管道应力师应知问题集锦.doc

1、AUDIT FOR CHINESE STRESS ENGINEER A) UNDERSTANDING CAESAR II 1. What kind of calculation and evaluation is not covered by C2 in piping system? 蠕变分析，管道或设备的局部应力分析，管道失稳等How to check if piping system expose to buckling problem by using C2? 负压、偶然荷载、集中荷载、埋地管的土壤约束等荷载都会引起管道的失稳；但 CAESAR II 并不能评定管道的失稳（需要借助压力容

2、器设计软件进行管道的失稳设计） ；CAESAR II addresses negative pressures as follows: the absolute value of the longitudinal pressure stress (PD/4t) term is added to the appropriate code equations; pressure thrust forces applied to expansion joint ends will be compressive; and buckling is not addressed in CAESAR II临界

3、失稳压力： CDEIPmc3214E弹性模量（MPa） ；I截面惯性矩（mm4/mm） ；v泊松比，0.350.45；Dm管道平均直径；C椭圆修正系数， ，r1椭圆管道的弯曲半径，r0圆形管道半径；310/r允许的管壁冲击荷载： 5.030)/(2)( mwDEIBRFSN2. Global/local loads in C2 output, The reason why we need the local elements loads? 为了获得作用在设备管口上准确的外载，以进行局部应力分析；另外通过局部坐标推力的分析，可以仔细察看管道单元内部的相互作用关系，协助发现问题，并尽快找到答案。3

4、. On input sheet, what is different for Force, Uniform load, Rigid element with weight. -the temperature base of Elastic modulus input?集中力（力或弯矩作用于管道上一点，一般模拟外载力的作用效果，对于一些额外重量，如支架根部，最好不用力来输入，因为如果计算地震，这些质量都不存在。 ） 、均布载荷（荷载均布于管道所有点上，我们一般用它来模拟雪载） 、带重量的刚性件（横向刚度无穷大横向没有弯曲，刚性件只传导位移和力，我们一般用它来模拟阀门，管道设备等，但要注意，刚性

5、件有直径何壁厚，他们对他的横向变形会有影响。 ） 。软件缺省的弹性模量是冷态的。但用户可以选择。4. What is non-linear system? Area there any special cautions in input/output for non-linear case? 非线性系统就是：依据胡克定律 F=K*X，我们认为 k 是变化的。管道在使用支架、吊杆，支架加间隙，摩擦力的情况下，系统变成非线性的。管系从冷态热态或热态偶然工况过程中由于非线性约束的作用导致管系刚度发生改变；如果你输入过多的非线性支架，可能导致软件计算不收敛。陷入时循环。我们一般先判断，根据直观感觉决定

6、一些点，加入非线性约束。其他处根据计算结果，在调整支架。5. How to check the lift-off support point? What should Engineer check for lift-off problem? What is hot sustained stress? 检查约束报告，垂直方向受力为 0 的点即支架托空点；支架托空点应考虑采用弹性支吊；Hot sustain stress计算热态持续应力。依据 B31.3 Appendix P, 用户可以校核热态持续应力。主要是考虑支架脱空情况下持续应力。Generally Hot sustained stress

7、 is carried out by removing the support at the point of lift off , and in another, Bourdon test means were larger than unbending test means. In both data sets, there was a large and significant pretest bending effect, which enhanced the magnitude of unbending test minus pretest scores. These results

8、 were consistent with our theory but not the theories of Walker and Shank. The variance of unbending test matches, 3-4 times that of Bourdon test matches, reflected the task difficulty. We propose that subjective obtuse angle contraction that exceeds real obtuse angle contraction explains the fact t

9、hat unbending effects are larger in subjective than in real contours.10. What are different for Hot load setting and Cold load setting? 答：热态荷载设置和冷态荷载设置的区别：冷态荷载：W、P热态荷载：W、T 、PSUS=W+P; OPE=W+P+T11, Are there any special caution for load combination method to get valid stress and support load? If syste

10、m include the non-linear case, how to prepare load combination for each stress (SUSOCC, EXP)? 答: SELECT COMBINATION METHOD FOR COMBINATION CASES ONLY Summary of most commonly used combination types: ALG - signed algebraic combination disp./force level Scalar - signed combination disp./force/stress l

11、evel ABS - unsigned combination disp./force/stress level Detailed Description of all combination types: ALG - Combine the displacement vectors and the force vectors ALGebraically and calculate the stresses from the combined forces. Displacements are the algebraic combination of the displacement vect

12、ors. Forces are the algebraic combination of the force vectors. Stresses are not combined; stresses are calculated from the algebraically combined forces. ALG would typically be used to calculate EXP code stresses. Scalar - Combine the displacement vectors, the force vectors, and the stress scalars.

13、 Displacements are the algebraic combination of the displacement vectors. Forces are the algebraic combination of the force vectors. Stresses are the scalar combination of the stress scalars. The Displacements and Forces of an ALG case and Scalar case are equivalent. There may be variation at the st

14、ress level, since in an ALG combination the stresses are calculated and in a Scalar combination the are combined. For example: Load Case 1: Bending stress = 100 psi, due to X-moment Load Case 2: Bending stress = 100 psi, due to Z-moment Algebraic (vectorial) sum = sqrt(100*100 + 100*100) = 144 psi S

15、calar sum = 100 + 100 = 200 psi Scalar would typically be used to sum (SUS + OCC) code stresses. SRSS - Combine square root of the sum of the squares (SRSS) of the displacements, square root of the sum of the squares (SRSS) of the forces, and square root of the sum of the squares (SRSS) of the stres

16、ses. Displacements are the the square root of the sum of the squares of the displacements of all cases included in the combination. Forces are the the square root of the sum of the squares of the forces of all cases included in the combination. Stresses are the the square root of the sum of the squa

17、res of the stresses of all cases included in the combination. SRSS would typically be used to combine seismic directional components. ABS - Combine the ABSolute value of the displacements, the ABSolute value of the forces, and the ABSolute value of the stresses. Displacements are the sum of the abso

18、lute value of the displacements of all cases included in the combination. Forces are the sum of the absolute value of the forces of all cases included in the combination. Stresses are the sum of the absolute value of the stresses of all cases included in the combination. MAX - Compare the ABSOLUTE v

19、alues of the displacements, forces, and stresses and report the MAXimum displacement, the MAXimum force, and the MAXimum stress value of the cases combined (retaining the original sign). Displacements are the displacements having the maximum ABSOLUTE values of all the load cases included in the combination.