0037_an advanced computational investigation on bolt tension of a flanged pipe joint subjected to...

An Advanced Computational Investigation on

Bolt Tension of a Flanged Pipe Joint Subjected

to Bending

Submitted by

Md. Riasat Azim

Student No. 0504048

Course: CE 400 (Project and Thesis)

Thesis

Submitted in Partial Fulfillment of the Requirements for the Degree of

BACHELOR OF SCIENCE IN CIVIL ENGINEERING

Department of Civil Engineering

BANGLADESH UNIVERSITY OF

ENGINEERING AND TECHNOLOGY, DHAKA

November, 2010

i

DECLARATION

Declared that except where specified by reference to other works, the studies embodied in thesis

is the result of investigation carried by the author. Neither the thesis nor any part has been

submitted to or is being submitted elsewhere for any other purposes.

Signature of the student

(Md. Riasat Azim)

ii

Table of Contents

Declaration i

Table of Contents ii

List of Tables v

List of Figures viii

Acknowledgement xi

Abstract xii

Chapter 1 Introduction

1.1 General 1

1.2 Objective 1

1.3 Methodology 2

1.4 Scopes and Limitations of the Study 2

1.5 Organization of the Thesis 3

Chapter 2 Literature Review

2.1 Introduction 4

2.2 Types of Pipe Joint 9

2.3 Types of Flange 10

2.4 Flanged Connection Subjected to Bending 12

2.5 Previous Works 12

2.5.1 Stress in Bolted Flanged Connection 12

2.5.2 Comparison of Performance of Bolts and Rivets 16

2.6 Conventional Analysis 17

Chapter 3 Methodology for Finite Element Analysis

3.1 Introduction 20

3.2 The Finite Element Packages 20

iii

3.3 Types of Analysis on Structures 21

3.4 Finite Element Modeling 22

3.4.1 Modeling of Pipe and Flange 23

3.4.2 Modeling of Bolt and Surface Spring 25

3.4.3 Modeling of Stiffening Beam 27

3.5 Finite Element Model Parameters 29

3.6 Meshing 29

3.6.1 Meshing of the Pipe 29

3.6.2 Meshing of the Flange 30

3.6.3 Properties of Contact Element 30

3.6.4 Properties of Bolts 31

3.7 Boundary Conditions 31

3.7.1 Restraint 31

3.7.2 Loading 32

3.8 Typical Results 32

Chapter 4 Parametric Study

4.1 Introduction 36

4.2 Study Parameters 36

4.3 Presentation of Results 37

4.4 Interpretation of FE Analysis 51

4.4.1 Effect of Mesh Size and Element Type 51

4.4.2 Effect of Number of Bolts 51

4.4.3 Effect of Flange Width and Thickness 51

4.5 Comparison of FEA with Conventional Analysis 52

Chapter 5 Development of a Procedure for Determining Bolt Tension

5.1 Introduction 54

5.2 Development of the General Equation 54

iv

5.3 Generalized Equation for Maximum Bolt Tension 55 5.4 Comparison of Bolt Tension Values 55

Chapter 6 Conclusion

6.1 General 77

6.2 Outcome of the Study 77

6.3 Scope for Future Investigation 78

REFERENCES 79

APPENDIX

A ANSYS Script Used in this Analysis 80

B Tabular Representation of Bolt Tension Values 86

v

LIST OF TABLES

Table 3.1 SHELL 92 Input Summery 24

Table 3.2 COMBIN 39 Input Summery 26

Table 3.3 BEAM 4 Input Summery 28

Table 3.4 Various Parameters 29

Table 4.1 Study Parameters for a flanged pipe joint 36

Table 4.2 Various parameters for 125 mm diameter pipe (fw =100mm) 38

Table 4.3 Bolt tension for various numbers of bolts on 125 mm diameter pipe with 100 mm flange-width 38



Table 4.6 Various parameters for 150mm diameter pipe (fw =100mm) 40


















vi





Table B1 Comparison of Bolt tension for 125 mm diameter pipe and 100 mm flange width (ft =pt) 86










Table B11 Comparison of Bolt tension for 300mm diameter pipe and 125 mm flange width (ft =pt) 89



Table B14 Comparison of Bolt tension for 125 mm diameter pipe and 100 mm flange width (ft =2pt) 90











vii








Table B32 Comparison of Bolt tension for 200mm diameter pipe and 100 mm flange width (ft =3pt) 95








viii

LIST OF FIGURES

Figure 2.1 Pipe columns supported the industrial building of Abdul Monem Ltd, near Shahbag, Dhaka. 6

