Bolt Arrangement Research Articles

Discussion On The Optimization of Circumferential Distance Of The System Bolt In A Highway Tunnel

The setting of circumferential distance of system anchor rod in highway tunnel is related to the safety of tunnel structure, and also affects the project cost. The “code for design of highway tunnels” issued in 2018 also adjusted the circumferential spacing arrangement of the system bolts of the tunnel. Based on a highway tunnel project, the circumferential spacing of system bolts in deep buried section of grade V surrounding rock is adjusted from 0.8m to 1.2m, and the numerical simulation and comparative analysis before and after the optimization of bolt spacing are carried out. The field monitoring and measurement data show that the surrounding rock deformation after adjustment has little effect, and the cavern is stable as a whole, which can guide the optimization implementation of subsequent sections.

Numerical performance of blind-bolted demountable square CFST K-joints

A demountable connection is an effective solution to separate and reuse steel or composite components after their first-stage design life, and could therefore benefit the environment by reducing material consumption and saving natural resources. Blind bolts and through-bolts are usually served as connectors in such demountable connections to replace traditional welding works. This paper puts forward a novel design on demountable square concrete-filled steel tubular (CFST) K-joints fabricated with concrete filled chord, hollow braces, flush endplate, blind bolts and through-wall bolts. Advanced finite element analysis models of the novel joints were established using verified modelling techniques. Among the investigated flush endplate designs and bolt arrangements, it is found that the design with through-bolt anchored beneath the tensile brace and a continuous flush endplate has advantages in material efficiency, joint strength and limiting endplate-chord separation, and is therefore chosen as the prototype design. Analysis on the failure modes shows that brace buckling failure prevents premature failure of the other members and ensures the safety as well as reusability of the main composite chord. Furthermore, discussions on the strength prediction based on numerical analysis and parametric study on key factors such as flush endplate thickness and brace-chord width ratio are given.

Changing bolt arrangement and their effect on bearing capacity of single shear connections

In steel structures, bolted joints are used to connect structural elements. Due to the ease of its making, the square and rectangle arrangement of bolts are the prevalent pattern in these structural joints. To investigate the effect of changing the arrangement of bolts on the bearing capacity of single shear joint, square, circular and diamond are the patterns of bolts that have been chosen in this study. Nine specimens represent all these configurations experimentally have been tested under tension load. The results indicated that the highest bearing capacity of a single shear connection could be achieved using a square arrangement of bolts. While stresses could not be equally distributed around holes in circular and diamond pattern specimens of the same connection.

New nodal connection of thin-walled cold formed profiles with a trapezoidal wall using separate welded bushings

The article suggests a new constructive solution of the node made of thin-walled cold-formed profiles with a part of concave flat wall with the use of separate welded bushings for bolt arrangement. To assess the load-carrying capacity of the proposed node numerical and experimental study of a prototype model, consisting of thin-walled cold-formed profiles connected by a gusset plate with a bolt, using separate welded bushings was fulfilled. By results of researches character of pressure distribution in places of bolts installation is revealed and actual carrying capacity of new node is defined. The significance of the obtained research results for the construction industry lies in the fact that the new design solution of the node with the use of separate welded bushings makes it possible to eliminate the gap between the gusset plate and trapezoidal wall of the profile, thus performing the bolt fastening in this place and improving the actual work of the node. It should be noted that the proposed solution of connection with the use of separate welded bushings allows increasing the carrying capacity of the node, taking into account the installation of bolts in the concave part of the profile wall.

Numerical study on the behaviour of vertical bolted joints for precast concrete wall-based low-rise buildings

This paper presents a numerical study on the cyclic behavior of the vertical bolted joints in low-rise precast concrete buildings. A finite element analysis model was developed for predicting the cyclic behavior of the joints which was proved with the experimental results. A step-by-step procedure was developed to carry out the finite element analysis for the contact analysis in the bolted connections. The developed approach was then applied for a parametric study to investigate the effects of main structural design factors on the joints, including the number of bolts per joint, the compressive strength of concrete, the yield strength and diameter of bolts, the thickness of blocks, the yield strength and thickness of gusset plates, the clearance of bolt as well as the arrangement of bolts in joints. Results show that the number of and the properties of steel bolts both have a significant influence on the connection performances of and the failure modes of the joints. Based on the analysis results, a smiplified model was proposed for predicting the shear capacity of the bolted joints which was expected to improve the design of proposed low-rise precast concrete buildings.

