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Home My WebLink AboutREINFORCING CONCRETE LETTER - Main Street Station - Luce, Greg - Rezone from LDR & MDR to HDRIri'� To: Tom Wilson From: Val Christensen Fax: (208)344-7203 Pages: One including cover Phone: Date: 6/12/2002 Re: Main Street Station CC: [Click here and type name] ❑ Urgent ❑ For Review ❑ Please Comment x Please Reply ❑ Please Recycle e Comments: Tom, About the reinforcing in the concrete, as I pointed out in the review, the 1997 Uniform Building Code Section 1914.3.5 requires smaller spacing than what you are showing. I have attached a copy of that section. Lets not hold up the building permit process with this, but get me an addendum back before the contractor needs to place concrete. Thanks, Val 1997 UNIFORM BUILDING CODE permitted to reduce the resulting computed moments in such pro- portion that the absolute sum of the positive and average negative moments used in the design need not exceed the value obtained t from Formula (13-3). 1913.7.7.5 Distribution of moments at critical sections across the slab -beam strip of each frame to column strips, beams and middle strips as provided in Sections 1913.6.4, 1913.6.5 and 1913.6.6 shall be permitted if the requirement of Section 1913.6.1.6 is satis- fied. SECTION 1914 -WALLS C_ 1914.0 Notations. Ag = gross area of section, square inches (mm2). f c = specified compressive strength of concrete, pounds per square inch (MPa). h = overall thickness of member, inches (mm). k = effective length factor. k = vertical distance between supports, inches (mm). Me, = cracking moment 5 VfJ 'C19/y, (For SI: 0.42 f '-Ig/yd for regular concrete. M„ = nominal moment strength at section, inch pound (N -m). M„ = factored moment at section, inch pound (N -m). See Sec- tion 1914.8.3. Pnw = nominal axial load strength of wall designed by Section 1914.4. P„ factored axial load at midheight of wall including tribu- tary wall weight. P ratio of nonprestressed tension reinforcement. pb = reinforcement ratio producing balanced strain condi- tions. See Formula (8-I). = strength -reduction factor. See Section 1909.3. 1914.1 Scope. 1914.1.1 Provisions of Section 1914 shall apply for design of walls subjected to axial load, with or without flexure. 1914.1.2 Cantilever retaining walls are designed according to flexural design provisions of Section 1910 with minimum hori- zontal reinforcement according to Section 1914.3.3. 1914.2 General. 1914.2.1 Walls shall be designed for eccentric loads and any lat- eral or other loads to which they are subjected. 1914.2.2 Walls subject to axial loads shall be designed in accor- dance with Sections 1914.2, 1914.3 and either Section 1914.4 or 1914.5. 1914.2.3 Design for shear shall be in accordance with Section 1911.10. 1914.2.4 Unless demonstrated by a detailed analysis, horizontal length of wall to be considered as effective for each concentrated load shall not exceed center -to -center distance between loads, or width of bearing plus four times the wall thickness. 1914.2.5 Compression members built integrally with walls shall conform to Section 1910.8.2. 1914.2.6 Walls shall be anchored to intersecting elements such as floors or roofs or to columns, pilasters, buttresses, and intersecting walls and footings. CHAP. 19, DIV. II 1913.7.7.4 1914.4 1914.2.7 Quantity of reinforcement and limits of thickness re- quired by Sections 1914.3 and 1914.5 shall be permitted to be waived where structural analysis shows adequate strength and sta- bility. 1914.2.8 Transfer of force to footing at base of wall shall be in ac- cordance with Section 1915.8. 1914.3 Minimum Reinforcement. 1914.3.1 Minimum vertical and horizontal reinforcement shall be in accordance with Sections 1914.3.2 and 1914.3.3 unless a greater amount is required for shear by Sections 1911.10.8 and 1911.10.9. 1914.3.2 Minimum ratio of vertical reinforcement area to gross concrete area shall be: 1. 0.0012 for deformed bars not larger than No. 5 with a speci- fied yield strength not less than 60,000 psi (413.7 MPa), or 2. 0.0015 for other deformed bars, or 3. 0.0012 for welded wire fabric (plain or deformed) not larger than W31 or D31. 1914.3.3 Minimum ratio of horizontal reinforcement area to gross concrete area shall be: 1. 0.0020 for deformed bars not larger than No. 5 with a speci- fied yield strength not less than 60,000 psi (413.7 MPa), or 2. 0.0025 for other deformed bars, or 3. 0.0020 for welded wire fabric (plain or deformed) not larger than W31 or D31. 1914.3.4 Walls more than 10 inches (254 mm) thick, except base- ment walls, shall have reinforcement for each direction placed in two layers parallel with faces of wall in accordance with the fol- lowing: 1. One layer consisting of not less than one half and not more than two thirds of total reinforcement required for each direction shall be placed not less than 2 inches (51 mm) or more than one third the thickness of wall from exterior surface. _ 2. The other layer, consisting of the balance of required re- inforcement in that direction, shall be placed not less than 3/4 inch (19 mm) or more than one third the thickness of wall from interior surface. 1914.3.5 Vertical and horizontal reinforcement shall not be spaced farther apart than three times the wall thickness, nor 18 inches (457 mm). Unless otherwise required by the engineer, I the upper- and lowermost horizontal reinforcement shall be placed within one half of the specified spacing at the top and bot- tom of the wall. 1Y14,J.b vertical reinforcement need not be enclosed by lateral ties if vertical reinforcement area is not greater than 0.01 times gross concrete area, or where vertical reinforcement is not re- quired as compression reinforcement. 1914.3.7 In addition to the minimum reinforcement required by Section 1914.3.1, not less than two No. 5 bars shall be provided around all window and door openings. Such bars shall be extended to develop the bar beyond the comers of the openings but not less than 24 inches (610 mm). 1914.3.8 The minimum requirements for horizontal and vertical steel of Sections 1914.3.2 and 1914.3.3 may be interchanged for precast panels which are not restrained along vertical edges to in- hibit temperature expansion or contraction. 1914.4 Walls Designed as Compression Members. 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