Design of Steel Structures Vol 2

916 Pages·9.08 MB·English

by  Dr. RAM CHANDRA

DESIGN OF STEEL
STRUCTURES
(VOLUME II)
[S.I. UNITS]
By
Dr. Ram Chandra
B.E., M.E. (Hons.), M.I.E., Ph.D. (Roorkee) , MIE
Professor and Head
Department of Structural Engineering
M.B.M. Engineering College
University of Jodhpur, Jodhpur (Rajasthan)
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Design of Steel Structures VOl–II
Published by:
RAJINDER KUMAR JAIN
Standard Book House
Unit of: Rajsons Publications Pvt. Ltd.
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First Published : 1971
Second Edition : 1976
Third Edition : 1981
Fourth Edition : 1984
Fifth Edition : 1987
Sixth Edition : 1989
Seventh Edition : 1991
Eight Edition : 1992
Ninth Edition : 1994
Tenth Edition : 1996
Eleventh Edition : 1998
Twelveth Edition : 2000
Thirteenth Edition : 2003
Fourteenth Edition : 2006
Fifteenth Edition : 2008
Sixteenth Edition : 2010
Seventeenth Edition : 2012
Eighteenth Edition : 2015
Nineteenth Edition : 2016
Twentieth Edition : 2018
© Publishers
All rights are reserved with the Publishers. This book or any part thereof, may not be
reproduced, represent, photocopy or in any manner without the prior written permission
of the Publishers.
````` 495.00
ISBN: 978-81-89401-41-2
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FOREWORD iii
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YYYYY EEEEEAAAAACCCCCHHHHHEEEEERRRRRSSSSS
Words from the Publishers
Seventh edition of this book Design of Steel Structure Vol I and II is based on
IS : 800–1984 as amended in 1997 and so also newly revised IS : 883–1994 for
structural timber.
New code of practice, IS : 800 is likely to be issued soon. In this it is likely to
introduce ‘Limit State Design of Steel Structure’.
For unsymmetrical bending and even for simple theory of bending, concept
of shear-centre and axis of bending are essentially needed. These topics may be
better appreciated, in case, the position and the location of shear centre for
open thin-walled steel sections are nicely known. Illustrative examples have
been given to explain the location of shear centre.
Instead of IS : 883–1970, complete text for timber structures has also been
revised as per revised and new code IS : 883–1994
Inspite of careful scrutiny of the manuscript, it is possible that some
typograhical and computational errors are still left are noticed, publisher shall
feel highly obliged to those, who bring these errors to their notice. Suggestions
and comments from the readers for further improvement of the forthcoming
editions of the shall be appreciated.
2015
Foreword
Tables and clauses from the Indian Standard Specifications have been
reproduced in the book with the kind permission of the Indian Standards
Institution.
It is desirable that for complete detail, reference be made to the latest versions
of the Standards Institution, Manak Bhavan, 9, Bahadur Shah Zafar Marg,
New Delhi-1, or from its branch offices at Mumbai, Kolkata, Kanpur and
Chennai.
SYSTEM INTERNATIONAL d’ UNITES
(SI System of Units)
In order to avoid the conversion of results obtained by engineers working with
the Foot Pound Second (FPS) System (gravitational) of units in terms of
centimetre-gram second absolute system of units used by the scientists, a need
of common system of units was realised. The General Conference on Weights
and Measures held at Paris in 1960 finalised the System International d’ Unites
(SI). It is an absolute system of units. The mass is considered as fundamental
unit and not the force. BIS has included a comment of transition in IS 3616–
1966. ‘Recommendation on the International System (SI) Units’ that this system
has begun to replace older system of units in several branches of science and
technology. The SI is a universal system of units and it has been adopted in
France as a legal system and it is likely to become common in many countries.
SI units have the following six basic units.
Unit of Length (metre, m)
The length equal to 1,650, 763.73 wavelengths, in vacuum, of the radiation
corresponding to the transition between 2p19 and 5d5 levels of the krypton η
atom of mass 86 is known as one metre.
Unit of Mass (kilogram, kg)
The mass of platinum-indium cylinder deposited at the International Bureau of
Weights and Measures and declared as the international prototype of the
kilogram by the First General Conference of Weights and Measures is called as
one kilogram.
Unit of Time (second, s)
1131, 566, 925, 974.7 of the length of the tropical year for 1900, the year
commencing at 1200 hours universal time on the first day of January, 1900 is
termed as one second.
Unit of Electric Current (ampere, A)
The constant current which flows in two parallel straight conductors of infinite
length of negligible circular cross-section and placed at a distance of one metre
from each other in vacuum producing a force of 2 × 10–7 New tons per metre
length between the conductors is defined as an ampere.
FOREWORD vii
Unit of Thermodynamic Temperature (degree Kelvin, K)
The degree interval of the thermodynamic scale on which the temperature of
triple point of water is 273.16 degrees, is known as one degree Kelvin.
Units of Luminous Intensity (candela, cd)
One sixtieth part of luminous intensity normally emitted by one hundred
millimetre square of integral radiator (black body) at the temperature of solidifi-
cation of platinum is called as one candela.
The SI units make the use of multiples and sub-multiples 1000 times or
1/ 1000 times the unit quantity and in powers of 103 (kilo) or 10–3 (milli) in respect
of still larger and smaller quantities respectively. The lengths are measured usually
in kilometre (1 km = 1000 m), metre and millimetre (1 mm = 10–3 m).The symbols
of units are not to be suffixed with V for plural.
The force is a derived quantity and physical law connecting the quantity to
the fundamental quantities or previously obtained derived quantities is force =
mass × acceleration. It is defined as that force which produces unit acceleration
i.e., 1 m per sec2 in a unit mass of 1 kg. Its unit is Newton (N). Though, the
