Types Of Fasteners Research Articles

Research on Material Selection Construction Method Construction Technology with the High-Support Formwork Construction of NingBo Cultrural Plaza Grand

The project of NingBo Cultural Plaza Grand Theare adopts the fastener type high modulus construction technology. This engineering safety conditions high, difficult construction. Combining NingBo Cultural Plaza Grand Theare, The paper discussed the High-support formwork construction, including material selection construction method construction technology etc.

Hysteretic characterization of cold-formed steel stud-to-sheathing connections

The series of experiments reported here aims to characterize the hysteretic behavior of the connection between cold-formed steel (CFS) studs and sheathing when subject to in-plane lateral demands. This connection provides the key energy dissipating behavior in wood sheathed CFS shear walls, and provides bracing to the studs under gravity and out-of-plane loads. A testing rig is developed consisting of two CFS lipped channels facing toe-to-toe connected on the flanges by sheathing (oriented strand board, or gypsum board) and cycled such that the eight connecting fasteners experience shear. Sheathing configuration, fastener spacing, steel thickness, and fastener type are varied to determine connection performance. The dominant role of sheathing type and stud thickness is highlighted in the results. The hysteretic behavior of the experimental results is summarized for further use in the analysis of shear walls and under gravity and lateral load. The work serves as a supplement to North American efforts to advance seismic performance-based design of CFS structures and is part of a larger effort to better understand CFS lateral force resisting systems.

Rail Component Detection, Optimization, and Assessment for Automatic Rail Track Inspection

In this paper, we present a real-time automatic vision-based rail inspection system, which performs inspections at 16 km/h with a frame rate of 20 fps. The system robustly detects important rail components such as ties, tie plates, and anchors, with high accuracy and efficiency. To achieve this goal, we first develop a set of image and video analytics and then propose a novel global optimization framework to combine evidence from multiple cameras, Global Positioning System, and distance measurement instrument to further improve the detection performance. Moreover, as the anchor is an important type of rail fastener, we have thus advanced the effort to detect anchor exceptions, which includes assessing the anchor conditions at the tie level and identifying anchor pattern exceptions at the compliance level. Quantitative analysis performed on a large video data set captured with different track and lighting conditions, as well as on a real-time field test, has demonstrated very encouraging performance on both rail component detection and anchor exception detection. Specifically, an average of 94.67% precision and 93% recall rate has been achieved for detecting all three rail components, and a 100% detection rate is achieved for compliance-level anchor exception with three false positives per hour. To our best knowledge, our system is the first to address and solve both component and exception detection problems in this rail inspection area.

Automatic Fastener Classification and Defect Detection in Vision-Based Railway Inspection Systems

The detection of fastener defects is an important task in railway inspection systems, and it is frequently performed to ensure the safety of train traffic. Traditional inspection is usually operated by trained workers who walk along railway lines to search for potential risks. However, the manual inspection is very slow, costly, and dangerous. This paper proposes an automatic visual inspection system for detecting partially worn and completely missing fasteners using probabilistic topic model. Specifically, our method is able to simultaneously model diverse types of fasteners with different orientations and illumination conditions using unlabeled data. To assess the damages, the test fasteners are compared with the trained models and automatically ranked into three levels based on the likelihood probability. The experimental results demonstrate the effectiveness of this method.

Researching Technical Prevention Measures for Development and Design Utilizing Highly-Accuarate CAE Analysis: Automotive Nut-Loosening Mechanism

In recent years, the authors have been conducting research on the establishment of technical prevention measures for development and design utilizing highly-accurate CAE analysis. This research investigates the mechanisms that cause nut loosening, which is a matter of concern for automobile manufacturers around the world. Specifically, actual machine tests were conducted using three types of bolt and nut fasteners with

Analysis of Slotted Counter Sunk (35NCD16 Steel) Aerospace Fasteners

Fasteners form the integrating elements of any aerospace hardware and provide the required mechanical integrity. Various types of fasteners including screws, rivets, bolts, pins, blind rivets, blind bolts, anchor nuts, solid inserts, collars etc. are used in aerospace application. Aerospace fasteners needs to be more durable, lighter and shall withstand high loads, vibrations and hostile environments such as deep space etc. In order to achieve this, aerospace fasteners are processed through specialized forging, heat treatment and thread rolling. Finite element analysis is done simulating the tensile testing of slotted counter sunk head screws and experiments are also conducted to verify the analysis results. A comparison is made on the stress distribution contours of slotted 120 degree countersunk head screw and slotted 90 degree countersunk head screw.