Statistical evaluation of bearing resistance and related strength functions for bolted connections

The paper is concerned with the statistical analysis of strength functions for bolted connections, namely the bearing resistance, the block tearing resistance, the net cross-section resistance and the resistance of angles in tension connected by a single row of bolts in one leg to obtain partial factors. These strength functions are proposed in the second generation of EN 1993-1-8 and EN 1993-1-1. The statistical analysis is performed using 884 test results available in the background documentation to Eurocode 3 and an additional 380 test results of lap connections with different bolt arrangements, which are available in the literature. A suitable sampling criterion of the test results allowed sufficiently large data sets with a small coefficient of variation, which allowed the assumption of partial factor γM2 = 1.25. EN 1993-1-8 provides the design check of the effective net cross-cross section resistance of angles connected by a single row of bolts in one leg (EN 1993-1-8, 3.10.3). It is demonstrated that this design check is superfluous and can be completely replaced by the design block tearing resistance, taking into account the design upper limit of the net cross-section resistance.

Mechanical Properties of Strengthened RC Beams using Steel Plates

The focus of this analysis is the review of steel plate strengthened RC beams using Single row and Stagger row bolt arrangements and to compare the bonding behaviour of different bolts arrangement under flexure. Also, to investigate the behaviour, load bearing capacity and the deflection for control and steel plate bonded beams. This research is constrained by FEM analysis utilizing ANSYS to the actions of standard RC Beam and RC beam steel plate associated.

Deformation and load transfer analysis of staggered composite-steel lap joints subjected to progressive damage

In bolted composite connections design, staggered arrangements might offer a good area usage especially for structural elements with a small width. In this research, experimental and numerical works were employed to study the composite-steel double lapped joints with staggered bolts arrangement under static loads. Staggered bolt arrangement was studied with different bolt diameters and numbers. The predictions of developed models were compared to the experimental results and a good correlation was evaluated. The experimental study shows that the side distance in the staggered bolted joint has a significant influence on the maximum load due to the out-of-plane rotation. Simulation of the experimental work shows that this out-of-plane rotation produces a horizontal force on the direction causing early failure for the joint. A parametric study was performed to investigate the effect of bolt numbers and diameters. It was found that the number of bolts has a more significant effect on increasing joint failure load than the bolt diameter. In all cases, the first bolt from the composite plate side has the maximum force, therefore, the first damage happened under this bolt.Considering the axial applied load direction as a reference direction, high perpendicular to parallel forces ratio was evaluated on the bolts of the staggered joint. It is recommended to consider this force during the design of the laminate. Furthermore, the staggered bolt arrangement was found to cause a significant out-of-plane bending which is recommended to be taken into consideration.

Block shear failure of S275 and S690 steel angles with single-line bolted connections

Block shear is a common failure mode for bolted-steel shear connections. However, limited research has been conducted on the block shear failure of bolted high-strength steel (HSS) angle members. In this study, a test programme was conducted using eight single-line bolted angle specimens made of grade S690 steel and five S275 counterparts, to examine their block shear behaviour. The test parameters included steel grades, bolt arrangements (bolt number, pitch, and edge distance), and connection legs. Eleven of the specimens failed by block shear, and the remaining two by shear-out. Finite element models were developed to study the behaviour of the test specimens and to investigate the effects of connection legs on the block shear resistance. Laboratory tests and numerical analyses indicated that the block shear resistance increased only slightly with increasing lengths of the angle legs, and the relatively lower ductility of HSS did not significantly influence the block shear resistance of the HSS angles. It was also found that the predictions made by AISC 360–16 and Eurocode 3 were conservative, whereas CSA S16–14 provided unconservative predictions. The predictions obtained from design equations proposed in previous studies were also evaluated for their accuracy.

Behavior of Circular Hollow Sections Solid Flanged Splice

As the use of circular hollow section (CHS) is growing due to its aesthetic shape, attention should be given to its connections. Splicing the CHS is essential for its use as long flexural member. This research investigates the behavior of flanged CHS splice under pure bending. A finite element study is conducted to investigate the behavior of flanged splice with eight bolts arrangement and three different diameters. The finite element model is verified against experimental results. It showed good agreement in terms of both ultimate moment and flexural stiffness. Three different modes of failures are observed and investigated. Generally, mode of failure depends on the thickness of the end plate. Results of different end plate thicknesses is presented and the transition thickness between different modes is determined.

Cyclic performance of splice connections for hollow section fibre reinforced polymer members

This study investigates the cyclic performance of splice connections developed for hollow section fibre reinforced polymer (FRP) members. Splice connection specimens, each consisting of a steel bolted flange joint between two hollow section steel-FRP bonded sleeve joints, are prepared in three configurations with difference in bolt arrangement or bond length. Correspondingly, detailed finite element (FE) models are constructed with consideration of yielding of the steels, damage in the adhesive bond, pre-tensioning of the bolts and contact between the bolt-fastened parts. Tested under a cyclic flexural loading, the specimens experience different levels of yielding in the steel flange-plates before ultimate failure in the FRP member or in the steel flange-plate. Excellent ductility and energy dissipation capacity are demonstrated in a specimen where plastic deformation of the steel flange-plates is fully developed. The strain responses are also analysed to identify damage in the adhesive bond and yielding in the flange-plates. The FE modelling agrees well with the experimental results in terms of moment-rotation and load-strain responses, and can also predict the initiation of the ultimate failure in the FRP using the Tsai-Wu failure criterion.

