scholarly journals Shear Strength of Flat Joint considering Influencing Area of Bolts

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Hang Lin ◽  
Penghui Sun ◽  
Yifan Chen
Keyword(s):  
Shear Strength ◽  
Jointed Rock ◽  
Calculation Model ◽  
Bolted Joints ◽  
Rock Joints ◽  
Joint Surface ◽  
Influence Coefficient ◽  
Test Results ◽  
Bolted Joint ◽  
Joint Shear Strength

Bolt is popular in the reinforcement of geotechnical engineering, which can significantly improve the strength and stability of jointed rock mass. For bolted joint, the bolting area is a certain scope instead of the entire joint surface; therefore, it is necessary to study the effect of bolt influencing area on the shear strength of rock joints. In this paper, a series of laboratory direct shear tests were executed on the bolted joints to explore the influence of bolts on the joint shear strength, as well as the influencing area of bolt. Via successively changing bolting angle and bolt number, the shear stress-shear displacement curves of bolted joints were recorded and the variation law of shear strength was analyzed. Based on the assumption of the circular influencing area of bolt, the influence coefficient m (defined as the diameter ratio of the influencing area to the bolt) was introduced to establish the theoretical calculation model of the shear strength of bolted joint, which was verified by test results. Furthermore, the value of m was changed, and the shear strengths of bolted joints under different bolting condition were calculated to compare with the test results. The average relative error Eave was selected to determine the optimal value of m under the corresponding bolting condition, and it tends to sufficiently small values under the case of m > 30 for one-bolted joint and m > 25 for two-bolted joint, as well as m > 20 for three-bolted joint, which demonstrates that m can be applied to effectively calculate the actual influencing area of bolt.

Non-Linear Analysis and Modeling of the Structure with Bolted Joints

2015 ◽  
Vol 656-657 ◽  
pp. 694-699
Author(s):  
Xin Liao ◽  
Jian Run Zhang ◽  
Dong Lu
Keyword(s):  
Dynamic Stiffness ◽  
Element Model ◽  
Outer Radius ◽  
Bolted Joints ◽  
Structure Model ◽  
Test Results ◽  
Bolted Joint ◽  
Joint Structure ◽  
Non Linear ◽  
Simulation Results

In this study, a non-linear finite element model for a simplified single-bolted joint structure model is built. Static analysis on the structure under different shear force and pretension effect is done, and the non-linear contact behavior is analyzed. Through comparing datum, it is found that interface area of each bolted joint region can be described an annular region around bolt hole, whose outer radius has increased by 85% compared with radius of bolt hole. Also, the frequency responses of the multi-bolted joint structure under sinusoidal excitation are investigated. Simulation results show that the resonance regions basically remain unchanged in different pretension effect and the largest amplitude will increase with the increasing preloads. Finally, the vibration experiments are conducted. Interface nonlinear affect dynamic stiffness considerably. The test results illustrate that dynamic behaviors of bolted joint agree with the simulation results and the proposed non-linear contact model was reasonable.

Shear Strength of Jointed Rock Mass with Different Joint Surface Characteristic in Subsea Tunnel

2019 ◽  
Vol 94 (sp1) ◽  
pp. 301
Author(s):  
Qin Jin ◽  
Jie Hu ◽  
Hongliang Liu ◽  
Shuguang Song ◽  
Jinpei Liu ◽  
...  
Keyword(s):  
Shear Strength ◽  
Rock Mass ◽  
Jointed Rock ◽  
Surface Characteristic ◽  
Jointed Rock Mass ◽  
Joint Surface ◽  
Subsea Tunnel

Model Testing and Analysis Study on Shear Strength of Rock Mass Containing Multiple Cracks under Compression-Shearing Loading

2008 ◽  
Vol 33-37 ◽  
pp. 617-622
Author(s):  
Wei Shen Zhu ◽  
Bin Sui ◽  
Wen Tao Wang ◽  
Shu Cai Li
Keyword(s):  
Shear Strength ◽  
Rock Mass ◽  
Rock Sample ◽  
Failure Process ◽  
Jointed Rock ◽  
Multiple Cracks ◽  
Test Results ◽  
Failure Model ◽  
Two Phase ◽  
Bridge Failure

Two-phase modelling testing was performed to study the shear strength of rock bridges of jointed rock mass in this paper. The failure process of rock sample containing multiple collinear cracks was observed. Based on theory of fracture mechanics and analytical method, a rock-bridge failure model was proposed and the expression of shear strength was derived. Comparison of calculated shear strength and the model test results was made and they agree well.

