Types Of Bolts Research Articles

Bolted Shear Connectors Performance in Self-Compacting Concrete Integrated with Cold-Formed Steel Section

In conventional composite construction involving hot-rolled steel section, the composite action is usually achieved by using conventional headed shear studs connectors. However, use of headed studs is not practical for cold-formed steel (CFS) section due to its very thin form that is difficult to weld. A suitable bolt and nut type shear connector was proposed; experimental tests were carried out to evaluate its performance. This study also investigated the use of Self-Compacting Concrete (SCC) integrated with CFS by means of bolted shear connectors to develop composite action. Therefore, the objective of this paper was to investigate the performance of bolted shear connectors in SCC integrated with CFS section as composite beam system. Eighteen push-out test specimens comprising of M12, M14 and M16 sized bolted shear connector of grade 8.8 with longitudinal spacings of 150 mm, 250 mm and 300 mm centers were fabricated, cast and tested until failure. The experimental results showed that all bolted shear connectors possessed a good shear resistance capacity. Not much difference in strength capacity of specimens with M14 and M16 bolted shear connectors was found, perhaps due to CFS failure. Varying the size and longitudinal spacing of the bolted shear connectors revealed that the connectors' strength capacity changed slightly between M14 and M16 bolts specimens but, significantly for M12 bolt specimens.

고단속 기어의 가공 시 진원도 향상을 위한 지그척 개발

Recently, the requirements for high precision and efficiency machining are gradually increased to raise international competitiveness at the industrial fields of automotive and gears. This trend had made effects on the industrial fields in Korea and which needs further studying of high accuracy and efficiency machining. This study is to investigate the effects of Jig type chuck for roundness improvement in CNC turning machining of high stage speed gear. After hobbing machining, Dimensional change before and after heat treatment was very largely generated. In order to solve this problem was to develop a jig type chuck. After the heat treatment, the operation of the chuck which was the most distinguished equipment among Jig type chuck(0.006mm), Scroll type chuck(0.05mm) and Bolt type chuck(0.04mm). Therefore, Jig type chuck was satisfied the requirement from the actual field(0.02mm).

Flexural behaviour of composite steel–concrete beams utilising blind bolt shear connectors

This paper investigates the feasibility of utilising blind bolts as shear connectors to develop demountable steel–concrete beams. The flexural behaviour of composite beams with two blind bolt types and welded stud connectors were experimentally investigated using full-scale beam specimens. A set of push-test specimens was tested based on the Eurocode 4 to compare the slip response of these connectors. The ultimate design loads of the test beams were calculated based on rigid plastic analysis (RPA) using the actual material properties. The beam experiments were simulated by using three-dimensional non-linear finite element models (FEMs). The material behaviour for concrete and steel in FEMs was described using concrete damage plasticity and steel plasticity models respectively. The FEMs were validated by comparing the load–midspan deflection curves of the beam specimens obtained from the experiments and modelling. The effects of the concrete compressive strength, steel yield strength and the shear connection ratio on the flexural behaviour of the composite beams were studied by utilising the validated FEMs. The experimental and numerical results suggest that the ability of the blind bolts to achieve and maintain composite action in steel–concrete beams under flexural loading is comparable to that of the welded stud connectors.

Improved probabilistic neural network PNN and its application to defect recognition in rock bolts

The probabilistic neural network (PNN) model is developed based on Bayesian criteria of multivariate pattern classification. Because PNN has the advantages of low training complexity, high stability, quick convergence, and simple construction, it can be well applied in the area of defect recognition. The application of PNN has a bottleneck problem; that is, the selection of smoothing parameters will seriously affect PNN recognition accuracy. In this paper, we propose an improved PNN model that employs a differential evolution algorithm to optimize the smoothing parameters. Furthermore, a defect recognition approach is proposed based on the improved PNN, which is successfully applied to an anchoring testing field. The proposed approach includes two key steps. The first step involves extracting the energy eigenvector of the defect signal with normalization based on a wavelet packet. The second step involves recognizing defects based on the improved PNN. Simulation results show that our improved PNN model is superior to the traditional PNN model. Thus, the improved PNN can provide useful references for recognizing the defect type of rock bolts in engineering.

