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1、ACI ITG-3-04 became effective September 10, 2004. Copyright 2004, 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 electronic or mechanical device, printed, written, or or
2、al, or recording for sound or visual reproduc- tion or for use in any knowledge or retrieval system or device, unless permission in writing is obtained from the copyright proprietors. ACI Committee Reports, Guides, Standard Practices, and Commentaries are intended for guidance in planning, designing
3、, executing, and inspecting construction. This document is intended for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations and who will accept responsibility for the application of the material it contains. The American Concrete I
4、nstitute disclaims any and all responsibility for the stated principles. The Institute shall not be liable for any loss or damage arising therefrom. Reference to this document shall not be made in contract documents. If items found in this document are desired by the Architect/Engineer to be a part
5、of the contract documents, they shall be restated in mandatory language for incorporation by the Architect/Engineer. ITG-3-1 It is the responsibility of the user of this document to establish health and safety practices appropriate to the specific circumstances involved with its use. ACI does not ma
6、ke any representations with regard to health and safety issues and the use of this document. The user must determine the applicability of all regulatory limitations before applying the document and must comply with all applicable laws and regulations, including but not limited to, United States Occu
7、pational Safety and Health Administration (OSHA) health and safety standards. Report on Bridge Decks Free of Steel Reinforcement Reported by ACI Innovation Task Group 3 ACI ITG-3-04 Emerging Technology Series This document outlines procedures for the design of bridge decks free of steel reinforcemen
8、t and requirements for design and installation of straps to restrain rotation of edge beams to achieve arching action in a deck slab. Keywords: arching; bridge; composite action; corrosion; deck slab; fiber- reinforced concrete; reinforcement-free; transverse confinement; transverse constraint. PREF
9、ACE The concept for the design of a steel-free bridge deck slab described in this report is patented. Therefore, use of the information in this document may require payment of royalties to the owners of the patents. At the time of printing, the United States and the United Kingdom have granted a pat
10、ent for the steel-free cast-in-place bridge deck slabs, with a patent pending in Canada. The steel-free precast slab is also patented in the United States, and the global patent is pending. Interested parties are invited to submit information regarding the identification of an alternative(s) to this
11、 patented item to ACI Headquarters. Your comments will receive careful consideration at a meeting of the responsible standards committee, which you may attend. The American Concrete Institute takes no position respecting the validity of any patent rights asserted in connection with any item mentione
12、d in this report. Users of this report are expressly advised that determination of the validity of any such patent rights, and the risk of infringe- ment of such rights, are entirely their own responsibility. The inventor of the reinforcement-free bridge deck concept described in this report sponsor
13、ed preparation of the report and provided reimbursement to the authors to assist in recovery of their costs and expenses related to travel to meetings; however, none of the authors received an honorarium. Gerald H. AndersonHarold R. Sandberg Andrzej S. NowakSteven L. Stroh Joe Gutierrez Chair ACI en
14、courages the development and appropriate use of new and emerging technologies through the publication of the Emerging Technology Series. This series presents information and recommendations based on available test data, technical reports, limited experience with field applications, and the opinions
15、of committee members. The presented information and recommendations, and their basis, may be less fully developed and tested than those for more mature technologies. This report identifies areas in which information is believed to be less fully developed, and describes research needs. The profession
16、al using this document should understand the limitations of this document and exercise judgment as to the appropriate application of this emerging technology. ITG-3-2ACI COMMITTEE REPORT Conclusions from research conducted since the document was first written are included in Appendixes B and C. CONT
17、ENTS Chapter 1Introduction, p. ITG-3-2 1.1Purpose 1.2Scope and objectives 1.3Further research needs Chapter 2Definitions and abbreviations, p. ITG-3-3 Chapter 3Design methodology, p. ITG-3-3 3.1Composite action 3.2Beam spacing 3.3Slab thickness 3.4Diaphragms 3.5Haunches 3.6Transverse confinement 3.7