Experimental study on mechanical properties of laminated bamboo beam-to-column connections

Moment-rotation behavior of three types of beam-to-column connections intended for laminated bamboo structures are presented: (a) conventional bolted connections with slotted-in steel plates; (b) T-shaped extended end plate connections with side plates that confine the beam; and, (c) an L-shaped end bracket connection which partially confines both the beam and column. Each connection was tested under monotonic and reversed cyclic loads and the influence of bolt arrangement and the local inclusion of cross-laminated laminae locally in the connection region were investigated. Specimens having cross-laminated laminae did not exhibit parallel-to-grain splitting initiating at the bolt lines which was prevalent otherwise. Connections fabricated with slotted-in steel plates clearly exhibited slip deformation and lower stiffness and capacities than the T-connections and L-connections. Load-carrying capacities calculated according to Eurocode 5 were found to conservatively estimate the capacities of the T-connections and L-connections. For the I-connections, the safety margin was considerably lower.

Experimental investigations into magnetic abrasive flow finishing process on aluminium 6061-T6

The magnetic abrasive flow finishing (MAFF) process has been developed and investigated as an advanced fine finishing process. It is used for a surface finish (SF) of the straight and complex intricate profile using the ferromagnetic nature of abrasive media. This article presents an experimental investigation on the newly developed MAFF attachment, which was mounted on a shaper machine. A custom design workpiece fixture was used in MAFF attachment for the finishing of a straight hollow cylinder shape workpiece, which can easily modify based on workpiece shapes. A curved workpiece seat was prepared and fasting with two brass plates by nut and bolts arrangement. Taguchi design of experiment approach applied for experimentation on aluminium 6061-T6 workpiece material by MAFF setup. The main process parameters considered for experimentation are magnetic flux density (MFD), number of cycles, abrasive concentration, and piston speed while responses are material removal (MR) and surface finish (SF). The results found after finishing by MAFF were also compared with the AFF. It was identified that remarkable enhancements observed in MAFF responses. The finished surfaces were also observed by scanning electron microscope (SEM) and X-ray diffraction (X-RD).

Effect of cross-sectional dimensions and bolt arrangement on deformed bearing limit resistance of high-strength frictional bolted joints after major slip

Effect of cross-sectional dimensions and bolt arrangement on deformed bearing limit resistance of high-strength frictional bolted joints after major slip

An Experimental and Numerical Study on the Flexural Performance of Over-Reinforced Concrete Beam Strengthening with Bolted-Compression Steel Plates: Part II

This study presents an experimental investigation and finite element modelling (FEM) of the behavior of over-reinforced simply-supported beams developed under compression with a bolt-compression steel plate (BCSP) system. This study aims to avoid brittle failure in the compression zone by improving the strength, strain, and energy absorption (EA) of the over-reinforced beam. The experimental program consists of a control beam (CB) and three BCSP beams. With a fixed steel plate length of 1100 mm, the thicknesses of the steel plates vary at the top section. The adopted plate thicknesses were 6 mm, 10 mm, and 15 mm, denoted as BCSP-6, BCSP-10, and BCSP-15, respectively. The bolt arrangement was used to implement the bonding behavior between the concrete and the steel plate when casting. These plates were tested under flexural-static loading (four-point bending). The load-deflection and EA of the beams were determined experimentally. It was observed that the load capacity of the BCSP beams was improved by an increase in plate thickness. The increase in load capacity ranged from 73.7% to 149% of the load capacity of the control beam. The EA was improved up to about 247.5% in comparison with the control beam. There was also an improvement in the crack patterns and failure modes. It was concluded that the developed system has a great effect on the parameters studied. Moreover, the prediction of the concrete failure characteristics by the FE models, using the ABAQUS software package, was comparable with the values determined via the experimental procedures. Hence, the FE models were proven to accurately predict the concrete failure characteristics.

Monotonic and cyclic tests on beam to column bolted connections with thermal insulation layer

This paper deals with the mechanical performances of bolted connections with intermediate thermal insulation layer used to attach an external steel structure (balconies, passageways) to a steel facade. In the proposed solution, thermal bridging is significantly limited by inserting a PVC or plywood plate between an end-plate connection and a steel column. Static and cyclic tests are performed on a cantilever beam connected to a steel column in order to investigate the effect of the thermal insulation layer on the rotational stiffness, bending moment resistances and failure modes. These tests highlight that both the thermal insulation layer and the bolt arrangement (extended and flush end-plate, stiffeners, RHS or I profile) have a significant influence of the connection response.

