ML20205B056

Forwards Addl Info Re Structural Analysis of Bldg 10 & Walkover Structure,Per 860625 Request,Including Seismic Model Used for Bldg & Rev 0 to SAD-481, Evaluation of Structure-Soil-Structure..

ML20205B056
Person / Time
Site:	Fort Saint Vrain
Issue date:	07/28/1986
From:	Warembourg D PUBLIC SERVICE CO. OF COLORADO
To:	Berkow H Office of Nuclear Reactor Regulation
Shared Package
ML20205B059	List: ML20205B056 ML20205B071
References
P-86489, TAC-55287, NUDOCS 8608110511
Download: ML20205B056 (8)

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Seubiicservice- - . . - -

Company of Colorado 2420 W. 26th Avenue, Suite 1000, Denver, Colorado 80211 July 28, 1986 Fort St. Vrain Unit No. 1 P-86489 Director of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555 Attn: Mr. H.N. Berkow, Director Standardization and Special Projects Directorate Docket No. 50-267

SUBJECT:

Request for Additional Information on FSV Building 10 and Walkover Structure

REFERENCE:

1) NRC Letter Heitner to Walker, dated June 25, 1986, (G-86342)

Dear Mr. Berkow:

Attached please find the additional information regarding the structural analysis of Building 10 and Walkover Structure as requested in the above referenced letter. The subjects of these attachments are:

l Attachment 1 - Seismic Model Used for Building 10 Attachment 2 - Soil Structure Interaction at Building 10 Attachment 3 - Structure-Soil-Structure Interaction Between Building 10 - Walkover Structure and Turbine Building Attachment 4 - Differential Displacement Calculations Between Adjacent Buildings Attachment 5 - Evaluation of Checker Plate Gaps and Building 10 j Step Structure pMf 8600110511 860728 ADOCK 05000267 PDR P PDR l M

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P-86489 Page 2 July 28, 1986 If you have any questions regarding this subject, please contact Mr. M. H. Holmes at (303) 480-6960.

Very truly yours, A2 JY /TwY D.W. Warembourg, Q Manager Nuclear Engineering Division DWW/fH:pa Attachments

s-Attachment 1- SEISMIC MODEL USED FOR BUILDING 10 The buildicg was analyzed using a lumped mass dynamic model. This model was analyzed for the safe shutdown earthquake (SSE) as defined in the Nuc! ear Regulatory Commission Guide 1.60. The following steps wore taken to perforts Jhe analysis. This analysis was done for each of the two sets of dynamic soil springs we calculated.

1. Determine the mass prcperties (magnitudes, centers of mass, mass moments of inertia) of the floor and wall system of the building. Each floor level is taken as a single mass in this model.

2. Determine the section properties (areas, center of rigidity, moments of inertia) of the shear walls. This will be used to model the stiffness between floor levels.

3. Determine stiffness matrices for equivalent msnibers between lumped masses. This matrix is is adjusted to consider the inclination of principal axes and offsets between centers of mass and rigidity.

4. Perform the dynamic raodal analysis of the structural model. From this we obtain the eigenvalues and eigenvectors, mass matrix for the next step in the analysis.

5. Perform the time history dynamic analysis to compute the amplified response spectra for each floor level for each translational direction for various damping values. This program uses the safe shutdown earthquake (SSE) as defined in the Nuclear Regulatory Commission Guide 1.60 as the base excitation.

6. Plot the amplified response spectra for each translational degree of l freedom and damping value.

_PAGE l l

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Fort St. Vrain - Building 10 STRUDL model Roof Mass El. 4850.6'!' (Joint 6)

Walls El. 4835'-6" to 4852'-0" g>

Stiffness Matrix 5 1

4 > Floor El. 4835.76' (Joint 5) 4 Walls El. 4824'-0" to 4834'-3" Stiffness Matrix 4 l4g Floor El. 4823.40' (Joint 4)

Walls El. 4811'-0" to 4823'-6" Stiffness Matrix 3 Floor El. 4811.22' (Joint 3)

Walls El. 4800'-6" to 4810'-6" Stiffness Matrix 2 Floor El. 4800.33' (Joint 2)

