RS-03-115, Additional Information Regarding Request for License Amendment Related to Heavy Loads Handling

Additional Information Regarding Request for License Amendment Related to Heavy Loads Handling

ML031700384
Person / Time
Site:	Dresden
Issue date:	06/12/2003
From:	Simpson P Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-03-115
Download: ML031700384 (25)

Text

ExelonM Exelon Generation www.exeloncorp.com Nuclear 4300 Winfield Road WaTrenville, IL 60555 RS-03-115 June 12, 2003 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Dresden Nuclear Power Station, Units 2 and 3 Facility Operating License Nos. DPR-19 and DPR-25 NRC Docket Nos. 50-237 and 50-249

Subject:

Additional Information Regarding the Request for License Amendment Related to Heavy Loads Handling

References:

(1) Letter from K. R. Jury (Exelon Generation Company, LLC) to U. S. NRC, "Request for License Amendment Related to Heavy Loads Handling,"

dated February 26, 2003 (2) Letter from U. S. NRC to J. L. Skolds (Exelon Generation Company, LLC), "Dresden Nuclear Power Station, Units 2 and 3 - Request for Additional Information Regarding Heavy Loads Handling Amendment Request," dated May 23, 2003 In Reference 1, Exelon Generation Company (EGC), LLC, requested a change to Facility Operating License Nos. DPR-1 9 and DPR-25, for Dresden Nuclear Power Station (DNPS), Units 2 and 3. The proposed change will allow DNPS to revise the Updated Final Safety Analysis Report to include a description of a load drop analysis performed for handling reactor cavity shield plugs weighing greater than 110 tons with the Unit 2/3 reactor building crane during power operation.

In Reference 2, the NRC requested additional information regarding this proposed change. to this letter provides the requested information.

In addition, Attachment 2 to this letter provides information discussed between Mr. L. W.

Rossbach and other members of the NRC and Mr. A. R. Haeger and other members of EGC in a teleconference on June 10, 2003, regarding the planned initial movement of the top layer of reactor shield plugs. to this letter provides various references discussed in Attachments 1 and 2.

Should you have any questions conceming his letter, please contact Mr. Allan R. Haeger at (630) 657-2807.

'\D

June 12, 2003 U. S. Nuclear Regulatory Commission Page 2 I declare under penalty of perjury that the foregoing is true and correct. Executed on the 12t day of June, 2003.

Respectfully, Patrick R. Simpson Manager, Licensing Mid-West Regional Operating Group : Responses to NRC Questions : Description of Planned Initial Movement of Reactor Shield Plug Top Layer : Copies of Selected Reference Materials cc: Regional Administrator - NRC Region IlIl NRC Senior Resident Inspector - Dresden Nuclear Power Station Office of Nuclear Facility Safety - Illinois Department of Nuclear Safety

Attachment I Additional Information Regarding Request for License Amendment Related to Heavy Loads Handling Responses to NRC Questions Question I The load drop of a shield plug during lifting of the plug from the cavity in Unit 3 and laying it down on top of Unit 2 shield plugs is analyzed as Scenario 1 of the load drop analysis (Attachment 3 of the amendment request). The calculations for deternining the bearing capacity of the top shield plug on page 29 of 95, utilize a strength reduction factor of 0. 7 for the bearing strength of concrete and a 2/3 factor to account for the spaces between the bearing bars. Provide the basis and applicable reference material for the use of this strength reduction factor and 213 factor.

Response to Question 1 Strength Reduction Factor Reference 1, in Section 9.3.1, "Design Strength," states that the design strength provided by a member shall be taken as the nominal strength multiplied by the strength reduction factor (0) in Sections 9.3.2 and 9.3.4.

Reference 1, in Section 9.3.2.4 specifies the value of the strength reduction factor (0) in "bearing on concrete" as 0.70. This value is used on page 29 of Reference 2 when calculating the bearing capacity of the top shield plug, which is a normal weight reinforced concrete.

213 Factor As described on page 29 of Reference 2, the 213 factor is to account for the spaces between the bearing bars. It is also mentioned on page 29 that the bearing bars are 1" x 24" and the space between the bars is 12". This assumed spacing is conservative compared to the spacing of 1" between the bars shown in Section 12-12 on the attached drawings B-242 (Unit 2) and B-672 (Unit 3).

With 24" long bars located with 12" space between them, the center-to-center distance between the bars will be 12 + A(24 + 24) = 36".

With the 36" center-to-center distance between the bars, the length of bars available for bearing is %a(24 + 24) = 24".

Hence, the ratio of bearing length to center-to-center length is 24/36 or 2/3.

Therefore, as the bearing bars are not continuous (for the full length) and the calculation considers a space of 12" between them, on page 29 the factor of 2/3 is used to arrive at the reduced bearing strength of the concrete of the top plug (half circle). This is a conservative factor, given that the spacing between the bars shown on the drawings is 1".

