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1、STD-AC1 SP-L4-ENGL 1799 I 0bb2949 054b480 30b DEVELOPMENT O F SEISMIC STEEL REINFORCEMENT PRODUCTS AND SYSTEMS SP-184 international- Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:36:
2、01 MSTNo reproduction or networking permitted without license from IHS -,-,- STD-AC1 SP-L4-ENGL 1999 W Obb2949 054b481 242 Development of Seismic Steel Reinforcement Products and Systems international SP- 184 Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS E
3、mployees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:36:01 MSTNo reproduction or networking permitted without license from IHS -,-,- STD-AC1 SP-LB4-ENGL 1999 Obb2949 054b482 L89 = DISCUSSION of individual papers in this symposium may be submitted in accordance with general requir
4、ements of the AC1 Publication Policy to AC1 headquarters at the address given below. Closing date for submission of discus- sion is May 1, 2000. All discussion approved by the Technical Activities Com- mittee along with closing remarks by the authors will be published in the September/October 2000 i
5、ssue of either AC1 Structural Journal or AC1 Materials Journal depending on the subject emphasis of the individual paper. The Institute is not responsible for the statements or opinions expressed in its publications. Institute publications are not able to, nor intended to, supplant indi- vidual trai
6、ning, responsibility, or judgment of the user, or the supplier, of the information presented. The papers in this volume have been reviewed under Institute publication proce- dures by individuals expert in the subject areas of the papers. Copyright O 1999 AMERICAN CONCRETE INSTITUTE P.O. Box 9094 Far
7、mington Hills, Michigan 48333-9094 Ail 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 visual reproduction or fo
8、r use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors. Printed in the United States of America Editorial production: Jane D. Carroll Library of Congress catalog card number: 99-64291 Copyright American Concrete Institute Provide
9、d by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:36:01 MSTNo reproduction or networking permitted without license from IHS -,-,- STDmACI SP-184-ENGL 1999 Obb2949 054b483 O15 E PREFACE Over the past decade there have been many chan
10、ges to the traditional range of reinforcing systems available for engineers and contractors. These changes have included development of new types and styles of welded wire reinforcement. With new steel-making technology and the latest practices of cold-working rod to wire, the industry is producing
11、higher strength and higher ductility wire and welded wire for more structural uses. New headed reinforcing bar criteria is discussed that promises mechanical anchorage of reinforcing to eliminate or reduce development lengths and ease construction over conventional hooks. There is new guidance crite
12、ria to qualify mechanical reinforcement splices for designs requiring high-strain energy capacity. At the AC1 1997 Spring convention in Seattle, Wash., AC1 Committee 439, Steel Reinforcement, sponsored a full day technical session comprised of two parts. Both parts were a mix of various reinforcemen
13、t products and systems. The presentations provided state-of-the-art coverage of important developments in reinforcing systems that have occurred in recent years. Seven papers were submitted for this symposium volume that cover welded wire reinforcement applications and design approaches, headed rein
14、forcing bar applications and mechanical reinforcement splice system design, and performance standards. These papers will provide engineers and contractors with up-to-date information on new technologies that are available now to improve the performance of reinforced concrete structures, especially i
15、n zones of high seismicity and to make design and construction more cost effective. The manuscripts in this publication were assembled by R. H. Reiterman, who also ensured that each was reviewed according to Institute publication policies. . 111 Copyright American Concrete Institute Provided by IHS
16、under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:36:01 MSTNo reproduction or networking permitted without license from IHS -,-,- CONTENTS INTERRELATIONSHIPS BETWEEN REINFORCING BAR PHYSICAL PROPERTIES AND SEISMIC DEMANDS by J. McDermoti .
17、i DESIGN AND PERFORMANCE OF BRIDGE CAP BEAMCOLUMN JOINTS USING HEADED REINFORCEMENT AND MECHANICAL COUPLERS by S. Sritharan, J. Ingham, M. Priestley, and F. Seible 7 DESIGN AND DETAILING WITH HEADED REINFORCEMENT FOR SEISMICALLY RESISTANT CONCRETE BRIDGE STRUCTURES by D. Berner, T. Dahlgren, and K.