18、Strap spacing 3.8Strap size 3.9Strap connection 3.10Strap connection in negative moment regions 3.11Edge stiffening 3.12Reinforcement for transverse negative moment 3.13Reinforcement in longitudinal negative moment 3.14Fibers in concrete 3.15Crack control Chapter 4Materials, p. ITG-3-7 Chapter 5Spec
19、ial considerations, p. ITG-3-8 5.1Transverse edge stiffening 5.2Skew angle 5.3Concrete parapet connection 5.4Cracking 5.5Splitting stresses 5.6Provisions for safety 5.7Fatigue resistance of deck slabs Chapter 6Design examples, p. ITG-3-12 6.1Common features 6.2Transverse edge beams 6.3Parapet wall C
20、hapter 7Case histories, p. ITG-3-14 Chapter 8Construction and constructibility, p. ITG-3-14 8.1Connection straps 8.2Formwork for slab 8.3Mixing fibers 8.4Finishing FRC surfaces 8.5Precast installation Chapter 9Maintenance and cost effectiveness, p. ITG-3-16 9.1Maintenance 9.2Repair 9.3Costs Chapter
21、10References, p. ITG-3-17 10.1Cited references Appendix APostcracking strength of FRC test method, p. ITG-3-19 Appendix BCrack control and fatigue resistance of reinforcement-free deck slabs, p. ITG-3-19 B.1Purpose and scope B.2Comparative results B.3References Appendix CFibers and control of cracks
22、 due to volumetric changes, p. ITG-3-21 C.1References Appendix DResearch needs, p. ITG-3-21 D.1Research goals D.2Areas of major R the Crowchild Trail Bridge in Calgary, Alberta; the Waterloo Creek Bridge in British Columbia; and the Lindquist Bridge in British Columbia, which is on a forestry road a
23、nd incor- porates a precast slab. A reinforcement-free precast slab has also been used in the reconstruction of a wharf structure in Halls Harbour, Nova Scotia. The research conducted on reinforcement-free deck slabs in Canada over the past 12 years is reported in the tech- nical literature (Section
24、 10.1) along with the histories of bridges incorporating the new concept. Chapter 10 is a listing of the published papers referenced in this document. In addition to the work done in Canada, research on the reinforcement-free deck slab is also being conducted in the United States (Seible et al. 1998
25、) and Japan (Matsui et al. 2001). 1.3Further research needs While the reinforcement-free bridge deck design leads to elimination of the problem of corrosion from steel reinforce- ment, it also raises several other concerns. Those concerns relate to the possibility that significant longitudinal crack
26、ing will be observed over time, and other types of cracks may lead to serviceability problems. Another area of concern is the potential for deterioration of the steel straps due to corrosion and the lack of their protection from a possible fire or impact. To address this issues, Appendices B, C, and
27、 D provide supplemental information and list areas of additional research that should be considered to answer the afore- mentioned concerns. CHAPTER 2DEFINITIONS AND ABBREVIATIONS AFRParamid fiber-reinforced polymer. CFRPcarbon fiber-reinforced polymer. fiberssmall-diameter filaments of materials of
28、 relatively high strength, which can be glass, carbon, aramid, or low- modulus polymer. FRCfiber-reinforced concrete; a fiber-reinforced composite in which the matrix is portland-cement concrete, and in which the fibers are discontinuous and uniformly and randomly distributed. FRPfiber-reinforced po
29、lymer; a fiber-reinforced composite with a polymeric matrix and continuous fiber reinforcement. fiber volume fractionthe ratio of the volume of the fibers to the volume of the fiber-reinforced composite. GFRPglass fiber-reinforced polymer. low-modulus fibersfibers of thermoplastic polymer with a mod
30、uli of elasticity less than 1450 ksi (10 GPa), such as nylon, polyolefin, polypropylene, and vinylon. matrixthe continuous material in a fiber-reinforced concrete or polymer component that contains aligned or randomly distributed fibers. multispine bridgea box-girder bridge in which the bottom flang
31、e is discontinuous in the transverse direction. RCreinforced concrete. reinforcementin this document, this term refers to bars that are added to concrete to enhance its tensile strength. Bars provided for only crack control are not referred to as reinforcement. strapa linear component of steel, FRP,
32、 or other material used to provide external transverse confinement in the rein- forcement-free bridge deck slabs. CHAPTER 3DESIGN METHODOLOGY The design methodology employing the concept described in this report relies mainly on transverse straps (Fig. 3.1 through 3.3), which may be made of steel, c
33、onnected to the top flanges of adjacent girders for preventing their outward relative displacement; such displacement would normally occur when a load is applied on the slab between two girders. A combination of flange restraint against lateral movement and the cracking of concrete at the bottom of