Question 2 Provide justification for not taking the concrete reinforcement into consideration in the determination of the weight of the slab, beams and column in the calculations related to the "Full drop of a shield plug on single column" which is Scenario 2 of the load drop analysis.

Page 1 of 5

Attachment I Additional Information Regarding Request for License Amendment Related to Heavy Loads Handling Responses to NRC Questions Resoonse to Question 2 The unit weight of concrete, considered as 150 pounds per cubic foot (pcf) on page 47 of Reference 2, is the unit weight normally taken for the design of reinforced concrete members.

Reference 3 on page 7 states, Natural stone aggregates conforming to ASTM C33 are used in the majority of concrete construction, giving a unit weight for such concrete of about 145 pcf (pounds per cubic foot) or 2320 kg/m3 (kilograms per cubic meter). When steel reinforcement is added, the unit weight of normal weight reinforced concrete is taken for calculation purposes as 150 pcf, or 2400 kg/m3. Actual weights for concrete and steel are rarely, if ever, computed separately.

Reference 4 on page 6-9 provides the weights of building materials. For plain concrete 1" thick, the weight is shown as 12 pounds per square foot. This value, when converted to one-foot thickness, corresponds to a unit weight of plain concrete of 144 pcf. The weight of 1" thick reinforced concrete is given as 12.5 pounds per square foot. When converted to one-foot thickness, the unit weight of the reinforced concrete will be 150 pcf.

The two references quoted above provide the justification for considering the unit weight of the reinforced concrete as 150 pcf.

Question 3 The full drop of a shield plug on a system of two adjacent slabs with a beam in between the slabs, is analyzed as Scenario 3 of the load drop analysis. In this calculation the combined beam and slab moment resistance factor, as discussed on page 68 of 95, is obtained on the basis of an equation provided on this page. Provide an explanation of how this equation reduces the beam moment resistance that accounts for the area of the two adjacent slabs as indicated.

Resoonse to Question 3 Beam 5B6 flexural resistance is calculated on pages 52-56 of Reference 2 (see attached drawing B-208). This beam supports two identical slabs, one on each side. The slab flexural resistance is calculated on pages 62-66. The slab flexural resistance is computed on the basis that beams exist on all the four sides to resist the reactions of the loaded slab. For each of the two slabs, the beams are available to resist the reactions from three sides. The fourth side of each of the two slabs is resisted by beam 5B6.

Therefore, this part of the slab resistance must be subtracted from the beam total resistance. This part amounts to one-fourth of the resistance of each slab.

The above load resistance system can be expressed as follows:

Two SlabsL Beam 5B6 f One Fourth of Each of the Two Resistancf l Resistancef -l Slabs Supported by Beam 5B6 J Page 2 of 5

Attachment 1 Additional Information Regarding Request for License Amendment Related to Heavy Loads Handling Responses to NRC Questions The above expression represents the equation on page 68 of Reference 2 that is used to compute the combined resistance of the two slabs and beam 5B6 located between them.

Question 4 The full drop of a shield plug on wall at column 44 is analyzed as Scenario 5 of the load drop analysis. Provide a definition ofthe factor "Kwal =0.8"used on page 89 of 95 of this calculation and explain how it is obtained.

Response to Question 4 Reference 4 on page 5-134 states that "K" is a factor to equate the strength of a framed compression element of length "L" to an equivalent pin-ended member of length (also called effective length) KL" subject to axial load only. Reference 3 on page 543 provides the equivalent pin-end lengths for various rotational and translation end restraint conditions.

Reference 4 on page 5-135 also provides Table C-C2. 1, giving theoretical and recommended K" values for various rotational and translation end restraint conditions.

Based on the sizes of the end restraint members for the wall at Column Row 44 (Reference 2, pages 87-90), and the fact that the wall ends at plant elevation 613'-0" (see attached drawing B-208) and is continuous at elevation 589'-0" (see attached drawing B-226), the wall was considered to have "one end unrestrained and the other end restrained."

For these end conditions, value of "K" on page 543 of Reference 3 is 0.7. This same value 0.7 is also shown as the theoretical K" value in Reference 4 on page 5-135.

However, this same table recommends using design value of 0.80 for "K" for these end conditions when ideal conditions are approximated. Accordingly, Reference 2 on page 89, conservatively considers the value of "Kwall" as 0.8.

Question 5 Provide a drawing or illustration of the maximum height that a top shield plug can drop and explain why this height is the maximum possible drop height.

Response to Question 5 Attached drawing B-216 (Section C-C) shows the three layers of the shield plugs located over the reactor cavity before the top shield plug is lifted.

Pages 28 thru 37 of Reference 2 provide the analysis for lifting of the shield plugs (including top layer plugs) above the reactor cavity, for a height of up to 1'-0" above the floor at elevation 613'-0". Therefore, the load drop of the top layer shield plugs, from a maximum height of 1'-0" above the floor level at the reactor cavity, has been analyzed.

