ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary

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Add Another. Standard Search Advanced Search. Javascript must be enabled for narrowing. Results 1 - 1 of 1. Search took: 0. Harmonizing the reinforcement development and splice length for next gen nuclear construction. Munshi, Javeed ; Li, Jia , E-mail: jamunshi bechtel. Abstract Abstract. This evaluates and discusses the differences in development and splice length requirements in the above-mentioned Codes for CAT I and Non-Safety-Related structures and explores opportunities for harmonization of requirements among the three Codes, where possible and appropriate.

The development and splice length requirement for higher grade reinforcement Gr 75 and Gr 80 , which are expected to be allowed in the next editions of the US nuclear codes will also be discussed. Country of publication.


Descriptors DEI. Descriptors DEC. A larger value of d, less than 0. In Eq. See also 7. For beam action, the slab or footing shall be designed in accordance Where Vu exceeds 0. For two-way action, the slab or footing shall be designed Av fy d in accordance with Vc shall be computed in with Vs shall When than 0. For fm2 tensile and exceeding 0. For fm2 compressive and less than Vc shall be For fm1 tensile and exceeding 0. For fm1 compressive and less than anchorage requirements of Shearhead arms shall not be inter- The maximum shear stress due to Vu and Mu shall The critical section shall be located so that its perimeter bo is a minimum, where Vc is as defined in The design shall Hooks from a concentrated load or reaction area, or when openings shall not be used to develop bars in compression.

For No. It shall be permitted 0. For other situations, b For degree hooks of No. However, ld shall not be less than ldh. The first tie or stirrup shall enclose the bent portion of the hook, within 2db of the outside of the bend, where db is the diameter of the hooked bar. Where reinforcement provided is in strength of reinforcement without damage to concrete is excess of that required, ld may be reduced in accordance permitted to be used as anchorage.

Length ld shall not be less than 6 in. It shall be The expressions in parentheses are used as constants permitted to reduce ld in accordance with When using the welded section of a member provided the design strand stress at that wire reinforcement factor from Provisions of Excess embedment length, hooks, or mechanical anchorage. Spacing s shall In beams, such reinforcement for No.

The second wire shall be permitted to be located on the stirrup leg beyond a bend, or on a bend where Mn is calculated assuming all reinforcement at the with an inside diameter of bend not less than 8db. If staggered mechanical splices are flexural reinforcement closest to the face. In members at least 18 in. Individual bar staggered at least 30 in. Entire bundles shall For less compression. Lap splices of No. Where it is deemed necessary, the engineer be permitted. A splice shall satisfy shall be not less than the largest of one spacing of cross wires requirements for all load combinations for the column.

Tie legs perpendicular to dimension h shall whose surfaces are located within the column and the capital be used in determining effective area. Mechanical or welded splices in columns shall meet the The continuing bars in each face of the column is less. Column strip includes beams, if any. Minimum length of lap for lap splices of welded plain wire In the slab Class A tension splices or with mechanical or welded splices Splices shall be located as shown in discontinuous edge shall extend to the edge of slab and have Fig.

At least two of the column strip bottom bars or embedment, straight or hooked, at least 6 in. At or wall at a discontinuous edge, or where a slab cantilevers exterior columns, the reinforcement shall be anchored at the beyond the support, anchorage of reinforcement shall be shearhead or lifting collar. An amount of rein- band parallel to the diagonal in the top of the slab and a band forcement equivalent to that interrupted by an opening shall perpendicular to the diagonal in the bottom of the slab.

Alternatively, the special reinforcement shall be placed in An amount of reinforce- In computing required slab reinforcement, the thickness of the drop panel below the slab shall not be Refer to Live load shall For unbalanced moments at interior Value of ln used in Circular or regular spans in each direction. Positive factored moment Interior Linear interpolations shall be made between values shown. Resistance to total shear occurring on a panel shall be provided. Chapter Such bars shall be extended to develop the bar beyond the corners of the Design for shear shall where be in accordance with provisions of Chapter At midheight, For footings supporting a column or pedestal with provided in Chapter Other pile caps shall satisfy either Appendix A, or both If See shall be distributed in accordance with Depth of footing above bottom reinforcement shall not be In addition, reinforcement, dowels, or mechanical connectors Design of precast members and Dowels shall not be larger than No.