Newton is a small unit, a still larger unit kN may be used. The intensity of force
(viz., stress) due to 1 Newton over a unit area of one metre square is known as
one pascal. It is denoted by symbol, Pa. (1 Pa = 1 N/m2 and 106. Pa = 1 N/mm2,
viz. 1 MPa = 1 N/mm2).
SI system of units have many advantages. The units are very handy. The
burden of non-decimal coefficients in foot-pound second system is avoided. It
has relatively large main units in contrast to centimetre-gram-second system.
At the same time, it is closely related to centimetre-gram-second system of units.
In practice, it results in perfectly reasonable number when the value of g = 10
m/sec2 is used instead of 9.806 m/sec2.
(Professor V.S. Mokashi, Visvesvaraya Regional College of Engineering,
Nagpur in his paper titled as International System (SI) Units and their
Application to Engineering published in Journal of Institution of Engineers,
India, Vol. 19, March 1970 has highlighted the advantages and discussed SI
units. A reference has been made to this paper).
Structural Engineering is the science and art of planning, design,
construction, operation, maintenance and rehabilitation of structures. The term
“structures” includes bridges, buildings and all types of civil engineering
structures (towers, shells, etc.) composed of any structural material.
(Reference: Brochure, International Association for Bridge and Structural
Engineering, Final Invitation to the International Conference, Structural
Eurocodes, Daros, Switzerland September 14–16, 1992).
Author
Preface to the First Edition
In this book, the author with his long teaching experience in the subject has
made an attempt to present the subject matter of design of steel structures in a
way which lays emphasis on the fundamentals, keeping in view the difficulties
experienced by the students. Every basic principle, method, equation or theory
has been presented in simplified manner. Metric system of units has been used
throughout the text. Indian Standards Specifications have been followed. The
book is intended for the use of degree, diploma and A.M.I.E. students in various
branches of engineering. The book deals with design of structural members and
their connections.
Each topic introduced is thoroughly described. A number of design problems
including problems for examinations of the University of Jodhpur, and A.M.I.E.
has been solved to illustrate the theory and practice. Slide-rule computation
accuracy is adequate for the design and has been followed. The chapters have
been so arranged that it facilitates self-understanding of the subject, during
study. In spite of careful scrutiny of the manuscript, it is possible that some
typographical and computational errors are still left. The author shall be highly
obliged to any one who brings these errors to his notice.
The author is thankful to Shri J.N. Srivastava and other colleagues who have
very generously helped with their suggestions. The author is also thankful to
the University of Jodhpur, Jodhpur and the Institution of Engineers, India, for
following the use of their examinations, problems.
Suggestions from the readers for the improvement of the book are welcome.
21 July, 1971 Ram Chandra
Preface to the Seventh Edition
In the subsequent editions of this book, since first edition published in 1970
uptil now, the author enhanced the text by adding useful matter, fresh topics
such as column formulae for axial stress in compression, design of built-up and
perforated cover plate columns, modified and adjusted interaction formulae,
equivalent axial load method of design of eccentrically loaded columns,
approximate method of design of combined footing, graphical method of
curtailment of flange plates, corrugated aluminium sheets used for roof covering
and several examples. The author also added further text of design of high
strength friction grip bolts.
The twelveth edition of the book itself is a fourth edition in S.I. system of
units (viz., system international d’ unites) and revised, rewritten and updated
as per the latest code (viz., ‘Code of Practice for General Construction in Steel.
IS : 800–1984) incorporating the revision of permissible stresses, effective length
of the columns with idealised support conditions and columns in framed
structures and Merchant Rankine formula for the allowable stresses. The concept
of shear lag, design of semi-rigid connections, their behaviour (linear and non-
linear) and methods of analysis have also been included.
The abbreviated symbols for Rolled Steel Sections as recommended
in IS: 808–1989 have been used throughout the text of the book. Various
definitions relating to the new and rational concept of Wind-Load as per
IS: 875 (Part III)–1987 have been given in Chapter 2. Accordingly Chapter 9
(viz. Design of Roof Trusses) has been completely revised and determination of
wind load has been thoroughly described and illustrated.
Author expresses his sincere thanks to his colleagues, members of staff in
various engineering colleges and students for appreciating the efforts made by
them. The author also expresses his personal thanks for the Publishers Shri
Rajinder Kumar Jain and Shri Sandeep Jain for getting the book prepared by
latest technique and bringing out the book in such a nice getup.
Author shall welcome the suggestions from the readers for the further
improvement of the book in forthcoming editions.
Jodhpur Dr. Ram Chandra
August 21, 1991
Contents
PART 1 DESIGN OF STEEL BRIDGES
CHAPTER 1 GENERAL 3–32
1.1 Introduction 3
1.2 Classification of Steel Bridges 4
1.3 Movable Bridges 10
1.3.1 Swing Bridge 10
1.3.2 Bascule Bridge 11
1.3.3 Rolling Bridge 12
1.3.4 Vertical Lift Bridge 12
1.3.5 Transporting Bridge 13
1.3.6 Floating Swing Bridge 13
1.4 Comparison of Fixed and Movable Bridges 13
1.5 Selection of Type of Bridges 14
1.5.1 Foundation Condition 14
1.5.2 Clearance Requirement 14
1.5.3 Length of the Bridge 14
1.5.4 Width of the Bridge 15
1.5.5 Live Load on the Bridge 15
1.5.6 Initial Cost 15
1.5.7 Operation and Maintenance Cost 15
1.5.8 Appearance 15
1.6 Erection Methods for Bridges 15
1.6.1 By Construction of Staging (Falsework) 16
1.6.2 By Rolling or Pushing from the Bank 17