1、Section 16 INTERACTION SYSTEMS SOIL-REINFORCED CONCRETE STRUCTURE 16.1 GENERAL 16.1.1 Scope Specifications in this Section govern the design of buried reinforced concrete structures. A buried reinforced concrete element becomes part of a composite system comprising the reinforced concrete section an
2、d the soil envelope, both of which contribute to the structural be- havior of the system. 16.1.2 Notations = effective tension area of concrete surrounding the flexural tension reinforcement and hav-ing the same centroid as that reinforcement, divided by the number of bars or wires, sq in.; when the
3、 flex- ural reinforcement consists of several bar sizes or wire the number of bars or wires shall be com- puted as the total area of reinforcement divided by the area of the largest bar or wire used (Arti- cles 16.6.4 and 16.7.4) = total active lateral pressure acting on pipe, Ibs/ft (Article 16.4.5
4、 and Figure 16.4C) = tension reinforcement area on width b, inS2/ft (Articles 16.4.6.6, 16.6.4.7, 16.7.4.7, and 16.8.5.7) = area of total inner cage reinforcement required in length b, in2/ft (Article 16.4.6.6) = area of total outer cage reinforcement required in length b, in2/ft (Article 16.4.6.6)
5、= stirrup reinforcement area to resist radial ten- sion forces on width b, in.2/ft in each line of stirrups at circumferential spacing s (Article 16.4.6) = required area of stirrups for shear reinforcement, = steel area required for an individual circumferen- tial wire for flexure at a splice or at
6、the point of maximum moment for quadrant mat reinforce- ment, in2 (Article 16.4.7) (Article 16.4.6.6.6.2) = width of section which resists M, N, V-Usually = out-to-out horizontal span of pipe or box, ft (Ar- = horizontal width of trench at top of pipe or box, ft = bedding factor (Article 16.4.5) = e
7、arth load bedding factor = live load bedding factor = crack control coefficient for effect of cover and = out-to-out vertical rise of pipe, ft (Figure 16.4C) = load coefficient for embankment installations (Article 16.4.5) = load coefficient for trench installations (Article 16.4.4) = constant corre
8、sponding to the shape of pipe (Ar- ticle 16.4.5) = parameter which is a function of the distribution of the vertical load and the vertical reaction (Ar- ticle 16.4.5) = crack control coefficient for type of reinforce- ment (Article 16.4.6) = distance from compression face to centroid of tension rein
9、forcement, in. (Articles 16.4.6.6, 16.6.4.7, 16.7.4.7, and 16.8.5.7) = thickness of concrete cover measured from ex- treme tension fiber to center of bar or wire located closest thereto (Articles 16.6.4.7, 16.7.4.7, and 16.8.5.7) = D-load of pipe, three-edge bearing test load ex- pressed in pounds p
10、er linear foot per foot of span to produce a 0.01-inch crack (Article 16.4.5) = inside diameter of pipe, in. = service load stress in reinforcing steel for crack control (Articles 16.6.4.7, 16.7.4.7, and 16.8.5.7) = maximum allowable strength of stirrup material, Ibs/in.2 (Article 16.4.6.6.6) = spec
11、ified yield strength of reinforcement, lbs/in.2 (Article 16.4.6) b = 12 inches (Article 16.4.6) ticles 16.4.4, 16.4.5, 16.6.4, and 16.7.4.) (Articles 16.4.4, 16.6.4, and 16.7.4.) spacing of reinforcement (Article 16.4.6) 407 408 HIGHWAY BRIDGES 16.1.2 F, = Fc, = Fd = Fe = Fei = Fe2 = F, = F, = F, =
12、FN = f, = h= H= HAF = j= K= M, = Mu = n= factor for effect of curvature on diagonal tension (shear) strength in curved components (Article 16.4.6.6.5) factor for adjusting crack control relative to aver- age maximum crack width of 0.01 inch when F, = 1.0 (Article 16.4.6.6.4) factor for crack depth e
13、ffect resulting in increase in diagonal tension (shear) strength with decreas- ing d (Article 16.4.6.6.5) soil-structure interaction factor (Articles 16.4.4, 16.6.4, and 16.7.4) soil structure interaction factor for embankment installations (Articles 16.4.4, 16.6.4, and 16.7.4) soil-structure intera
14、ction factor for trench installations (Articles 16.4.4, 16.6.4, and 16.7.4) factor for process and local materials that af- fect the radial tension strength of pipe (Article 16.4.6) factor for pipe size effect on radial tension strength (Article 16.4.6.6.3.1) factor for process and local materials t
