2024年2月17日发(作者：)

3）动态计算结果有没有更合理的解释，结果如下：

DISPLACEMENT REPORT, Nodal Movements

(OCC)SHOCK CASE # 1

--------Translations(mm.)-------- --------Rotations(deg.)---------

NODE DX DY DZ RX RY RZ

In the report below, each item consists of (3) lines of data:

- Line 1 is the total response.

- Line 2 is the contribution of the max contributor to the total response.

- Line 3 details the maximum contributor:

(a) the mode, the load component (direction and sequence number)

(b) missing mass contribution and associated load

(c) pseudo-static contribution and associated load.

101 7.1162 4.1858 3.3531 0.0426 0.0383 0.0232

1.6914 1.5135 1.4224 0.0103 0.0094 0.0080

8 X(2) 37 Y(1) 4 X(1) 25 Y(3) 21 X(1) 37 Y(1)

This can be interpreted as follows:

Line 1 gives the total system response. In this case, the DY displacement of the system at node 50 was 1.8718

in. This total system response is made up of many different components – the response of each and every mode

to each and every load, the missing mass contribution associated with each load (if activated), and the

pseudostatic, or restraint displacement, component of each seismic load (if activated).

第一行给出系统的全部响应。上面节点101，DX位移位7.1162mm.全部响应包含许多个响应成员，主要是以下三大类：

the response of each and every mode to each and every load, 每个荷载作用下的每个模态的响应

the missing mass contribution associated with each load (if activated) 在每个荷载作用下，丢失质量的响应。

the pseudostatic, or restraint displacement, component of each seismic load (if activated).假静态，约束位移，每个地震荷载的响应。

Line 2 indicates the maximum (absolute value) contribution from among all of the components listed above. In

this case, one of the individual loading components provided a DY displacement of 1.4828 in.

第二行给出全部响应中，最大的贡献响应量。上面节点101，最大位移贡献是1.6914mm。

Line 3 identifies which component provided that contribution. In this case, “1 Y(1)” indicates that mode 1,

responding to the first entered (in the particular spectrum case) Y-direction load, was the culprit. Knowing this

information, the displacement can be reduced by modifying (or eliminating) either the 1st mode of vibration or

the 1st listed Y-direction load.

第三行告诉我们那种元素贡献的最大位移。 8 X(2) 模态8 在X方向，您输入的第2个X方向动态荷载力。您或知该信息，如果要降低该位移贡献，可以通过消除该模态，或该X向力的大小。

Line 3 is always in the following format:

第三行往往形式如下：

“M D(n)” – “M” indicates the number of the mode responding to a load labeled with the direction “D” (can be

X, Y, Z, or S – indicating “Skewed”) which is the nth load in the spectrum case labeled that has label “D”, or:

M――模态数

D可以是方向X, Y, Z, or S – indicating “Skewed”

(n)荷载力的顺序号

“1 D/nM” (note that the “1” and “M” are constants here, while the “D” and “n” are variables) – this indicates

that the maximum contributor was the missing mass contribution corresponding to the nth load listed in the “D”

direction, or:

“1” and “M”是常量。

该形式表明最大贡献是丢失质量引起的。

是第n个偶然荷载力，在D方向上引发的。

“1 D/nP” (note that the “1” and “P” are constants here, while the “D” and “n” are variables) – this indicates that

the maximum contributor was the pseudostatic (restraint movement) contribution corresponding to the nth load

listed in the “D” direction

“1” and “P”是常量

该形式表明最大贡献是假静态（约束位移）

是第n个偶然荷载力，在D方向上引发的。

Include Missing Mass Components (Y/N)

(Active for: Spectrum and Time History)

During spectrum (either seismic or force spectrum) or time history

analyses, the response of a system under a dynamic load is

determined by superposition of modal results. One of the

advantages of this type of modal analysis is that usually only a

limited number of modes are excited and need to be included in the

analysis. The drawback to this method is that although

displacements may be obtained with good accuracy using only a few

of the lowest frequency modes, the force, reaction, and stress

results may require extraction of far more modes (possibly far

into the rigid range) before acceptable accuracy is attained.

CAESAR II provides a feature, called the "Missing Mass Correction",

which helps solve these problems. This feature offers the ability

to include a correction which represents the contribution of the

higher order modes not explicitly extracted for the modal/dynamic

response, thus providing greater accuracy without additional

calculation time. When this option is activated (by entering Yes

for this parameter), the program automatically calculates the net

(in-phase) contribution of all non-extracted modes and combines it

with the modal contributions - avoiding the long calculation time

associated with the extraction of the high order modes and the

possible excessive conservativism of the summation methods.

When considering force spectrum analyses for loads such as fluid

hammer, relief valve, slug flow, etc., the applied load is not a

function of the system mass, so the correction is truly a "missing

force" correction.

Including the missing mass correction is especially effective when

performing force spectrum calculations. This is because force

spectrum loads due to causes such as fluid hammer and slug flow

act axially along the pipe, and therefore excite most highly the

extremely rigid axial extension modes. Therefore the rigid response

represented by the missing mass correction often provides a very high

proportion of the total force spectrum response.

Include Pseudostatic (Anchor Movement) Components (Y/N)

(Active for: Spectrum/ISM)

This option is only used when Independent Support Motion (anchor

movement) components are part of a shock load case. The excitation

of a group of supports produces both a dynamic response and a static

response. The static response is due to the movement of one group

of supports or anchors relative to another group of supports/anchors.

These static components of the dynamic shock loads are called

"pseudostatic components". USNRC recommendations, as of August

1985, suggest that the following procedure be followed for

pseudostatic components:

1) For each support group, the maximum absolute response should be

calculated for each input direction.

2) Same direction responses should then be combined using the

absolute sum method.

3) Combination of the directional responses should be done using

the SRSS method.

4) The total response should be formed by combining the dynamic

and pseudostatic responses, using the SRSS method.

Therefore pseudostatic components should be included whenever

Independent Support spectral loadings are used.