Types Of Bolts Research Articles

Mechanism and quantitative evaluation model of slip-induced loosening for bolted joints

PurposeBolted joints are the most common type of mechanical connections, and improving the anti-loosening performance of bolts for the reliable performance of mechanical and building structures is highly significant.Design/methodology/approachBecause of the lack of sufficient theoretical basis for the evaluation and design of anti-loosening bolts, a quantitative evaluation model exhibiting the following two evaluation criteria for anti-loosening bolts is introduced: bolt rotation angular acceleration criterion and critical transverse load criterion. Based on the relationship among bolt tension, transverse load and bolt rotation angular acceleration, a critical transverse load calculation model is put forward, and the mechanism by which the critical transverse load increases with the increase of bolt tension is revealed.FindingsBased on the above model, a new type of anti-loosening bolt is designed, which generates additional bolt tension when the transverse load increases, and then improves the critical transverse load of the bolt. The effectiveness of the new type of anti-loosening bolt is verified by theoretical calculations and experiments.Originality/valueThe proposed model and method set a preliminary theoretical foundation for the evaluation of bolt anti-loosening performance and the design of a new anti-loosening bolt.

Bolt connection performance post fire in steel bridges

Fire events reduce the strength of the steel structure on the bridge and can cause collapse which results in losses, so it is necessary to consider the effects of fire when planning construction. Considering that the joints affect the performance of steel structures, the results of research on the performance of steel beams need to be augmented by testing the post-fire girder bridge bolt connection performance. Structural tests will be carried out on six specimens of bridge steel beam elements with high quality bolt connections in the center of the beam with sliding type bolt connections. Two control specimen beams were tested with shear loads without combustion. Two specimens with temperature of 700°C and 900°C with different torque bond variables. From the displacement control test using UTM on six specimens, it will be known the performance of each type of connection by evaluating changes in carrying capacity, stiffness, deflection capacity, ductility, and stress-strain capacity due to the influence of temperature acting during the fire process. The results can prove which type of bolt connection is better for use on bridges with fire risk.

Monitoring and correction of the stress in an anchor bolt based on Pulse Pre‐Pumped Brillouin Optical Time Domain Analysis

AbstractBolt is an important connection in underground construction and monitoring its stress characteristics is essential to evaluate the effectiveness of bolt. The strain information collected along a rock bolt reveals the long‐term movement characteristics of rock mass, which greatly helps toward disaster prevention and risk warning. Grooving on the surface of a bolt and embedding an optical fiber is one of the main methods for monitoring the anchorage performance and stress distribution around the bolt in underground engineering. In this study, Pulse Pre‐Pumped Brillouin Optical Time Domain Analysis (PPP‐BOTDA) technology is used to evaluate the stress, axial force, and shear stress distribution of the bolt under tensile load for different types (grooved and nongrooved) of bolts embedded in concrete with resin as anchoring agent. The results show that the PPP‐BOTDA sensor can be used to monitor the stress state of the bolt embedded in concrete with resin as anchoring agent when the bolt is subjected to a tensile force. However, the apparent stress value measured in this way is not the actual stress value of the bolt, but is an increased value caused due to the groove. The closer to the exposed end of the bolt, the greater is the deviation between the apparent stress value and the actual stress value of the bolt. Based on the monitoring results from this experimental study, a stress reduction calculation method is proposed, which can change the measured value into the actual stress of the bolt.

Possibilities of modelling the bolts in program ANSYS

In this paper, the techniques of modelling bolts in program ANSYS are investigated. Several types of the bolt models are proposed and compared. The finite element models with solid bolt with and without thread, and no-solid model. The pretension effect is applied for all types of bolts. Different types of connections and finite elements are used for modelling. In addition, the assembled mechanical structure is loaded by pretension effect and the field of stress and displacement of points around holes for bolts are investigated. Moreover, the stresses in the bolts computed by three-dimensional finite elements are investigated.