Figure 2.2 Foot over bridge supported by pipe columns at BUET campus, Dhaka 6

Figure 2.3 Circular pipe columns supported the track of the roller coaster at Fantasy Kingdom Entertainment

Park, Ashulia. 7

Figure 2.4 Water tank supported on nine tubular columns at Lalmatia, Dhaka 7

Figure 2.5 A large advertisement bill board supported by a circular pipe column at Shahbag, Dhaka. 8

Figure 2.6 Cylindrical column of a T.V. mast at, Yorkshire (Appleby-Frodingham Steel Company). 8

Figure 2.7 A 3-legged circular pipe transmission tower of BTTB at Katabon, Dhaka. 9

Figure 2.8 A flanged pipe joint with different components. 10

Figure 2.9 Different types of flanges. 11

Figure 2.10 Illustration of earlier methods of calculating stress in a bolted flange connection. 12

Figure 2.11 3-D views of a typical flanged pipe joint with 12 bolts and 12 in. diameter pipe. 17

Figure 2.12 Front views of a typical flanged pipe joint with 12 bolts and 12 in. diameter pipe. 18

Figure 2.13 Plan and force distribution of a typical flanged pipe joint with 12 bolts and 12 in. diameter pipe. 18

Figure 3.1 General sketch of the flanged pipe joint studied. 22

Figure 3.2 SHELL92 (8-Node Structural Shell). 23

Figure 3.3 COMBIN39 (Nonlinear Spring). 25

Figure 3.4 BEAM4 (3-D Elastic Beam). 27

Figure 3.5 Force - deflection behavior of contact springs. 30

Figure 3.6 Force – deflection behavior of bolts. 31

Figure 3.7 Finite elements mesh of a flanged pipe joint. 32

Figure 3.8 Finite elements mesh with loading and boundary conditions 33

Figure 3.9 Typical deflected shape of a flanged pipe joint. 33

Figure 3.10 Contour depicting Z component of strain 34

ix

Figure 3.11 Contour of 1st Principal Stress 34

Figure 3.12 Contour of 2nd Principal Stress 35

Figure 3.13 Contour of 3rd Principal Stress 35

Figure 4.1 Effect of number of bolts on bolt tension for 125 mm diameter pipe and 100 mm flange width. 38













Figure 5.1 Comparison of Bolt Tension for 125 mm diameter pipe when flange width is 100 mm (ft =pt) 56











x



Figure 5.14 Comparison of Bolt Tension for 125 mm diameter pipe when flange width is 100 mm (ft =2pt) 63


























xi

ACKNOWLEDGEMENT

At first the author would like to express his wholehearted gratitude to the Almighty for

each and every achievement of his life. May the benediction of Almighty lead every

individual to the way which is best suited for that particular individual.

The author has the pleasure to state that, this study was supervised by Dr. Khan Mahmud

Amanat, Professor, Department of Civil Engineering, Bangladesh University of

Engineering and Technology (BUET), Dhaka. The author is also greatly indebted to him

for all his affectionate assistance, adept guidance and enthusiastic encouragement

throughout the progress of this thesis. It would have been impossible to carry out this

study without his dynamic direction and critical judgment of the progress.

I would like to thank immensely my parents, their undying love, encouragement and

support throughout my life and education. Without their blessings, achieving this goal

would have been impossible. I thank all my friends for their assistance, motivation and

appraisal throughout the completion of this study.

xii

ABSTRACT

Apparently there is no analytical method for the analysis of bolt tension of a flanged pipe joint,

when pipe joints are subjected to bending. Generally approximate linear distribution method is

used for such analysis, which is often not accurate. In this project, an investigation is made to

find the effects of various parameters relating to flanged pipe joint connection, so that a definite

guideline, on determining the bolt tension can be developed. In addition results are compared

with the conventional analysis.

To carry out the investigation, a flanged pipe joint subjected to bending has been modeled using

finite element method, which also includes contact simulation. In this analysis, shell element has

been used for the modeling of pipe and flange. Non-linear spring has been used to model contact

and bolt. Non-linear finite element analysis method has been used to find out results till failure

by yielding of pipe. Joint has been subjected to ultimate moment and under this moment; the

maximum bolt tension has been evaluated. Based on the study, an attempt has been made to

present a guideline to find out bolt tension that is structurally effective for a flanged pipe joint.

The whole process is carried out under various parametric conditions within certain range.

