scholarly journals Loosening of Bolted Connections under Transverse Loading in Timber Structures

Forests ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 816
Author(s):  
Jiawei Chen ◽  
Honghong Wang ◽  
Yabin Yu ◽  
Ying Liu ◽  
Dong Jiang
Keyword(s):  
Helix Angle ◽  
Transverse Load ◽  
Timber Structures ◽  
The Finite Element Method ◽  
Bolted Connections ◽  
Load Amplitude ◽  
Load Location ◽  
Bolt Loosening ◽  
Bolt Connection ◽  
Main Factor

Bolted joints are widely used in timber structures, and the loosening of bolt connections will reduce the structural performance. In this paper, a mechanical model of bolt connection for timber structures is established, and the process of bolt loosening under a transverse load is investigated. By using the finite element method to construct an accurate thread model with a helix angle, the thread contact state during the bolt loosening procedure was analyzed in detail, and the factors such as load amplitude, load frequency, load location, and different timber materials on bolt loosening are also studied. In the timber structure, the load amplitude is the main factor affecting the bolt loosening, the decay rate of the preload in the bolted joint is positively correlated with the amplitude of the cyclic transverse load. The frequency of the loading has a smaller effect on the looseness, the preload decreases as the frequency increases. When the load is applied to the smooth rod part of the bolt, the preload force will decrease rapidly, and the distance between the load position and the bolt has no effect on the change in looseness. The decreasing range of the preload is different with different timber material, but the decreasing law is the same. The model can be applied to analyze the loosening rule of bolted connections in timber structures.

Bonded Joints in Water-Repellent Timber Structures

2016 ◽  
Vol 714 ◽  
pp. 3-9
Author(s):  
Jana Daňková ◽  
Tereza Majstríková ◽  
Pavel Mec
Keyword(s):  
Flame Retardants ◽  
Water Repellent ◽  
Bonded Joints ◽  
Timber Structures ◽  
Degradation Processes ◽  
Knowledge Based ◽  
Treatment Technologies ◽  
Physical And Chemical ◽  
Gaseous Form ◽  
Main Factor

Water in liquid and gaseous form is the main factor which significantly affects degradation processes in the wood. The mechanism and rate of wooden degradation processes can be effectively influenced by appropriate methods and technologies for its protection. However new knowledge, based on the possibilities of application of modern physical and chemical analytical methods, confirms that most well-known and previously commonly used protective equipment damages wooden structure. Many chemical substances, which are included in preservatives such as organic and inorganic biocides, or also flame retardants, are declared to be environmentally unacceptable. Nowadays, environmentally friendly treatment technologies of wood have increased attention to the above reasons. Wooden treatment by silicones ranks among the technologies which repellent, fire resistant and corrosion effectiveness is demonstrated by many authors. This article presents results of the experimental study that deals with the mechanical properties of bonded joints in the wood treated by silicones.

Nonlinear Analysis Method Research of Multi-Bolt Connection Structure of Primary Equipment Support

2017 ◽  
Author(s):  
Jianrong Zou ◽  
Shaochong Zhou
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Steam Generator ◽  
Support System ◽  
Analysis Method ◽  
The Finite Element Method ◽  
Reactor Coolant ◽  
Asme Code ◽  
Bolt Connection ◽  
Coolant System

The main equipments of the reactor coolant system include the steam generator, the reactor coolant pump, the pressurizer and the reactor coolant loop. The reactor coolant system is equipped with a steam generator for each of the two loops, and pressurizer is connected with the hot leg of loop 1 using the surge line. The main loop support system design of AP series greatly simplifies the RCS loop support system. Pressurizer supports consist of columns, lower lateral supports, upper lateral support and ring girder, and the steam generator supports consist of columns, lower lateral supports, upper lateral supports and intermediate lateral supports. Ring Girder of pressurizer consists of two semi-circular girders, vertical supports and splice connection of girder and the two half-ring girders are connected with splice connection using 11 bolts. The steam generator upper lateral support is mainly composed of bracket, snubber, pin and ubar and the ubar and the steam generator is connected via 16 bolts in the initial design. These bolts are to ensure the support junction can withstand the force and torque of various conditions of the reactor coolant system, which are important components of the main equipment support. There are large numbers of bolts in the splice connection of ring girder and ubar of upper lateral support of steam generator, and the bolts load was calculated using the uniform method in the general engineering design and analysis. During the design review it was found that the bolts load was uneven and in order to determine the non-uniformity of the bolts the finite element method was used to calculate the load on each bolt, and the resulting stress ratio was greater than 1 did not meet the requirements of the ASME Code. In this paper, the calculation method was studied and the design improvements for parts was made using the nonlinear analysis method to meet the requirements of ASME Code in the case of master supports of main equipment supports have been made good. At the same time the impact of bolts load because of gap was studied. It had very good economic benefits. The calculation and research of this paper show that the finite element method can calculate the force of bolts finely, and can get a more reasonable result than the empirical formula. It can be referred to when the multi-bolt connection structure needs to be refined, such as flange connection of important equipments and valves and flange and bolt design optimization.

