《ACI-355.1R-1991-R1997.pdf》由会员分享，可在线阅读，更多相关《ACI-355.1R-1991-R1997.pdf（71页珍藏版）》请在三一文库上搜索。
1、ACI 355.1R-91 STATE-OF-THE-ART REPORT ON (Reapproved 1997) ANCHORAGE TO CONCRETE Reported by ACI Committee 355 Patrick J. Creegan Harry A. Chambers Chairman Secretary Edwin A. Burdette Robert W. Cannon Peter J. Carrato Peter D. Courtois Rolf Eligehausen Raymond R. Funk C. Raymond Hays Paul R. Hollen
2、bach Gerard B. Hassehvander Harry B. Lancelot III* Douglas D. Lee Alexander Makitka, Jr. Donald F. Meinheit Richard S. Orr Moorman L Scott George A. Senkiw Harry Wiewel Jim L Williams Richard E. Wollmershauser *Committee Chairman during the formative years of this report. For the first time concrete
3、 anchoring knowledge based on worldwide test programs is presented in a state-of-the-art document. Performance of different anchor types, including cast-in-place, grouted, expansion, torque-controlled, chemical (adhesive), and undercut anchors is presented in both uncracked and cracked concrete. Fai
4、lure modes in tension and shear, spacing and edge distance, group performance, and load displacements are offered. The effect of loading conditions for structural supports, column bases, and pipe supports as well as base plate flexibility, how load is transferred to anchors, and ductility are discus
5、sed. Design criteria and existing code requirements, both domestic and foreign, are presented. KEYWORDS: Adhesive anchors; anchorages; anchors; anchor groups; base plates; bolts; cast-in-place anchors; chemical anchors; code requirements; combined loads; compression zone; concrete; cracked concrete;
6、 creep; deformation; design criteria; drilling; ductility; dynamic loads; edge distance; embedment; expansion anchors; failure modes; fatigue loads; fasteners; flexible base plates; grouting; loads; load transfer; load-displacement; post-installed anchors; preload; pullout; seismic loads; shear load
7、s; slip; spacing; spalling; static loads; stiffness; studs; structural design; tensile strength; tension loads; tension zone; temperature; torque; torque-controlled anchors; ultimate strength; undercut anchor, yield strength. FORWARD This state-of-the-art report on anchorage to concrete is the first
8、 of a two-volume project being undertaken by ACI Committee 355. The second volume, currently being developed, is a design manual. This first volume includes no design aids or procedures, per se, but with emphasis on behavior will serve as the guide for preparation of the second volume. Committee 355
9、 is working with Committees 349 and 318 toward the objective of including the subject of anchorage to concrete in ACI 318-95. ACI Committee Reports, Guides, Standard Practices, and Commentaries are intended for guidance in designing, planning, executing, or inspecting construction, and in preparing
10、specifications. Reference to these documents shall not be made in the Project Documents. If items found in these documents are desired to be a part of the Project Documents, they should be phrased in mandatory language and incorporated into the Project Documents. ACI 355.1R-91 became effective JuIy
11、1, 1991. Copyright 0 1991, American Concrete Institute. All rights reserved including rights of reproduction and use in any form or by any means, including the making of copies by any photo process, or by any electronic or mechanical device, printed or written or oral, or recording for sound or visu
12、al reproduction or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors. 355.1 R-l 355.1R-2 MANUAL OF CONCRETE PRACTICE TABLE OF CONTENTS Chapter 1-Introduction, p 355.1R-2 1.1 Purpose 1.2 Significance of the subject 1.3 Scop
13、e Chapter 2-Types of anchoring devices, p 355.1R-2 2.1 Introduction 2.2 Scope 2.3 Anchor systems 2.4 Cast-in-place systems 2.5 Post-installed systems Chapter 3-Behavior of anchors, p 355.1R-9 3.1 Introduction 3.2 Behavior of anchors in uncracked concrete 3.3 Behavior of anchors in cracked concrete 3
14、.4 Behavior of cast-in-place anchor bolts in uncracked concrete piers 3.5 References Chapter 4-Design considerations, p 355.1R-53 4.1 Introduction 4.2 Functional requirements 4.3 Materials 4.4 Design basis 4.5 Construction practices 4.6 References Chapter 5-Construction considerations, p 355.1R-60 5
15、.1 Introduction 5.2 Shop drawings/submittals 5.3 Tolerances 5.4 Installation of anchors 5.5 Inspection 5.6 Grouting 5.7 Field problems Chapter 6-Requirements in existing codes and specifications, p 355.1R-66 6.1 Introduction 6.2 Existing codes and specifications 6.3 Application and development of co
16、des 6.4 References Appendix A-Conversion factors, p 355.1R-71 Appendix B-Notations, p 355.1R-71 CHAPTER 1 -INTRODUCTION 1.1-Purpose The purpose of this document is to summarize the current state of the art in anchorage to concrete. 1.2-Significance of the subject To date, anchorage to concrete has r
