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1、STEEL FIBER REINFORCED CONCRETE Compilation 27 American Concrete Institute COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services A C 1 COMP*27 * E 0662949
2、 0538223 969 W 3 8 14 20 29 30 36 Steel Fiber Reinforced Concrete AC1 Compilation 27 Steel Fiber Reinforced Concrete in Industrial 41 Floors, by P.C. Tatnall and L. Kuitenbrouwer Steel Fibers Reinforce Auto Assembly Plant Floor, by Chuck Robinson, Angelo Colasanti and Gary Boyd 47 Applications of St
3、eel Fiber Reinforced Concrete, by Gary L. Vondran 52 Steel Fiber Reinforced Shotcrete for Support of Underground Openings in Canada, by Dudley R. Morgan 56 Steel Fibers Reinforce Accelerator Tunnel fining, by Don Rose 62 Designing Fiber Reinforced Concrete Based on Toughness Characteristics, by J. M
4、oens and D. Nemegeer 68 Influence of Fiber Geometry in Steel Fiber Rein- forced Dry-% Shotcrete, by Nemkumar Banthia, Jean-Francois Trottier, David Wood, and Denis Beaupre 72 Influence of Fiber Geometry in Steel Fiber Rein- forced Wet-Mix Shotcrete, by Nemkumar Banthia, Jean-Francois Trottier, Denis
5、 Beaupre, and David Wood Repaired Reinforced Concrete Beams Failing i n Shear, by G. Andrews and A.K. Sharma Fiber-Reinforced Rapid-Setting Concrete, by P. Balaguru RCC Pavement Reinforced With Steel Fibers, by Antonio Nanni and Aziz Johari SIFCON Connections for Seismic Resistant Frames, by Antoine
6、 E. Naaman, James K. Wight, and Hossam Abdou Slurry Infiltrated Mat Concrete (SIMCON), by Lloyd E. Hackman, Mark B. Farrell, and Orville O. Dunham Tests of Reinforced Concrete Continuous Beams Repaired With and Without Fibro-Ferrocrete, by AK. Sharma COPYRIGHT ACI International (American Concrete In
7、stitute) Licensed by Information Handling Services COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services A C 1 COMP*27 * 0662949 0538224 8T5 Preface AC1 Compilations combine material previously published in Institute periodicals to provide compact and re
8、ady reference on specific topics. The Material in a compilation does not necessarily represent the opinion of an AC1 technical committee - only the opinions of the individual authors. However, the information presented here is considered to be a valuable resource for readers interested in the subjec
9、t. James I. Daniel Chairman, AC1 Committee 544 Fiber Reinforced Concrete On The Cover: The new Chrysler Jefferson North Assembly Plant in Detroit contains approxi- mately 1.5 million square feet of steel fiber reinforced concrete slab-on-grade. Use of steel fibers in the concrete allowed control joi
10、nt spacing to be increased, thereby eliminating 3 miles of jointing on the project, and made it possible to place most of the concrete using trucks. (See article starting on page 8.) American Concrete Institute, Box 191 50, Redford Statlon, Detroit, Mlchlgan 48219 COPYRIGHT ACI International (Americ
11、an Concrete Institute) Licensed by Information Handling Services COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services A C 1 COflP*27 * - 0662947 0518225 731 Observations about large scale tests in Industrial Floors n the European industrial building ind
12、ustry, steel fibers have been used in place of conventional re- inforcement in the form of rein- forcing bars or welded wire fabric for many concrete floors on grade for 15 years. In that time, the use of these floors has grown steadily: in Belgium and the Netherlands, it is conserva- tively estimat
13、ed that at least 49 per- cent, well over 32.5 million ft (2.5 million m ) of the concrete floors con- structed in 1991 contain steel fiber re- inforcement. In Europe over 320 million ft2 (25 million m ) of steel fi- ber reinforced concrete (SFRC) floors are in use. The use of SFRC for indus- trial f
14、looring is also growing in North America due to the economies it pro- vides. Practical experience is available with SFRC floors that have been in service for many years. Kowledge and experience about the materials poten- tial is becoming more widespread in the design world, and SFRC is being specifi
15、ed more systematically, demon- strating its increasing acceptance by designers, builders, and owners. To date, very little is available in the way of instructions, specifications, or standards for designing SFRC floors. Only the Netherlands Commission for Active Research (Nederlandse Com- missie voo
16、r Uitvoerende Research, or C.d.R.), under the umbrella of the Netherlands Concrete Society, has published a document about SFRC floors.* In fact, standards covering tradi- tional concrete floor design are also limited. France has its “Regles Profes- sionnelles” (revised in 1990),3 and in the United
17、Kingdom there is “Techni- cal Report 34,” published by the Con- crete Society in 19W4 The AC1 Building Code does not mention slabs- on-grade, and the AC1 Committee 302 and 360 documents are reports to be used only as guides for the design and 2 1 l construction of floors. All of these are typical of