18、Dahl 23 EFFECTS OF CYCLIC BEHAVIOR OF REINFORCING STEEL ON SEISMIC PERFORMANCE OF REINFORCED CONCRETE MEMBERS by M. Rodriguez . 45 NEW DEVELOPMENTS WITH STRUCTURAL WELDED WIRE REINFORCEMENT (WWR) IN ZONES OF HIGH SEISMICITY by R. C. Richardson . 65 AN UPDATE-HIGH-STRENGTH CONCRETE REINFORCEMENT IN C
19、URRENT CODES by R. H. Reiterman . 79 V Previous page is blank Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:36:01 MSTNo reproduction or networking permitted without license from IHS
20、-,-,- STD-AC1 SP-LB4-ENGL 1999 0662949 05Yb485 498 SP 184- 1 Interrelationships between Reinforcing Bar Physical Properties and Seismic Demands by J. McDermott This paper (Title no. S-17) w a s published in the March-Apd 1998 AC1 StructirralJourPial, p. 175-182. Therefor, the following is a summary
21、of the paper, plus a postscript included in the convention presentation. Reinforcing bar physical properties are m a i n determinants for reinforc modulus of elasticity; reinforcing bar 1 Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001,
22、User=listmgr, listmgr Not for Resale, 03/05/2007 02:36:01 MSTNo reproduction or networking permitted without license from IHS -,-,- STD-AC1 SP-LBY-ENGL 1999 0662749 054b48b 824 9 2 McDermott The analysis strategy included (1) relating Sd to e/L. where L is the beam elastic length and e is the depth
23、from the reinforcing bar centroid to the neutral axis, (2) stating a reasonable denition for tensile stress along the beam, in temu of the unknown length of plastic hingui column; footing; reinforcement 7 Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Emplo
24、yees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:36:01 MSTNo reproduction or networking permitted without license from IHS -,-,- H Obb2949 054b492 028 W 8 Sritharan et al. INTRODUCTION The 1989 Loma Prieta earthquake caused significant damage to bridge stock in the San Francisco
25、Bay area 4. This damage, combined with post-earthquake analysis, identified several design shortcomings in existing bridge structures 8, emphasizing the need for a critical review of California bridge seismic design procedures. Consequently, comprehensive research programs were initiated at several
26、institutions in California investigating possible retrofit techniques for existing structural deficiencies and establishing seismic design guidelines for modem bridges. One of the design deficiencies identified in existing bridges was inadequate detailing of cap bedcolumn connections, whose performa
27、nce is critical at the survival limit state. Collapse of, or damage to a number of bridges in the Loma Prieta earthquake, including the double-deck Cypress viaduct, was attributed to poor detailing of the beardcolumn joints 4. As outlined in the following section, when joints are detailed in accorda
28、nce with the conventional design philosophy based directly on shear forces, considerable reinforcement congestion is likely. In this paper, testing conducted at the University of California at San Diego (UCSD) is used to demonstrate that simplified reinforcement details can be obtained for structura
29、l members when utilizing new reinforcement products such as headed rebars and mechanical couplers in conjunction with joint force transfer models. This significantly reduces congestion problems, particularly in cap beamcolumn connections, while providing satisfactory overall seismic performance for
30、the structure. SEISMIC DESIGN PROCEDURE The capacity design philosophy, which now forms the basis for bridge design in most seismically active countries of the world, emphasizes ductile structural performance under severe seismic loading. In concrete bridges, ductile response is typically developed
31、by forming plastic hinges at the top and/or bottom of bridge columns. The reinforcement located in these hinge regions is carefully detailed to accommodate large inelastic reinforcement strains and local member rotations, allowing seismic energy to be dissipated in the form of hysteretic damping. Th
32、e remaining elements of the structure are protected from significant inelastic action by providing a strength hierarchy sufficient to cope with potential strain hardening and uncertainties in material strengths. Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IH
33、S Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:36:01 MSTNo reproduction or networking permitted without license from IHS -,-,- 0662949 0546493 Tb4 Seismic Steel Reinforcement Products and Systems 9 The elastic design of non-critical structural members (typically the brid