Anchor bolts shall be designed in accordance with Anchor bolts shall This waiver shall not apply to members that require be constructed to ensure action as a unit. Not less than two ties Chapters 10 or 14, except that the area of horizontal and shall be provided for each precast panel. Where shear is the primary result of imposed loading, it shall Concrete bearing strength shall be as given in Ties shall be such as dowels or inserts that either protrude from the provided over interior wall supports and between members concrete or remain exposed for inspection shall be permitted and exterior walls.

Ties shall be positioned in or within 2 ft to be embedded while the concrete is in a plastic state of the plane of the floor or roof system. Provi- or tied to reinforcement within the concrete. The factored horizontal shear force Vu For Class C flexural members, Where computed tensile stresses ft exceed the limits in b or Effects a Extreme fiber stress in compression of temperature and shrinkage shall also be included. Load Combinations , , , , For structures subject to fatigue or exposed to corrosive envi- The spacing of It shall be permitted to take fdc equal to the This provision distributed between lines that are 1.

At least four bars or wires shall be a Two-way, unbonded post-tensioned slabs; and provided in each direction. Spacing of bonded reinforcement b Flexural members with shear and flexural strength at shall not exceed 12 in. In Adjustment of the sum of these moments Effects of prestress, creep, shrinkage, Effects of d Where beams or brackets frame into all sides of a abrupt change in section shall be considered. Nominal tensile stress of and stability. A minimum of two tendons b Linear stress analysis including finite element analysis shall be provided in each direction through the critical shear or equivalent ; or section over columns.

Special consideration of tendon c Simplified equations where applicable. Such reinforcement shall be placed symmetrically Calcium chloride shall not be used. The prestressing steel shall be completely coated uniform distribution of materials, passed through screens, and and the sheathing around the prestressing steel filled with pumped in a manner that will completely fill the ducts.


Required elongation Equilibrium checks of internal forces and external loads shall be made to ensure consistency of results. For bonded portions of the structure shall be considered. The shell shall be permitted to be thickened Nonlinear variations in circumferential The strength considered. It shall be permitted to base reinforcement Concrete directions and shall be proportioned such that its resistance strengths shall be determined as specified in 5. The engineer shall or through supporting members by embedment length, justify such an increase based on the load intensity used for hooks, or other mechanical anchorage in accordance with the test compared to the governing load combination for Chapter The engineer shall specify the tolerances for the shape of If construction results in deviations from the shape the structure to be subject to load is at least 56 days old.

If the greater than the specified tolerances, an analysis of the effect owner, engineer, and all other involved parties agree, it is of the deviations shall be made. For approval of special The engineer shall specify the appropriate material properties required for analysis, analytical evaluations testing parameters. Required data shall be determined in accordance with More than one test If deemed necessary by the The total test load including dead load already in indicating the imminence of shear failure.

Measurements shall be and functional requirements of the structure in question made at locations where maximum response is expected. Additional measurements shall be made if required. The ensure uniform distribution of the load transmitted to the load testing shall not interfere with the operating status of the structure or portion of the structure being tested. Arching of nuclear plant, or violate any plant Technical Specifications the applied load shall be avoided. This level does not necessarily coincide with the ground level.

Spalling and crushing of compressed transverse reinforcement. Boundary elements do not concrete shall be considered an indication of failure. Edges of openings within walls and diaphragms following conditions shall be provided with boundary elements if required by The hooks 4 shall engage peripheral longitudinal bars.

The repeat test shall be conducted not earlier than 72 hours after removal of the first test load. A closed tie beginning of the second test. A continuously wound tie The effective cross-sectional area of the joint, Aj, ASTM A resist the design seismic forces. A a The actual yield strength based on mill tests does not moment frame is a cast-in-place frame complying with the exceed fy by more than 18, psi retests shall not exceed requirements of In addition, the require- this value by more than an additional psi ; and ments of Chapters 1 through 18 shall be satisfied.

Hooks shall These frame structural walls—walls proportioned to resist combinations members shall also satisfy the conditions of A shearwall is a cast-in-place structural wall At least two bars shall be Neither the negative nor the in the design and analysis of the structure. These frame members shall also satisfy Column flexural strength shall be calculated for the factored d 12 in.