Beyond the reactor cavity area, the top layer shield plugs will move along the load path identified on page B2 (attachment B) of Reference 2. The maximum height that the top layer shield plugs will be lifted above the floor level as noted on attachment page B2 is Page 3 of 5

Attachment I Additional Information Regarding Request for License Amendment Related to Heavy Loads Handling Responses to NRC Questions 1'-0". Pages 38 thru 85 of Reference 2 provide the load drop analysis for this height, for the various scenarios, as the top layer plug moves along the load path. Pages 96-99 summarize the results of the analysis of all plugs including the top layer shield plugs.

Pages 14-15 describe the movement of the Unit 3 top layer shield plugs and the maximum lift height mentioned is 1'-0". The movement of the Unit 2 top layer shield plugs will be in the opposite direction from the Unit 3 plugs.

Based on the travel path and lift height of the shield plugs explained above, the maximum lift height of the top layer shield plug will be 1'-0" above the floor at elevation 613'-".

Question 6 Are the 1997 Code Requirements for Nuclear Safety Related Concrete Structures (AC/

349-97) and the 1999 Building Code Requirements for Structural Concrete (ACI 318-99) referenced in calculation DRE02-0064 attached to your submittal the current versions of these codes? If there are later versions, why werent they used and how would they affect the calculation?

Response to Question 6 The 1999 edition of ACI 318 was subsequently revised in 2002 (i.e., ACI 318-02). The 1997 edition of ACI 349 was subsequently revised in 2001 (i.e., ACI 349-01).

DNPS has followed an intemal controlled guidance document for DNPS and Quad Cities Nuclear Power Station. Topical Design Basis Document TDBD-DQ-1, Structural Design Criteria," Section 3.3, Codes and Standards," provides guidelines regarding this question.

ACI 318-99 Section 3.3.4 of TDBD-DQ-1 relates to ACI 318, the basic concrete design code. It states, The latest issue of the ACI shall be used for new design of the Dresden and Quad Cities Stations."

Reference 2 does not design a new structure. It evaluates the existing concrete structure for various load drop conditions. Hence, intemal guidance would not require use of the latest code.

In 1990, Sargent and Lundy had performed a generic code reconciliation to compare a previous version of the ACI code (i.e., 318-89) to the original code of construction for DNPS, ACI 318-63. This reconciliation recommended use of ACI 319-89 for new design and for reassessment as long as all pertinent structural safety provisions contained in the latest code revisions are met. ACI 318-99 was used as the code for calculation DRE02-0064, since ACI 318-99 has a similar technical basis as ACI 318-89. Therefore, it is acceptable to use ACI 318-99 for the reassessment of the existing concrete structure for load drop analysis.

Page 4 of 5

Attachment I Additional Information Regarding Request for License Amendment Related to Heavy Loads Handling Responses to NRC Questions It is also expected that if the ACI 318-02 code were used in the analysis, the end results of the calculation would not change. While the 2002 edition of the code did change the strength reduction factors (0) slightly, this would not affect the conclusion of the calculation.

ACI 349-97 Reference 2 used ACI 349-97, Appendix C to provide guidelines for "lmpulsive and Impactive Effects" as a technical aid to ascertain ductility limits. Page 7 of the calculation states, "The ductility limits are determined from the Table 5.1 of Reference 1 and Appendix C of Reference 4.' Reference 4 as shown on page 10 is ACI 349-97.

A general review of the relevant sections C.2, "Dynamic strength increase,' and C.3, "Deformation," of both ACI 349-97 and ACI 349-01 shows no change in the corresponding technical parameters.

Based on above, the use of codes ACI 318-99 and ACI 349-97 is appropriate. The use of the latest codes is not required for reassessment of designs. If the latest codes are considered, the conclusions of the analysis, "Load Drop Evaluation of the Reactor Shield Plugs," (Reference 2) will not change.

References

1. "Building Code Requirements for Structural Concrete (ACI 318-99) and Commentary (318R-99),- 1999 Edition, ACI Intemational

2. Calculation DRE 02-0064 (Revisions 0 and OA), Attachment 3 to letter from K. R.

Jury (Exelon Generation Company, LLC) to U. S. NRC, aRequest for License Amendment Related to Heavy Loads Handling," dated February 26, 2003

3. "Reinforced Concrete Design," (text book) Fourth Edition, by Wang and Salmon

4. "Manual of Steel Construction," Ninth Edition, American Institute of Steel Construction Page 5 of 5

Attachment 2 Additional Information Regarding Request for License Amendment Related to Heavy Loads Handling Description of Planned Initial Movement of Reactor Shield Plugs Top Layer

Background

The concrete shield plugs (plugs) over the reactor cavities of Unit 2 and Unit 3 are stacked in three layers as shown in the attached drawings B-242 (Unit 2) and B-672 (Unit 3). The plugs are semi-circular in shape with the uppermost plug having a diameter equal to 43'-0".

Currently, the top layer plugs are oriented with the diameter in the north-south direction as shown on the above referenced drawings. Page B2 (attachment B) of the calculation DRE 02-0064 in Reference 2 provides the analyzed load path for the movement of the top layer plugs.

