Bolt Rows Research Articles

Finite element analysis of the behaviour of double-row bolted fin-plate connections

Fin-plate connections are among the most prevalent shear connections in the United States and Australia due to their simplicity in manufacturing and erection. Eurocode 3 Part 1-8 (Eurocode 3, 2005) classifies fin-plates as connection components that can transmit significant moments despite being classified as pinned connections. This study aims to investigate fin-plate connections with double rows of bolts and their effect on joint behaviour and strength, including the effect of plate thickness on the Torsional Moment-Angle of Twist and Moment-Rotation relationship. The results were analysed to determine the influence of these factors on behaviour and joint strength, and they were utilized to assess the efficacy of the Eurocode 3 Part 1-8 design approach. To fulfil the study's objective, finite element models were developed using the finite element analysis software Abaqus. The modelling considers material and geometric non-linearity to evaluate the overall behaviour of the connection and the individual components involved in this type of connection. The results were compared with those obtained from experimental testing to validate the finite element models.

Effect of the washers on the bearing resistance of the bolted connections

Abstract Bolted connections are the most common method of joining thin-walled galvanized sheets on site. Small diameter bolts (M8, M10 or M12) and the corresponding nuts are used for this purpose. Washers should be provided both under the heads of the bolts and the nuts in case of a single shear connection with one row of bolts, according to the standard BDS EN 1993-1-8. I.e. it is unnecessary to place washers under the bolt head in case of two or more rows of bolts. In laboratory tests of bolted connections with two rows of bolts without washers under the nuts, is accounted bearing capacity lower than the theoretically determined one. The initial explanation is that the lack of flat washers results in high bolt rotations and hence reduced load resistance. To verify this seemingly logical explanation, the authors has conducted series of finite element analyses (FEA) on connections with two rows of bolts. It turned out that this was not the reason for the reduced bearing resistance. The presence of washers under the bolt head and the nut had a negligible effect.

Modified Use of the Component Method to Get More Realistic Force Distribution in Joints of Steel Structures

According to the EN 1993-1-8 Standard, the moment resistance of end-plated connections can be calculated with the use of the component method. In this, a pair-of-force defines the moment resistance. The magnitude and the location of the compression force can be accurately identified. The tension force part is usually the resultant of parallel forces appearing in line with the bolt rows. Following the rules of manual calculation and using a mechanical finite element model, where each component is modelled with spring elements, in some—easily identifiable—cases, leads to different force distribution. The simplifications defined in the Standard provide a longer arm for the same force, and because of this, larger moment resistance at the expense of safety. In this work, an alternative calculation method will be presented that provides the same force values in each bolt row, as the mechanical model of the connection, without constructing the finite element model.

Experimental and numerical characterization of column webs/faces loaded out-of-plane in steel joints

This paper presents a comprehensive investigation into the behavior of column webs/faces under out-of-plane loading within steel joints. The experimental component of the study involves testing five profiles, encompassing both open and closed sections with varying web slenderness and steel grade, subjected to direct out-of-plane tensile loads through bolted connections, utilizing both single and double rows of bolts. Concurrently, numerical simulations are conducted using finite element models, thoroughly calibrated with the experimental results. Drawing upon the calibrated numerical models, the paper systematically explores the influence of key parameters, including web slenderness, bolt arrangement, and analysis methods, through a parametric study involving 167 cases. A careful comparison of the observed behavior of the component from experimental tests, numerical models, and analytical models for initial stiffness is presented. Finally, the initial stiffness formulation derived from a recent model developed by the authors is improved to align with the observations from the experimental and numerical results.

Structural Performance of Bolted Lateral Connections in Steel Beams under Bending Using the Component-Based Finite Element Method

Structures must provide strength, stability, and stiffness to buildings and at the same time be efficient. This study addressed the effect of design elements and parameters on the strength of bolted lateral connections in steel beams under bending using the component-based finite element method. The variables evaluated were plate thickness, horizontal and vertical spacing between bolts, and geometric arrangement of bolts. Finite element software was used to evaluate the stress state of the junction plate, its plastic deformation, and bolt shear. A sensitivity analysis was performed to determine which bolt arrangements result in safer and more efficient designs using the same components. Stress distribution within the junction plate and plastic deformation values were used to evaluate the structural performance of the joints according to EuroCode 3. The results showed that placing bolts near the edge of a plate affected the bolts’ utilization, especially with thinner plates. Additionally, introducing an offset between central and outer bolt rows is not recommended as it worsened the stress distribution and the structural performance.