Double Shear Load Carrying Capacity of Kempas and GFRP Dowelled Connections

Glass fibre reinforcement polymers (GFRP) application for reinforcement of wood, concrete and steel member is relatively becoming more variety in construction applications. Although it is possible to build large monolithic structures with composite materials, there are still several reasons for the structure to fail. One of the main reasons that contribute to this failure is the connection performance due to its function in carrying load across the structure. Thus having the right fundamental data for connection design purposes according to the specific and technological upgraded materials is very important. One of the basic methodologies in gaining the design data is through experimental double shear test which can be verified by European Yield Model (EYM) theory. Therefore, the objective of this research is to determine the load carrying capacity of double shear strength behaviour connections made of Kempas timber species as the main member and dowelled by the GFRP or the Kempas rod. The specimens were tested under the shear load with 2mm/min rate and tested until failure. From the experiment, it was found that the average ultimate shear strength of member dowelled with GFRP rod is 21.36% higher compared to one doweled with Kempas rod. According to mode of failure between two types of bolt, GFRP dowelled performs well (Mode I& IV) rather than Kempas dowelled (Mode IV).

Attempted suicide with a crossbow

IntroductionAirway management and control of bleeding are essential aspects of the management of attempted suicide involving the head and neck. Attempted suicide using a crossbow is exceptional. The patient's respiratory status, the position of the crossbow bolt in the head and neck, the type of bolt and its exit wound required airway management that has not been previously reported in the literature. Case reportThis conscious patient had attempted suicide by shooting a crossbow bolt to the head. The radiological assessment (contrast-enhanced CT scan) did not reveal any vascular, ophthalmological or neurological lesions. The submental entry wound of the bolt avoided any damage to the lingual and ethmoidal arteries, lamina papyracea, or frontal lobe. The bolt induced mechanical trismus and its position limited access to the base of the neck, preventing orotracheal intubation. Nasotracheal intubation and primary tracheotomy were also difficult in this situation. It was therefore decided to remove the bolt while the patient was still conscious, rapidly followed by intubation, with no complications. ConclusionIn attempted suicide by crossbow involving the head and neck, airway management depends on the possibility of exposure of the glottis, the bolt exit wound and safe access to the anterior neck.

Design and Optimization of Suspension and Steering System of Efficycle – Human Powered Hybrid Tricycle

Suspension is a system of tires, springs, shock absorbers, and linkages that connects a vehicle’s chassis to its wheels and allows relative motion between the two. Steering is a mechanism that provides a direction to the vehicle, it basically consists of gears, shaft, joints, steering column, steering wheel, and furthermore. The main objective of this paper is to design a system of suspension and steering for a three-wheeled human-electric hybrid trike. A system of directly actuated double wishbone suspension system is chosen for the front and a pushrod actuated 2-link trailing arm suspension system for the rear. The steering system used is a type of Single tie rod and drag link system. A knuckle-to-knuckle drag link provides continuity to the wheels and a tie rod to the bell crank provides steering rotation. This paper also talks about the single nut hub-shaft system which is being used in the front suspension system. Based on the research using various input parameters, the inboard and outboard suspension hardpoints are decided to maximize the tire contact patch at every vehicular motion (mainly during body roll). Forces and stresses are calculated with the help of Free Body Diagrams (FBD) and Multi-Body Dynamics (MBD) software LOTUS Shark. The paper discusses the calculations regarding the roll and ride rates and for the custom springs of specific stiffness used in front and rear shock absorbers and the variation of roll steer and bump steer on changing various parameters of the steering system. Key points also include the procedure of selections of various types of bearings, rod ends, and bolts. This paper also talks about laser-cut jigsaw uprights that are used in the front wheel assembly. The finite element method was used to analyze the designs using DS Solidworks and Ansys Workbench. Static structural and explicit dynamics analysis was performed on the wheel assembly components both individually and assembled

Experimental Study on Bolt‐Spliced Prefabricated Steel Frame Beams

The prefabricated steel structural residence is characterized by modularization and standardization, which meets the requirement of industrial development. The steel frame beam needs to be fabricated in segments and assembled in site due to the limitation of transportation. In practical engineering, the steel frame beams need to be spliced along the beam span. A robust connection between the two steel beam segments is necessary as it will influence the load bearing capacity, stiffness, and stability of the steel frame. In total, 12 specimens were tested to investigate the influence of spliced types, loading patterns, and bolt types on the performance of the steel frame. The observed failure modes, load versus displacement curves, and moment versus rotation angle curves are presented. The test results show that the strength and deformability of bolt‐spliced connections are generally good and similar to those of the prototype beam.