Equation shall seismic hooks at both ends and closed by a crosstie. Consec- be satisfied for beam moments acting in both directions in utive crossties engaging the same longitudinal bar shall have the vertical plane of the frame considered. If the longitudinal reinforcing bars secured by the crossties are confined by a slab on only one side of the flexural Lap splices shall be It shall within transverse reinforcement conforming to If the lower end of the b The total cross-sectional area of rectangular hoop column terminates on a wall, transverse reinforcement as reinforcement, Ash, shall not be less than required by required in Crossties of the same bar center spacing, s, not exceeding the smaller of six times the size and spacing as the hoops shall be permitted.

Each diameter of the longitudinal column bars and 6 in. Consecutive crossties shall be alter- These joint forces shall be determined using the Eq. The member shears need not verse reinforcement shall be provided with a spacing not exceed those determined from joint strengths based on Mpr exceeding 6 in. Concrete cover to the additional trans- of the transverse members framing into the joint. In no case verse reinforcement shall not exceed 4 in. The value of so shall not exceed 6 in. Length lo shall not be less a column shall be extended to the far face of the confined than the largest of a , b , and c : column core and anchored in tension according to Transverse reinforcement as required in At these locations, the spacing required in Reinforcement spacing each way in structural walls shall not For joints confined on all four faces Reinforcement contributing to Vn shall be For joints confined on three faces or continuous and shall be distributed across the shear plane.

A member that frames into a face is considered to provide A joint is considered to Chapter 12 except: be confined if such confining members frame into all faces a The requirements of Aj is the effective cross-sectional area within a joint b At locations where yielding of longitudinal reinforcement computed from joint depth times effective joint width. Joint is likely to occur as a result of lateral displacements, the depth shall be the overall depth of the column. Effective joint development length of longitudinal reinforcement shall width shall be the overall width of the column, except where be 1.

Splices of web For any one of the individual wall piers, Vn shall not be development lengths in The maximum longitudinal spacing of Acw is the area of concrete section of a horizontal wall transverse reinforcement in the boundary shall not segment or coupling beam. Concrete and developed longitudinal reinforce- horizontal reinforcement. The effects of Boundary groups of diagonally placed bars placed symmetrically about elements shall be provided if the maximum compression the midspan of the beam shall satisfy a through f : strain in the cross-section analysis exceeds 0.

For the purpose of computing Ag for use in the requirements of The surface of the previously diaphragms on a precast floor or roof shall not exceed hardened concrete on which the topping slab is placed shall be clean, free of laitance, and intentionally roughened. The be permitted to serve as a structural diaphragm, provided the required web reinforcement shall be distributed uniformly in cast-in-place topping acting alone is proportioned and both directions.

Topping slabs placed over precast floor be proportioned to resist the sum of the factored axial forces or roof elements, acting as structural diaphragms and not acting in the plane of the diaphragm and the force obtained relying on composite action with the precast elements to from dividing Mu at the section by the distance between the resist the design seismic forces, shall have thickness not less boundary elements of the diaphragm at that section. Mechanical and diaphragms shall be in conformance with 7. Reinforcement welded splices shall conform to Reinforcement diameters, but not less than 2 in.

Precompression from unbonded tendons shall be permitted to resist diaphragm design forces if a complete This reinforcement shall extend The slenderness effects of D-region—The portion of a member within a distance h Closed ties the joint intersect. A foundation subjected to flexure from columns that are part of strut represents the resultant of a parallel or a fan-shaped the lateral-force-resisting system shall conform to The design drawings shall clearly member, or of a D-region in such a member, made up of state that the slab-on-ground is a structural diaphragm and struts and ties connected at nodes, capable of transferring the part of the lateral-force-resisting system.

The truss model shall length resisting design tension forces. The longitudinal rein- contain struts, ties, and nodes as defined in A. The truss forcement shall be detailed to transfer tension forces within model shall be capable of transferring all factored loads to the pile cap to supported structural members. Struts shall reinforcement in accordance with If the reinforcement is in only one direction, entering a single node shall not be taken as less than 25 degrees. In such cases, the nominal strength of A. It shall be permitted where the centroid of the reinforcement in the tie leaves the to assume the compressive force in the strut spreads at a extended nodal zone.