Experimental evaluation and numerical investigation on the anti-collapse performance of beam-to-column connections in the minor-axis direction

This study examined the effects of structural resistance in both major- and minor-axis directions on the anti-collapse performance of a fully bolted composite frame. Current research in the field has focused predominantly on the anti-collapse performance of H-columns in the major-axis direction, potentially hindering accurate determination of anti-collapse transmission path within a structure. Herein, monotonic static loading experiments were conducted on two substructures in the minor-axis direction: one equipped with welded flange and bolted web connections and the other with fully bolted connections. The ductility development curve, dynamic collapse response curve, and resistance mechanism correlation curve were employed to evaluate the test results. Fully bolted connections exhibited superior nonlinear rotation capacity, which is essential for the development of a structure's catenary resistance The failure mechanisms and resistance development processes of the structures were reproduced using the ABAQUS/Explicit dynamic quasi-static modeling technique. A full-scale finite element model was developed for the frame with fully bolted connections loaded in the minor-axis direction. This research will contribute to the robust design of fully bolted structural frames that considers the effects of the column stiffness, thickness of the splicing cover plate, number of bolt rows, and bolt apertures of flange connections on deformation and resistance to loading in the minor-axis direction.

Experimental response of semi-rigid reinforced concrete beam-column joints with bolted angle dissipating connections

Accelerated building construction is a challenge and opportunity for modern construction techniques such as prefabricated building. However, insufficient connection detail for precast structures resulted in serious damages (even collapse) in past earthquake, which significantly hit the further development of prefabricated building. With satisfactory seismic performance and minimal residual displacement, self-centering joint is an excellent alternative with respect to traditional prefabricated joint. In self-centering system, bolted connections are sufficiently utilized as energy dissipation system. However, the information about connection details is quite limited. Thus, a comprehensive experimental study was conducted to characterize the seismic behavior of semi-rigid reinforced concrete (RC) beam-column joints with bolted angle dissipating connections, namely, semi-rigid joints. Ten full-scale semi-rigid joints were tested under cyclic loading, taking the connection detail as variable. The main configurations of semi-rigid joints based on Eurocode 3 were angle thickness, angle stiffener, bolt diameter, column bolt gauge, rows of beam bolts, and grouting of beam bolts. The test results showed that, by adopting the ductile connection concept, it was possible to produce high ductility and abundant energy dissipation, control damages within the connection zone, and even achieve equivalent monolithic behavior through mobilizing a sufficient rigidity. Feasibility of replacing the damaged connection with a new one with the identical or higher capacity thus obtaining the equivalent or better performance with respect to the original tested joint is also evaluated. Finally, a theoretical model was proposed to evaluate the initial stiffness and bearing capacity of the joints. A good correlation was achieved as comparing to the test results. This research provides significant insight into the performance of precast semi-rigid joints and offers essential data for further investigation of developing design-oriented procedures.

Case study on the secondary support time and optimization of combined support for a roadway under high in-situ stress

Roadway support can effectively improve the stability of roadway excavation and ensure the safety of underground mining. This study investigates the secondary support time and parameter optimization of combined support for a deep roadway in the stage of resource replacement in the Huize lead–zinc mine in Yunnan Province, China. The aim of this study is to increase the stability and safety of the roadway and decrease the cost of support. Research on support methods and failure modes has shown that under the action of high in-situ stress in deep mining, the surrounding rock of the roadway exhibits obvious rheological phenomena. The change in the radial displacement of the roadway is combined with creep tests of the main exposed surrounding rock to determine the secondary support time. Numerical simulations and orthogonal tests are utilized to optimize the support parameters in terms of the roof subsidence, floor heave displacement, side displacement, and plastic zone by analyzing the effects of the sprayed concrete thickness, bolt length, bolt row spacing, and bolt diameter on the support results. The proposed secondary support time and combined parameters can provide a reference for roadway support in similar strata.

