Examples - CAESAR II - Help

CAESAR II Users Guide

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CAESAR II
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CAESAR II Version
13

Example 1

Define a shock load case that excites the entire piping system with a vibration of one times the El Centro earthquake in the X direction, one times the El Centro earthquake in the Z, and 0.667 times the El Centro earthquake in the Y direction.

Spectrum

Factor

Dir.

ELCENTRO

1

X

ELCENTRO

1

Z

ELCENTRO

0.667

Y

Example 2

Define a shock load case that excites the piping system with the horizontal and vertical components of the Reg. Guide 1.60 shock spectra for a 2 percent critically damped system. The maximum ground acceleration is 0.22 g’s.

The maximum ground acceleration is set on the Control Parameters tab and has no effect on the shock load case definitions.

Spectrum

Factor

Dir.

1.60H2

1

X

1.60V2

1

Y

1.60H2

1

Z

Example 3

Define a shock load case that is comprised of custom shocks BENCH1 and BENCH2. BENCH1 acts in the X and Z directions, and BENCH2 acts in the Y direction. The scale factor for all shocks is 1.0.

Spectrum

Factor

Dir.

BENCH1

1

X

BENCH2

1

Y

BENCH1

1

Z

One of the shock load cases excites the piping system along a line that is 45 degrees off the global axes in the horizontal plane. It is suspected that this direction of excitation yields the worst possible results. Apply the custom shock BENCH1 in the horizontal direction and BENCH2 in the vertical direction.

Spectrum

Factor

Dir.

BENCH1

1

(1,0,1)

BENCH1

1

(-1,0,1)

BENCH2

1

Y

Example 4

Define a shock load case that excites the piping system with a vibration of two times the El Centro earthquake in the X, Y, and Z directions. There should be two shock load cases. The first should use an independent summation and the second a simultaneous summation.

The load cases are defined as shown. Remember that independent summation means MODAL then SPATIAL, and simultaneous means SPATIAL then MODAL.

There are several ways to accomplish the same objective using parameters on other tabs, such as the Control Parameters tab. Only the method using the explicit definition of the load case combination method is shown in this example.

LOAD CASE 1 SHOCK CONTRIBUTIONS

MODAL(GROUP), SPATIAL(SRSS), MODAL COMBINATIONS FIRST

Spectrum

Factor

Dir.

ELCENTRO

2

X

ELCENTRO

2

Y

ELCENTRO

2

Z

LOAD CASE 2 SHOCK CONTRIBUTIONS

SPATIAL(SRSS), MODAL(GROUP), SPATIAL COMBINATIONS FIRST

Spectrum

Factor

Dir.

ELCENTRO

2

X

ELCENTRO

2

Y

ELCENTRO

2

Z

Example 5

Define a shock case that has the custom spectrum 1DIR acting only in the Z direction. Set the stress type for the case to be operating and use modal summations before spatial summations. Modal or spatial summations are not shown below because modal summation is the CAESAR II default and is controlled by Spatial or Modal Combination First on the Control Parameters tab.

Stress Types: OPE

Spectrum

Factor

Dir.

1DIR

1

Z

Example 6

The support nodes 5, 25, 35, 45, and 56 are pipe shoes sitting on concrete foundations. The support nodes 140, 145, 157, 160, and 180 are second level rack supports, that is, pipe shoes sitting on structural steel beams in the second level of the rack. The ground level shock spectrum name is GROUND04, and the second level rack spectrum name is RACKLEVEL2-04. Set up the shock load case to define these independent support excitations and omit any relative support movement.

GROUND LEVEL EXCITATION


Spectrum


Factor


Dir.

Start Node

Stop Node


Increment

Anchor Movement

GROUND04

1

X

5

56

1

0

GROUND04

1

Y

5

56

1

0

GROUND04

1

Z

5

56

1

0

RACK LEVEL 2 EXCITATION


Spectrum


Factor


Dir.

Start Node

Stop Node


Increment

Anchor Movement

RACKLEVEL2-04

1

X

140

180

1

0

RACKLEVEL2-04

1

Y

140

180

1

0

RACKLEVEL2-04

1

Z

140

180

1

0

Next, set up a shock load case, and define all combinations options explicitly. Use the same shock components as defined above, except assume that the pseudostatic component is added using the SRSS combination method. Also change the modal summation method to SRSS. This is the recommended method. When the modal summation method is SRSS it does not matter whether modal or spatial combinations are performed first. The order is only a factor when closely spaced modes are considered in the grouping, 10 percent, and DSRSS methods.

MODAL(SRSS),PSEUDOSTATIC(SRSS),SPATIAL(SRSS)

GROUND LEVEL EXCITATION


Spectrum


Factor


Dir.

Start Node

Stop Node


Increment

Anchor Movement

GROUND04

1

X

5

56

1

GROUND04

1

Y

5

56

1

GROUND04

1

Z

5

56

1

RACK LEVEL 2 EXCITATION


Spectrum


Factor


Dir.

Start Node

Stop Node


Increment

Anchor Movement

RACKLEVEL2-04

1

X

140

180

1

RACKLEVEL2-04

1

Y

140

180

1

RACKLEVEL2-04

1

Z

140

180

1

Example 7

The last elbow in the relief valve piping is at node 295. The spectrum name: BLAST contains the DLF response spectrum for relief valve firing. SPECTRUM/TIME HISTORY FORCE SET #1 contains the load information and its point of application. Show the load case input that provides the most conservative combination of modal results. Because there is only a single loading, no consideration is given to spatial or directional combinations.

Shock Name, Factor, Direction, and Force Set #

ABSOLUTE MODAL SUMMATION, ONLY A SINGLE LOADING

COMPONENT AND SO NO CONSIDERATION GIVEN TO SPATIAL OR

DIRECTIONAL COMBINATIONS.

BLAST, 1, X, 1

MODAL (ABS)

Click Directives to open the Directive Builder dialog box and select these values. For more information, see Directive Builder.

Use the same example above and combine the modes using the grouping method. This will produce the most realistic solution.

BLAST, 1, X, 1

MODAL (GROUP)

Example 8 (Force Response Spectrum)

There are two elbow-to-elbow pairs that are of significance in this job. Water hammer loads act on the elbow at 40 in the X direction and on the elbow at 135 in the Y-direction. In the SPECTRUM/TIME HISTORY FORCE SET input, force set #1 is defined as the load at 40 and force set #2 is defined as the load at 135. Add the response quantities from each load component first, using an ABS summation, and then the resulting modal response quantities, using the grouping summation method. Two identical methods for achieving the same results are shown.

Shock Name, Factor, Direction, and Force set #

BECAUSE THE "DIRECTION" INPUT IS THE SAME, THAT IS "X", FOR BOTH,

LOAD CONTRIBUTIONS, THE DIRECTIONAL COMBINATION METHOD

WILL GOVERN HOW THE HAMMER40 AND HAMMER135 RESPONSES

ARE COMBINED.

HAMMER40, 1, X, 1

HAMMER135, 1, X, 2

DIRECTIONAL (ABS), MODAL(GROUP)

or

BECAUSE THE "DIRECTION" INPUT IS DIFFERENT, THAT IS "X" AND "Y,"

THE SPATIAL COMBINATION METHOD WILL GOVERN HOW THE

HAMMER40 AND HAMMER135 RESPONSES ARE COMBINED. NOTE THAT

ON THE DIRECTIVE LINE THE "SPATIAL" DIRECTIVE COMES BEFORE

THE "MODAL" DIRECTIVE.

HAMMER40, 1, X, 1

HAMMER135, 1, Y, 2

SPATIAL(ABS), MODAL(GROUP)