A-4 A. C-4 through C Estimation of these areas, or both Otherwise, the factor for that load shall be in A. When considering of Appendix C. Chapter 9 notations are applicable to this these concentrated loads, local sections strengths and Appendix. For addi- C. The effective embedment depth will normally be compression-controlled sections to 0. For cast-in headed anchor bolts and headed studs, the effective C. The embedment may be fabricated of plates, ties, nodal zones, and bearing areas in such models Expansion anchors and undercut anchors are attachment—the structural assembly, external to the examples of post-installed anchors.

Specialty inserts are often used for concrete pryout strength—the strength corresponding to handling, transportation, and erection, but are also used for formation of concrete spall behind short, stiff anchors anchoring structural members. Testing is required D. The design strength shall be safety-related attachments and structural members.

Safety determined using the strength-reduction factor specified in levels specified are intended for in-service conditions, rather D. It shall be permitted to assume that than for short-term handling and construction conditions. Through bolts, multiple anchors embedment, the design side blowout strength of the embed- connected to a single steel plate at the embedded end of the ment, and the design pullout strength of the anchors exceed anchors, and direct anchors such as powder or pneumatic the nominal tensile strength of the embedment steel and actuated nails or bolts, are not included.

Reinforcement used when the design concrete breakout shear strength and design as part of the embedment shall be designed in accordance concrete pryout strength exceed the nominal shear strength with other parts of this Code. Grouted embedments shall of the embedment steel. The design concrete tensile strength, meet the requirements of D.

D are included. Post-installed anchors are D. The anchor design strength D. The design D. The requirements for the are determined in accordance with D. Plastic analysis approaches D. Assumptions used in distributing loads a The nominal tensile strength of the reduced section shall within the embedment shall be consistent with those used in be greater than the yield strength of the unreduced the design of the attachment.

Cast-in headed studs D. Condition B applies where such supplementary reinforce- D. Shear toward free edge The materials used in the tests shall ii Shear loads For nominal strengths ii Shear loads Limits on edge ii Tension loads distances and anchor spacing in the design models shall be Cast-in headed studs consistent with the tests that verified the model. This requirement shall ii Shear loads If the require- ments of 9. D-9 and for the calculation of Ncbg in Eq. ANc is the D.

D-7 is ANco is the projected concrete failure area of a single When analysis indicates cracking under the load combina- anchor with an edge distance equal to or greater than 1. The the load combinations specified in 9. If ca2 for the single-headed anchor is less than 3ca1, the D. The effective perimeter shall not exceed than 6ca1, the nominal strength of anchors along the edge in the value at a section projected outward more than the a group for a side-face blowout failure Nsbg shall not exceed thickness of the washer or plate from the outer edge of the head of the anchor.

D , shall where n is the number of anchors in the group and futa shall not exceed not be taken greater than the smaller of 1. Alterna- Where anchors are located at varying distances from the tively, Eq. D shall be permitted to be used. D shall be taken as zero.

In this case, it shall be permitted to D. The a single anchor in cracked concrete, Vb , shall not exceed nominal shear strength resulting from friction between the l 0. D or D , respectively, where le is defined in D. Vb is the basic concrete edges, the value of ca1 used in Eq. D through D breakout strength value for a single anchor.

Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary

It shall be permitted to evaluate AVc as the base of a truncated D. It shall be anchors are loaded in shear in the same direction of the free permitted to evaluate AVco as the base of a half-pyramid with edge, only those anchors that are loaded in shear in the direction a side length parallel to the edge of 3ca1 and a depth of 1. For anchors located in a region of a concrete member D. For cast-in headed No. In the absence of product- reinforcement shall be designed to intersect the concrete specific test information, the minimum edge distance shall breakout failure surface defined in D.

D-4 and D-5 , specify use of anchors with a minimum edge distance as respectively. The use of special grouts, containing epoxy or inserts other binding media, or those used to achieve properties such D. Grouted embedments installed in the web shall be designed for the shear, and the flanges shall tension zones of concrete members shall be capable of be designed for the tension, compression, and bending.

Tests shall be D. Embedment design shall be description and details of the testing programs, procedures, according to D. When multiple shear lugs E. The E. The tension anchor steel area required to resist external gradient temperature distribution—the temperature loads shall be added to the tension anchor steel area required distribution minus the mean temperature distribution across due to shear friction.

After exposure to these temperatures, the tion in the immediate area, without changing the overall serviceability of the structure needs to be assessed before component or member behavior for example, areas around resuming the operation of the plant. The extent of the assess- hot piping penetrating transversely through the component. For higher temperatures temperature distribution across the concrete section.