Study on mechanical behavior of Q690D high strength steel bearing-type bolted connections

The failure modes and ultimate bearing capacities of Q690 high strength bolted joints under different bolt arrangement were compared and analyzed through static tension test and finite element simulation. Then the influences of different bolt end pitch, edge pitch, pitch, bolt strength grade and bolt diameter were discussed with theoretical calculation and the applicability of EC3 and other standards were investigated. The results show that when the bolts were transversely arranged, the major failure modes of the specimens were pre-hole thrust failures, the stress of the connecting plate distributed symmetrically along the middle line of the bolt hole spacing, and the ultimate bearing capacities increased significantly with the increase of the bolt end distance, edge distance and bolt pitch in a certain range. According to Eurocode 3, the bearing capacities of the connection joints predicted by the deformation of bolt hole presented a large deviation. When the bolts were arranged longitudinally, the end bolts were subjected to large forces, and the net cross-sectional failures occurred in all specimens. The effect of edge distance on the bearing capacity was significant, while the change amplitudes of specimens with end distance and bolt pitch on the bearing capacities were little. Eurocode 3 was applicable to the calculation of the bearing capacity of the joint. The increase of bolt strength grade can improve the static friction forces between plates, and the increase in bolt diameter can improve the bearing capacity of the joint significantly.

PARAMETRIC STUDY OF THE CURVED T‐STUB IN TENSION

AbstractThis paper presents parametric study of the T‐stubs with curved end‐plates in tension. Influence of the key parameters such as curvature, bolt arrangement and the thickness of the end‐plate on the strength and stiffness of the T‐stub is investigated. In curved T‐stubs bolts not only undergo tension, but are also subjected to shear, which limits the use of the conventional prying models. Apart shear, due to curvature, determination of the total effective length of a T‐stub is not trivial, and the collapse mechanisms of the end‐plate are uncertain. To clarify behaviour of the curved T‐stub and to determine the influence of the curvature on prying and shear, FEM results of 108 T‐stubs were analysed.

Determination of Coal Pillar Width and Support Parameters in Deep Coal Mines—A Case Study

Abstract With the depletion of shallow mineral resources, many large mines have turned to deep mining. The mine pressures associated with deep mining activities induce severe damage and deformation in the surrounding rock. The stability of coal pillars in the mining area is an important factor in maintaining roadway stability, so reasonable retainment of coal pillars is a primary issue in safety production. In this article, the stresses on coal pillars and roadways under different coal pillar widths are analyzed with ABAQUS software (Dassault Systèmes, Vélizy-Villacoublay, France). The result is a reasonable coal pillar width of the first mined face in the Kongzhuang mine, which was determined to be approximately 5 to 7 meters. This width ensures that the coal pillar will not be crushed or fractured and avoids both spontaneous combustion of the coal and waste of resources. The roadway’s support parameters are determined by empirical calculation and then verified by numerical simulations and field tests. The reasonability of the arrangement of bolts and cables are verified in the same fashion.

Strainburst characteristics under bolt support conditions: an experimental study

Strainburst, defined as a burst that occurs on the periphery of tunnels, is always associated with intact and hard brittle rocks and high geo-stress. In practical engineering, the prevention of strainburst by bolting does not achieve the desired effects. Deep insight into the strainburst process and mechanisms under bolt support conditions is necessary to ensure safe underground construction. In this study, strainburst characteristics under bolt support conditions were investigated using a true-triaxial rockburst testing system, which was equipped with an acoustic emission monitoring system. High-speed cameras were also used to capture the ejection failure process. Two indicators, namely kinetic energy and maximum decibel, were used to comprehensively evaluate the rockburst intensity. In addition, characteristic stresses, failure mode and cracking mechanisms under different bolt spacing conditions were investigated. The test results demonstrated that rockburst is greatly affected by the bolt arrangement. Rockburst changes from the way occurring in the form of a local failure in weak area to the way striking the bolt position and even the overall free face with the decrease in bolt spacing. The use of the bolt increases the rockburst intensity, but the intensity decreases as the bolt spacing decreases. Characteristic stresses including crack initiation stress, crack damage stress and peak strength increase monotonously with the use of bolt and the decreasing bolt spacing. During the strainburst, tensile failure dominates the cracking process regardless of bolt spacing; however, with the use of bolt and decrease in bolt spacing, tensile splitting near the free face become less obvious and the proportion of shear failure gradually increased.