15、hat affect the shear strength of pipe (Article 16.4.6.6.5) coefficient for effect of thrust on shear strength (Article 16.4.6.6.5) design compressive strength of concrete, lbs/in.2 (Articles 16.4.6, 16.6.2, and 16.7.2) overall thickness of member (wall thickness), in. (Articles 16.4.6.6,16.6.4.7, 16
16、.7.4.7, and 16.8.5.7) height of fill above top of pipe or box, ft (Articles 16.4.4, 16.4.5, 16.6.4, and 16.7.4) horizontal arching factor (Figure 16.4A) coefficient for effect of axial force at service load stress, f, (Articles 16.4.6.6.4, 16.6.4.7, 16.7.4.7, and 16.8.5.7) coefficient for moment arm
17、 at service load stress, f, (Articles 16.4.6.6.4, 16.6.4.7, 16.7.4.7, and 16.8.5.7) ratio of the active unit lateral soil pressure to unit vertical soil pressure-Rankines coefficient of active earth pressure (Figures 16.4B-D) development length of reinforcing wire or bar, in (Article 16.4.7) factore
18、d moment acting on length b as modified for effects of compressive or tensile thrust, in- lbs/ft (Article 16.4.6.6.5) moment acting on cross section of width, b, ser- vice load conditions, in-lbs/ft (Taken as absolute value in design equations, always c) (Articles 16.4.6.6.4, 16.6.4.7, 16.7.4.7, and
19、 16.8.5.7) factored moment acting on cross section of width b, in.-lbs/ft (Article 16.4.6.6.6.1) number of layers of reinforcement in a cage-1 or 2 (Article 16.4.6.6.4) N, = axial thrust acting on cross section of width b, service load condition (+ when compressive, - when tensile), lbs/ft (Articles
20、 16.4.6.6.4,16.6.4.7, 16.7.4.7, and 16.8.5.7) = factored axial thrust acting on cross section of width b, lbs/ft (Article 16.4.6) = projection ratio (Article 16.4.5.2.1) = negative projection ratio (Figure 16.4A and Table 16.4A) = PL denotes the prism load (weight of the column of earth) over the pi
21、pes outside diameter, lbs/ft (Figure 16.4.A) q = ratio of the total lateral pressure to the total verti- cal load (Article 16.4.5) rs = radius of the inside reinforcement, in. (Article 16.4.6.6.3.1) rsd = settlement ratio (Article 16.4.5.2.1) s = spacing of reinforcement wire or bar, in. (Article 16
22、.4.6.6.4) s, = circumferential spacing of stirrups, in. (Article 16.4.6.6.6) se = spacing of circumferential reinforcement, in. (Ar- ticle 16.4.6.6.4) Si = internal horizontal span of pipe, in. (Articles 16.4.6.6 and 16.4.5.1) tb = clear cover over reinforcement, in. (Article 16.4.6.6.4) Vb = basic
23、shear strength of critical section, lbs/ft where M,/(V,d) = 3.0 (Article 16.4.6.6.5) V, = nominal shear strength provided by width b of concrete cross section, lbs/ft (Article 16.4.6.6.6) Vu = factored shear force acting on cross section of width b, lbs/ft (Article 16.4.6.6.5) Vu, = factored shear f
24、orce at critical section, lbs/ft where M,/(V,d) = 3.0 (Article 16.4.6.6.5) VAF = vertical arching factor (Article 16.4.4.2.1.1) w = unit weight of soil, lbs/ft3 (Article 16.4.4) WE = total earth load on pipe or box, lbs/ft (Articles 16.4.4, 16.4.5, 16.6.4, and 16.7.4) Wf = fluid load in the pipe as
25、determined according to Article 16.4.4.2.2, lbs/ft WL = total live load on pipe or box, lbs/ft (Articles 16.4.4 and 16.4.5) W, = total load, earth and live, on pipe or box, lbs/ft (Articles 16.4.4 and 16.4.5) x = parameter which is a function of the area of the vertical projection of the pipe over w
26、hich lateral pressure is effective (Article 16.4.5) = coefficient of internal friction of the soil (Fig- ure 16.4B) = coefficient of friction between backfill and trench walls (Figure 16.4B) = central angle of pipe subtended by assumed dis- tribution of external reactive force (Figure 16.4F) Nu p p
27、PL p p CI 16.1.2 DIVISION I-DESIGN 409 p +f +r 4“ = ratio of reinforcement area to concrete area (Ar- = strength reduction factor for flexure (Article = strength reduction factor for radial tension (Arti- = strength reduction factors for shear (Article ticle 16.4.6) 16.4.6.6.1) cle 16.4.6.6.3.1) 16.