Damage Assessment of Connections Used in Cross-Laminated Timber Subject to Cyclic Loads

AbstractCross-laminated timber (CLT) products are gaining popularity in the North American market and are being used in midrise wood buildings, in particular, in shearwall applications. Shearwalls provide resistance to lateral loads such as wind and earthquake loads, and therefore it is important to gain a better understanding of the behavior of CLT shearwall systems during earthquake events. This paper is focused on the seismic performance of connections between CLT shearwall panels and the foundation. CLT panels are very stiff and energy dissipation is accomplished by the connections. A literature review on previous research work related to damage prediction and assessment for wood frame structures was performed. Furthermore, a test program was conducted to investigate the performance of CLT connections subjected to simulated earthquake loads. Two different brackets in combination with five types of fasteners were tested under monotonic and cyclic loading protocols. In total, 98 connection tests were co...

Investigation on the Self-Tapping Screws Capability to Induce Internal Stress in Timber Elements

In refurbishment operation of existing timber floors could prove of some interest the possibility of hogging the existing timber beams, in case of the presence of excessive permanent midspan deflections. In the case of sagged timber floors which cannot be buttressed due to heritage issues, the possibility of cambering a timber beam by simply putting another wooden beam on the top of it and inserting screws inclined at 45° relative to the beam axis has been experimentally investigated, with some promising result. The cambering procedure has proved to be more effective when the fastener are inserting starting from the internal part of the beam, permitting to obtain significant values of upward deflection (it has been observed an upward deflection of about one three-hundredth of the total beam length): the values could possibly be increased by reducing the screw spacing or by using fasteners able to generate a greater pressure. The effectiveness of this method is based on the capability of self-tapping screws to induce internal stress in timber element during the drilling procedure: the horizontal component of the resultant pressure yielded by the inclined screws is directly related to the possibility to hog the composite system. The aim of the experimental campaign described in this paper was to investigate the values of the internal stress induced by different type of fasteners during the drilling procedure, studying the influence of different parameters such as screw angle with respect to the grain direction, initial pressure, head penetration length, threaded part length, connector typology, wood density, time-dependence.

The methods of assessing the load-bearing properties of the elements of wing mechanization honeycomb structure with consideration of exploitation

To restore the load-bearing properties of heavy transport aircraft cellular structure spoiler, finite-element model spoiler repair scheme was developed and performed. The result of structures deformation, analysis and comparison with other types of spoiler structure, including the original cellular structure The analysis showed that the tension and movement that occur in structure when calculating the strength does not exceed the specified requirements of strength and rigidity. Developed spoilers repair scheme does not leaded to significant weight gain. The design of repair is chosen for reasons of: • economic profitability; • ease of production; • possible changes of technical parameters and use of other type fasteners. The discussion of layered composites with cellular honeycomb core usage in aircraft structure designs is included in the paper, together with the brief description of published domestic and foreign literature monographs treating about the subject

강화플라스틱 연결구를 이용한 데크의 내력 성능평가

Existing wood decks brings out negligent accident because fastener can be pulled-out by cyclic load of pedestrians. When deck and joist are connected, it also causes the problems, which are cracking of wood decks and rapid decay by material of fastener. In this study, strength property of deck unit using reinforced plastic connector made by domestic A company was evaluated. Southern yellow pine (Pinus palustris Miller) were used for deck material. Bending strength of deck units were implemented for fastener type and joist spacing (400, 600 mm). In the result, carbon steel screw into reinforced plastic connector was the best in average bending strength(Joist spacing : 400, 600 mm). In the result of bending strength for joist-width (40, 50, 70, 80 mm), the average maximum bending strength was measured when the joist spacing was 40 mm.

Characterization of Mechanically Enhanced FRP Bonding System

Despite extensive research on externally bonded fiber-reinforced polymer (EB-FRP) for rehabilitation of concrete structures in the past two decades, the industry has been slow to embrace the technology owing to some difficult problems that are yet to be resolved fully. Among these, premature debonding is one of the critical problems. Since the tensile strength of concrete is inherently low and unreliable (in the long term), EB-FRP by surface adhesion might not be the final solution; augmentation of the interfacial bond by mechanical fastening may be unavoidable. To this end, the first author proposed a bond augmentation system, hybrid-bonded FRP (HB-FRP), where a special type of mechanical fasteners are used to enhance the interfacial bond. Although the HB-FRP system has been experimentally shown to increase bond strength several fold, effectively overcoming the debonding problem, there has been no systematic theoretical study of the system. In this paper, HB-FRP joints are characterized through experimental testing and analytical modeling, leading to a theory for design and construction of the HB-FRP system.