Currently, when the Unit 2 top layer plugs are moved during reactor disassembly, they are lifted and rotated 90 degrees while being moved south and towards the center between columns 40 and 42. The plugs are rotated in order to have the diameter in the east-west direction. The plugs are then moved west between columns L and M until the plugs are located between columns 46 and 48. The plugs are then moved north and placed on the top of the Unit 3 plugs. When the plugs are to be reinstalled on Unit 2, the above steps are reversed.

The Unit 3 top layer plugs require same steps as the Unit 2 plugs, except that the plugs move from west to east.

A detailed review of the steps required to move the plugs was performed to design interlocks for the movement of the top layer plugs to ensure that the movement remains within the analyzed area, as discussed in Reference 2. In order to stay within the analyzed area between columns L and M, the plugs must be rotated to the east-west orientation from their installed north-south orientation. Further, in order to properly rig the plugs from their installed north-south orientation, the crane hook must be moved east or west of the center of the analyzed area between columns 40 and 42 for Unit 2 (columns 46 and 48 for Unit 3). It was noted that if all the top layer plugs were oriented in the east-west direction in their installed position, the plugs could be moved from the top of one unit reactor cavity to the top of the other unit reactor cavity without being rotated during the movement, and the crane hook could remain near the center of the analyzed area for all portions of the movement.

Changing the installed orientation of the top layer plugs to the east-west direction is also required in order to allow for a practical design for the interlocks, since the interlocks can then be designed to restrict crane movement to the center of the analyzed load path, given that rotation of the plugs will no longer be needed. If the interlocks allowed movement significantly beyond the center of the analyzed path, then rotation of the plugs could result in a portion of the plugs being outside the analyzed path. EGC has decided to design the interlocks with this in mind and revise the installed orientation of the plugs.

This change will be performed under the engineering change process and the relevant drawings will be revised.

Page 1 of 2

Attachment 2 Additional Information Regarding Request for License Amendment Related to Heavy Loads Handling Description of Planned Initial Movement of Reactor Shield Plugs Top Layer Effect on Commitments in Oriainal License Amendment Request In Reference 1, EGC stated that the electrical interlocks or mechanical stops would be activated whenever the top layer plugs weighing over 110 tons are moved. To accomplish the objectives discussed in the above section, on a one-time basis during the first time the top layer plugs of Units 2 and 3 are moved following approval of the Reference 1 request, it will be necessary to de-activate the interlocks for a short time until the plugs are lifted and brought within the path defined by the interlocks. During this one-time initial movement, the following will be performed.

• The plug will be lifted to a maximum height of 1 foot above the floor, as assumed in the load drop analysis.

• The plug will be moved towards the center of the intended travel path (i.e., center of the analyzed area between columns 40 and 42 for Unit 2 and between columns 46 and 48 for Unit 3) before being moved south or being rotated.

• The interlocks will be activated.

• The plug will be moved south.

• The plug will be rotated 90 degrees to an east-west orientation while being moved south. Given space limitations, it may not be possible to avoid rotating the plug until it has been moved far enough south to completely clear the reactor cavity. However, rotation will not begin until the plugs have been moved as far south as possible while remaining north of column M and the plug will always remain over the analyzed area.

EGC will perform these moves under administrative controls to ensure that the plugs remain within the analyzed load path shown in page B2 (atachment B) and that the lift height of the plugs is limited to a maximum of '-O", as assumed in the load drop analysis. These controls will be specified in the maintenance work package for the lift.

The work package will specify the specific steps for the movement, as described above.

The work package will also specify that a spotter be present with a drawing showing the analyzed area. The spotter will be instructed to ensure that the plugs remain within the analyzed area while the interlocks are deactivated.

Reference

1. Leter from K. R. Jury (Exelon Generation Company, LLC) to U. S. NRC, Request for License Amendment Related to Heavy Loads Handling," dated February 26, 2003 Page 2 of 2

Attachment 3 Additional Information Regarding Request for License Amendment Related to Heavy Loads Handling Copies of Selected Reference Materials References Supplied ACI 318-99, Sections 9.3 and 9.3.2.4 uReinforced Concrete Design," pages 7, 543

• Manual of Steel Construction," pages 5-134, 5-135, 6-9 Drawings B-208, B-216, B-226, B-242, B-672

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CODE COMENTARY-I 9.8 - Load factors -For post-tensioned anchor- R9.8 - The load factor of 12.applied to the maximunr age zone design a load factor of 1.2 shall be applied to tendon jacking force results in a deiign load of about 1l3%

the maximum tendon jacing force. of the specified ndon strength but not more than 96%

Df the nominal ultimte stngth of the tendon. This com pares well uvit the maximum attainable jacking force which is limited by the anchor efficiency factor.