Calculation and Reliability Assessment of Timber Structure Bolt Connection Subjected to Double Unequal Shears

2015 ◽  
Vol 752-753 ◽  
pp. 648-651 ◽  
Author(s):  
Josef Musílek ◽  
Karel Kubečka
Keyword(s):  
Reliability Assessment ◽  
Timber Structure ◽  
Thin Plates ◽  
Bolted Connections ◽  
Double Shear ◽  
Timber Member ◽  
Bolt Connection

The paper shows the calculation and reliability assessment of bolted connections subjected to unequal double shear with thin plates as outer members and inner timber member. The concrete example is calculated and explained.

Wrinkling analysis and control of rectangular space membrane

2016 ◽  
Vol 231 (11) ◽  
pp. 1959-1969
Author(s):  
Mingjun Liu ◽  
Jin Huang ◽  
Yali Wang
Keyword(s):  
Control Method ◽  
Plate Theory ◽  
Plane Deformation ◽  
The Finite Element Method ◽  
Membrane Structures ◽  
Wrinkling Analysis ◽  
Out Of Plane ◽  
And Control ◽  
The Relationship ◽  
Main Factor

Wrinkling, a common phenomenon found in space membrane structures, is the main factor affecting the performance, stability, and dynamic characteristics of these membrane structures. This article presents an active control method to improve the surface accuracy of membrane structures. A model of a thin rectangular membrane subjects to uniaxial uniform tensile stress is discussed. Initially, the relationship between the out-of-plane deformation of the wrinkles and the boundary conditions is built with the Föppl–Von Karman plate theory by introducing the slow varying Fourier series. Because vertical tensions perpendicular to the direction of the initial wrinkles are necessary to reduce these wrinkles, reasonable locations and magnitudes of these tensions are the key problems. The finite element method and variational principle method are used to solve this issue. Finally, a manufacturing error is added to the model as an initial defect, and the robustness of the controller is verified. Simulation results show that wrinkles are reduced quickly and effectively with the proposed method.

scholarly journals Free vibration analysis of a DST-0285 truck crane considering changes in the system load configuration

2018 ◽  
Vol 157 ◽  
pp. 03005
Author(s):  
Tomasz Geisler
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Free Vibration ◽  
Vibration Analysis ◽  
Free Vibration Analysis ◽  
Free Vibrations ◽  
The Finite Element Method ◽  
System Load ◽  
Load Location ◽  
Fundamental Units

A model of a truck crane, consisting of the fundamental units of the crane, is presented in this paper. The finite element method and a COSMOS/M package were applied to perform the modelling. Research into the influence of a change in the crane radius and load location on changes in the chosen free vibrations was carried out using the built models. Diagrams containing changes in the frequency of vibrations for chosen values of the crane radius and the load are presented and conclusions are drawn.

Bolted wood–steel and wood–steel–wood connections: verification of a new design approach

2001 ◽  
Vol 28 (2) ◽  
pp. 254-263
Author(s):  
M Mohammad ◽  
J HP Quenneville
Keyword(s):  
Stress Analysis ◽  
Failure Mode ◽  
Research Program ◽  
Shear Failure ◽  
Ductile Failure ◽  
Connection Strength ◽  
Bolted Connections ◽  
Design Procedures ◽  
Strength Failure ◽  
Bolt Connection