Withdrawal Capacity of Plain, Annular Shank, and Helical Shank Nail Fasteners in Spruce-Pine-Fir Lumber

Abstract This study examines the withdrawal load and energy capacity of three types of nail fasteners that are commonly used to attach sheathing to framing members: 8d common, annular ring shank, and helical shank. A baseline set of data was collected for single nails in accordance with test methods defined in ASTM D1761. Tests were performed until complete withdrawal occurred in order to quantify the total withdrawal energy. The average peak loads from testing were within 7 to 8 percent of predicted values. The annular and helical nails had much higher peak load capacity as expected, and the withdrawal energy was also greater. A new device was developed in order to subject multiple nails to withdrawal loading simultaneously. Reinforced sheathing was used to transfer load from the hydraulic actuator to the nails, which is more representative of actual structural response where there is load sharing among the nails. This device allowed direct comparison with the single nail results. Further, it also allowed the examination of a “stitched” nailing pattern, where fasteners are driven at alternating angles of ±60° measured from the framing member face. It was found that the stitched pattern resulted in 42 percent higher peak load capacity per fastener for 8d common nails, but for the helical and annular nails, peak load was similar to that achieved with a normal 90° drive angle. Withdrawal energy was 24 to 48 percent higher for all nail types using the stitched pattern.

In-Plane Monotonic and Cyclic Racking Load Testing of Structural Insulated Panels

AbstractStructural insulated panel (SIP) wall systems have been used in residential and light commercial buildings for the past 60 years. Lack of sufficient published research results on racking load performance and understanding of the influence of fastener types on seismic response has been a deterrent in the widespread use of the wall system in seismically active areas. This paper summarizes the results of a full-scale racking load testing study in which a total of 17 2.4×2.4-m (8×8-ft) SIP wall panels were tested under monotonic and cyclic loading. Four 114-mm (4.5-in.) thick SIP specimens were tested under monotonic loading, while 13 114-mm (4.5-in.) thick SIP specimens were tested under the Consortium of Universities for Research in Earthquake Engineering loading protocol. Parameters such as fastener type, spline design, hold-down anchor location, and sheathing bearing were adjusted throughout the testing to determine their effects on the SIP’s performance. Performance parameters such as peak load a...

Dynamic Property Analysis of Rubber Absorber in Rail Fastenings of Different Force Condition

This paper studies the dynamic property of rubber absorber in rail fastening by electro-hydraulic testing machine. Two different types of rail fastening are tested. In one fastening the rubber component is in compressed condition (RCRF). While in another the rubber is in sheared (RSRF). A nonlinear dynamic model of rubber absorber in rail fastening is proposed. The model parameters are obtained by the least square method. The accuracy of the obtained model is verified by measured result. The two results are in good agreement. The dynamic stiffness and damping are analyzed, and the results show that dynamic stiffness and damping are closely related to the frequency and amplitude of excitation. Nonlinear characteristic becomes greater with increasing excitation amplitude for the both rail fastenings. For different excitation frequency, the vibration reduction effect of RSRF is more stable than that of RCRF.

Behavior of dowelled and bolted steel-to-timber connections exposed to fire

This study focuses on the load distributions among fasteners in steel-to-timber connections loaded in tension parallel-to-grain under fire exposure. The experimental results of some types of connections with various geometrical configurations are available. The influence of the type of fasteners (bolt, dowel) on the thermo-mechanical behavior of the connections is studied. A three-dimensional finite element model validated on the basis of experimental results is used. Good agreements were observed between the simulated and the experimental values of temperatures and failure times. The type of metal fasteners is crucial to the thermo-mechanical behavior of connections. In the studied connections, one bolt is used in each row of fasteners to prevent the separation between the assembled members. The presence of the bolts greatly influences the behavior of the connections mainly under fire. Various geometrical configurations of connections with only dowels or changing the positions of the bolts are studied. An analytical approach is proposed, from a specific type of connections, by varying some influent geometrical characteristics. A numerical experimental design is realized from the calculated time to failure of the connections.

Consideration of plasticity within the design of timber structures due to connection ductility