Walls El. 4791'-0" to 4800'-0" Stiffness Matrix 1 Ground El. 4790.00' (Join 1)

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<> \ Soil Springs j , KFX, KFY, etc.

w PAGf 2

d Attachment 2 - SOIL INTERACTION MODEL USED FOR BUILDING 10 General Methodology - Utilizing the method described in reference 1, determine an equivalent cantilever to model the soil-pile-foundation interaction. An important component of this modelis to find the length of the caisson in bending direction (L3) as a function of lateral soil support (modulus of subgrade reaction (Kh)) and caisson stiffness. This equivalent cantilever will model the stiffness of the soil, and will allow easy calculation of an equivalent set of soil springs.

From the Stone & Webster calculation 13569.04-G-1, we obtain the listed Kh as a function denth.

Depth Kh 0-10' 50lbAn3 10-27.5' 170 lb/in3 27.5-45' 47lbAn3 45-59' 85lbAn3 From Eq 9 & 11 Ref.1 Lb = 1.85(El/K h )"

where L =b equivalent caisson bending length E = Modulus of elasticity of concrete I = Moment of inertia of caisson Reference 1 only addresses constant Kh . So we will calculate two sets of soils springs based on the Khvalues for the top two layers of soils and analyze building response for both cases. The two equivalent lengths 1, calculated are:

Lb= 17.3 ft for Kh= 50 lbAn3 Lb= 13.5 ft for Kh= 170 lbAn3 Because the caisson reinforcement is carried into the building mat, the caissons will be considered fixed head case. In the axial direction the length (L c) is taken as the distance to bedrock.

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From this we obtain an equivalent structure with the given dimensions and coordinates as shown on Fig.1.

Using this equivalent structure we will use equations 17-21 from Ref.1 to obtain soil springs for Building 10. These equations are generalized for caissons in any orientation. Because our model has caissons are always parallel to one of the coordinate axes, they can be simplified to the following forms.

Vertical KFY U c^ (From Eq.17)

C Horizontal 12nEcl KFX - KFZ - 3 (From Eq.18)

Lb.

Rocking About Y

• 4nEeI KMZ- L k + (From Eq.19)

Rocking About X

• 4nEeI KMX= k + (From, Eq. 20)

Torsion About Z KMY- rk (From Eq. 21)

Lb -i where n = number of caissons = 6 Ec= Modulus of elasticity of concrete A = Area of caisson 4 = equivalent caisson bending length Lc= caisson axiallength Ix 2k = 6(14.5)2 = 1262 ft2 Iyk 2= 4(20)2 = 1600 ft2 Ir 2.

g Ix,2 + Iyg2 = 2862 ft2 Page 2 L

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d Substituting these values into the stiffness equations with 3

L3= 17.3 ft (K n= 50 lb/in ) and Lb= 13.5 ft (Kh= 170 lb/in3)

We obtain the following values for the dynamic soil springs:

D.O.F. Kh = 50 lb/in^3 Kh = 170 lblin^3 KFX 8.50E+04 h/ft 1.79E+05 k/ft KFY 7.05E+05 k/ft 7.05E+05 k/ft KFZ 8.50E+04 k/ft 1.79E+05 k/ft KMX 1.96E+08 ft-k/ rad 1.99E+08 ft-k/ rad KMY 4.05E+07 ft-k/ rad 8.53E+07 ft-k/ rad KMZ 1.57E+08 ft-k/ rad 1.59E+08 ft-k/ rad Reference 1 - Design of Machine Foundations on Piles, Journa! of the Geotechnical Engineering Division, J.P. Singh, N.C. Donovan, A.C. Jobsis, August 1977, pages 863-877 l

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A4 I

j Y sa spring

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3 O

(-14.5, 20.o)

O (14.5.20 0)

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l l J L

! O O 'X Lb

! V V Sod spring or j (-14.5, 0) s (14.5,o) Lc 1r O O M M .s%M

(-14.5, -20.0) (14.5, -20.0) i A-A j

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g Equivalent Cantilever Structure s

Figure 1

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