Loading characteristics of mechanical rib bolts determined through testing and numerical modeling

Underground coal mines use mechanical bolts in addition to other types of bolts to control the rib deformation and to stabilize the yielded coal ribs. Limited research has been conducted to understand the performance of the mechanical bolts in coal ribs. Researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted this work to understand the loading characteristics of mechanical bolts (stiffness and capacity) installed in coal ribs at five underground coal mines. Standard pull-out tests were performed in this study to define the loading characteristics of mechanical rib bolts. Different installation torques were applied to the tested bolts based on the strength of the coal seam. A typical tri-linear load-deformation response for mechanical bolts was obtained from these tests. It was found that the anchorage capacity depended mainly on the coal strength. Guidelines for modeling mechanical bolts have been developed using the tri-linear load-deformation response. The outcome of this research provides essential data for rib support design.

Experimental Research on the Shear Performance of the Two-Storey Composite Cold-Formed Thin-Walled Steel Wall

The composite wall made of the cold-formed thin-walled steel has good shear performance. When it is used in buildings, its weak part is located at the joint of floors and becomes the first broken part under the action of the earthquake. The shear test of five Two-storey Composite Cold-formed Thin-walled Steel Walls (TCS) under cyclic loading has been carried out. The influences of axial pressures, types of anti-pulling bolts and panel materials on shear performances are examined. The results show that under the same working condition, the energy dissipation capacity of calcium silicate panel specimens is significantly lager than that of the gypsum panel specimens, and the ultimate bearing capacity is also greater. The axial pressure has a great influence on the ultimate bearing capacity and energy dissipation capacity of the specimens. Compared with the specimens designed according to the Ref. (JGJ227-2011, 2011), the energy dissipation capacity of all specimens is increased by 3.25 times. The extrusion between the self-tapping screw and the wall panel causes the screw to fall off, resulting in a sharp decrease in the rigidity of the specimens at the initial loading stage. After the failure of the wall panel, the bottom and top beam are restricted by double nuts of the anti-pulling bolt at the joint of floors, so the bearing capacity of specimens decreases slowly at the later loading stage. The tilt angle of anti-pulling bolt increases when the TCS wall is loaded to the later stage. The force state of the self-tapping screw on the hold-down is changed from bearing shear force to bearing tension and shear force, resulting in fast failure of the anti-pulling bolt suit. The load borne by the anti-pulling bolt suit is transferred to floor beams and their supporting stiffeners, causing them to collapse rapidly.

Transverse vibrations of tightened bolts: Simplified modeling of tension-dependent boundary stiffness and damping

An axially pre-stressed Bernoulli–Euler beam with end linear springs and dampers is derived to model tightened bolts. The boundary stiffness and damping are analytically expressed as functions of the tensile axial force. The theoretical frequencies and damping ratios resulting from the beam model compare agreeably with the experimental data obtained from two types of bolts. An attempt to explain the apparently linear behavior of the boundary conditions is given, based on a model comprised of coupled mass-spring chains, which is reduced to a one-degree-freedom mass-spring system whose effective restoring force is sought depending on the number of mass-spring systems. The frequency response of the coupled chains and the shape of the restoring force of the reduced system indicates a nearly linear behavior of the coupled chains as the number of chains increases. The results of this work could potentially be used in a vibration based technique to estimate bolt tension from measured vibration.

Performance and mechanism of bolt and slurry bonds in anchor systems for earthen sites

Fully grouted anchor systems have been widely used for stability control at earthen sites. The bond performance between the bolt and the slurry, which is determined from the bolt type, bolt diamete...

A Preclinical Model to Assess Brain Recovery After Acute Stroke in Rats.

