AISC DESIGN GUIDE 17-2002 High Strength Bolts A Primer for Structural Engineers.pdf

1、17Steel Design GuideHigh Strength BoltsA Primer for Structural EngineersGeoffrey Kulak Professor Emeritus University of AlbertaEdmonton, CanadaAMERICAN INSTITUTE OF STEEL CONSTRUCTIONCopyright 2002byAmerican Institute of Steel Construction, Inc.All rights reserved. This book or any part thereofmust

2、not be reproduced in any form without thewritten permission of the publisher.The information presented in this publication has been prepared in accordance with rec-ognized engineering principles and is for general information only. While it is believed tobe accurate, this information should not be u

3、sed or relied upon for any specific appli-cation without competent professional examination and verification of its accuracy,suitablility, and applicability by a licensed professional engineer, designer, or architect.The publication of the material contained herein is not intended as a representatio

4、nor warranty on the part of the American Institute of Steel Construction or of any otherperson named herein, that this information is suitable for any general or particular useor of freedom from infringement of any patent or patents. Anyone making use of thisinformation assumes all liability arising

5、 from such use.Caution must be exercised when relying upon other specifications and codes developedby other bodies and incorporated by reference herein since such material may be mod-ified or amended from time to time subsequent to the printing of this edition. TheInstitute bears no responsibility f

6、or such material other than to refer to it and incorporateit by reference at the time of the initial publication of this edition.Printed in the United States of AmericaFirst Printing: October 2002copyright page.qxd 9/30/2002 2:35 PM Page 1ACKNOWLEDGEMENTSThe author would like to thank the reviewers

7、for their assis-tance in the development of this design guide. Their com-ments and suggestions have enriched this design guide.AUTHORFollowing several years experience as a bridge designer,Geoffrey Kulak spent most of his career as a universityteacher and was Professor of Civil Engineering at the Un

8、i-versity of Alberta (Edmonton, Canada) from 1970 to 1996.He is now Professor Emeritus at that University. He is a rec-ognized authority on member stability, behavior of weldedand bolted connections, and fatigue of fabricated steelmembers. He has extensive experience in building codedevelopment, res

9、earch, teaching, and consulting. His edu-cation includes B.Sc. in Civil Engineering at the Universityof Alberta, M.S. at the University of Illinois, and the Ph.D.degree from Lehigh University. He has published exten-sively, and these publications include the Guide to DesignCriteria for Bolted and Ri

10、veted Joints, A Fatigue Primer forStructural Engineers, and the principal undergraduate steeldesign textbook in Canada, Limit States Design for Struc-tural Steel. Roger L. BrockenbroughCharles J. CarterEdward R. Estes, Jr.Rodney D. GibbleJohn L. HarrisChristopher M. HewittThomas J. LangillWilliam A.

11、 MilekHeath MitchellThomas M. MurrayRex V. OwenCharles R. PageDavis G. ParsonsDavid T. RickerWilliam SeguiJohn ShawW. Lee ShoemakerJames A. SwansonThomas S. TarpyCharles J. WilsonvTABLE OF CONTENTS1. Introduction1.1 Purpose and Scope 1 1.2 Historical Notes. 1 1.3 Mechanical Fasteners 1 1.4 Types of

12、Connections 4 1.5 Design Philosophy. 6 1.6 Approach Taken in this Primer 7 2. Static Strength of Rivets 2.1 Introduction . 9 2.2 Rivets Subject to Tension 9 2.3 Rivets in Shear. 9 2.4 Rivets in Combined Tension and Shear 10 3. Installation of Bolts and Their Inspection 3.1 Introduction . 13 3.2 Inst

13、allation of High-Strength Bolts 13 3.2.1 Turn-of-Nut Installation. 14 3.2.2 Calibrated Wrench Installation 17 3.2.3 Pretensions Obtained using Turn-of-Nut and Calibrated Wrench Methods . 17 3.2.4 Tension-Control Bolts . 18 3.2.5 Use of Direct Tension Indicators . 19 3.3 Selection of Snug-Tightened o

14、r Pretensioned Bolts. 19 3.4 Inspection of Installation . 20 3.4.1 General. 20 3.4.2 Joints Using Snug-Tight Bolts. 21 3.4.3 Joints Using Pretensioned Bolts 21 3.4.4 Arbitration . 21 4. Behavior of Individual Bolts 4.1 Introduction . 23 4.2 Bolts in Tension. 23 4.3 Bolts in Shear 24 4.4 Bolts in Com