An Accurate Method of Evaluating Relaxation in Bolted Flanged Connections

1997 ◽  
Vol 119 (1) ◽  
pp. 10-17 ◽  
Author(s):  
A. Bouzid ◽  
A. Chaaban
Keyword(s):  
Accurate Method ◽  
Bolted Joints ◽  
Fe Modeling ◽  
Test Results ◽  
Bolted Joint ◽  
Asme Code ◽  
Thermal Dilatation ◽  
Joint Rigidity ◽  
Analytical Tools ◽  
Leakage Assessment

Bolted flanged joint assemblies may begin to leak some time following a successful hydrostatic test. One of the reasons is that the gasket experiences a drop in its initial compressive stress due to creep, thermal dilatation, and thermal degradation. The need to pay attention to the relaxation behavior of bolted joints for high-temperature applications is recognized by the ASME Code, but no specific guidelines are given to help engineers, neither at the design nor maintenance levels. This paper deals with the basic analytical tools that have been used to develop a computer program “SuperFlange” that can be used to make accurate predictions of the relaxation of bolted flanged joints, and hence be able to provide a reasonable leakage assessment over time. A simplified analytical method of relaxation analysis will also be presented. These proposed methods are supported by test results obtained on a real bolted joint fixture and by FE modeling. A strong emphasis will be put on flanged joint rigidity, which is one of the major controlling parameters of relaxation besides the material properties involved.

Gasket Catastrophic Failure Modes

2018 ◽  
Author(s):  
Warren Brown ◽  
Nathan Knight
Keyword(s):  
Failure Modes ◽  
The Body ◽  
Bolted Joints ◽  
Test Results ◽  
Bolted Joint ◽  
Critical Factors ◽  
Test Set ◽  
Set Up ◽  
Industry Experience ◽  
Corrugated Metal

This paper outlines how, under certain scenarios, gaskets may catastrophically blow out of pressure boundary bolted joints. Supporting the observations on industry occurrences of such failures, attempts were made to re-create one of the failure modes in a test set-up. The tests managed to highlight critical factors for blow out of Corrugated Metal with Covering Layer (CMCL) gaskets. A summary of the known industry experience with gasket blow out and the CMCL test results are included in the body of this paper. Conclusions and recommendations for considering these failure modes in both pressure boundary bolted joint design and also risk assessment are made.

scholarly journals Intelligently Predict the Rock Joint Shear Strength Using the Support Vector Regression and Firefly Algorithm

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Jiandong Huang ◽  
Jia Zhang ◽  
Yuan Gao
Keyword(s):  
Machine Learning ◽  
Shear Strength ◽  
Support Vector Regression ◽  
Firefly Algorithm ◽  
Rock Joint ◽  
Rock Joints ◽  
Support Vector ◽  
Joint Shear Strength ◽  
Joint Shear ◽  
Combined Algorithm

Abstract To propose an effective and reasonable excavation plan for rock joints to control the overall stability of the surrounding rock mass and predict and prevent engineering disasters, this study is aimed at predicting the rock joint shear strength using the combined algorithm by the support vector regression (SVR) and firefly algorithm (FA). The dataset of rock joint shear strength collected was employed as the output of the prediction, using the joint roughness coefficient (JRC), uniaxial compressive strength (σc), normal stress (σn), and basic friction angle (φb) as the input for the machine learning. Based on the database of rock joint shear strength, the training subset and test subset for machine learning processes are developed to realize the prediction and evaluation processes. The results showed that the FA algorithm can adjust the hyperparameters effectively and accurately, obtaining the optimized SVR model to complete the prediction of rock joint shear strength. For the testing results, the developed model was able to obtain values of 0.9825 and 0.2334 for the coefficient of determination and root-mean-square error, showing the good applicability of the SVR-FA model to establish the nonlinear relationship between the input variables and the rock joint shear strength. Results of the importance scores showed that σn is the most important factor that affects the rock joint shear strength while σc has the least significant effect. As a factor influencing the shear stiffness from the perspective of physical appearance, the change of the JRC value has a significant impact on the rock joint shear strength.