The purpose of this study was to establish and validate an animal brain ischemia model in the recovery and sequela stages. A middle cerebral artery occlusion/reperfusion (MCAO/R) model in male Sprague-Dawley rats was chosen. By changing the rat's weight (260-330 g), the thread bolt type (2636/2838/3040/3043) and the brain infarct time (2-3 h), a higher Longa's score, a larger infarct volume and a greater model success ratio were screened using the Longa's score and TTC staining. The optimum model condition (300 g, 3040 thread bolt, 3 h brain infarct time) was acquired and used in a 1-90 day observation period after reperfusion via assessment of sensorimotor functions and infarct volume. At these conditions, the bilateral asymmetry test had a significant difference from 1 to 90 days, and the grid-walking test had a significant difference from 1 to 60 days; both differences could be a suitable sensorimotor functional test. Thus, the most appropriate condition of a novel rat model in the recovery and sequela stages of brain ischemia was found: 300 g rats that underwent MCAO with a 3040 thread bolt for a 3 h brain infarct and then reperfused. The appropriate sensorimotor functional tests were a bilateral asymmetry test and a grid-walking test.

PREVENTION OF METAL BRIDGE SPANS FROM FATIGUE CRACKING

At present, more than four thousand metal bridge spans are in operation all over the Russian railway network. Through the years of operation, about thirty types of fatigue cracking were identified. The dynamics of the types Т-9 and Т-10 cracks formation has increased significantly in recent years. The formation and growth of fatigue cracking is influenced by such factors as residual welding stress, stress-strain state of the bridge structure, defects, damages, and non-observing the operation and maintenance standards, bridge location and bridge span structure. At present, neither measures nor repair are performed to prevent fatigue cracking not exceeding 20 mm in length. Only when a creak reaches a certain length, the regulatory documents require to drill a hole at a crack mouth in order to prevent its further development. The hole diameter should be equal approximately to the doubled wall thickness. In order to prevent further crack growth and cover the hole, a high-tensile bearing type bolt is fixed into it, creating a volume stress. As a rule, such a repair is not enough to stop the cracking process. The article suggests a number of measures based on induction heating that allows to prevent cracking (including forging reducing gaps between connecting plates and horizontal sheets in a truss), to carry out repair (crack mouth soldering) and reinforcement (fixing metal plates onto a wall with a hole).

Experimental Research Examining the Stray Current Corrosion of Rock Bolts in the DC Transit System

Rock bolts are widely used in the main structure of the DC transit system and play the role of the main body reinforcement and support. Because of the extensive stray current in the subway system, the corrosion risk of rock bolts is greatly increased. Therefore, the rock bolt was experimentally studied by simulating the input stray current and monitoring the polarization potential in this paper. After the stray current corrosion (SCC) process was finished, a tensile and breaking experiment of the corroded specimens was conducted for the mechanical properties. As an important parameter to indirectly characterize the corrosion strength of the stray current, the polarization potential was analyzed. Two types of rock bolts were compared for their mechanical properties and corrosion parameters. The result shows that the rock bolt with stranded steel wire as the rod has better corrosion resistance than the HRB500 rebar. Hence, the bonded stranded steel wire is more resistant to the stray current corrosion than the HRB500 rebar, which is adaptive for rock bolts in the direct current (DC) transit system.

Impact of Steel Properties on the Corrosion of Expandable Rock Bolts

The selection of ground support for underground excavations typically focuses on matching a system to the anticipated ground conditions. In this context, the emphasis on materials selection involves picking a rock bolt type that meets a set of predefined capacity and deformation properties to manage the applied loads. Exposure of ground support to corrosive environments in underground hard rock mines can result in significant material degradation and loss of mechanical performance. This can have significant repercussions on the structural integrity of excavations in rock and potential falls of ground that may endanger the safety of workers and equipment. Consequently, there is a need to ensure that the selected rock bolt provides sufficient resistance to corrosion for the working life of the excavation. Current design practice is limited in selecting rock bolt types perceived as more resistant to corrosion, e.g., grouted versus friction rock stabilizer bolts. This investigation suggests, however, that there are significant variations in corrosion susceptibility of rock bolts that may otherwise display similar mechanical behavior. This has significant implications for mines operating in very corrosive environments.