Optimization of the Mechanical Properties of Bolted Connections between Concrete-Filled Tubular Columns and Steel Beam with Reinforcing Rings

To study the mechanical performance of bolted connections with different structural forms of reinforced rings, based on the results of monotonic loading tests on two bolted connections between a concrete-filled steel tubular column and a steel beam with an outer reinforcing ring, this article uses ABAQUS v.2020 software to establish a three-dimensional refined finite element analysis model of such connections using appropriate constitutive models for concrete and steel. Subsequently, the effect of the dimensions of the steel beam, reinforcing ring, and cover plate on the load-bearing properties and the failure mechanism of the connections is investigated, and the numerical model is consistent with the verification test results. Then, the numerical simulations comparing bolted exterior reinforced rings under seven different construction measures (i.e., number of bolts, stiffeners) based on a conventional welded exterior reinforced rings with rigid connections (i.e., CGJ) are standardized. The research results indicate that when four rows of bolts are introduced on exterior reinforced rings, the web of steel beam is welded with stiffeners, and the top and bottom reinforced rings are also added with stiffeners; this bolted connection with an external reinforcing ring (i.e., GZ-7) can achieve the rigidity and load-bearing capacity of a fully welded external reinforcing ring rigid connection. At the same time, the reinforcing ring plate is bolted to the flange of the steel beam, and the force transmission path at the connection is changed to avoid the brittle fracture easily caused by the welded flange joints. It is also in line with the development trend of sustainable construction of “assembly” and “disassembly”.

Flexural behavior of cold‐formed U‐shaped steel members encasing concrete composite beam using continues stud bolts

AbstractThe current paper presents an innovative form of the cold‐formed U‐shape steel encasing concrete composite beam (CUCB). The suggested CUCB consists of a cold‐formed U‐shaped steel encasing plain concrete beam which are connected to each other using continuous transversal threaded stud bolts. The experimental program consisted of eight beam specimens tested in the four‐point bending set‐up. One of them was a normal reinforced concrete beam and considered as a reference specimen while the remaining specimens were CUCB specimens without ordinary flexural and shear reinforcement. Four parameters were studied in this paper: (i) the thickness of the U‐shaped steel, (ii) the spacing between the stud bolts, (iii) the arrangement of the bolts, and (iv) the number of the bolt's rows. Results indicated an overall improvement in the load‐carrying capacity and stiffness of most CUCB specimens in comparison with the reference specimen. It was found that the using of three rows of bolts can significantly improve the ductility and toughness of the CUCB specimen in comparison with two rows of bolts. On the contrary, an increase in the bolt spacing entails a decrease in the CUCB specimens' toughness.

Seismic behaviour of dissipative beam‐to‐column steel and steel‐concrete composite joints

AbstractThe present paper deals with the seismic behaviour of bolted steel and steel‐concrete composite partial‐strength beam‐to‐column joints with endplate connections. In a series of experiments in total 12 two‐sided internal joint specimens were tested, of which 3 were all‐steel and 9 steel‐concrete composite. For those, 5 parameters were varied, (i) thickness of endplate tep, (ii) vertical distance of T‐stub bolt rows e4, (iii) distance of first shear stud to face of the endplate l, (iv) reinforcement ratio of concrete slab ρ and (v) number of bolt rows. The design of the specimens was performed with the help of both the component model as given in EN 1993‐1‐8 and a FEM model. The chosen parameter values were optimised to provide, for given beam and column sections, an upper and lower limit regarding moment capacity and rotational stiffness, for sufficient energy dissipation and ductility. The experimental results show that the stiffness of the concrete slab leads to a significantly different response of composite compared to all‐steel joints, especially regarding rotational stiffness and capacity of the joint as well as flexural stiffness of the (composite) beams. The composite joints present an overall better seismic behaviour compared to all‐steel ones.

Study on Tensile Performance of Double-Bolted Joints between Carbon Fiber Reinforced Polymer Plate and Aluminum Plate

Carbon fiber reinforced polymer (CFRP) with high specific strength, specific modulus, and other outstanding properties, which could be used in aerospace, shipbuilding, and railway. The joint of carbon fiber composite material plate and metal material plate plays an important role in the overall performance of the structure. In this paper, a carbon fiber reinforced polymer (CFRP) progressive damage model is developed based on composite laminate theory and 3D Hashian theory. The model of the double bolt single lap joint shear connection is established for the CFRP plate and the finite element method is used to carry out the stress analysis and failure prediction of the lap structure. The effect on structural performance under tensile conditions was studied through the change of double bolt spacing. The results show that the decrease in bolt row spacing can lead to the interference effect between holes. In addition, the progressive damage of the composite plate is located near the center line of the bolt hole.