Short applied to design allowables. Also, evidence shall be provided term for the purposes of E. These loads must be combined with other loads in accordance with 9. Impactive and impulsive effects are treated and base temperature during normal operation or accident separately herein because of the nature of the effects as well conditions shall be considered.

The evaluation may be based on cracked section F. Impactive loading may be defined in terms of c All concurrent loads, as specified in 9. Impactive loads to be considered; and considered shall include, but not be limited to, the following d The coefficient of thermal expansion of concrete may be types of loading: taken as 5.

Impulsive b The reduction of long-term stresses due to relaxation loads to be considered shall include, but not be limited to, the and creep. The d pipe-whip restraint reactions. The maximum specified yield strength of reinforce- ment at the effective yield point Xy of the structural member ment fy shall be 60, psi. Grade and area of flexural refer to Fig. To establish the effective yield displace- reinforcement used shall be only that specified; substitution ment, the cross-sectional moment of inertia shall be taken as of bars with higher yield strengths or greater cross-sectional 0.

In addition to the deformation limits imposed areas shall not be permitted. Consideration shall b the ratio of the actual ultimate tensile strength to the also be given to the requirements of F. Both top and bottom reinforce- the rotational capacity as defined in F. These require- The resistance available for the impulsive load must be ments apply to each direction of two-way structural members.

The calculation of the DLF shall be based on the Strain energy capacity is limited by the the longer dimension in the case of rectangular columns or ductility criteria in F. Mass F. Simplified bilinear definitions of stiffness F.

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The for both local effects and overall structural response. Minimum bar size perforation, scabbing, and punching shear. Each end formulas or pertinent test data. Minimum cover of supplementary F. In the absence of scab shields, the shear at supports. These provisions shall also and hence punching shear failure, design for punching shear apply in cases of reaction shear at supported edges of slabs in accordance with F. Punching shear strength of slabs and walls shall be F. These metric units are those conforming to the for the convenience of users.

Metric Standards Act of Area Moment of inertia U. Temperature Weight density U. Length U. Stress pressure U. Load Volume U. Units U. Stress U. Section U. A tr f yt A tr f yt s n 10s n. Section This commentary discusses provisions in the retention as a permanent record for the life of the structure.

Code that differ from the Building Code.

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In preparing ACI Drawings and specifications should be prepared under the , the committee has followed the text of the Building direction of a licensed professional engineer competent in Code wherever appropriate. This In the following commentary, all references to the Code requires that the owner be responsible for drawings Building Code and its commentary ACI R are to the and calculations, but does not preclude him or her from revision unless specifically noted otherwise.

Provisions of assigning the function of detailed implementation to others. If the owner s directly employ concern. The scope of the Code provides requirements for inspection personnel, the owner shall be permitted to follow the analysis, design, construction, testing, and evaluation of ASTM E as a quality enhancement. Hence, potentially suit- loss of coolant accident. The owner is to identify nuclear able systems or components might be excluded from use by safety-related structures and establish which of them are implication if means were not available to obtain acceptance.

The Code is the adequacy of their system or component to the Regulatory applicable to radioactive waste repository structures; Authority, which presently is the United States Nuclear Regu- however, considerations of thermal loads, load combina- latory Commission USNRC in the United States. Some special concrete structures also need to be evaluated for R1.

Although no maximum concrete compressive strength is specified, the applicability of R1. In addition to the requirements of this Code, the Authority and states that the owner is responsible for the designer should consider other issues, as outlined in ACI establishment and execution of programs developed by his R1.

More Ground. The definitions that differ from or are not listed in ACI 1. ASCE 7 and modify equations listed in 6. Additionally, the designer should address reinforcement. For further comments on the 60, psi potential adverse reactions with dissimilar metals that can reinforcement limit, refer to R9. For reference to R9. ACI Degradation of the epoxy ance in altering concrete mixtures when significant changes coating, under certain environmental conditions, may in strength occur.

Such alterations can both achieve increased adversely affect reinforcing steel performance and anchorage, assurance against low strengths and reduce the standard resulting in splitting effects. Adequate performance of the deviation of strengths, providing a means of optimizing the epoxy-coated reinforcement and concrete should be cement contents and reducing the heat of hydration effects in demonstrated for the particular environmental application these relatively massive structures.