17、eceived little attention in structural codes. Emphasis has been primarily on the tensile and shear capacities of anchorage devices.As designs became more sophisticated and analyses more exacting, more emphasis was placed on the transfer of loads through single anchors and anchor systems. It was reco
18、gnized that performance of anchors controlled these load transfers, and that generally, failure modes at ultimate anchor capacities were important. There were no definitive design codes or anchorage performance criteria on which designers and installers could rely. Subsequently, a myriad of approach
19、es were developed. 1.3-Scope This state-of-the-art report summarizes anchor types and provides an overview of anchor per- formance and failure modes under various loading conditions in both uncracked and cracked con- crete. It covers design and construction considerations and summarizes existing req
20、uire- ments in codes and specifications. References are given for further review. CHAPTER 2 -TYPES OF ANCHORING DEVICES 2.1-Introduction There are many types of devices used for anchoring structures or structural members to concrete. The design of anchorages, involving the selection and positioning
21、of these devices has been based on the Engineers experience and judgment, private test data, manufacturers data, and existing (sometimes obsolete) code requirements. It is proposed to promote a design of anchorages that more consistently reflects the performance potential of each type of anchor. 2.2
22、-Scope This report relates to the most widely used types of anchor, in sizes ranging from 1/4 in. (6.35 mm) to 2 l/2 in. (63.5 mm) in diameter. Included for consideration are only those devices which can generally be considered bolt and insert-type -,-,- ANCHORAGE TO CONCRETE 355.1R-3 anchors. Exclu
23、ded from consideration are shear lugs, structural shapes, powder actuated fasteners, light plastic or lead inserts, hammer driven concrete nails, screw driven systems, and cables. These are excluded because there is a paucity of test data regarding their performance. The anchors included in this rep
24、ort are either commercially available or may be fabricated. 2.3-Anchor Systems According to present practice, there are two 2.4-Cast-in-place systems 2.4.1 - Embedded Anchors, Non - Adjustable - These anchors may have an end attachment, such as a coil loop, head, nut, or plate, which will enhance an
25、chorage properties and develop full potential strength by means of bond, and/or bearing, or both. Typical examples of these anchors are: Common bolts - structural steel bolts placed with the head into the concrete. (Fig. 2.1)broad groups of anchoring systems: cast-in-place systems (anchors installed
26、 before the concrete is cast) and post-installed systems (anchors installed in holes drilled after the concrete has been cast and cured). Table 2.1 identifies these two groups of anchors. Table 2.1 -Types of anchors in concrete Hooked “J“ or “L“ bolts Threaded rod Cast-in-place systems Reinforcing s
27、teel Embedded, nonadjustable Threaded inserts Common bolts Hooked “J“ however, the concrete is usually well confined by reinforcement. The structural behavior of cast-in-place anchor bolts with long embedment lengths installed in supporting members with limited dimensions is distinctly different fro
28、m that described in the preceding sections.This section summarizes some significant results from extensive research con- ducted for this type of anchor bolt application at the University of Texas at Austin (see Breen 1964; ANCHORAGE TO CONCRETE 355.1R-45 Lee and Breen 1966; Lee and Breen 1970; 3.4.2
29、 General behavior under loading-A single Hasselwander, Jirsa, and Breen 1974; anchor bolt transfers tension load to the concrete Hasselwander, Jirsa, Breen, and Lo 1977; and member in three successive stages: (1) steel-to- Jirsa, Cichy, Calzadilla, Smart, Pavluvcik, and concrete bond, (2) bearing ag
30、ainst the washer of Breen 1984). The test results and design the anchorage device, and (3) a wedging action by recommendations are valid for anchors in well- the cone of crushed and compacted concrete in confined concrete. front of the anchorage device. These three stages These studies focused on ma
31、ny significant are not entirely distinct, but the exact nature of factors affecting anchor bolt behavior including the transition from one stage to the next is highly clear cover, embedment length, bolt diameter, indeterminate and can only be discussed in a bearing area, type of anchorage device, co
32、ncrete general manner. strength, steel yield strength, shape of piers, and Fig. 3.43 shows tail stress plotted against lead bolt group configuration. In addition, a series of stress for three 1 3/4 in. anchor bolts with clear exploratory and supplementary studies were made covers of 3 l/2 in. and th
33、ree different to determine the influence of cyclic loading, lateral embedments: 10, 15, and 20 bolt diameters. loading, transverse reinforcement, and method of Adhesion or bond between the bolt and concrete loading on the bolt behavior. Diameters of anchor is the predominant load carrying mechanism