34、ge cap beam) is generally well established. However, the design of joints which the bridge members frame into is in comparison poorly understood and is not specifically addressed in bridge design codes such as AASHTO i and Caltrans specifications 3. Two alternative methods may be considered for deta
35、iling bridge joints to ensure satisfactory performance complying with capacity design criteria. I. Building Code Approach In building codes that require specific design ofjoints, such as NZS 3101: 1995 2 and AC1 318-95 12, the design of beamcolumn connections is based upon the maximum joint shear fo
36、rce which is expected at the ultimate limit state. If a similar approach is considered for the design of bridge joints, robust joint performance is ensured. However, this design procedure, when applied to bridge joints, has been found to require an unnecessarily conservative amount of reinforcement,
37、 resulting in major congestion within the joint 6,9,1 i. 2. Rational Force-Transfer Method In research studies at UCSD the design of bridge joints has been investigated 5 - 111 using force transfer mechanisms which ensure a satisfactory pathway for forces through the joint. It has been shown experim
38、entally that good seismic bridge joint response can be obtained using significantly less than the code-recommended quantity of joint reinforcement when the design is based on force transfer mechanisms. In a well-designed bridge joint, the flexural capacity of the column, which frames into the joint,
39、 dictates the shear demand within the joint. Consequently, when a concrete bridge bent is designed with high longitudinal reinforcement content in the columns (pi 2 2.5%), the required reinforcement in the joint region based on force transfer models can also create congestion problems. In such circu
40、mstances, joint reinforcement congestion can be alleviated using altemative reinforcement products as demonstrated in the two large-scale tests presented in this paper. Headed Reinforcement Corp., 11200 Condor Ave., Fountain Valley, CA 92708. Copyright American Concrete Institute Provided by IHS und
41、er license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 03/05/2007 02:36:01 MSTNo reproduction or networking permitted without license from IHS -,-,- M Obb294 0546494 TO 1 O Sritharan et al. RECENTLY-DEVELOPED REINFORCEMENT PRODUCTS In recent years a large number
42、 of products have become available in the United States to simplie the anchorage and lap splicing of conventional reinforcement. Two such products, namely headed reinforcement and mechanical couplers (or bar extenders) were used in large-scale experiments on bridge structural systems at UCSD. These
43、reinforcement products were designed and manufactured by Headed Reinforcement Corporation. When new reinforcement products are used in seismic design, it is not always sufficient to assess these products based upon monotonic stress-strain response. Depending upon the design, it may be necessary to e
44、nsure that the product can withstand cyclic inelastic strains to produce a satisfactory structural response when subjected to earthquake loading. In all cases, it is required that the ultimate capacity of the reinforcement product be not less than the ultimate capacity of the parent reinforcing bar.
45、 Description and relevant laboratory tests performed on the headed reinforcement and bar extender products are as follows. 1. Headed Reinforcement Headed reinforcement provided in the knee joint unit was manufactured by friction welding forged circular heads to conventional ASTM A706/A706M-90 grade
46、60 (414 MPa) weldable reinforcement (see Fig. la). In the process of quality-assurance tests performed by the manufacturer, the headed reinforcement exhibited cyclic behavior identical to that of the parent reinforcing bar with ultimate failure consistently occurring in the reinforcement, not at the
47、 friction weld. To veri that the full capacity would be developed in the parent reinforcing bar, a total of eight headed bars were randomly selected during construction of the knee joint unit at the UCSD facilities, and tested in uniaxial tension. In all cases, fracture of these randomly selected sa
48、mples occurred in the reinforcing bar, away from the fiction weld. 2. Mechanical Coupler (or Bur Extender) System The mechanical coupler system used in the second test unit incorporated two fixtures which coupled two headed reinforcing bars using standard threads (see Fig. lb and lc). The reinforcement heads were formed using a technique Copyright American Concrete Institute Provided by IHS under license with ACI Licensee=IHS Employees/1111111001, User=listmgr, listmgr Not for Resale, 0