It has been found that some parameters like flange thickness, width of flange and numbers of

bolts have found to have significant effect on effective bolt tension. Based on the results of the

analysis, an empirical equation has been developed to determine the bolt tension for different

number of bolts and flange thickness for different pipe diameter. It has been shown that, the

suggested empirical equation is useful in structural analysis for calculating the effective bolt

tension with reasonable degree of accuracy when the flanged pipe joint is subjected to bending.

Introduction 1

CHAPTER 1

INTRODUCTION

1.1 GENERAL

Day by day with the advent of new and complex construction practices, steel pipes are

availed for many types of constructions works. But extensive uses of pipes for

structural purposes are possible when reliable and economical methods of determining

bolt tension at a pipe joints are devised. Bolts concatenate two flanges in a pipe joints

and are subjected to bending resulting from application of loads. It is difficult yet

paramount to determine the bolt tension for the design of a flanged pipe joint. As a

general procedure, the linear distribution of bolt force method (analogous to the

flexural stress calculation on a beam section subjected to bending) is used for

determining tension that develops in bolts. But this method is not always valid for

application and more regretfully no particular guidelines are available to assist the

designer to make a decision in case of flanged pipe joint design. Due to the

complexity of the moment-transfer mechanism between the flange and the bolt under

loading and inadequacy of reasonable assumptions that may lead to a correct

prediction of the flange pipe joint response, there are significant scopes to delve into

investigation of this matter. This study is expected to provide the design engineer

some definite guidelines to estimate the effective bolt tension.

1.2 OBJECTIVE

The objective of this present study is to examine a flanged pipe joint under loading

and to develop a decisive guideline to determine the effective bolt tension for a

flanged pipe joint structure under various parametric conditions. The pipe joint with

bolted flange connection, subjected to bending moment will be considered. For this

purpose, a typical problem is going to be studied under various parametric conditions

that effect the bolt tension. A flanged pipe joint subjected to bending shall be modeled

using Finite Element Method, which shall also include contact simulation. Based on

the study, an attempt shall be made to present a definite guideline to find bolt tension

that is structurally effective for a flanged pipe joint.

Introduction 2

1.3 METHODOLOGY

To carry out the investigation, a flanged pipe joint would be studied under different

parametric conditions. Analysis would use “Shell Element” for the modeling of pipe

and flange. Nonlinear Spring would be utilized to model contact element and bolt. In

this analysis, pipe shall be subjected to ultimate moment. Under this moment, the

maximum bolt tension shall be evaluated under some parametric conditions by

varying the parameters like flange thickness, flange width, number of bolts. Based on

the results found, a generalized empirical equation will be generated to appropriately

determine the bolt tension. The whole process is carried out under various parametric

conditions within certain range.

1.4 Scope and Limitations of the Study

The whole analysis performed in this research has certain scopes, assumptions and

limitations like

• The investigation is based on nonlinear geometric analysis by Finite

Element Method.

• AISC standard weight steel pipe sections (40 ksi yield strength) are used

in this analysis to make the analysis results practically applicable.

• Out of 15 available standard weight steel pipe sections, only 5 sections

with large diameters are considered to find out the maximum possible

bolt tension values.

• Parameters like flange width, flange thickness, number of bolts are varied

in such a way, so that the sections can be used in real life situation.

• End restrained conditions are simplified in FE analysis than that

represents actual case, i.e. bolt connections are simulated by linear spring

elements which are equally strong in tension and compression.

• Material imperfections are not considered in this analysis.

• Differential temperature effects are neglected.

• Static and nonlinear 3D analysis will be performed.

Introduction 3

• Only bending effect will be analyzed. Shear force and axial load are not

taken into account for this present analysis.

• Bolt diameter used in this analysis is 20 mm.

1.5 ORGANIZATION OF THIS REPORT

The report is arrayed to best delinate and discusses the problem and findings that

ensued from the studies performed. Chapter 1 introduces the problem, in which an

overall idea is presented before entering into the main studies and discussion. Chapter

2 is Literature Review, which represents the research performed up to present date in

connection with it garnered from different references. It also describes the strategy of

advancement for the present problem to a success. Chapter 3 is all about the finite

element modeling exclusively used in this problem and it also shows some figures

associated with this study for proper presentation and understandings. Chapter 4 is the

core of this thesis write up, which describes the computational investigation made

throughout the study in details with presentation by many tables and figures followed

by some definite remarks. In chapter 5 an empirical equation for actuating maximum

bolt tension is proposed and its development is elucidated. The last chapter is Chapter

6, which summarizes the whole work as well as points out some further directions.

0037_an advanced computational investigation on bolt tension of a flanged pipe joint subjected to...

Documents