Evaluation of energy accumulation, strain burst potential and stability of rock mass during underground extraction of a highly stressed coal seam under massive strata-a field study

Severe geotechnical problems like strain burst, side spalling, roof fall, irregular caving, the premature collapse of rib/remnant pillars, etc. are frequently observed during the mining of highly stressed coal seams under massive overlying strata. In this study, different underground structures and adequate support systems under such complex geological conditions are designed by evaluating energy accumulation, strain burst potential, stress conditions and stability of the rock mass. An energy-based safety factor is derived and implemented through numerical modelling to identify the yield zones in the surrounding rock mass. The strain burst potential in different locations is also evaluated by the elastic energy accumulation and the Burst Potential Index (BPI) whose maximum values reach 628 kJ/m3 and 47.6% respectively during depillaring operations. These values indicate the significant strain burst and side spalling conditions which are corroborated by the field investigations and monitoring data by geotechnical instruments. Control measures have been taken by leaving the optimum size of rib/remnant pillars in the goaf and installing adequate support systems in the working areas. It is observed in the field that rib/remnant pillars, designed with a safety factor of ∼0.17 are found suitable for regular caving of overlying massive strata in the goaf. The side spalling and the strain burst are minimised by installing the glass-reinforced plastic (GRP) bolts and the wire mesh. The uncontrolled caving of the overlying massive strata in the working area is prevented by installing closely spaced two rows of rock bolts at the goaf edge. This study would be helpful to design different underground structures and to ensure the safety of working areas during the extraction of highly stressed coal seams under massive strata.

Experimental and numerical investigation of semi-rigid behavior top and seat T-Section connections with different triangular designed stiffener thicknesses

The top and seat T-section connections created using the IPE standard profile and T-shaped elements differ from those in the literature, which utilize welded plates. Thus, the elimination of the problems occurring at the welds of connections, such as fracture points and the inability to perform well in place, is expected. Knowledge of their behavior is needed to recommend the use of weld-less T-section connections. However, T-section connections that use the IPE standard profile are not mentioned or investigated in Eurocode 3. Furthermore, the T-section connections from standard IPE profiles aimed to use residue IPE standard profiles efficiently and back to the consumption cycle. This paper reports the results of 24 new laboratory tests on the moment-rotation curve characteristics of top and seat T-section connections with different triangular-designed stiffener thicknesses under static loading. Additionally, to understand the effects of the web length (T-section connection) and different triangular-designed stiffener thicknesses on the moment-rotation curve characteristics, the web length was chosen according to Eurocode 3 width of the T-section was taken to equal the width of the beam (IPE 160). Furthermore, the T-section ratios of flange thickness (tf) to web thickness (tw) were selected between 1.46 and 1.52 to understand how the effect of this ratio on the characteristics of the moment-rotation curves. The experiments also established and validated the finite-element models (ANSYS-work bench). The test results show that the maximum moment and energy dissipation value increased with increasing tf/tw (flange thicknesses to web thicknesses) ratios from 1.46 to 1.52. Moreover, the stiffness ratio values increased with increasing tf/tw ratios from 1.46 to 1.52, while they decreased with increasing tf/tw ratios from 1.46 to 1.48. Moreover, the number of bolt rows increased from 1 to 2, and the Frye-Morris values became much smaller than the experimental values. Additionally, in the model comparison with the 1 row of bolts T-connection, the stiffener used does not affect the moment capacity of the Frye Morris models. The mean value of the Mexp/MF-M ratio is between 1 and 1.8 for the models with 2 rows of bolts. Therefore, the length of the T-connection used the stiffener effect on the moment capacity of the Frye Morris model with the two rows of bolts.

