Non-Linear Finite Element Analysis of Extended Shear Tab Connections.

149 Pages·2013·4.17 MB·English

Non-Linear Finite Element Analysis of Extended Shear Tab
Connections

A dissertation submitted to the Graduate School
of the University of Cincinnati
in partial fulfillment of the
requirements for the degree of

Doctor of Philosophy (Ph.D.)
In Civil Engineering
In the School of Advanced Structures
of the College of Engineering & Applied Sciences
University of Cincinnati, Cincinnati, Ohio, USA

by
Mohamed Fawzi Suleiman
M.Sc., University of Tripoli

Committee Chair: Bahram M. Shahrooz, Ph.D.

April 2013
Non-Linear Finite Element Analysis of Extended Shear Tab
Connections

Mohamed Fawzi Suleiman, PhD
University of Cincinnati, 2013

ABSTRACT

The Manual of Steel Construction AISC14th Edition refers to an extended shear tab as a
single plate shear connection. This method of providing simple connections has become quite
popular with both fabricators and erectors. Extended shear tab connections were formally
introduced in the 13th Edition of AISC Steel Construction Manual. Using experimental data from
extended shear tab connections, Sherman and Ghorbanpoor introduced a design methodology in
2002 for extended shear connections. Twisting of the shear tab controlled the capacity of the
specimens tested by Sherman and Ghorbanpoor, which were not laterally braced. In the latest
edition of AISC Steel Manual, design equations are provided to assess the need for stabilizer plates
in the connection region of extended shear tabs.
In an effort to understand whether twisting of the shear tab can be a controlling design limit
state, three-dimensional nonlinear finite element analyses in conjunction with design case studies
were conducted. The analyses included 364 connections with different configurations were studied
with an “a” distance of ( 9, 11, and 16 inches).
The finite element models were comprehensive in terms of simulating nonlinear material
properties, boundary conditions, pretensioning in the bolts, geometric nonlinearity, etc. It was
possible to accurately replicate the responses (shear force-connection vertical deflection and shear
force-connection angle of twist) measured in a number of previous tests, and to fairly well predict
the observed failure modes.
Using a 3D nonlinear finite element analysis technique, the response of 16 selected
connections, which had been designed to meet all the applicable limit states in AISC Steel Manual,
were evaluated. The presence of floor slab, which braces the top flange of the beam, was simulated
in the analyses. For a number of cases, the connection behavior at the ultimate limit state was
dominated by twisting, i.e., the relationship between torsional moment and angle twist indicated a
noticeable level of loss of stiffness in comparison to that from the shear-vertical displacement
relationship. However, the level of lateral displacement of the shear tab was small, particularly for
unfactored loads when control of deformations is an important design objective.
According to AISC provisions (Eq.10-6), stabilizer plates would not be required for any of
these 16 connections, which were evaluated by 3D nonlinear FEA. Therefore, current AISC
provisions are a good predictor of the expected level of out-of-plane displacement of the shear tab
due to twisting. It should be noted that large lateral displacements occurred at the ultimate state
when the connection ductility is the main design consideration but not the magnitudes of
deformations and distortions. Therefore, this equation can be used to determine whether stabilizer
plates are needed or not; however, it does not predict whether the response at the ultimate limit
state will be dominated by excessive loss of torsional stiffness of the shear tab.
Instead of using stabilizer plates, a thicker plate can be used for the shear tab. This solution is
considered to be more economical and easier than welding stabilizer plates in the connection
region.
Copyright © by Mohamed F. Suleiman
2013
Dedication
This dissertation is dedicated to my mother, Sohair Anwar Shaheen,
for her endless love, support and encouragement.
Acknowledgements