The plastic behavior of fasteners in timber structures has gained more and more interest within recent years. In particular, dowel type fasteners show a significant ductile behavior if a certain embedded length of the dowel is ensured. The embedded length is either found by using the formulas based on the design codes (DIN (2008) [3], DIN EN 1995-1-1 [4], etc.) or by verifying the slenderness ratio λ (Jorissen (1998) [5] and Mischler et al. (2000) [32]). A further important issue is the prevention of splitting of the timber itself. Full threaded self-drilling screws enable an effective method to prevent the connection of such a failure (Bejtka (2005) [10]). Most of the inherent material properties of timber, except the behavior in compression, do not allow a plastic design in pure timber structures. Connections accomplished with dowel type fasteners however enable to bridge that gap. The ability of forming plastic hinges by ductile joints within statically undetermined systems provides substantial advantages for a structure. First and foremost, the capability to dissipate energy provides some benefits, such as the integration to the earthquake analysis and in addition to increase the robustness of the structure. A load redistribution within statically undetermined systems can also be achieved, and thereby the possibility of a higher utilization of the structural system. Within this paper, the possibility to redistribute internal forces in timber structures is shown and some application criteria to form plastic hinges are given. Since timber is an inhomogeneous material and is characterized by the scattering of the material properties, the influence of the scattering of the modulus of elasticity to the required rotation of the joint is presented. In order to implement the ductility to timber structures, it is necessary to appraise the ductility as an interaction of the different types of fasteners within timber. Based on conducted experiments the evaluation of the displacement at the point of yielding with respect to existing appraisal models is discussed. Furthermore, different existing methods to evaluate the point of yielding and the ductile behavior of fasteners in timber structures are discussed.

Experimental Study on Composites with Single-Lap Countersunk Head Bolt Joints

An investigation was performed to study the response of laminated composites with bolt joints. The configuration was single-lap single countersunk head bolt. The major focus was to characterize bearing behavior of laminates and the effect of some parameters such as lap types, fastener types, hole diameter, and stiffness of lapped plate on the bearing strength and stiffness. For this purpose, hundreds of specimens were tested to obtain ultimate loads and stiffness of joints. According to different configurations of joints, three contrast tests were carried out, and some useful conclusions were drawn. Firstly, comparing the stiffness, the joints with protruding head bolts are slightly stiffer than those with countersunk head bolts. And bearing strength of the joints with protruding head bolts are about 10% higher than those with countersunk head bolts. Secondly, ultimate load and stiffness of single-lap double bolts are similar to double-lap single bolt, which are twice bigger than single-lap single bolt. Thirdly, the stiffness of joints can be improved by using bigger hole diameter or stiffer lapped plates. When the hole diameter and stiffer lapped plates are in a reasonable range, bearing strength increase. However, larger stiffness of joint structure may cause transient breaking, which is dangerous for the structure. So in engineering, it is needed to balance the bearing strength and stiffness of joints.

Identification of the type of fastening of a triangular membrane from its first natural frequency

A membrane shaped as an isosceles right triangle with each of its sides satisfying either Neumann or Dirichlet boundary conditions is considered. The solution to the corresponding spectral problem, which allows no separation of variables, is refined. The refinement is used to solve the problem of identifying the type of fastening of the triangular membrane from its first natural frequency.

Long-term load–deformation behaviour of timber–concrete joints

This paper discusses the long-term mechanical behaviour of timber-to-concrete joints made with dowel-type fasteners. Despite the influence that the long-term behaviour of joints has on the mechanical behaviour of a timber–concrete structure and consequently on its design, there is still a lack of research in this area. This paper presents experimental research, carried out at the University of Coimbra and Delft University of Technology, on seven joint configurations using different types of fasteners and different materials. For each joint configuration, either four or ten tests were performed resulting in a total of forty tests. A comprehensive description of the test specimens and test setup is given. The experimental creep–time curves were fitted to a creep–time model and used to predict joint creep values over longer timeframes (10 and 50 years). The values obtained were compared with values available in the literature for timber-to-concrete joints with other types of fasteners and timber-to-timber joints with dowel-type fasteners. The approach for timber-to-timber joints suggested by Eurocode 5 was used to determine creep values for timber-to-concrete joints. The results obtained were compared with test results to assess the accuracy of predicting creep values of timber-to-concrete joints with dowel-type fasteners. It was concluded that creep values measured in long-term experimental tests are usually higher than those obtained from the model indicated in Eurocode 5, particularly for environmental conditions corresponding the service class 2.

Experimental Study and Numerical Simulation on Bonding Behavior of the New HB-FRP Strengthening Technology

AbstractTo find an alternative way of improving bonding and restricting sliding displacement, a new technique that combines fiber-reinforced polymer (FRP) surface adhesion [externally bonded FRP (EB-FRP)] with a new type of mechanical fastening, namely hybrid bonding (HB-FRP), is developed. The beam specimens are investigated and compared in a new modified beam-shear program to examine the bonding behavior of HB-FRP and EB-FRP. The finite element analysis is conducted to simulate the interfacial shear on the basis of different bolt pretension force by Pretension 179 element and compact pairs of ANSYS software. Also the anchoring parameters of the hybrid bonding of FRP are studied by a drawing test program to study the anchor depth of screw bolts and by the finite element analysis to simulate the contact compression stress on the basis of different sizes of capping plate and bolt pretension for the selection of the capping plates and bolts. On the basis of experiments and the finite element analysis, the f...