15、bined Tension and Shear 25 5. Bolts in Shear Splices 5.1 Introduction . 27 5.2 Slip-Critical Joints. 28 5.3 Bearing-Type Joints 30 5.3.1 Introduction . 30 5.3.2 Bolt Shear Capacity . 30 5.3.3 Bearing Capacity . 31 5.4 Shear Lag 33 5.5 Block Shear . 34 6. Bolts in Tension 6.1 Introduction . 37 6.2 Si

16、ngle Fasteners in Tension. 37 6.3 Bolt Force in Tension Connections . 38 7. Fatigue of Bolted and Riveted Joints 7.1 Introduction . 41 7.2 Riveted Joints 41 7.3 Bolted Joints 42 7.3.1 Bolted Shear Splices . 42 7.3.2 Bolts in Tension Joints 43 8. Special Topics 8.1 Introduction . 45 8.2 Use of Washer

17、s in Joints with Standard Holes. 45 8.3 Oversize or Slotted Holes 45 8.4 Use of Long Bolts or Short Bolts 46 8.5 Galvanized Bolts . 46 8.6 Reuse of High-Strength Bolts 47 8.7 Joints with Combined Bolts and Welds. 48 8.8 Surface Coatings 48 References 51 Index. 55 1Chapter 1 INTRODUCTION 1.1. Purpose

18、 and ScopeThere are two principal types of fasteners used in contemporary fabricated steel structuresbolts and welds. Both are widely used, and sometimes both fastening types are used in the same connection. For many connections, it is common to use welds in the shop portion of the fabrication proce

19、ss and to use bolts in the field. Welding requires a significant amount of equipment, uses skilled operators, and its inspection is a relatively sophisticated procedure. On the other hand, bolts are a manufactured item, they are installed using simple equipment, and installation and inspection can b

20、e done by persons with only a relatively small amount of training. Engineers who have the responsibility for structural design must be conversant with the behavior of both bolts and welds and must know how to design connections using these fastening elements. Design and specification of welds and th

21、eir inspection methods generally involves selecting standardized techniques and acceptance criteria or soliciting the expertise of a specialist. On the other hand, design and specification of a bolted joint requires the structural engineer to select the type of fasteners, understand how they are to

22、be used, and to set out acceptable methods of installation and inspection. Relatively speaking, then, a structural engineer must know more about high-strength bolts than about welds. The purpose of this Primer is to provide the structural engineer with the information necessary to select suitable hi

23、gh-strength bolts, specify the methods of their installation and inspection, and to design connections that use this type of fastener. Bolts can be either common bolts (sometimes called ordinary or machine bolts) or high-strength bolts. Although both types will be described, emphasis will be placed

24、on high-strength bolts. Because many riveted structures are still in use and often their adequacy must be verified, a short description of rivets is also provided. 1.2. Historical Notes Rivets were the principal fastener used in the early days of iron and steel structures 1, 2. They were a satisfact

25、ory solution generally, but the clamping force produced as the heated rivet shrank against the gripped material was both variable and uncertain as to magnitude. Thus, use of rivets as the fastener in joints where slip was to be prevented was problematic. Rivets in connections loaded such that tensio

26、n was produced in the fastener also posed certain problems. Perhaps most important, however, the installation of rivets required more equipment and manpower than did the high-strength bolts that became available in a general way during the 1950s. This meant that it was more expensive to install a ri

27、vet than to install a high-strength bolt. Moreover, high-strength bolts offered certain advantages in strength and performance as compared with rivets. Bolts made of mild steel had been used occasionally in the early days of steel and cast iron structures. The first suggestion that high-strength bol

28、ts could be used appears to have come from Batho and Bateman in a report made to the Steel Structures Committee of Scientific and Industrial Research of Great Britain 3 in 1934. Their finding was that bolts having a yield strength of at least 54 ksi could be pretensioned sufficiently to prevent slip

29、 of connected material. Other early research was done at the University of Illinois by Wilson and Thomas 4. This study, directed toward the fatigue strength of riveted shear splices, showed that pretensioned high-strength bolted joints had a fatigue life at least as good as that of the riveted joint

30、s. In 1947, the Research Council on Riveted and Bolted Structural Joints (RCRBSJ) was formed. This body was responsible for directing the research that ultimately led to the wide-spread acceptance of the high-strength bolt as the preferred mechanical fastener for fabricated structural steel. The Cou

31、ncil continues today, and the organization is now known as the Research Council on Structural Connections (RCSC). The first specification for structural joints was issued by the RCRBSJ in 1951 5. At about the same time as this work was going on in North America, research studies and preparation of s

32、pecifications started elsewhere, first in Germany and Britain, then in other European countries, in Japan, and elsewhere. Today, researchers in many countries of the world add to the knowledge base for structural joints made using high-strength bolts. Interested readers can find further information