34、the slab leads to the formation of a shallow arch in the slab with the straps acting as ties. The degree of lateral restraint provided by the straps controls the relative lateral movement of adjacent girders and governs the ultimate load at which the slab fails in punching. The failure load can be s
35、everal times greater ITG-3-4ACI COMMITTEE REPORT than the load that causes flexural cracking of the slab, and is markedly greater than the failure load of an RC slab having the same dimensions. The design guidelines that follow are for cast-in-place and precast bridge deck slabs in accordance with t
36、he load and resistance factor design (LRFD) format of the AASHTO Specifications (1998). This method for designing bridge deck slabs can be modified suitably to address slabs of other structures, such as parking garages and marine wharves. A cast-in-place or precast slab supported on beams satisfying
37、 the conditions set forth as follows need not be analyzed except for negative transverse moments due to loads on the overhangs and concrete parapets. 3.1Composite action The deck slab should be composite with parallel supporting beams in the positive moment regions of the beams. The composite action
38、 of the deck slab with the supporting beams provides the necessary confinement in the longitudinal direction of the beams (Bakht, Mufti, and Jaeger 1998). The condition for the composite action in the positive moment regions should be considered in conjunction with Section 3.10, which deals with the
39、 composite action in the negative moment regions. For precast deck slabs, the longitudinal confinement can be provided within the panel itself, elim- inating the need for the composite action (Mufti, Banthia, and Bakht 2001). A deck slab supported on multispine box girders without external bracing e
40、xperiences significant transverse moments under eccentric live loads. Such transverse moments cannot be dealt with by the arching action in the slab. Accordingly, neither cast-in-place nor precast deck slabs without reinforce- ment should be used on multispine box girders unless the box girders are
41、prevented from excessive relative rotation by means of suitable bracing between them. 3.2Beam spacing The spacing of the supporting beams, S, should not exceed 12 ft (3.7 m). The largest spacing of the supporting beams of RC deck slabs designed by the empirical methods of AASHTO is 13.5 ft (4.11 m).
42、 Cast-in-place and precast deck slabs have been tested in the laboratory with a beam spacing of up to 13.1 ft (3.99 m). To be conservative, however, the maximum spacing of bridge girders is limited to 12 ft (3.7 m). The spacing can be increased if approval is obtained from the authority having juris
43、diction over the bridge. The approval process can be facilitated by conducting tests on full-scale models. The spacing of the girders for the first reinforcement steel-free deck slab was 8.9 ft (2.71 m). Before this slab was built, its full-scale model was tested to failure (Newhook and Mufti 1996a)
44、. Subsequently, precast deck slabs with beam spacing of 11.5 ft (3.51 m) were tested at full-scale in the laboratory and implemented in the field (Sargent, Mufti, and Bakht 1999). As noted in Chapter 7, the precast slab of a marine structure is supported on beams at a spacing of 13.1 ft (3.99 m). Th
45、e use of beam spacing greater than 12 ft (3.7 m) should be based on tests of full-scale models and not on the basis of analysis alone. 3.3Slab thickness The deck slab thickness t should be at least 6.5 in. (165 mm), and should not be less than S/15, where S is the spacing of the supporting beams, in
46、 inches (mm). To predict the failure load of deck slabs under concen- trated loads, an analytical model was developed by Mufti and Newhook (1998b). The limiting ratio of beam spacing to slab thickness required in this condition was partially estab- lished by using this method, which has been validat
47、ed with experimental results. Also according to this method and veri- fied by experiment, even a 6 in. (150 mm) thick slab provides sufficient strength to the deck slab supported on beams spaced at 6.6 ft (2.01 m) (Bakht and Lam 2000). To be conser- vative, however, a minimum slab thickness of 6.5 i
48、n. (165 mm) was used. Structures that are not subjected to heavy vehicular Fig. 3.1Haunch between the deck slab and top of the supporting beam. Fig. 3.2Transverse confinement by directly connected straps. Fig. 3.3Illustration of transverse confinement by partially studded straps. BRIDGE DECKS FREE O
49、F STEEL REINFORCEMENTITG-3-5 loads, such as parking garages, can have thinner slabs, but only after confirmatory tests on full-scale models have been conducted. 3.4Diaphragms Unless justified by rigorous analysis, the supporting beams should be connected with transverse diaphragms, or cross-frames, at a spacing of not more than 26 ft (7.9 m). The transfer of wheel loads to beams remote from the live loads takes place primarily through the transverse flexural action of the deck slab. For most bridges, the transve