VM-NR1677-01-3-a

VM-NR1677-01-3-a
NUREG/CR-1677: Volume 1, Benchmark Problem No. 3

Overview

Reference:P.Bezler, M. Hartzman & M. Reich, Dynamic Analysis of Uniform Support Motion Response Spectrum Method, (NUREG/CR-1677), Brookhaven National Laboratory, August 1980, Problem 3, Pages 81-121.
Analysis Type(s):
Modal analysis (ANTYPE = 2)
Spectral analysis (ANTYPE = 8)
Element Type(s):
Elastic straight pipe elements (PIPE16)
Elastic curved pipe elements (PIPE18)
Spring-Damper Element (COMBIN14)
Structural Mass element (MASS21)
Input Listing:

Test Case

This benchmark problem is an expanded version of

VM-NR1677-01-1

(refer to Figure 621: FE Model of the Benchmark Problem). The problem contains several anchors and branch connection representing a real piping system. The problem also has intermediate spring supports to simulate hangers and snubbers. Modal and response spectrum analysis is performed on the piping model. Frequencies obtained from modal solve and the nodal/element solution obtained from spectrum solve are compared against reference results.

Figure 621: FE Model of the Benchmark Problem

FE Model of the Benchmark Problem

Material PropertiesGeometric PropertiesLoading

Pipe Elements:

E = 24 x 106 psi
Nu = 0.3
Density = 0.001057 lb-sec2/in4

Mass Elements (lb-sec2/in):

Mass @ Node 18 = 1.518 lb

Spring-Damper Elements (lb/in):

Because there are multiple Spring Supports at different locations, the Stiffness for the Spring Damper Elements are listed based on real constant set number.

Set 3: K = 0.1 x 105
Set 4: K = 0.1 x 104
Set 5: K = 0.1 x 1011

Straight Pipe:

Outer Diameter = 7.288 in
Wall Thickness = 0.241 in
Bend Pipe:
Outer Diameter = 7.288 in
Wall Thickness = 0.241 in
Radius of Curvature = 36.30 in

Internal Pressure on Pipe Elements: 350 psi

Acceleration Response Spectrum Curve defined by FREQ and SV commands

Results Comparison

Table 40: Frequencies Obtained from Modal Solution:

ModeTargetMechanical APDLRatio
19.360 9.3591.00
212.710 12.7051.00
315.380 15.3761.00
417.800 17.7961.00
521.600 21.6021.00
625.100 25.0971.00
732.030 32.0331.00
838.070 38.0671.00
940.290 40.2911.00
1048.90048.8951.00

Table 41: Maximum Displacements and Rotations Obtained from Spectrum Solve

Result NodeTargetMechanical APDLRatio
UX at node14 0.2290.2200.964
UY at node8 0.098 0.0950.971
UZ at node9 0.1660.1630.985
ROTX at node3 0.0020.0020.985
ROTY at node7 0.0050.0040.985
ROTZ at node17 0.0020.0020.985

Table 42: Element Forces and Moments Obtained from Spectrum Solve

ResultTargetMechanical APDLRatio
 
Element 1
PX(I)154.400 150.9440.978
VY(I)209.200 206.317 0.986
VZ(I)463.300457.6470.988
TX(I)13090.000 13297.2171.016
MY(I)43130.000 42520.7770.986
MZ(I)18060.000 17807.561 0.986
 
PX(J) 154.400 150.9440.978
VY(J) 209.200 206.317 0.986
VZ(J) 463.300 457.6470.988
TX(J) 13090.000 13297.2171.016
MY(J) 18760.00018477.8030.985
MZ(J)8095.000 7975.5930.985
 
Element 20
PX(I) 633.300 630.0700.995
VY(I) 471.200 448.7780.952
VZ(I) 1012.000 1010.4540.998
TX(I) 5724.000 5437.0120.950
MY(I) 9985.000 9858.4700.987
MZ(I) 8126.000 7745.9460.953
 
PX(J) 633.300 630.0700.995
VY(J) 471.200 448.7780.952
VZ(J) 1012.000 1010.4540.998
TX(J) 5724.000 5437.0120.950
MY(J) 44680.000 44642.8500.999
MZ(J)27570.000 26253.3840.952
 
Element 7
PX(I) 270.600 268.3840.992
VY(I) 39.150 38.8350.992
VZ(I) 1813.000 1788.5400.987
TX(I) 5823.000 5729.9570.984
MY(I) 20040.000 19858.3600.991
MZ(I) 5439.000 5363.4250.986
 
PX(J) 1200.000 1184.2530.987
VY(J) 39.150 38.8350.992
VZ(J) 1386.000 1366.9130.986
TX(J) 7810.000 7688.1750.984
MY(J) 31740.000 31295.5230.986
MZ(J)2256.0002245.9120.996

Note:  PX (I) and PX (J) = Section axial force at node I and J.

VY (I) and VY (J) = Section shear forces along Y direction at node I and J.

VZ (I) and VZ (J) = Section shear forces along Z direction at node I and J.

TX (I) and TX (J) = Section torsional moment at node I and J.

MY (I) and MY (J) = Section bending moments along Y direction at node I and J.

MZ (I) and MZ (J) = Section bending moments along Z direction at node I and J.

The element forces and moments along Y and Z directions are flipped between Mechanical APDL and NRC results.