectors to determine the factors influencing static strength of shear connectors. The feasibility and accuracy of the 3-D finite element model developed in this work was validated by comparing with experimental results obtained from push-out tests. Experimental and finite element modelling results revealed that the blind bolt shear connectors would be an appropriate alternative to the traditional welded stud for sustainable purposes under static loading conditions.

Vertical and horizontal push tests on specimens with a Trefoil decking profile

The vertical push test has historically been the primary means used to evaluate the strength of shear connectors used in steel-concrete composite floors; however, these tests can be difficult to conduct and generally their results have been shown to not well represent the behaviour of shear connectors in a full sized composite beam. This paper describes a series of twenty-four push tests on composite beam specimens with Trefoil profile steel decking and headed, through-deck welded shear connectors (shear studs) using two different test set-ups. Twelve push tests on specimens with 19 mm and 22 mm shear studs were conducted using the double sided vertically oriented setup from AS/NZS 2327 and Eurocode 4, with transverse load applied across the slab faces. Twelve further push tests were conducted on specimens with 19 mm diameter studs using a new horizontal set-up. The results of the vertical tests suggest that the equations in Eurocode 4 for the determination of design shear resistance may be unconservative for 19 mm and 22 mm shear studs in 80 mm deep Trefoil decking ribs. The horizontal test specimens showed the same poor post-peak load retention that is characteristic of push tests conducted using the vertical test set-up without the application of transverse load. These parallel test programs are an exploratory step towards understanding the differences in behaviour observed in vertical and horizontal push tests and are the initial efforts in a continuing research program to develop a horizontal push test that provides a close approximation of the behaviour observed in full-beam tests.

Behavior of rubber-sleeved stud shear connectors under fatigue loading

The fatigue performance of the rubber-sleeved stud shear connector, which is a composite of ordinary stud and rubber sleeve, is not clear yet, which limits its application in steel and concrete composite structures subjected to fatigue loading. In this paper, fatigue push-out tests on nine shear connector specimens were conducted to provide insight into the influence of shear stress range and rubber sleeve height on the fatigue performance of shear connectors. Nominal shear stress-based fatigue strength curves for rubber-sleeved stud shear connectors were established. It was observed that the fatigue strength of shear connectors decreases with the rubber sleeve height. In addition, rubber sleeves with low stiffness lead to a larger relative slip growth rate of rubber-sleeved stud shear connectors. However, the static stiffness degradation laws of the ordinary stud and rubber-sleeved stud shear connectors are similar, and a unified static shear stiffness degradation model was established. Moreover, fatigue failure mechanism of rubber-sleeved stud shear connectors was analyzed. The results illustrated in this paper can provide reference for the fatigue design of rubber-sleeved stud shear connectors and support their application in steel and concrete composite structures.

ОГНЕСТОЙКОСТЬ КОНСТРУКЦИИ, ОБЕСПЕЧИВАЮЩЕЙ СДВИГОВОЕ СОЕДИНЕНИЕ СТАЛЕЖЕЗОБЕТОННЫХ БАЛОК

Most of Russian research about composite structure fire resistance are dedicated to the composite slab behavior. The composite beams fire resistance had been never investigated in enough volume: the temperature evaluation within the scope of the actual Russian design codes leads to the significant reduction in the shear connection strength. Meanwhile, there no correlation between the strength decreasing and type of the shear connection. The article provides an overview of the relevant researches and offers some approaches which could take into account bearing capacity reduction of the shear connectors within composite structures design.

Experimental study on fatigue performance of UHPC-orthotropic steel composite deck

UHPC-orthotropic steel composite deck is an innovative and efficient bridge deck system, however the failure mode of this composite bridge deck under fatigue load is still not well understood, particularly when the deck is in hogging bending. To investigate the fatigue behavior of the UHPC-orthotropic steel composite deck, two multi-span full scale composite bridge decks in hogging bending were experimentally studied. To simulate the bridge deck under negative bending, the specimens were designed with the mid-span deck simply supported and two overhanging decks each side. Each specimen was tested twice. In the first test phase, the specimen was loaded with a vertical force acting on one side span, while in the second test phase, the specimen was vertically loaded on another side span. Tests revealed that among the all fatigue-prone details of an orthotropic steel deck, only the longitudinal cracks were observed occurring in the low portion of rib web which was near the weld toe of the rib to the transverse diaphragm. The fatigue strength of these specific cracks longitudinally orientated can be evaluated in a term of the vertical stress range of the rib below the weld toe under the fatigue details category C of AASHTO or category 71 MPa of Eurocode3. Shear connection failure of the composite deck was also found featuring with delamination between UHPC and steel bridge deck. Fatigue damage of the short headed studs was further inspected and evaluated by means of drilling test. It is found that the fatigue life of the shear connection is governed by the fatigue shear strength of the short headed studs, which is much longer than the fatigue life codified in the specifications for studs of conventional composite beams. The fatigue shear connection strength of the composite bridge deck can be assessed conservatively in a term of the fatigue shear strength of the headed studs.