9.3 - Design strength R9.3 -Design strength

_-.4 9.3.1 - DeVn strength provided by a member, It R9.31 - The term design strength of a member, refers 1 the nominal streng ciulated in accordance with t connections to other members,. andtts woss sections, requirements sdpulated in this code multiplied by a strengi Interms of flexure, axial load, shear,'and torsion, shalt reduction factor , wbich.is always less t one..

be.taken as the nominal strength calculated in accor-dance with requirements and assumptons of this The .urposes of 'fie srgth eduction factor are ()

code, multiplied- iy the stength'reduction factors Iin allow for the probability of undestrgth members di.e i, 1_

i i

9.3.2 and 9.3.4. Variations in mater strengths and dimensions, (2) to ao for inaccuraies.in the design quations,.(3) to reflact II degree of ductility nd.required reliability of th.me iI under the load effects being considered, and (4) to refei the importince of ie member in the sjctnse.9 9 3 Fi example, a loier is used for columns than for bems' because columns generally have less ductiity, are more sen-.

sitive to variations in concrete stength, and generally sup-port larger loaded areas than beams. Firthemoe, tpirl columns are assigned a higher # than tied columns dce they have greater ductility or toughness.

. S .3.1. - If the stcura3 framing includes primary R93.Ll - Appendix C has been included to facilitate members of other materals proportioned to.satisfy the computations for buildings witi substanti portions oftheir

)ad factor combinations In Secton 2.3 of ASCE 7, t structural famintg provided by elements other tan concrete.

shall be permifted to proporton the concrete members If the strength reduction factors in Appendix C a used for

\;

sing te set of strength reduction actors listed in ihe concret elements, the required srengts are to be deter-Appendix C and the load factor.combinations In ASCE 7. imined using the load factor combinatons in Secdon 2.3 of ASCE 7. 4!

i.3.2 - Strength reduction factor ¢ shall be as follows:

9.3.2.1 - Flexure, without axial load .................. 0.90 R932.1 - In applying 9.3.2.1 and 9.3.2.2, the axial:ten-sions and compressions to be considered are those caused by external forces. Effects of prestressmg forces are not included.

,I 9.3.2.2 -Axial load, and axial load wfith flexure. R93.2.2 - For members subjected to axia load with

'i ~~~I flexumr, design strengths arm determined by multiplyinga For axial load..Wih flexure, both axial load and ioment nominal trength shall be multiplied by appro- both P, and U, by the appropriate single value of . or rnate single value of +) members subjected to flexure and relativelj small axia compression loads, failure is initiated by yielding of the ten-(a)Axial tension, and axia sion reinforcement and lakes place in an increasingly more tension with flexure .................  ; 0.90 ductile mnner as the ratio of axial load to monent decreases. At the same time the variability of the stegth (b) Axial corpession, anKl axial compres- also decreases. For smal axial loads, the value of + may be

• sion with fiexure: increased from that for compression members to 0.90 per-Members with 4biral reinforcement con- mitted for flexure as de design axial load strngth P, t a.- .s..J.

A

. . . . 0.75 decreass from a specified value to zero.

' ..' . 7...0....

V 1.,: t6 For emb ers ieeting the limitations specified for

.; r4) -akldf,. the transition starts at a desig axial-e~~~~rA.

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=~~~~~~~~~~~~~~~~~~...I7 - - - p

• - . CHAPI 'ER 9 318/318R-95 ii CODE CORENTARY to be Increased in accordance with the load strength, P.of 0.10 fe'Ar. For other conditions, Pb I should be calculated to determine the upper value of design LI axia load strength e (the smallr f 0.10fc'Ag and #Pb) mbers In which Iydoes not exceed 60,000 psi, below which au increase in 0 can be made. U rmmetric reinforcement, and with (h -d'- ds5)h ss than 0.70, shall be permitted to be .1 ed linearly to 0.90 as P,. decreases from

4. to zero.

.her reinforced members, 0 shall be permitted to creased linearly to 0.90 as Edecreases from

'1 Ii A or Pb, whichever Is smaller, to zero.

3.Q4-Bearing on concrete (except for...

-ensioninganchorage zones) ......... 0.70 32.5 - Post-tensioned anchorage zones ..... 0.85 R9.32 The -fctor of 0.85 reflects the wide scattr

.-. . of results of experimental anchorage zone studies. Since 18.13A.2 limits the nominal compressive strength of uncon-fined concete in the general zone to 0.7Ijf, the effective design strengti for unconfined concrete is 0AS x 0.7Af 4 Li; - , . .

~ ~~~~~~0.61Aft.

-Development lengths specified In Chapter 12 it require a -factor.