18、 what one finds worldwide; in some cases, documents mention the possible use of SFRC, but the respon- sibility is completely up to the design engineer. Besides the practical experience, a great deal of research has been re- ported on SFRC. Much of this research was conducted on concrete with a steel
19、 fiber content of at least 1 volume per- cent (132 lb/yd3, or 78 kg/m3) and is not applicable to concrete floors where the usual proportion of steel fibers is between 0.25 and 0.5 volume percent. A few studies have been devoted spe- cifically to SFRC floors, and these have been carried out on the in
20、itiative of the fiber manufacturers. As a result, it is possible to draw a first cautious connection between the material char- acteristics of the composite SFRC and its behavior on a large scale. In this way the picture of the behavior of SFRC with respect to load-bearing ca- pacity, fatigue, impac
21、t resistance, shrinkage, and corrosion can be sketched. By extension, this may lead to the formulation of standards and specifications governing its practical use. Material characteristics of SFRC Two countries, the United States and Japan, have established standards for characterizing the propertie
22、s of SmC - ASTM C 101g5 and JSCE-SF4,6 re- spectively. Both standard test methods, originally published in 1984, define the same two properties, namely, flexural strength and toughness. The standards prescribe a four-point bend- ing test on a prismatic test specimen in which the load is recorded as
23、a func- tion of the deformation of the test specimen. The testing equipment must be able to maintain a constant rate of deflection of the test specimen. The Netherlands C.U.R. Recommendation 10 is based on these principies. Flexural strength In the ASTM Standard, flexural strength is defined at the
24、occurence of the first crack in the test specimen. This is the point at which the load-de- flection curve deviates from a straight line - Point A in Fig. 1. Flexural strength is calculated from the load at first crack and the dimensions of the test specimen. In the Japanese Stand- ard, flexural stre
25、ngth is defined in terms of the maximum load - Pu in Fig. 2 - and the dimensions of the test specimen, the so-called modulus of rupture. Toughness In both standards, toughness is based on the energy required to de- form the test specimen. This energy is represented by the area under the load- deflec
26、tion curve. The ASTM standard defines a toughness index that is the ratio of the absorbed energy up to a given deflec- tion of the test specimen, as indicated in Fig. 1, to the absorbed energy up to first crack. The Japanese Standard defines an equivalent flexural strength that is de- rived from the
27、 average load up to a de- flection of the specimen of 11150 of the specimen span length. This aver- age load is found by dividing the ab- sorbed energy up to the preset deflection by that deflection, as shown in Fig. 2. Testing The Institute for Building Materials and Structures of the Netherlands O
28、r- ganization for Applied Scientific Re- search (TNO) performed a series of bending tests, each consisting of a minimum of six specimens, on con- crete containing different types of steel STEEL FIBER REINFORCED CONCRETE 3 COPYRIGHT ACI International (American Concrete Institute) Licensed by Informat
29、ion Handling Services COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services A C 1 COMPt27 tt W 0662949 051822b b78 W 9 3 Fig. I bh2 f*=P,- kh- 5.56 -4 I H 3 however, with the slab tests, there is a redistribu- tion of the bending moments (stresses) after
30、 the first-peak load, which leads to higher ultimate load capacities and thus enhanced performance for the de- signer and owner. Thames Polytechnic, Dartford The Civil Engineering Department of Thames Polytechnic in Dartford, United Kingdom, carried out a com- parative study on a number of test slab
31、s on ground. Each of the slabs measured 9.8 x 9.8 ft (3 x 3 m) square and was 6 in. (150 mm) thick, The base consisted of a compacted sand bed, of which the Westergaard modu- lus of subgrade reaction k was re- corded as 130 psi/in. (0.035 MPdmm), or an equivalent CBR of 4. More than nine slabs were
32、cast: non reinforced, conventionally reinforced, and with s m c . All the slabs were loaded until fail- ure with a point load at the center of the slab on a 4 x 4 in. (100 x 100 mm) base plate. The load was applied in 4 AC1 COMPILATION COPYRIGHT ACI International (American Concrete Institute) Licens
33、ed by Information Handling Services COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services A C 1 COMP*27 8% W Ob62949 0538227 504 W Table 1 - Netherlands beam bending tests Table 2 - Imperial College supported slab tests 2.25 kip (10 kN) increments, and s
34、lab deflelction was recorded at each incre- ment. In particular, the load at first vis- ible crack (at the slab edge) and the maximum load reached were recorded. The test results relevant here are from nonfibrous slabs and slabs rein- forced with drawn wire steel fibers with hooked ends, described a