28、4.6.6.5) 16.1.3 Loads Design loads shall be determined by the forces acting on the structure. For earth loads, see Article 3.20. For live loads see Articles 3.4 through 3.8 and Articles 3.11 and 3.12. For loading combinations see Article 3.22. 16.1.4 Design Design may be based on working stress or u
29、ltimate strength principles. The design criteria shall include structural aspects (e.g. flexure, thrust, shear), handling and installation, and crack control. Footing design for cast-in-place boxes and arches shall be in conformity with Article 4.4. 16.1.5 Materials The materials shall conform to th
30、e AASHTO materials specifications referenced herein. 16.1.6 Soil Structural performance is dependent on soil structure interaction. The type and anticipated behavior of the ma- terial beneath the structure, adjacent to the structure, and over the structure must be considered. 16.1.7 Abrasive or Corr
31、osive Conditions Where abrasive or corrosive conditions exist, suitable protective measures shall be considered. 16.1.8 End Structures Structures may require special consideration where erosion may occur. Skewed alignment may require special end wall designs. 16.1.9 Construction and Installation The
32、 construction and installation shall conform to Sec- tion 27, Division II. 16.2 SERVICE LOAD DESIGN 16.2.1 For soil-reinforced concrete structure interaction systems designed with reference to service loads and al- lowable stresses, the service load stresses shall not exceed the values shown in Arti
33、cle 8.15 except as modified herein. 16.2.2 For precast reinforced concrete circular pipe, elliptical pipe, and arch pipe, the results of three edge- bearing tests made in accordance with AASHTO mate- rials specifications may be used in lieu of service load design. 16.3 LOAD FACTOR DESIGN 16.3.1 Soil
34、-reinforced concrete structure interaction systems shall be designed to have design strengths of all sections at least equal to the required strengths calculated for the factored loads as stipulated in Article 3.22, except as modified herein. 16.3.2 For precast reinforced concrete circular pipe, el-
35、 liptical pipe, and arch pipe, the results of three edge-bear- ing tests made in accordance with AASHTO materials specifications may be used in lieu of load factor design. 16.4 REINFORCED CONCRETE PIPE 16.4.1 Application This Specification is intended for use in design for pre- cast reinforced concr
36、ete circular pipe, elliptical pipe, and arch pipe. Standard dimensions are shown in AASHTO material specifications M 170, M 206, M 207, and M 242. Design wall thicknesses other than the standard wall di- mensions may be used, provided the design complies with all applicable requirements of Section 1
37、6. 16.4.2 Materials 16.4.2.1 Concrete Concrete shall conform to Article 8.2 except that eval- uation off, may be based on cores. 16.4.2.2 Reinforcement Reinforcement shall meet the requirements of Articles 8.3.1 through 8.3.3 only, and shall conform to one of the following AASHTO material specificat
38、ions M 3 1, M 32, M 55, M 221, or M 255. For smooth wire and smooth 410 HIGHWAY BRIDGES 16.4.2.2 TABLE 16.4A Standard Embankment Installation Soils and Minimum Compaction Requirements Installation Type Bedding Thickness Outer Bedding Lower Side Haunch and 5Pe 1 BJ24” (600 mm) minimum, not less than