34、for bolts ranged from 1 to 3 in. Steel yield strengths early stages of loading; little increase in tail stress ranged from 33 ksi (A7) to 105 ksi (A139). is observed with increasing lead stress. The longer Embedment lengths ranged from 10 bolt diameters the bolt, the more load the bolt can carry by
35、the to 20 bolt diameters. A typical test specimen bond mechanism.Under increasing load, bond geometry is shown in Fig. 3.42. strength decreases along the length of the bolt and 8- o”_ I ANCHOR 8OLl- I J/4” ANCHOR BOLT - SECTION A-A SECTION B-B Fig. 3.42 - Typical specimen geometry -,-,- 355.1R-46 MA
36、NUAL OF CONCRETE PRACTICE tail stress begins to increase. The load that was previously carried by a bond mechanism must be transferred to a bearing mechanism. In Fig. 3.43 the bond-to-bearing transition is most clearly seen for the bolt with 200 embedment. For a given load increment, the tail stress
37、 increases more than the lead stress as the load carried by bond is unloaded into bearing on the anchorage device. The bond-to-bearing transition is dependent on the embedment of the bolt; the shorter the bolt, the shorter and less well-defined the transition. After the bond-to-bearing transition, t
38、ail stress increases uniformly with increasing lead stress as the load is carried by bearing or by wedging action. 3.4.3 Failure modes-The failures observed during testing can be described as: (1) bolt failure, (2) concrete cover failure by spalling, and (3) concrete cover failure by wedge-splitting
39、. While these three categories represent distinct failure modes, combinations of these modes were observed in several instances. Bolt failures occurred in several bolts by necking in the threaded portion of the bolts. Little damage to the concrete cover over the bolt was observed at bolt failure. A
40、relatively sudden spalling of the concrete cover over the anchorage device at low loads characterized the failure of bolts with small amounts of clear cover Fig. 3.44(a). For larger amount of clear cover, the failures were characterized by the splitting and spalling of the concrete cover into distin
41、ct blocks by the wedging action of a cone of crushed and compacted concrete which formed in front of the anchorage device Fig. 3.44(b). The distinguishing feature of a wedge-splitting failure was the diagonal cracks marked B in Fig. 3.44(b) which started just in front of the washer on the bolt cente
42、rline and extended toward the front and each side of the specimen. These diagonal cracks were frequently accompanied by a longitudinal crack along the bolt axis C in Fig. 3.44(b), a transverse crack parallel to and near the washer of the anchorage device A in Fig. 8 ?II Is I 10 20 30 40 50 60 70 Tai
43、l Stress, ksi Fig. 3.43 - Tail stress versus lead stress for different embedment lengths -,-,- 3.44(b) or both. Cracking generally started near the anchorage device and extended toward the front, toward the sides of the specimen, or both under increasing load. Tension Tension Cover Spalling Failure
44、Wedge-Splitting Failure Fig. 3.44 - Concrete cover failures 3.4.4 Lead-slip relationships (effect of clear cover and embedment length)-Bolt tension versus lead slip curves associated with different clear covers and embedments are shown in Fig. 3.45 and 3.46. Slip of the anchor bolts was measured rel
45、ative to the front face of the specimen (lead slip). Fig. 3.45 illustrates the effect of clear cover. Since the effect f concrete strength varied approximately with P d lead stress in Fig. 3.45, calculated on the basis of the anchor bolt stress area, was normalized with respect to /- d and plotted a
46、gainst lead slip for four 1 3/4 in. bolts each with an embedment of 15 bolt diameters (15D) and an anchorage device consisting of a nut and a 4 in. diameter, l/2 in. thick washer. As seen in Fig. 3.45, the slopes of the curves are essentially the same until each bolt approaches ultimate capacity. A
47、definite trend of increasing ultimate strength with increasing clear cover is indicated. Fig. 3.46 illustrates the effect of embedment length on the stress-slip relationships of three 1 3/4 in. bolts each with a clear cover of 3 l/2 in. and an anchorage device consisting of a nut and a 4 in. diamete
48、r, l/2 in. thick washer. The initial portions of the curves are essentially the same and there is no appreciable difference between the ultimate strengths of the 15D bolt and the 20D bolt; the ultimate strength of the 1OD bolt, however, is noticeably reduced. The failure of the 10D bolt developed in
49、itially as a typical wedge-splitting mode until the cracking propagated to the sides and front face of the specimen. The result was the complete loss of a rectangular block of concrete cover extending back to the anchorage device over the full width of the specimen, as opposed to the usual group of triangular wedges with a common apex over the anchorage device.Such a failure indicates that the wedge-splitting mechanism did not fully develop and theref