- In structures that rely on special moment R9.3A-Strength reduction factors in 9.3.4 are intended to

'isting frames or special reinforced concrete struc- compensate for uncertainties in estimation of ;strngth of walls to resist earthquake ffects, the strength strucural members in buildings. They are based primri dubton factors # shall be modified as follows: . on Cxpenence with constant or s ily increasing aplied load For construction in regions of high sesmic isk, some Y"Tihe strength reduction factor for shear shall be of the strength reduction factors have been modified in 9.3.4 gA for any structural membr that Is designed to to account for the effects of displacement reversals into the sist earthquake effects. f Its nominal shear strength I nonlinear range of response on strength.

tfess than the shear corresponding to the develop-

,dnt of the nominal flexural strength of the member. Sectdon 9.3.4(a) refers to brittle members such as low-rise

.inominal flexural strength shall be determined con- walls, portions of wals between openimgs, or diaphragms 1b'etihg the rhost critical factored axial loads and that are impactical to reinforce to raise their nominal shear LFuding earthquake effects;. strength above nominal flexural strength for the pertinent loading conditions.

X The strength reduction factor for shear In dia-

'pla,gms shall not exceed the minimum strength Short structural walls were the pimary vertical elements of

.duction factor for shear used for the vertical compo- the lateral-force-resisting system in many of the parking

,ients of the primary lateral-force-resisting system; . structures that susaed damage durng fte 1994 Northridge eartquake. Section 9.3.4(b) requires the shear stength AP)The strength-reduction factor for shear In joints and reduction factor for diaphragms to be 0.60 if the shear iiagonally reinforced coupling beams shall be 0.85. strength reduction factr for the walls is 0.60.

I . ACI 318 Building Code and Commentary

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1.5 Aggregates 7 ingredients and the added to the first three types of cement in ASTM C150 or to the blended is placed and cured. hydraulic cements in ASTM C595 at the time the concrete is mixed.

ions of the-materials Portland blast-furnace-slag cement has lower heat of hydration than kt is intended to be ordinary Type I cement and is useful for mass concrete structures such as standard references dams; and because of its high sulfate resistance, it is used in seawater con-struction. Portland-pozzolancement is a blended mixture of ordinary Type I cement with pozzolan. Pozzolan is a finely divided siliceous or siliceous and aluminous material which possesses little or no inherent cementitious property, but in the powdery fprm and in the presence of moisture, will roperties enabling it chemically react with calcium hydroxide at ordinary temperatures to form x this definition can compounds possessing cementitious properties. Blended cements with poz-reinforced concrete zolan gain strength more slowly than cements without pozzolan, hence they presence of water- produce less heat during hydration, and thus are widely used in mass con-rily of silicates and crete construction.

de) which is ground, cements chemicaly nass. The usual hy- 1.5 AGGREGATES as portland cement, Since aggregate usually occupies about 75% of the total volume of concrete, Ld stone found near its properties have a definite influence on the behavior of hardened con-obtained by Joseph crete. Not only does the strength of the aggregate affect the strength of the concrete, its properties also greatly affect, durability (resistance to deterio-puires about 14 days ration under freeze-thaw cycles). Since aggregate is less expensive than ed and construction cement, it is logical to try to use the largest percentage feasible. In general, ncrete is reached at for maximum strength, durability, and best economy, the aggregate should ed by ASTM (Amer- be pacled and cemented as densely as possible. Hence aggregates are usu-

)e I. Other types of ally graded by size and a proper mix has specified percentages of bothfine rable 1.4.1. and coarse aggregates.

Fine aggregate (sand) is any material passing through a No. 4 sievet

[i.e., less than about t in. (5 mm) diameter]. Coarse aggregate (gravel) is any material of larger size. The nominal maximum size of coarse aggregate lot required permitted (ACI-3.3.3)* is governed by the clearances between sides of forms ace or moderate heat and between adjacent bars and may not exceed "(a) the narrowest dimen-sion between sides of forms, nor (b) i the depth of slabs, nor (c) the minimum clear spacing between individual reinforcing bars... Additional information concerning aggregate selection and use is to be found in a report of Ao mmittee62 [10]... - .. --

' Natural stone aggregates conforming to ASTM C33 [11] are used in the clic cements (ASTM majority of concrete construction, giving a unit weight for such concrete of rtland-pozzolan ce- about 145 pcf (pounds per cubic foot) or 2320 kg/m3 (kilograms per cubic

, and slag-modjfied meter). When steel reinforcement is added, the unit weight of normul welght be referred to for reinforced concrete is taken for calculation purposes as 150 pcf, or 2400 lesignation IA, IIA, kg/m3. Actual weights for concrete and steel are-rarely, if ever, computed separately. For special purposes, lightweight or extra heavy aggregates re a] admixture finely used.

abbles on the order iroughout the con- t4 .75 mm according to ASTM Standard Ell.

ed durability against 5Numbers refer to sections in the "ACI Code," oEcialy ACI 318-83, BIlding Code Require-ing agents may be ments for Reinforced Concrete [9].

15.3 Equhadent Pin-d Lengths 543 j2 ir1008X0.200b 3 ) =

= Stfh 2 I'

(kLJ2

= 3.92bh kL = 22.5 s,\ ....

I KLu - 22.5 /- = 78 (abscissa of point C) *1 i .

1*

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EQUIVALENT PIN-END LENGTHS 1-

- ;ri conditions other than pin ends where the fictor k in Eq. (15.2.1) is 1.0, 4l tle equivalent pin-end length (also called effective length) factor k must be

'.. etrmined for various rotational and translational end restraint conditions.