Experimental and numerical evaluation of pultruded GFRP double-lap joints with different mechanical fasteners

Evaluating the structural behavior of connections is of core importance in the design of a Pultruded Glass Fiber Reinforced Polymer (PGFRP) structure. In this paper PGFRP double lap-joint specimens mechanically fastened by Through-Bolts (TB) and Hollo-Bolts (HB) were tested under uniaxial tension test in static conditions. A three-dimensional progressive Finite Element (FE) model was proposed and validated to simulate joint failure. A parametric study was conducted to investigate the influence of edge distance-to-hole diameter (e/d), number of bolts (single, double, and triple bolts), bolt diameter, width-to-hole diameter (w/d), and thickness. The model agreed well with the experimental results regarding load vs displacement, load vs strain and failure characteristics. From the result analysis, it was found that connection resistance increased with an increase in the number of bolt rows. Hence the triple HB connection with specimen ID T12H4 demonstrated an overall ultimate failure load of 57.75 kN. While the aforementioned values were approximately 26% higher when compared to TB for the same configuration.

Web crippling of pultruded GFRP built-up sections

Web crippling is a critical premature failure of pultruded glass fiber reinforced polymer (GFRP) composites. One solution is to combine several sections to form a built-up section to carry the web crippling load. However, there is no existing study on the web crippling behavior of built-up sections under transverse loading. This paper presents an experimental and analytical study on the web crippling behavior of built-up I-shaped sections. The I-shaped sections were made by connecting two single channel sections back-to-back. Two connections methods were used including adhesive bonding and mechanical bolting. The bolt arrangements including number of bolt rows in the longitudinal direction, bolt spacing were varied to understand their effects on the web crippling behavior. The built-up sections were tested under two loading conditions of ITF and ETF, and the failure modes, load–displacement curves, and web crippling capacities were reported. Finally a section integrity enhancement coefficient was introduced in the analytical model to predict the web crippling capacity of built-up I-shaped sections and the predictions agreed well with the experimental results. This study contributes to the understanding of web crippling behavior of built-up sections made with pultruded GFRP sections.

Tension failure assessment of composite bolted joints under bearing-bypass load interaction using analytical means

Bolted joints are often used in thin parts such as plates or shell-like components in lightweight structures, e.g. air- and spacecraft. This is also motivated by an inexpensive manufacturing and the ability to disassemble. To make these joints, holes need to be drilled and stress concentrations arise. Leading to the instantaneous destruction of the connection, attention should be drawn to fatal tension failure. The efficient and precise prediction of the corresponding failure stresses using analytical methods is the focus of this paper. Usually, rows of bolts are placed. Then, the load is partly introduced into one bolt while the rest stays in the plate. This setting is also referred to as bolted joint under combined bearing-bypass load, which shall be idealised as a linear 2D plate problem. The corresponding characteristic stresses are discussed for orthotropic laminates showing good agreement to Finite Element values. Then, failure analysis is conducted using Finite Fracture Mechanics. This part is dedicated to quasi-isotropic laminates. The size effect and in this context the failure stress reduction with increasing bolt diameter is analysed. Primary physical effects due to finite dimensions and the ratio of bearing and total load are identified. The higher this ratio and the larger the bolt diameter, the lower the sustained failure stress. Failure envelopes for the graphical determination of the critical bearing and bypass stresses are provided. All in all, a comprehensive and efficient framework for tension failure assessment of composite bolted joints under bearing-bypass load interaction is developed.

Communication and technological solutions regarding the construction of shelter objects at underground railway stations in fractured and water-logged rocks