33、on these developments in References 6, 7, 8, 9. 1.3. Mechanical Fasteners The mechanical fasteners most often used in structural steelwork are rivets and bolts. On occasion, other types of mechanical fasteners are used: generally, these are special forms of high-strength bolts. Rivets and bolts are

34、used in drilled, punched, or flame-cut holes to fasten the parts to be connected. Pretension may be present in the fastener. 2Whether pretension is required is a reflection of the type and purpose of the connection. Rivets are made of bar stock and are supplied with a preformed head on one end. The

35、manufacturing process can be done either by cold or hot forming. Usually, a button-type head is provided, although flattened or countersunk heads can be supplied when clearance is a problem. In order to install the rivet, it is heated to a high temperature, placed in the hole, and then the other hea

36、d is formed using a pneumatic hammer. The preformed head must be held in place with a backing tool during this operation. In the usual application, the second head is also a button head. As the heated rivet cools, it shrinks against the gripped material. The result of this tensile strain in the rive

37、t is a corresponding tensile force, the pretension. Since the initial temperature of the rivet and the initial compactness of the gripped material are both variable items, the amount of pretension in the rivet is also variable. Destructive inspection after a rivet has been driven shows that usually

38、the rivet does not completely fill the barrel of the hole. The riveting operation requires a crew of three or four and a considerable amount of equipmentfor heating the rivets and for forming the headsand it is a noisy operation. The ASTM specification for structural rivets, A502, provided three gra

39、des, 1, 2, and 3 10. Grade 1 is a carbon steel rivet for general structural purposes, Grade 2 is for use with higher strength steels, and Grade 3 is similar to Grade 2 but has atmospheric corrosion resistant properties. The only mechanical property specified for rivets is hardness. The stress vs. st

40、rain relationship for the two different strength levels is shown in Fig. 1.1, along with those of bolt grades to be discussed later. (The plot shown in Fig. 1.1 represents the response of a coupon taken from the parent rivet or bolt.) Since the only reason for dealing with rivet strength today is in

41、 the evaluation of an existing structure, care must be taken to ascertain the grade of the rivets in the structure. Very old structures might have rivet steel of lesser strength than that reflected by ASTM A502. (This ASTM standard, A502, was discontinued in 1999.) In fabricated structural steel app

42、lications, threaded elements are encountered as tension rods, anchor rods, and structural bolts. In light construction, tension members are often made of a single rod, threaded for a short distance at each end. A nut is used to effect the load transfer from the rod to the next component. The weakest

43、 part of the assembly is the threaded portion, and design is based on the so-called “stress area.“ The stress area is a defined area, somewhere between the cross-sectional area through the root of the threads and the cross-sectional area corresponding to the nominal bolt diameter. In the US Customar

44、y system of units, this stress area (stA ) is calculated as 2stn9743.0D 7854.0A = (1.1) where D is the bolt diameter, inches, and n is the number of threads per inch. Threaded rods are not a factory-produced item, as is the case for bolts. As such, a threaded rod can be made of any available steel g

45、rade suitable for the job. Anchor rods are used to connect a column or beam base plate to the foundation. Like tension members, they are manufactured for the specific task at hand. If hooked or headed, only one end is threaded since the main portion of the anchor rod will be bonded or secured mechan

46、ically into the concrete of the foundation. Alternatively, anchor rods can be threaded at both ends A490 bolts A502 grade 2 rivetsA502 grade 1 rivets 0.08 0.16 0.2450100150Strain Stress ksi Fig. 1.1 Stress vs. Strain of Coupons taken from Bolts and Rivets A325 bolts 3and a nut used to develop the an

47、chorage. Like threaded rods, anchor rods can be made of any grade of steel. One choice, however, is to use steel meeting ASTM A307, which is a steel used for bolts, studs, and other products of circular cross-section.1It is discussed below. Structural bolts are loosely classified as either common or

48、 high-strength. Common bolts, also known as unfinished, ordinary, machine, or rough bolts, are covered by ASTM Specification A307 11. This specification includes the products known as studs and anchor bolts. (The term stud is intended to apply to a threaded product that will be used without a nut. I

49、t will be screwed directly into a component part.) Three grades are available in ASTM A307A, B, and C. Grade B is designated for use in piping systems and will not be discussed here. Grade A has a minimum tensile strength of 60 ksi, and is intended for general applications. It is available in diameters from in. to 1 in. Grade C is intended for structural anchorage purposes, i.e., non-headed anchor rods or studs. The diameter in this grade can be as large as 4 in. Structural bolts meeting ASTM A307 are sometimes used in structural applications when the forces to