Determination of the Sliding Modulus and Limit Strength of Shear Connectors for Mixed Wood-Concrete Structures

Tests with specimens are still the most suitable way in order to get to know the mechanical and elastic behavior of shear connectors, which are used in mixed wood-concrete structures. The most used wood-concrete specimens are the symmetrical push-out type models. About the great diversity of connectors, considering type, stiffness, strength value and their position in the structural member, besides other varieties as: spaces between connectors, dimension variation and mechanical and elastic properties of the materials involved, several normative standards suggest that the wood-concrete specimens shall represent the real connection behavior. In Brazil, due to lacking of normative procedures, plenty of wood-concrete specimen models and criteria have been used for the determination of the limit strength and the slip modulus of these connections. In this paper some wood-concrete specimen models are presented, they were suggested in some normative documents and others presented into the international literature and national research. Some procedures are suggested for obtaining the slip modulus and limit strength, representing the real conditions of the connection.

Residual stiffness and strength of shear connectors in steel-concrete composite beams after being subjected to a pull-out pre-damaging: An experimental investigation

Horizontal stability of the medium rise steel frame structures is usually ensured by vertical bracings and diaphragm action of composite floors. Load transfer within the composite floor system is made through shear connectors, e.g. headed studs. In an event of explosion, such connectors must reserve sufficient residual stiffness and strength in order to avoid a sudden or delayed collapse of the building. These remaining capacities have not been experimentally studied yet in the literature. This paper presents large scale horizontal push out tests to determine the residual stiffness of the shear connectors after being initially damaged by explosion. The initial damaging is reproduced by a pull-out test using a quasi-static loading. Two types of numerical simulation have also been developed using ABAQUS/CAE software to provide a better understanding of the experimental results.

Development of a Shear Strength Equation for Beam\u2013Column Connections in Reinforced Concrete and Steel Composite Systems

In this study, we propose a new equation that evaluates the shear strength of beam–column connections in reinforced concrete and steel beam (RCS) composite materials. This equation encompasses the effect of shear keys, extended face bearing plates (E-FBP), and transverse beams on connection shear strength, as well as the contribution of cover plates. Mobilization coefficients for beam–column connections in the RCS composite system are suggested. The proposed model, validated by statistical analysis, provided the strongest correlation with test results for connections containing both E-FBP and transverse beams. Additionally, our results indicated that Architectural Institute of Japan (AIJ) and Modified AIJ (M-AIJ) equations should be used carefully to evaluate the shear strength for connections that do not have E-FBP or transverse beams.

Equations of the Sum of Shear Connector on the Double Shear Connection Strength using Different Connector Materials

Mangium wood from the timber estate have been developed continuously in an effort to reach the fulfilling of wood fiber and construction material needs to replace role of timber from the natural forests which has been decreased. Timber connection requires a connector such as bolt that can distribute both the load of wood to wood and the compression or tensile stress through all the connections. Bearing slip is a connector that is inserted into a hole in the wood, which bears pressure and shear. Bolted connection is the most commonly used because it is easy to apply, even though it is less efficient due to the shear forces will be retained by the bolts and wood only on the cross-sectional area of the bolt. This research trying to find the equations of the sum of bearing slip connector to the strength of double shear connection which composed of 17 years old mangium. The connector was made from different materials that consisted of the same mangium, compressed mangium, ironwood and steel. The bearing slip connector consisted of two forms (dowel and rectangular) and arranged on one until three pairs of connector. The size and placement of the double-shear component based on Anonymous (2002), each form of the sample was made in 4 replications and all of them have been tested using a 35-ton Baldwin UTM. The result showed that the rectangular steel bearing slip connector has the highest equation (y = 5322e0.329x ) meanwhile the lowest equation was the ironwood materials (y = 3164e0.405x ). All of equations give high correlations ( R2 between 0.743 to 0.947). Bearing slip connector can improve the ability of the connection in load-bearing. Densified of mangium able to raise the connection system's ability however not significantly, both in strength and displacement. Ironwood connector are not well used as a retaining shear pin because of easy to split and significantly much below in capacity than mangium wood. Steel connector resulted the higher load-bearing significantly than mangium and ironwood. Dowel do not differ in terms of strength as compared with rectangle, and each additional number of connector producing an increase in load-bearing ability significantly. Observation on the displacement value shows that for the value which applied usually in Indonesia reach the strength ratio (SR) as 92.21% to the proportion limit and 44.91% to the maximum load. This value was in below position of the US standard (24.17 and 11.77%) and of the Australian standard (51.46 and 25.06%) to the proportional limit and maximum load respectively. Displacement achievement at the proportional limit varies from 1.1 to 2.2 mm, so that the minimum requirement of 1.5 mm displacement is not fulfilled by some treatments, however all of the connection system have passed the 1 mm displacement.