The purpose of the work is to substantiate the choice of locations of underground shelter objects for the people protection during the warlike situation and methods and facilities for ensuring their stability and isolation, and to develop a combined supporting scheme taking into account mining and geological conditions. It is proposed to arrange the shelter objects in the vicinity of the boarding platforms of the underground railway stations connecting them with the passages, means for walking downstairs and upstairs and a transport network and providing areas for the long-term stay of people, areas for sleeping and eating, shower room, medical, shopping and other necessary blocks. The shelter should be connected to the networks of the underground railway station - electricity supply, water supply and drainage, ventilation and air conditioning. Sleeping areas should be built in the form of individual compartments and arranged in several tiers along the walls of the shelter object. This arrangement of underground objects will make it possible to create a single complex (the shelter object and subway station), reduce the total cost of the shelter construction, speed up the evacuation of people in the event of natural or man-made disasters or air strikes, and ensure a long-term comfortable stay for people. Load on supporting and parameters of roof-bolting systems were calculated for three categories of stability, which correspond to the conditions of the construction of underground railways in the Ukrainian crystalline shield. An algorithm for calculating parameters of the strengthened insulating-reinforcing protection system was built, which takes into account three types of support - rock-bolt structure, insulating-reinforcing rock-polymer layer and tubing. The developed technological solutions for the construction of underground objects assumes pre-bolting of their vaulted part according to a scheme which strengthens the interaction between the rows of bolts, improves the condition of the roof of the object, and ensures protection of the roadway and unsecured part near it during construction of the roadway. The rock-polymer layer protects the tubing against metal corrosion and leaching of concrete under the influence of groundwater, and, due to the high adhesiveness of the polymer resin, also binds the rock-bolt structure, the insulating-reinforcing rock-polymer layer and the tubing into a single reinforced system, which distributes the load around the object's perimeter. The use of modern elastic polymer resins in the protection system will contribute to resisting the alternating loads that spread in the soil during surface explosions, and ensures long-term stability and waterproofing of shelter object. The results of the research can be used in the development of scientific prerequisites for the improvement of methods and means of construction of underground shelter objects in order to ensure the safety of their operation in case of emergency situations. Keywords: underground structures, underground railway station, support, bolts, polymer resins.

Experimental study on the static and fatigue performances of GFRP-timber bolted connections

Steel plate connection is popular in modern timber structures. However, the steel plate may be subjected to corrosion issue due to the presence of moisture in timbers. This paper proposes to replace steel plate with glass fiber reinforced polymer (GFRP) plate for connecting timber elements, so that the durability of the timber structure is expected to be improved. An experimental study is presented on the static and fatigue performances of the proposed GFRP-timber bolted connections. Variables including bolt diameter, number of bolt rows, number of bolt columns were selected to understand their effects on the static and fatigue behaviours of the connections. Failure modes, load-displacement curves, static bearing capacities, fatigue lives, stiffness degradations of the GFRP-timber bolted connections were reported. The residue bearing capacities of the connections were tested after the fatigue loading tests to assess the fatigue effect on the connection static behaviour. This study contributes to the understanding of the mechanical behaviour of GFRP-timber bolted connections.

A Study on the Influence of Bolt Arrangement Parameters on the Bending Behavior of Timber–Steel Composite (TSC) Beams

The present paper investigates the impact of bolt distance, bolt diameter, and the number of bolt rows on the bending performance of timber–steel composite (TSC) beams. This study aims to facilitate the application of bolt connections in assembled TSC structures. Composite steel I-beams were designed with timber boards connected in the upper section with bolts. Three-point static bending tests were conducted on nine timber–steel composite beams divided into four groups (L1, L2, L3, and L4) with varying bolt arrangements. The destruction mode, ultimate bearing capacity, ductility coefficient, load–midspan deflection curve, and load–midspan strain curve of each specimen were obtained. In addition, the destruction mechanism, the quantitative relationship between the bolt area ratio and interfacial slip, and the ideal bolt area ratio were identified. It was found that when the midspan deflection of the timber–steel composite beam approached the prescribed limit, the main failure mode can be explained as follows: The top surface of the boards of all the specimens had longitudinal local splitting, except L1, which had fewer bolts and no obvious damage. Moreover, due to compression and because the stress at the lower edge of the I-beam entered the flow amplitude stage, some of the specimens were crushed but were not pulled off. The composite beams had high flexural load capacity and ductility coefficient, and the maximum relative slips of the timber–steel interfaces were in the range of 2–6 mm. It was also found that the maximum slip of the interface and the ductility coefficient decreased steadily as the bolt area ratio increased, while the specimen’s flexural bearing capacity increased. The optimal bolt area ratio was determined to be 8 × 10−3. Using the total bolt area, we designed the arrangement of the bolts on the board. For convenience, multiple bolt variables were converted into one bolt variable. The longitudinal distance of the bolts had a greater impact on the slip, and the bolt diameter had a smaller impact. The theoretical values of total relative slip were found to be in good agreement with the experimental results, which were based on the superposition of the relative slip equations with varying bolt distances. The effective bolt area ratio and the formula of the relative slip of each segment can provide instructions for the arrangement of bolts and the control of the relative slip of intersections in engineering practices.