This paper covers the verification tests carried out at the Royal Military College of Canada on wood–steel–wood and wood–steel bolted connections. Thirty groups of specimens were tested. Specimen configurations were selected in such a way to include fundamental brittle and ductile failure mode cases. Comparisons between experimental results and predictions from proposed equations developed from steel–wood–steel bolted connections are given. Proposed design equations were found to provide better predictions of the ultimate loads than current CSA Standard O86.1 design procedures especially for bearing. However, row shear-out predictions seem to overestimate the strength. An adjustment using the reduced (effective) thickness concept is therefore proposed. Experimental observations on specimens that failed in row shear-out indicated that shear failure occurred over a reduced thickness. Stress analysis confirms findings on the reduced thickness. The research program is described in this paper along with the results and the proposed design equations for wood–steel–wood and wood–steel bolted connections loaded parallel-to-grain.Key words: wood–steel–wood, wood–steel, bolt, connection, strength, failure, design, thickness.

The Study on Mechanical Properties of Single-Bolted Steel-Glulam-Steel Joints

2011 ◽  
Vol 255-260 ◽  
pp. 204-208 ◽  
Author(s):  
De Liang Xu ◽  
Wei Qing Liu ◽  
Ding Zhou ◽  
Jian Dong Ding ◽  
Ying Lei ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Bearing Capacity ◽  
Failure Mechanism ◽  
Failure Mode ◽  
Mechanical Performance ◽  
Timber Structures ◽  
Bolted Connections ◽  
Steel Connections ◽  
Steel Connection ◽  
Steel Joints

Seven groups, total of 31 single-bolted steel-glulam-steel joints, were tested for their mechanical performance. The mechanical properties of single-bolted steel-glulam-steel connection subjected to a load parallel to the grain have been studied. The failure mode and failure mechanism of bolted connections were discussed in detail. It is shown that the failure mode, bearing capacity, stiffness and ductility of the joint are mainly relative to the thickness of the glulam and the diameter of the bolt. Due to the wide application of bolted steel-glulam-steel connections in engineering, the present work can be taken as a reference in manufacture, and design of modern timber structures.

Finite Element and Finite Difference Methods in Engineering

1978 ◽  
Vol 100 (1) ◽  
pp. 188-192
Author(s):  
N. Perrone
Keyword(s):  
Finite Element ◽  
Finite Difference ◽  
Finite Difference Methods ◽  
Transverse Load ◽  
The Finite Element Method ◽  
Finite Difference Technique ◽  
Related Approach ◽  
Finite Difference Solution ◽  
Ritz Procedure ◽  
Difference Methods

By means of a simple example, a stretched string under transverse load, finite element and finite difference methods which are so widely used in engineering are illustrated. The finite element method is shown to be an essentially modified Raleigh-Ritz procedure. The finite difference technique is applied directly to the string differential equation; an energy related approach is also discussed. The manner in which a combination finite element/finite difference solution can be effected for the same physical problem is treated. Application of both the finite element and finite difference methods to more complex problems as well as selected programs and depositories are mentioned.

A novel control strategy for the multi-step straightening process of long/extra-long linear guideways

2018 ◽  
Vol 233 (9) ◽  
pp. 2959-2975 ◽  
Author(s):  
Yongquan Zhang ◽  
Hong Lu ◽  
Xinbao Zhang ◽  
He Ling ◽  
Wei Fan ◽  
...  
Keyword(s):  
Control Strategy ◽  
Complex Shape ◽  
Helix Angle ◽  
Single Step ◽  
Integral Model ◽  
The Finite Element Method ◽  
Section Shape ◽  
Curvature Integral ◽  
Point Pressure ◽  
Feeding Process

The straightening process for a linear guideway with particular cross-section shape is normally conducted by the three-point pressure bending method. However, the single-step straightening process (SSSP) of a long/extra-long linear guideway may make the workpiece from a single-curvature curve into a more complex shape. Due to these limitations of SSSP, a quantitative control strategy for the multi-step straightening process (MSSP) of a long/extra-long linear guideway is proposed in this paper based on the straightening principle of SSSP. Firstly, the predictive models for straightening stroke and helix angle after unloading with respect to SSSP are developed based on the elasto-plastic theory and curvature integral model. Depending on the established analytical model for SSSP, the MSSP is then mathematically modelled to obtain corresponding straightening parameters considering feeding process, clamping process and straightening process. Besides, the finite element method has been applied to validate the developed mathematical model for the MSSP. Taking the approach of a linear guideway as an example, the experimental results have also shown that the proposed control strategy is appropriate for the MSSP of a long/extra-long linear guideway.

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