Study of stainless steel bolted extended end-plate joints under seismic loading

Bolted stiffened extended end-plate (BSEP) joint is a commonly used beam-to-column joint in steel frames. In this paper, five full-scale stainless steel BSEP joints were tested under cyclic loading. The tested joints were made of Grade S31608 (EN 1.4401) stainless steel welded I-sections, assembled by four types of bolts, including galvanized high strength bolts of Grades 10.9 and 8.8, and austenitic stainless steel bolts of Grade A4-70 and A4-80. Variations of end-plates of different thicknesses (16 mm and 20 mm) were also considered in the design of the test specimens. Material properties of the plates were tested and the slip-resistant behaviour of the bolts with surface treatments were obtained prior to the joint tests. The test setup, loading protocol and instrumentation employed in the tests are described herein. The obtained test results are reported, including the full moment-rotation curves and the failure modes of the joints. It is observed from the seismic tests that hysteresis curves of all specimens show some sliding and pinching, especially for connections with stainless steel bolts or thin end-plates. The test results were used to validate finite element (FE) models, which can be employed for further numerical investigations. The test results were also employed to assess the stiffness and moment resistance capacity predictions according to the current European design provisions.

Laboratory-Based Investigation into Stress Corrosion Cracking of Cable Bolts.

Cable-bolt failures due to stress corrosion cracking (SCC) could significantly compromise the sustainability and long-term stability of underground constructions. To fully understand the SCC of cable bolts, a two-step methodology was implemented: (i) long-term cable-bolt coupon tests using mineralogical materials collected from underground mines; and (ii) accelerated full-scale cable-bolt tests using an acidified solution. In the long-term tests, a novel three-point bending coupon was designed. The effects of mineralogical materials on SCC were evaluated under the simulated underground bolting conditions through the application of “corrosion cells”. For accelerated tests, SCC resistance of different type of cable bolts was examined using the new designed tensile-loading apparatus under the periodically increasing strain-rate loading mechanism. It was identified that mineralogical materials and applied stress intensity accelerated the corrosion process of the cable bolts. The number of wires and wire surface conditions in different types of cable bolt directly affected SCC susceptibility. The cable bolts with a greater number of wires provided higher resistance to SCC. The developed experimental methodologies can be applied to study SCC in other reinforcement materials and the results can be used to design optimal support systems in different environmental and geotechnical conditions.

DESIGN OF BOLTED CONNECTIONS SUBJECT TO TORSION AND SHEAR IN THE ULTIMATE LIMIT STRESS STATE

Steel connections transferring axial and shear forces in addition to bending moment and/or torsional moment are widely used in steel structures. Thus, design of such eccentric connections has become the focal point of any researches. Nonetheless, behavior of eccentric connections subjected to shear forces and torsion in the ultimate limit state is still ambiguous. Most design codes of practice still conservatively use the common elastic analysis for design of the said connections even in the ultimate limit states. Yet, there are some exceptions such as the design method proposed by CAN/CSA-S16-14 which gives tabulated design aid for the ultimate limit state design of these connections based on an empirical equation that is derived for ¾ inch diameter A325 bearing type bolts and A36 steel plates. It was argued that results can also be used with a margin of error for other grade bolts of different sizes and steel of other grades. As such, in this paper, the performance of bolted connection subject to shear and torsion is experimentally investigated. The behavior, failure modes and factors affecting both are scrutinized. Twelve connections subject to shear and torsion with different bolts configurations and diameters are experimentally tested to failure. The accuracy of the currently available design equations proposed is compared to the outcomes of these tests.

EXPERIMENTAL STUDY OF LAMINATION COLUMN WITH SEVERAL TYPES OF WOOD USING ADHESIVE NAILS AND BOLT

The use of light wood combined with heavy wood can improve the quality of the combinationwood. Apart from being used as laminated beams, a combination of light wood and heavy wood can also be used as a laminated column given compressive loads. Based on SNI 7973-2013, the adhesive that was permitted on built up columns or laminated columns can be in the form of bolts and nails, so this study has also used adhesive nails and bolts. This study purpose to determine the compressive capacity of the laminated column which combines several types of wood. The specimens made were four variations of the laminate column. Furthermore, three layers of wood have been used on one laminated column with heavy wood types on the outermost layer. The results showed that all variations of the laminated column had a higher compressive capacity than the solid column. Keywords: compressive capacity, lamination column, light and heavy wood