The minimum thickness of most concrete members furnace slag should be demonstrated for the particular in nuclear plant construction is based on shielding requirements application before selecting such materials, such as in areas that are dependent on the density of the concrete.

ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary

Lightweight of high temperature and irradiation. There appears to be no advantage in using light- ASTM test methods before use.

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Retests for soundness these materials during storage. The name and R3. In addition, potential galvanic b A statement listing any chemical analyses, tests, exami- corrosion with other embedded metals, as well as hydrogen nations, and heat treatment required by the material generation and potential for hydrogen embrittlement, specification, which were not performed.

Research c A statement giving the manner in which the material is conducted by Sergi et al. References to deicing salts, the inclusion of maximum percentages of fly 3. Sergi, G. The commentary for this section on ACI is applicable to this section. Further, in 4. All references to lightweight aggregate R4. The FHWA test referenced4. An initial R4. If total chloride ion Values are provided for both severe and moderate exposures content, calculated on the basis of concrete proportions, depending on the exposure to moisture or deicing salts.

Some of the frozen in a saturated condition. In Table 4. A When concretes are tested for soluble chloride ion content moderate exposure is where the concrete in a cold climate the tests should be made at an age of 28 to 42 days. The limits will be only occasionally exposed to moisture prior to in Table 4. Examples are the concrete ingredients, not those from the environment certain exterior walls, beams, girders, and slabs not in direct surrounding the concrete.

Section 4. The limits for Such high-strength concretes will have lower water-cemen- reinforced and prestressed concrete of 0. References to lightweight aggregates and documents. For simplicity and to reflect the more critical lightweight concrete have been omitted from these code and nature of safety-related structures, more restrictive limits commentary discussions. The designer should evaluate Table 4. Epoxy-coated bars or concrete included in the calculation of water-cementitious material cover greater than the minimum required in 7.

Use of slag meeting ASTM C , fly ash meeting Recent research has demonstrated that the use of fly ash and ASTM C , and increased levels of specified strength silica fume produce concrete with a finer pore structure and, provide increased protection. Silica fume, conforming to therefore, lower permeability.

Certain sections of the AC1 Drahushak-Crow, R. Sivasundaram, V. Malhotra, ed. These large members rarely receive full 4. Whiting, D. Rosenberg, A. The need to control early Concrete I, American Ceramic Society, Westerville, Ohio, temperature rise increases in proportion to the minimum , p. Berry, E. Li, S. Dikeou, J. C, to the proposed materials and mixture designs.

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Bureau of Reclamation, Jan. It, therefore, has little Washington, D. Ozyildirim, C. Whiting and A. Walitt, eds. The reduced testing frequency Farmington Hills, Mich. It is not the function of the Code to assign respon- used to reduce hydration heat in the thick concrete members. Under the requirements of this section, cores taken to R5. The in-place strengths may be several times that of the Code Section 5.

It is not necessary placements. Nondestructive testing properly correlated that all water be removed. Code Section 5. For obvious reasons, these instructions cannot be bubbles are produced by the reaction of aluminum abraded dogmatic. The engineer should apply judgment as to the from the pipe with the alkalis in the concrete. These gas significance of low test results and whether they indicate need bubbles are retained in the hardened concrete and reduce for concern. If further investigation is deemed necessary, concrete strength.

See mortar containing the same proportions of cement, sand, and ASTM for additional cautions and clarifications of these water as used in the concrete, shall first be deposited in the tests. For cores, if required, conservatively safe acceptance forms to a depth of at least 1 in. The this again becomes a matter of judgment on the part of the practice, however, has merit and is retained since the engineer.

When the core tests fail to provide assurance of edition of ACI The use of reproportioned batches will structural adequacy, it may be practical, particularly in the aid in preventing honeycomb and poor bonding of the case of floor or roof systems, for the engineer to require a concrete with the reinforcement. The reproportioned load test Chapter Short of load tests, if time and conditions concrete or mortar should be placed immediately before permit, an effort may be made to improve the strength of the depositing the concrete containing larger aggregate and must concrete in place by supplemental wet curing.

Effectiveness be plastic neither stiff nor fluid when the concrete is placed. This patible with those coatings. Accept- there would be no conflict in Code applications for the many able methods should be clearly stated in the construction different piping systems used in nuclear plant construction. Certain mechanical 5.