35、s No. 2 and No. 3 in Table 1, and are shown in Table 3. The results show that the load-bear- ing capacity of the slabs reinforced with steel fibers is considerably higher than that of the non-reinforced slab. The maximum load is increased by more than SO percent when fiber No. 2 is used at an additi
36、on rate of 34 lb/yd3 (20 kg/m3), and when fiber No. 3 is used at 34 lb/yd3 (20 kg/m3) the maxi- mum load virtually doubles. It can rea- sonably be expected that a test carried out to the maximum with SO Ib/yd3 (30 kg/m) of fiber No. 3 would lead to a maximum load of over 90 kips (400 w. The occurren
37、ce of the first visible crack also appears to be delayed; at 34 lb/yd3 (20 kg/m3) of fiber No. 2, the load is 17 percent higher; at 50 Ib/yd3 (30 kg/m3) of fiber No. 3, the increase is 61 percent. The behavior is mark- edly different from that observed in four-point bending tests on beams, where the
38、 first-crack occurs at the same load as in a test specimen with- out steel fibers and where the load- bearing capacity after cracking does not increase significantly. Two parameters varied in this test program: the fiber quantity added and the diameter of the fiber used. These tests confirm that: a
39、higher quantity of fibers produces a higher load-bearing capacity a higher aspect ratio of the steel fi- ber produces a higher load-bearing capacity Two observations are made concern- ing this study: 1. Because of the limited number of test specimens, there is no statistical data concerning the reli
40、ability of the results. However, the results are com- pletely in line with expectations if the relation between the quantity of fibers added, the steel fiber characteristics, and the loads are considered. Where a higher first-crack load was achieved, the maximum load also increased. 2. This study le
41、ads to some conclu- sions concerning the behavior of steel fiber reinforced slabs on ground rela- tive to unreinforced slabs on ground. Extension of these conclusions to slabs with different types and quantities of fibers, with different dimensions, on different bases, and loaded in a differ- ent wa
42、y should be done with caution. For example, comer and edge loading were not investigated. Belgium Building Research Institute - in-situ testing The Scientific and Technical Center for the Building Industry in Belgium has conducted various load tests in- situ on two monolithically cast and finished i
43、ndustrial floors. Both floors were cast with SFRC with 50 lb/yd3 (30 kg/m3) of the wire fibers described as No. 3 in Table 1. Before placement of the ground slab the Westergaard modulus of subgrade reaction k was determined on the base. During placement, concrete specimens were cast for compression
44、and flexural testing at 28 days. The floors themselves were loaded after 28 days with a concentrated load on a base plate of 4 x 4 in. (100 x 100 mm). Three tests were performed in each of the following loading cases: 1. In the center of a floor slab sec- tion fomied by the sawn control joints 2. On
45、 a free (unsupported) edge 3. On a sawn joint 4. In the comer formed by a sawn joint and a free edge The results of these tests were com- pared with the theoretical cracking load calculated according to the classi- cal formulas for slabs on an elastic foundation (Westergaard). According to this theo
46、ry, cracks occur when the calculated tensile stresses in the floor equal the flexural strength of the con- crete as determined on prismatic beams in bending. The theoretical loads shown in Table 4 were calcu- lated based on the measured k-value and the results of the bending tests on the beam specim
47、ens. Because of limited loading capabil- ity, the cracking load for Case 1, cen- tral loading, was not reached for either Slab A or Slab B. Visual cracking was observed on the free edge condition, Case 2, in Slab A only. In all the other cases the crack formation could not be determined with certain
48、ty, and ultra- sonic measurements were used to esti- mate cracking loads. These test results show that crack formation occurs at much higher con- centrated loads than indicated by the classical calculation models. The con- tribution made by the steel fiber rein- STEEL FIBER REINFORCED CONCRETE 5 COP
49、YRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services COPYRIGHT ACI International (American Concrete Institute) Licensed by Information Handling Services A C 1 COMP*27 * m 0662949 0538228 440 I / Table 4 - Summary of theoretical and experimental loads, Belgium in-situ slab tests, kips PLATEAU LOAD II DEFLECTION _c Fig. 3 - Typical load-deflection relationship for Imperial Col- lecie steel fiber reinforced slabs. Table 3 - Thames Polytechnic slab on ground tests *In this f i r s t test, the capacity of the tesfing apparatus
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