EXPERIMENTAL ANALYSIS OF THE LOAD CAPACITY AND REPEATABILITY OF PRELOADED BOLTED JOINTS

Tribologia ◽  
2020 ◽  
Vol 292 (4) ◽  
pp. 71-77
Author(s):  
Marcin Szczęch ◽  
Wojciech Horak
Keyword(s):  
Axial Force ◽  
Experimental Analysis ◽  
Load Capacity ◽  
Bolted Joints ◽  
Test Results ◽  
Bolted Joint ◽  
Breaking Force ◽  
Torque Wrench ◽  
The Common ◽  
Lubrication Conditions

Bolted joints are among the most widespread and most important detachable connections used in mechanical engineering and construction. The common use of this connection group is reflected in the variety of types of screw connections. There are several geometric and material factors, and consequently tribological ones, that determine the load capacity and, which is often of key importance, the repeatability of the bolted joint. The paper presents a description of the test stand and the test results of preloaded bolted joints for different lubrication conditions. The measured parameters were the breaking force value of a double lap bolted joint and its repeatability and the axial force repeatability of the bolts tightened by an electronic torque wrench.

scholarly journals Shear Failure of Bolted Joints considering Mesoscopic Deformation Characteristics of Rock

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Yanhui Cheng ◽  
Dongliang He ◽  
Jianyu Yang
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Shear Strength ◽  
Contact Stiffness ◽  
Shear Stiffness ◽  
Bolted Joints ◽  
Rock Joints ◽  
Stiffness Ratio ◽  
Rock Engineering ◽  
Peak Shear Stress

In rock engineering of the cold region, there are a lot of rock joints. The shear characteristics of joints play a decisive role in the stability of rock engineering in the cold area. In this paper, based on the numerical simulation method of particle flow, reasonable microscopic parameters are selected for the numerical simulation of the direct shear test of bolted joints. The results show that the shear stiffness and contact modulus are linearly and positively correlated. The greater the contact modulus, the greater the residual stress, the better the synergetic effect between rock and bolt, and the more developed the microcrack. The smaller the contact stiffness ratio, the greater the residual stress. The shear stiffness decreases with the increase in the contact stiffness ratio, and the larger the contact stiffness ratio, the slower the shear stiffness decreases, while the shear strength does not change with the contact stiffness ratio. The contact stiffness ratio has a weak effect on the number of cracks in the model. The shear stiffness increases with the increase in the parallel bond modulus, and the shear strength decreases with the increase in the parallel bond modulus. The binding stiffness is independent of the shear stiffness, and the peak shear stress decreases with the increase in the binding stiffness ratio. The greater the bond stiffness ratio, the greater the number of cracks.

scholarly journals Uplift Behavior of Belled Short Piles in Weathered Sandstone

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Bai Yang ◽  
Jianlin Ma ◽  
Wenlong Chen ◽  
Yanxin Yang
Keyword(s):  
Shear Strength ◽  
Bearing Capacity ◽  
Calculation Model ◽  
Uplift Capacity ◽  
Test Results ◽  
Loading Test ◽  
Pull Out ◽  
Initial Stage ◽  
Uplift Load ◽  
Double Circuit Line

Field pull out test results of 500 kV double-circuit line of Luping-Fule are presented in this paper to investigate the uplift bearing behavior of rock-socketed belled short piles. A calculation model of rock-socketed belled short pile has been proposed. During the initial stage of loading test, uplift load is shared by even section and bell of the pile, and the bell continues to bear uplift load after the lateral resistance of even section pile reaches the limit. A different performance has been found on the case of long belled pile. At the ultimate state, the uplift resistance provided by bell accounts for about 54.9% and 34.7% of the total uplift capacity for the 6.0 m long and 7.0 m long piles, respectively. Increasing pile length has been found to noticeably increase the ultimate uplift bearing capacity, while it has less effect on the displacement of pile top. The uplift capacity of even section pile is associated with the shear strength of rock mass around the pile, and the test results demonstrate that the ultimate resistance can be equal to the shear strength. The calculation method proposed in this paper is proven to be able to accurately predict the ultimate uplift bearing capacity of the rock-socketed belled short piles.

Sign in / Sign up

Export Citation Format

Share Document