Bloem, D. See, for 5. Malhotra, V. Bartlett, M. Journal, V. Newlon, H. Research Council, Oct. Fowler, E. June , pp. In Mich. For the purpose of Section 7. Minimum reinforcement is required to control cracking R6. Minimum reinforcement is required with coating systems to assure a durable coating system. Commentary in 7. Reference to lightweight concrete in ACI has been R7.

Section 7. The R8. A value of 0. The design and construction of concrete nuclear safety-related general requirements and the section on required strength structures. The requirements for minimum reinforcement have been completely revised to reflect the requirements and physical limitation of massive concrete, however, have regarding loads and load combinations applicable to not been clear to the designers. ACI Committee The maximum studied and developed much useful information and data in specified yield strength of non-prestressed reinforcement fy regard to massive concrete structures.

It is highly recommended has been limited to 60, psi. Deflection limitations have that the designer obtain and study the specific reports by ACI been revised. In addition, requirements for the use of light- Committee for detailed and up-to-date information. Chapter 9 of the commentary on ACI should be R7.

The notations added as a 9. The ACI changes are explained as References follows: 7. The crane ington Hills, Mich. The definition of temperature load To has been modified to include other temperature-induced loads. In the first and design presented in Chapter 8 of ACI Some scenario, the thermal loads will depend on the restraint of the modifications have been made that reflect particular concrete member. In the second scenario, the induced requirements applicable to concrete nuclear safety-related thermal loads will continuously reduce as the deformation of structures.

Reference to the use of lightweight concrete and the concrete members increases in response to the thermal permanent fillers has not been made in this standard. In load. Eventually, the concrete members will arrive at a addition, the load requirements have been appropriately deformed state when the internal forces will equilibrate the altered. Chapter 8 of the commentary on ACI should be thermal load. In general, this load will not necessitate referenced for concrete nuclear safety-related structures except additional reinforcement, but will cause additional deformation.

This additional deformation may require further investigation. The provisions of Appendix E should be useful in investigating resulting load with dynamic amplification may be used these loads. For to include all items that are permanently attached to the the safety-related concrete structures in nuclear facilities, concrete structure, such as cable trays and conduits.

The operating basis earthquake load Eo should be reduction factors of the Code are moved to Appendix C. In the case of nuclear power revised, the commentary on ACI for this section is plants, Eo should be in accordance with Appendix S of generally applicable. For nuclear facilities, they are abnormal loads. For those reactions produced by normal operating temperatures older nuclear power plants and Department of Energy facil- acting on the piping system or equipment; piping reactions ities, Ess is defined as design basis earthquake DBE.

These generated by normal operation flow transients; and any other are low-probability environmental loads. These loads are reactions occurring during normal operation or shutdown. In explicitly defined in the documents controlling the facility ACI , Ro is considered to have lower variability in its design. For example, Wt for nuclear power plants could have estimation than that for the live load. This is based on the recurrence period as low as 10—7, while the recurrence period existing practice of estimating To as the maximum possible for Ess could vary from 10—3 to 10—6.

However, if it is recognized that there could be a these loads are from a design-basis accident DBA and are large uncertainty in estimating these parameters, the postulated to result from: designer should consider the use of larger load factors for To a A break in any of the high-energy piping existing in the and Ro. Note that dead load and earthquake reactions are not plant. This can create compartment pressurization, short- included in Ro. Under these concentrated loads, elastoplastic b A break in a small line containing high-temperature behavior may be assumed with appropriate ductility ratios, fluids or steam.

This would result in a long-term high provided resulting deformation will not result in loss of function temperature and associated pressure loading. The discharge of safety relief valves into a suppression In addition to the pressure Pa, temperature Ta, and reaction pool generates loads that are unique to BWR power plant loads Ra associated with a DBA, the loads could include the structures.

Specific classification of these loads is not given consequences of a rupture of a high energy pipe, that would by the Code. Other nuclear facilities R9. During initial design, most accidents postulated for those facilities. Once Section 9. The basic concept of ACI has assumptions should be confirmed. When designing for been adopted for ACI for concrete nuclear safety- weights or pressures from fluids, either existing in the structure related structures. The load combinations and load factors of or due to hydrostatic heads, both cases with fluid present or this section reflect consideration of the likelihood of individual- absent must be evaluated to establish the governing load and combined-event occurrences as well as possible excess condition.