Bond evaluation of steel bolts for concrete subjected to impact loading

The presented study deals with steel bolts for concrete subjected to impact loading. Impact loading induced by the Schmidt hammer was used to assess the quality of bond between the anchor bolt and the surrounding concrete. The effect of impact loading on the load-carrying capacity of 8, 10 and 12 mm diameter bolts with a constant embedment length and concrete strength was studied. Concrete quality, anchor alignment, diameter and water ingress were also taken into consideration. An analytical model is presented which takes into account the interfacial bonding between the bolt and surrounding concrete matrix, bolt geometric shape, diameter, alignment and embedment length. The comparisons between theoretical and experimental results revealed that the analytical model was capable to predict the maximum load carrying capacity and pull-out mechanism of the anchor bolts. From the presented results and discussion, it was found that the bond performance of the bolts and hidden defects can be identified by imparting impact energy. The proposed model can be used by engineers and researchers to judge the quality of the bond between bolt and surrounding concrete and for predicting their peak load carrying capacity and displacement of various types of anchor bolts.

Study of Fully Grouted Rock Bolt in Tabas Coal Mine Using Numerical and Instrumentation Methods

Understanding the interaction between rock bolts and underground rock movement is critical for safe and cost-effective underground excavation design. Although early research on this subject involved a balance of theoretical analysis and field measurement, the current work focused on analytical and numerical studies. The present study aimed to study fully grouted rock bolt in Tabas Coal Mine using numerical and instrumentation methods. Tabas Coal Mine is the first fully mechanized coal mine in Iran, producing 1.5 million tons of coal per year. The mine extracts coal by both longwall and room and pillar methods. The roadways have a rectangular profile of 4.5 m width and 3.5 m height. The field investigations and geotechnical characteristics of rocks showed that the rock masses are weak, requiring a suitable support system. The roadway is intersected by a major fault zone. For the designed roadway, four patterns (two types of bolt with transfer load capacity of 180 and 195 kN) were considered. FLAC analysis showed that 13 bolt 2.4 m with 2 NO flexi bolt 4-m patterns were better than other patterns within the faulted zone. Assessing the optimum pattern through instrumentation, there was compromise between the results of numerical modeling with instrumentation reading such as telltales, sonic extensometer, and strain gauge rock bolt. Thus, there was an inspiring agreement between numerical and field methods.

The influence of variation in host tree monoterpene composition on secondary attraction by an invasive bark beetle: Implications for range expansion and potential host shift by the mountain pine beetle

The range of mountain pine beetle (Dendroctonus ponderosae) has expanded in recent years to include many evolutionarily naïve forests in western Canada. These forests include novel populations of the principal host species, lodgepole pine (Pinus contorta), the novel species jack pine (Pinus banksiana), and their hybrids (P. contorta×P. banksiana). These novel forests are chemically and physically different than native forests, and recent studies have shown beetle reproductive performance is enhanced in these novel habitats. We conducted a field experiment to determine the effect of differing host chemistry, specifically α-pinene content, on secondary attraction by foraging mountain pine beetles. Alpha-pinene is the precursor molecule for the production of trans-verbenol, the main aggregation pheromone for this beetle species. We found that elevated relative concentrations of α-pinene in bolts significantly increased their attractiveness to in situ mountain pine beetles. Seventy-five percent of attacks were found on infested bolts with the most α-pinene relative to other monoterpenes. Other measures of terpene chemistry between bolt types could not explain the pattern of attacks. This result suggests that elevated concentrations of α-pinene could increase the rate of aggregation and attack success by the mountain pine beetle in novel pine forests. Newly invaded hybrid and jack pine in the western boreal forest are reported to contain 3–4 times the relative concentration of α-pinene than lodgepole pines in forests in which the beetle has coevolved. These elevated concentrations may help the mountain pine beetle overcome some of the potential restraints for establishment and spread in the boreal forest, such as low pine volume and connectivity, and continue expanding its range.