,..Where translation at both ends is adequately prevented, the distance be-tween points of inflection is shown in Fig. 15.3.1. For all such cases the

• 41

1) = 3.92bh equivalent pin-end length is less than the actual unbraoed length (i.e., k is kss than one).

med section, 5555 lIE 5, 5'

.0833bh 3 W Ip - T~~P W -P St id*s

[15.2.11] a) End rotations (b) End rotations (cl One end Id) Partially restrained unrestrained fully restrained restrained, at each end d,.

u nrestraine

'gure 15.3.1 Equivalent pin-end (.e., el Gi no joint translafion. .

If sidesway orjoint translation is possible, as in the case of the unbraced frame, the equivalent pin-end length exceeds the actual unbraced length "9

-.(ie., k is greater than one), as shown in Fig. 15.3.2.

inB) - - As reinforced concrete columns are in general part of a larger frame, it is necessary to understand the concepts of a bracedframe (where joint y; E = 29,000 ksi. translation is prevented by rigid bracing, shear walls, or attachment to an 't.

adjoining structure) and the unbracedframe (where bucding stability is I I

dependent on the stiffness of the beams and columns that constitute the frame). As shown in Figs: 15.3.3(a) and (c), the effective length kL. for cases where joint translation is prevented may never exceed the actual length L. t

)

W

:1

.

• S .

L i g i

5-134 Sect. C-C2]

I the top of the colun CHAPTER C tions, even where I very substantial in t FRAMES AND OTHER STRUCTURES chorage (Stang anc would generally be While in some case C2. FRAME STABILTY support for their b use of light curtair The stability of structures as a whole must be considered from the standpoint structures not prov of the structure, including not only the columns, but also' the beams, bracing a situation where i system and connections. The stability of individual elements must also be pro- support vided. Considerable attention has been given in the technical literature to this subject, and various methods of analysis are available to assure stability. The SSRC Guide to Design Criteriafor Metal Compression Members devotes sev-eral chapters to the stability of different.types of members considered as indi-vidual elements, and then considers the effects of individual elements on the stability of the structure as a whole (Galambos, 1988).

The effective length concept is one method for esimatimpg4ein ter a II X aess ofthe otalfrase ona olumn being considered!-This concelpt use _

U ctors to equate the strength of a framed compression element of length L to Buckled shape of is shown by dashe, an e sQalent pin-ended member of length KL subject to axial load only.

L-ther me'ds'e av'al'ble'for evaluatinig DiMETsity of frames subject to gravity and lateral loading and individual compression members subject to axial load and moments. The effective length concept is one tool available for handling several cases which occur in practically all structures, and it is an es-sential part of many analysis procedures. Although the concept is completely Theoretical K val valid for ideal structures, its practical implementation involves several assump- Recommended dE tions of idealized conditions which will be mentioned later. value when ideal tions are approxi Two conditions, opposite in their effect upon column strength under axial load-ing, must be considered. If enough axial load is applied to the columns in an unbraced frame dependent entirely on its own bending stiffness for resistance End condition cc to lateral deflection of the tops of the columns with respect to their bases (see I Fig. C-C2.1), the effective length of these columns will exceed the actual length. On the other hand, if the same frame were braced to resist such lateral movement, the effective length would be less than the actual length, due to the I It restraint (resistance to joint rotation) provided by the'bracing of other lateral support. The ratio K, effective column length to actual unbraced length, may be greater or less than 1.0.

I The theoretical K-values for six idealized conditions in which joint rotation and translation are either fully reahzed or nonexstent are tabulated in Table C-C2.1. Also shown are suggested design values recommended by the Struc-tural Stability Research Council for use when these conditions are approxi-mated in actual design. In general, these suggested values are sightly higher I

than their theoretical equivalents, since joint fiity is seldom fully realized.

A,.

I.- -

.;-Vgr.z If the column base in Case f of Table C-C2.1 were truly pinned, K would actu-1.!

1-:.;

i .".

ally exceed 2.0 for a frame such as that pictured in Fig. C-C2.1, because the s.I.,: flexibility of the horizontial member would prevent realization of full fixity at AmcA OF STEL CONSTRuCTON 1Nsrn3TE

.1:'i.I

Sect. CC2] FRA4ME STABILITY 5-135 the top of the column. On the other hand, the restraining influence of founda-tions, even where these footings are designed only for vertical load, can be very substantial in the case of flat-ended cohunn base details with ordinary an-chorage (Stang and Jaffe, 1948). For this condition, a design K-value of 1.5 would generally be conservative in Case f.