To say this work is by Mohamed F. Suleiman overstates the case. Without the significant
contributions made by other people this work would certainly not exist.
First and foremost, I would like to express the deepest appreciation to my committee chair
and advisor Dr. Bahram M. Shahrooz, who has the attitude and the substance of a genius. He
was not only my advisor, but my mentor and friend. His patience, flexibility, genuine caring and
concern, and faith in me during the dissertation process enabled me to earning my Ph.D. It has
been an honor to be a Ph.D. student under his supervision. Without his guidance and persistent
help this dissertation would not have been possible. Thank you Dr. Shahrooz!
I would like to thank my committee member, Dr. Herbert L. Bill. The good advice,
support and most importantly his friendship during my research time, has been invaluable on both
an academic and a personal level, for which I am extremely grateful.
I am very grateful to the remaining members of my dissertation committee, Dr. Patrick J.
Fortney and Dr. William A. Thornton. I am very grateful to for their scientific advice and
knowledge, many insightful discussions, and suggestions and for accepting to be the external
examiners in my committee. Their academic support and input are greatly appreciated.
I owe a great debt of gratitude to my teachers at English Language Institute (ELI) at
University of Pittsburgh, especially Stacy Ranson and Chris Ortiz. These teachers provided me
and their students with an excellent high education in English Language. As time goes on, I realize
more and more clearly the huge impact that both have had on my academic career.
i
I am thankful to my colleagues at the University of Cincinnati Dawit Alemayehu,
Temesgen Aure, Steven Mitchell, Luke Butler, Wei Zhang and Mayik Koriom for their
companionship. I have benefitted a lot from our discussions and exchange of ideas.
I would like to thank my friends Adel Altorban, Abdullah Masud, Ali Alghonas, Ali
Altarhuni, Ali Lahwal, Moftah Abid, Yousef Elmashae, Taher Shawesh, Kamal Shlbei, and
Ans Elmeshri for the great times that we have shared. I am very happy and proud of making those
wonderful friends. I might need to have three pages to write up all my other friends' names to thank
them. So thanks to all of you!
My brother, Saifallah and my sister Ghada have given me the spiritual support since the
day one here in the USA, thank you both.
To my beloved sons Saifallah and Sofian, and my beloved daughters Sohair and Ghada
"Oodee", I would like to express my thanks for being such good children and always cheering me
up. The joy you have given me will always make me happy.
The unconditional love and encouragement provided by my wife Samira served as a secure
anchor during the hard and easy times; thank you Samira!
My mother, Sohair, I don’t think I can find proper words to express my gratitude towards
you. Your encouragement and support from the very beginning of my life made it possible for me
to reach this stage. You are the one and only one who could drain all the stress and make me able
to pursue in my academic study. I love you Mom so much.
Above all, I owe it all to " الله" for granting me the wisdom, health, and strength to undertake
this research task and enabling me to its completion.
ii
Table of Contents
CHAPTER 1. INTRODUCTION ................................................................................................... 1
1.1 RESEARCH MOTIVATION AND BACKGROUND ......................................................... 1
1.2 RESEARCH OBJECTIVES ................................................................................................. 2
1.3METHODOLOGY ................................................................................................................ 2
1.4 DISSERTATION OUTLINE ................................................................................................ 3
CHAPTER 2. LITERATURE REVIEW ........................................................................................ 4
2.1 INTRODUCTION................................................................................................................. 4
2.2 PREVIUS RESEARCH ON SHEAR TAB CONNECTION……………………………………………4
2.2.1 Behaviour of Single Shear Tab Connections under Working Loads ............................. 4
2.2.2 Behaviour of Beams Subjected to Conentrated Loads ................................................... 4
2.2.3 Design and Behavior of Coped Beams .......................................................................... 5
2.2.4 Design Procedures of Weld and Bolt Eccentricites ....................................................... 7
2.2.5 Investigations of Several Strenght Limit State ............................................................... 8
2.2.6 Experimental Tests to Evaluate the Performance of Astaneh's New Procedure ........... 9
2.2.7 Full Scale Tests and Design Procedures of Extended Shear Tab Connections ........... 10
2.2.8 FE Model of Standard Shear Tab Connections ........................................................... 12
2.2.9 Behavior of Plate Shear Connections with Rigid and Flexiable Supports .................. 13
2.2.10 Exprimental Verification of Single Plate Shear Connection Design Model .............. 14
2.2.11 FE Model of Unstiffened and Stiffened Extended Shear Tab Connections ............... 16
2.2.12 The Need for Stiffeners for and the Effect of Lap Eccentricity on Extended Shear Tab
………………………………………………………………………………………………………….17
iii
2.2.13 Behavior of Single and Double Row Bolted Shear Tab Connections…………..……... 18
2.3 SUMMARY OF LITERATURE REVIEW ...................................................................................... 19
CHAPTER 3. DEVELOPMENT OF FINITE ELEMENT MODELS ......................................... 20
3.1 INTRODUCTION............................................................................................................... 20
3.2 THE METHOD OF MODELING .................................................................................................. 20
3.3 SELECTION OF ELEMENTS ..................................................................................................... 21
3.4 MESH REFINEMENT STUDY .................................................................................................... 22
3.5 TMATERIAL PROPERTIES ....................................................................................................... 25
3.6 GEOMETRIC NONLINEARITY .................................................................................................. 27
3.7 CONTACT INTERACTIONS ...................................................................................................... 27
3.7.1 Normal and Tangential Behavior ................................................................................ 28
3.8 BOLT PRETENSIONING ........................................................................................................... 29
3.9 TBOUNDRY CONDITIONS ....................................................................................................... 30
3.9.1 Beam ............................................................................................................................ 31
3.9.2 Column ......................................................................................................................... 32
3.9.3 Shear Tab ..................................................................................................................... 33
3.9.3 Bolts ............................................................................................................................. 33
3.10 LOADING ............................................................................................................................ 34
3.11 STEPS OF ANALYSIS ............................................................................................................ 34
CHAPTER 4. FINITE ELEMENT VALIDATION ..................................................................... 35
4.1 INTRODUCTION............................................................................................................... 35
4.2 EVALUATION OF EXPERIMENTAL DATA ......................................................................................... 35
4.2.1 Sherman and Ghorbanpoor (2002) .............................................................................. 35
iv