정하중 재하 시 실물 강성벽 일체형 철도보강노반의 성능평가

강성벽 일체형 철도보강노반의 열차하중 하에서의 성능을 평가하기 위하여 실물 단선 철도 노반과 동일한 규모인 높이*폭*길이(5m*6m*20m)의 보강노반을 건설하였다. 철도보강노반은 높이의 30~40%의 짧은 보강재와 강성벽체, 보강재 연직배치간격 30와 40cm를 적용한 특징이 있다. 경제성 및 시공성 향상을 위하여 강성벽체와 보강토체와의 일체화 연결방식을 3종류(용접형, 힌지볼트형, 굵은 철사형)로 다르게 설계하였다. 철도 설계하중 50kPa의 19.6배에 해당되는 0.98MPa (최대시험하중 5.88MN) 최대하중에 대하여 2회 정하중 재하시험을 실시하였다. 철도보강노반의 성능은 파괴에 대한 안정성, 지지력과 침하, 벽체 발생 수평변위, 보강재 발생 변형률에 대한 검토로부터 평가하였다. 실물 실대형 시험결과로부터 높이의 35% 수준의 짧은 보강재와 힌지 볼트형 연결방식을 채택한 강성벽체 일체형 철도보강노반에서 40cm의 보강재 연직간격을 적용하여도 열차 설계하중 하에서 좋은 성능을 보이는 것을 확인할 수 있었다. The Reinforced subgrade for railroad (RSR) was constructed for one way railway line with the dimension of 5 m high, 6 m wide and 20 m long to evaluate its performance under train design load. The RSR has characteristics of short length (0.3-0.4 H) of reinforcement and rigid wall, 30 and 40 cm vertical spacing of reinforcement installation. To enhance economics and constructability, three kinds of connections (welding, hinge & bolt, bold wire) were also designed to realize the integration between rigid wall and reinforced subgrade. Two times of static loading tests were done on the full size railroad subgrade. The maximum applied pressure was 0.98 MPa (the maximum test load 5.88 MN), which corresponds to 19.6 times of the design load for railroad subgrade, 50 kPa. The performance on the RSR was evaluated with the safety on the failure, subgrade bearing capacity and settlement, horizontal displacement of wall, and reinforcement strain. Based on the full scale test, we confirmed that the RSR with the conditions of 0.35 H (35% of height) short reinforcement length, hinge & bolt type connection for integration between rigid wall and reinforced subgrade, and 40cm vertical spacing of reinforcement installment shows good performance under train design load.

Optimization of the fully grouted rock bolts for load transfer enhancement

The purpose of this study is to investigate the role of bolt profile configuration in load transfer capacity between the bolt and grout. Therefore, five types of rock bolts are used with different profiles. The rock bolts are modeled by ANSYS software. Models show that profile rock bolt T3 and T4 with load capacity 180 and 195kN in the jointed rocks, are the optimum profiles. Finally, the performances of the selected profiles are examined in Tabas Coal Mine by FLAC software. There is good subscription between the results of numerical modeling and instrumentation reading such as tells tale, sonic extensometer and strain gauge rock bolt. According to the finding of this study, the proposed pattern of rock bolts, on 7+6 patterns per meter with 2 flexi bolt (4m) for support gate road.

Finite element modelling of blind bolted composite joints

This paper aims to develop a detailed three-dimensional finite element model to study the behaviour of blind bolted endplate composite joints that connect composite beams to a concrete filled steel tubular column. All connection components such as steel beam, profiled sheeting, shear stud, endplate, blind bolt, concrete infill, concrete slab, hollow steel column and reinforcing bars were separately modelled using shell, solid and truss elements. The obtained predictions of the moment–rotation curve and failure mode were compared with experimental results and a very good agreement was established. In addition, an analytical model for predicting the moment–rotation response of composite joints up to failure was also presented based on the component method. Finally, extensive parametric studies were carried out to investigate the influences of shear studs and reinforcement ratio, blind bolt types and diameters, column sections and thickness ratios on the joint performance.

Time-dependent behaviour of composite beams with blind bolts under sustained loads

The use of blind bolts in steel–concrete composite beams is beneficial for promoting sustainable design and for retrofitting existing steel structures. This paper presents an experimental study as well as finite element (FE) modelling analyses for the time-dependent behaviour of composite beams with blind bolts subjected to sustained loads. Four full-scale simply supported beams utilising different types of bolts and studs were tested under long-term static loads. The mid-span deflections were monitored for a period of over 260days. Short-term push-out tests were also carried out on the connectors used in the composite beams, and their slip deformation was recorded for determining the initial stiffness. The experimental results were modelled by using a three-dimensional FE model, in which the creep of the concrete was simulated through defining a viscoelastic response and the shrinkage of concrete was incorporated by means of notional thermal expansion. The FE model was validated against the experimental results reported herein and other independent results of composite beams using conventional welded studs reported elsewhere, and it was subsequently applied to carry out parametric studies. An extensive body of parameters was considered to clarify their effects on the time-dependent behaviour of composite beams with blind bolts, including the mechanical properties and configuration details of shear connectors, the concrete strength, the loading conditions, the span-to-depth ratio and the reinforcement ratio. It was demonstrated that the time-dependent behaviour was sensitive to the stiffness and the bolt-to-hole clearance of connectors, and some other parameters also possessed effects with different degrees. The research findings implied that using blind bolts in composite beams was beneficial to the time-dependent response due to their relatively lower deflections resulting from the creep and shrinkage of the concrete over time. The outcome may provide an important basis and guidance for designing such composite beams when considering their long-term response with time effects.