When a detailed dynamic analysis is performed load effects such as variations in loads, assumptions in the for crane systems, elevators, or other moving machinery, the structural analysis, and simplifications in the calculations. The basic criterion used in arriving at the Load Combina- random in nature or because the loads have simply been tions to normal and severe environmental loads postulated to occur together for example, LOCA and SSE follows the same logic as in ACI , which is based on without a known or defined coupling.

One approach, the so-called absolute or linear some extent, on Reference 9. The overall approach used, summation ABS method, linearly adds the absolute values however, is the same as that explained in the commentary of of the peak structural response due to the individual dynamic Section 2.

A second approach, referred to as the square root of Load Combinations to involve normal loads the sum of the squares SRSS method, results in a combined and normal loads in combination with severe environmental response equal to the square root of the sum of the squares of loads. Similar to ACI , this standard uses load factors of the peak responses due to the individual dynamic loads. Load factors for loads this method of combining dynamic responses is conservative Ro, To, W, and Eo are reduced significantly, to be compatible unless the structural responses are stochastically dependent.

Nuclear Regulatory Commission,9. However, the the performance of a linear elastic dynamic analysis. Thus, load factor on L has been kept as 0. This is based on the consensus estimate made in seismic event combined in Load Combination may be Reference 9. The operating temperature To induced loads have been are determined by elastic analysis. However, this does not treated consistent with the earlier editions of ACI In all cases, resultant dynamic loads should be and , for the local design of floors and beams, a fraction combined absolutely, considering both maximum positive of the live load L or roof load Lr, which is most likely to be and negative values, with applicable static loads.

Examples of such loads are Lr , for the purpose. The gravity load effects of these loads those induced by aircraft impact, or an accidental explosion. For the global seismic analysis, L and Lr in a manner similar to the loads generated by the design basis should be based on the mean value associated with these tornado in determining the required strength according to the loads, that is, 0.

Abnormal loads are not considered Unit load factors are used in Load Combinations and concurrently with the extreme environmental loads. A probability caused by the safe shutdown earthquake or the DBT are analysis should be performed to demonstrate that this combi- extreme and are of low probability. A probability of 10E or smaller is a Load Combination is associated with the basic loads reasonable measure to demonstrate incredibility. The following guidance will ACI in a manner that resulted in an equivalent structural be useful in designing for such low-probability events.

The reduction in strength-reduction factor for shear Dynamic load effects should be considered with would require a reduction in the load factor from 1. Instead of reducing the load factors below 1. Loads due to postulated accidents and natural specific Ess is the minimum required by the AHJ. For all new phenomena often yield dynamic response of short duration nuclear power plant applications, the NRC has established and rapidly varying amplitude in the exposed structures and Ess as having the probability of exceedance POE lower components. For some loading phenomena, the accident than 1.

For Performance Category 4 analysis provides a definitive time-history response and structures in DOE nuclear facilities, the POE has been allows a straightforward addition of responses where more established as approximately 1. If the POE than one load is acting concurrently. In other cases, no specified of a nuclear facility structure is higher than 1.

The Code then states that deflection combinations Design strength of a member refers to the nominal strength are to be made only if the requirements given by the manu- to be calculated in accordance with the requirements of facturers of the nonstructural elements are more stringent ACI ASCE 7, and the revised load combinations in Section 9. Consideration of extreme loads solid one-way slabs.

The Building Code also makes a distinc- is as required by the AHJ, and proper guidance for tion between the appropriate deflection limits for these two combining the abnormal loads in concert with the extreme groups of structural members. A more liberal or a more environmental loads is provided. The design strength of the members. Recommendations by ACI Committee , Deflection walls exhibit hysteresis that is characterized by degradation of Concrete Building Structures; and of stiffness and strength, and pinching. Although structural 2. A review of the minimum member sizes commonly components in safety-related nuclear structures are detailed used in ACI structures.

As such, loss of made: strength and stiffness due to cyclic inelastic loading in components of nuclear structures will be smaller than those 1. The stress in the reinforcing steel is 0. The immediate deflections are multiplied by a factor of delineated in Section 9. Thus, Section 9. This assumes that the equipment would be R9.

ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary
ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary
ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary
ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary
ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary
ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary
ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary
ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary

Related ACI 349-06: Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary

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