39、3” (75 mm). If rock foundation, use Bc/12” (300 mm) minimum, not less than 6” (150 mm). Bc/24“ (600 mm) minimum, not less than 3” (75 mm). If rock foundation, use BC/12” (300 mm) minimum, not less than 6” (150 mm). Bc/24” (600 mm) minimum, not less than 3“ (75 mm). If rock foundation, use Bc/12” (30
40、0 mm) minimum, not less than 6“ (150 mm). No bedding required, except if rock foundation, use BJ12” (300 mm) minimum, not less than 6” (150 mm). Type 2 (See Note 3.) 5Pe 3 (See Note 3.) 5Pe 4 95% sw 90% SW, 95% ML, or 100% CL 90% SW or 95% ML 85% SW, 90% ML, or 95% CL No compaction required, except
41、if CL, use 85% CL 85% SW, 90% ML, or 95% CL 85% SW, 90% ML, or 95% CL No compaction required, except if CL, use 85% CL NOTES: 1. 2. 3. 4. SUBTRENCHES 4.1 4.2 4.3 Compaction and soil symbols 4.e. “95% SW refer to SW soil material with a minimum standard proctor compaction of 95%. See Table 16.4C for
42、equivalent modified proctor values. Soil in the outer bedding, haunch, and lower side zones, except within B,/3 from the pipe springline, shall be compacted to at least the same compaction as the majority of soil in the overfill zone. Only Type 2 and 3 installations are available for horizontal elli
43、ptical, vertical elliptical and arch pipe. A subtrench is defined as a trench with its top below finished grade by more than O. 1H or, for roadways, its top is at an elevation lower than 1 (0.3 m) below the bottom of the pavement base material. The minimum width of a subtrench shall be 1.33 B, or wi
44、der if required for adequate space to attain the specified compaction in the haunch and bedding zones. For subtrenches with walls of natural soil, any portion of the lower side zone in the subtrench wall shall be at least as firm as an equivalent soil placed to the compaction requirements specified
45、for the lower side zone and as firm as the majority of soil in the overfill zone, or shall be removed and replaced with soil compacted to the specified level welded wire fabric, a yield stress of 65,000 psi and for de- formed welded wire fabric, a yield stress of 70,000 psi may be used. 16.4.2.3 Con
46、crete Cover for Reinforcement The minimum concrete cover for the reinforcement in precast concrete pipe shall be 1 inch in pipe having a wall thickness of 2% inches or greater and Y4 inch in pipe hav- ing a wall thickness of less than 2% inches. 16.4.3 Installations 16.4.3.1 Standard Installations S
47、tandard Embankment Installations are presented in Figure 16.4B and Standard Trench Installations are pre- sented in Figure 16.4C; these figures define soil areas and critical dimensions. Generic soil types, minimum com- paction requirements, and minimum bedding thicknesses are listed in Table 16.4A
48、for four Standard Embankment Installation Types and in Table 16.4B for four Standard Trench Installation Types. 16.4.3.2 Soils The AASHTO Soil Classifications and the USCS Soil Classifications equivalent to the generic soil types in the Standard Installations are presented in Table 16.4C. 16.4.4 Des
49、ign 16.4.4.1 General Requirements Design shall conform to applicable sections of these specifications except as provided otherwise in this arti- cle. For design loads, see Article 16.1.3; for standard in- stallation, see Article 16.4.3.1; and for bedding condi- tions, see Section 27, Division II-Construction and the Soil-Structure Interaction Modifications that follow. Live loads, WL, shall be included as part of the total load, WT, and shall be distributed through the earth cover as specified in Article 6.4, except that the 2-foot minimum in the first paragraph of Article 6.4 d