Cyclic Testing for Structural Detail Improvement of CFT Column-Foundation Connections

In this study, concrete-filled tube (CFT) column-to-foundation connections were investigated experimentally to improve the design of their structural details. Initially, five different types of foundation connections, which were classified according to the design parameters incorporating the types of anchor bolts, shear connectors, base members, and reinforced bars used, were fabricated. After conducting structural experiments on these foundation models, the performance and capacity of the individual model cases from the test results were compared with each other. The test results showed that some of the test models designed according to current design guidelines had problems related to the structural details. Therefore, this study proposed an adequate design methodology to improve the performance of foundation components, such as high tension bolt, base frame members, and embedded plate. An analytical investigation of the force-deformation relationship as well as the characteristic strains distributed over the individual foundation components was performed.

Tensile behaviour of anchored blind bolts in concrete filled square hollow sections

In this paper, the tensile behaviour of a new type of blind bolt, the anchored blind bolt, has been studied. This type of bolt consists of a conventional blind bolt with a headed stud extension that anchors it into the infill concrete. It has been developed for use in moment-resisting connections between I-beams and concrete-filled hollow section columns. The behaviour of these connections is highly dependent on the tensile behaviour of the anchored blind bolts. Hence, the fundamental mechanics of this behaviour has been studied here, both experimentally and in simulations using FE models. The complex interactions between the headed stud anchorage, the concrete infill, and the steel tube have been examined in detail. The experimental and numerical findings were used to understand the influence of important parameters in the tensile behaviour of the anchored blind bolts. It was found that the location of the bolt with respect to the side walls of the tube had a substantial influence on the behaviour of the anchored blind bolts. All the bolts located close to the side walls of the square hollow sections reached the ultimate tensile capacity of the equivalent structural bolts. This was due to the development of a concrete strut which transferred the load to the corner of the steel section. The bolt diameter also had a significant influence on the stiffness and strength of the anchored blind bolts.

Improvement of rock bolt profiles using numerical method

Current developments in numerical modelling techniques are presented to investigate the load transfer between the steel bolt surface and grout. Underground measurements of steel bolt performance indicate that amongst many parameters bolt profile configuration play an important role in load transfer capacity between the bolt and grout. This study proposes a new numerical solution to predict displacement, shear stress and shear strain of a fully grouted rock bolt intersected by single rock joint. The main characteristics of the numerical solution, consider the bolt profile and joint movement under pull test condition. In this paper, five types of rock bolts are used with different profiles. The rock bolts are modelled by ANSYS software. Profile rock bolt T3 and T4 with load capacity 180 kN and 195 kN in the jointed rocks, were choices as the optimum profiles. The results showed that there is a promising agreement between numerical and experimental methods.

Analysis of Yielding Steel Arch Support with Rock Bolts in Mine Roadways Stability Aspect

Abstract The result of the search for new technological solutions in the field of support for roadways in coal mines has in recent years been the widespread use of steel arch with rockbolt support systems. The efficiency of these systems is affected among other things by the option of installing rock bolts after the actual driving the mine roadway, the increased load capacity that these systems can support, and their resistance to dynamic weight. Large variation in the way that these steel arch support can be connected using different types of rock bolts necessitates mining research revealing the effectiveness of such solutions. Although the steel arch with rockbolt support system is used in the majority of European coal mines, it is still not possible to apply templates of schemes due to the diversity of geological and mining conditions. Therefore, throughout a period of several years, the authors of this article conducted research in situ under conditions of different schemes related to connecting arched support frames with rock bolts, with only selected results being presented in the article. The measurements of convergence, load supported by the system frame, load supported by the rock bolts, and the stratification of roof rocks were analyzed, carried out in two roadways with yielding steel arch support in which strand bolts were applied. The article also proposes the index for working maintenance nuw, used in preliminarily assessing the stability of a given working with a limited number of data concerning geomechanical conditions. Additionally considered are empirical methods used in Poland for designing steel arch with rock bolt support systems. The results of mine research indicate that strengthening yielding steel support with strand bolts through steel beams maintains the stability of a roadway, even when exposed to the exploitation stress. Aside from the impact of exploitation, deformations of the support system are negligible, despite the fact that the tensile forces acting on the rock bolts can reach values of up to 160 kN. Under favorable geological and mining conditions, support system frames can be spread up to 1.5 m apart when using rock bolts between them. The conducted measurement of convergence during a three year period revealed a compression amounting to a few centimeters. The results obtained by the research fully confirm the effectiveness of combined yielding steel arch with rock bolt support systems under different mining conditions.