. While in some cases the existence of masonry walls provides enough lateral support for their building frames to control lateral deflection, the increasing use of light curtain wall construction and wide column spacing for high-rise stndpoint 1 structures not provided with a positive system of diagonal bracing can create

,-bracing j! a situation where only the bending stiffness of the frame itself provides this

~sepro- support.

tUre to this Fility. The f.

votes sev-ed asindi-hi tson the C- (a) (b) (C) (d) (e) (1) saction ef-  ;

pt uses K- .,

Buckled shape of column  ; 'i Iength.L to, is shown by dashed line Jl/

load only.

subject to subject.to ailable for- m py~~~~I it is anes- :-i:.; -

comnpletetr -. ,ly .p Theoretical K value 0.5 0.7 1.0 1.0 2.0 2.0 rai asump %I Recommended design value when ideal condi- 0.65 0.80 1.2 1.0 2. 10 20 itions are approximated F ptation fixed and translation fixed End condition code l Rotation free and translation fixed E§5a Rotation fix*d and translation free Rotation free and tmnslation free 1

P. I l

Ki L

_ _-__N-II I1 .

i II I

II ..

F FigureC-C2.1 AamEcANLarnir or Sum Cremc

.6-9 3RAVITIES CYfEIGHTS OF BUILDINGMATER IALS

~.W - -,- e --;

istanceistance 1Lb. per Weight I Seii Cu. Ftj_ait CEIUNGS Materiels l L e t .1 PARTITIONS MaterIls r Lb.pe.R SEASONED Channel suspended Clay Tge itent by system I 3 In. 17 Lathing and plastering See Partitions 4 In. 18 mber 16 to 20% Acoustcal fiber ile 1 6in. 28 ir ip to 50%

red .......... 40. 0.62-0.65 8In. 34 te, red ........ 22 0.320.38 FLOORS - 10 hI. 40

......... ...... : 41 0.6 Steel Deck  ; See Gypsum Block 30

• 0.48 -- 2 In. 911/4 s spn...........

32 25

- 0.51 r\ Concrete-.Reinforced Stone 1 In. 3 In.

4 In.

10A 121k 45 0.72 29 0.42-.52 in. 14 49 0.740-.6 Lightweight 6 totO 6 in. 1B'A 46 0.7.773S Wood Studs 2 x 4 d..............

)00,0 43 0.68 Concrete-PlaIn 1 n. 12-16 in.oc 2 te.............

...t............

33 0S3 "4 54 IZ. Steel partioons 4 0.86 on ............. 59 0.95 S g 11 Plaster 1 in.

Cack ....... 41 46 0.65 Ughtweight 3to Cement 10 nt............. 0.74 GypsuM 5 32 0.51 Fills 1 In. .J Lathing 30 0.48 6 Metal 26 0.41 Gypsum R. on-e....... 44 0.70 I Sand 8 Gypsum Board In. 2 38 0.61 Cinders 4 s.............. SD 0.48 1 WALLS 26 0.42 Finishes Brick On ............. 27 0.40-0.46 Terrazzo 1 In. 13 40

• 1 38 0.61 4 In.

26 0.41 Ceramic or Quarry Tile 80

% In. 10 12 in. 120 UIDS Linoleum 4 In. 1 Holilw Concrete Block 0%............ 49 0.79 9 (Heavy Aggregate) 2d.kAk c 40% .....

...... 75 1.20 Mastic 3/44In.

91% .... 94 150 Hardwood 7hA In. 4 4 In. 30 ICe . ............

hurr..7%...... Softwood Y In. 21/4 61In. 43 112 1.80 66%...... 106 1.70 S In.

dble ....... 58 0.91-0.94 ROOFS 12hIn. 80 57 0.9D-0.93 'I Copper or tin S Hollow Concrete Block Istifmdenslty..

m40%........ 62428 1.0 See (Light Aggregate) 69.830 0.584 Corrugated steel 56 0.88-0.92 Manufacturer 4 In. 21 8 .125 3-ply ready roofing I 6 In. 30 water..........

a.............. 64 1.02-1.03 3-ply felt and gravel 51/4h 38

....... ....... 5-ply felt and gravel 6 12In. 55 Clay tfle iatrm..........

m .08071 1.0 ShIngles (Load Bearing)

.0478

.1234 1.5291 4 Wood 2 4 In. 25 Y noxid ...... .07821 0.9673 Asphalt 3 6 In. 30

.028-.038 0.30.45 Clay tle 9 to 14 8 In. 33 ng . .038-D39 0.47-0.48 45

.00559 0.0693 I Slate V4 10 12in. U

.............. .0784 0.9714 Stone 4 in. 55 k

.692 1.1056 Sheathing Glass Block 4 In. 18 f p

i Wood %lIn.

Gypsum I In.

3 4

Windows, Glass, Frame

& Sash Curtain Walls 8

See I

I I

Insulaton I In. Manufacturer -,i Loose 'A Stuctural Glass 1 in. 15 Poured-In-place 2 Corrugated Cement tof gases to air a OC. and 760 mm Rigid 1'A Asbestos /4 In. 3 le gravites, except where staed t For weights of other materials used In building construction, seepages 6-7 and 6-8 DcrN AMERAN Ismrrz 0wSTEEL CWrl