Performance of fully encapsulated rebar bolts and D-Bolts under combined pull-and-shear loading

The performance of two types of rock bolts, fully encapsulated rebar and D-Bolt, under combined pull and shear loading were studied in the laboratory. A new test approach was developed to apply the pull and shear loads to the rock bolt at the same time so that the bolt is displaced in a direction different from the bolt axis. Five displacing angles between 0° (pure pull) and 90° (pure shear) were employed in the tests. The test results show that the linear elastic stiffness of both the D-Bolt and the rebar bolt is mobilised quickly after a small displacement. When the displacing angle is larger than 40°, grout crushing may occur underneath the bolt shank, resulting in reduction in the stiffness of the bolt. The ultimate load of the bolts remains approximately constant no matter what the displacing angle is for both the D-Bolt and the rebar bolt. The displacement capacity of the D-Bolt, however, is dependent on the displacing angle. The ultimate displacement of a 1-m long D-Bolt section varies from 140mm under pure pull (0°) to approximately 70mm when the displacing angle is larger than 40°. The ultimate displacement of the rebar slightly increases from 29mm under pure pull to 53mm under pure shear. In general, the displacement capacity of the D-Bolt is larger than that of the rebar bolt. It is approximately 3.5 times the rebar under pure pull and 50% higher than rebar under pure shear. The test results show that the displacing angle of the bolt is larger than its loading angle, which is also confirmed by the analytical solutions.

Mechanical performance of bolted modular GFRP composite sandwich structures using standard and blind bolts

This paper presents a mechanically bolted modular assembly system of GFRP web–flange sandwich structures used for beam and slab applications. Built-up modular sections consisting of standard GFRP pultruded I or box profiles are incorporated between two GFRP plates to form a sandwich structure, which can then be assembled in the transverse direction to form a one-way spanning slab system. Modular sandwich specimens were prepared via mechanically bolting the component profiles, and were then tested under four-point bending. The load-carrying capacity was evaluated, and the degree of composite action and the detail of the bolted connections, such as the spacing and type of bolts, were investigated. It was found that the composite action offered by the bolted connections decreased with the increase of load, and only partial composite action was achieved at ultimate loads. In addition, the degree of composite action was also dependent upon the bolt spacing. Finally, a finite element modeling approach was established to predict structural stiffness and the degree of composite action of bolted GFRP sandwich specimens. The models showed good comparisons with the experimental results.

Durability of Multiple-Anticorrosive Bolts in a Corrosive Environment

Abstract This paper first introduces the structure of multiple-anticorrosive bolts and the anticorrosive mechanism. To thoroughly analyze the durability of multiple-anticorrosive bolts in a corrosive environment, different corrosive environments were simulated and experiments on the durability of double- and multiple-anticorrosive bolts were conducted. Apparent changes were observed and the bond strength after corrosion was measured. From these test data, the resistance to corrosion was compared for the two types of bolts, and formulae for the service life of double- and multiple-anticorrosive bolts were derived in different corrosive environments. At the same time, a number of modification coefficients for optimization of the service-life formulae were put forward. The anticorrosion performance of the multiple-anticorrosive bolt was mainly studied and compared with that of the double-anticorrosion bolt, and the multiple-anticorrosive bolt was verified to have superior durability in a corrosive environment. The conclusions drawn in this study can be applied in the design of anticorrosive bolts to be used in an underground structure and later applied in durability analysis, providing reference values for actual engineering.

Finite Element Analysis Based on ANSYS of Bolt of Roof Bolter

The three-dimensional solid models of five different length and shaft diameter anchor of bolt were constructed based on ANSYS software, and making static analysis and modal analysis on it to obtain the stress nephogram and natural frequency of bolt. Research on the stress condition of bolt in static analysis. In modal analysis, researching on the effect regular of the change of length and shaft diameter size on the bolt transverse vibration, the longitudinal and torsional vibration of three natural modes of different frequency, providing a reference for the structure design and reasonable choice of bolt type for corresponding condition.

볼트 접합 및 프리스트레스를 적용한 프리캐스트 콘크리트 보-기둥 외부접합부의 내진실험

In this study, experimental research was carried out to investigate the seismic and structural performance of precast concrete exterior beam-column joints using bolt type connection and prestressing method. A total of five full-scale exterior beam-column joints were constructed and tested under reversed cyclic loading, controlled by displacement. Results of the test are as follows: Energy dissipation capacity and pinching phenomenon of PC beam-column joints showed disadvantageous behavior compared to RC beam-column joints. However, drift capacity of the PC joint was excellent. Also, yield mechanism concentrated on embedded nuts was suitable as an exterior beam-column joint of lateral load resistance frame. Additional application of prestressing method was also very effective to control excessive pinching and cracking in the joint region, and thus improved an overall seismic performance of the PC joint.