位移应力及其强度条件

管道设计规范中所述的位移应力包括温差、端点位移等荷载产生的应力．而在容器设计规范中将温差引起的应力归为二次应力。本文通过一简单例子对温差荷载和端点位移荷载所产生应力的计算过程、应力性质进行了分析，指出由于位移应力具有自限性特点，因此位移应力就是二次应力。然后，对管道设计规范和容器设计规范中针对位移应力和二次应力的强度条件进行了讨论。

Displacement Stress and Its Intensity Limitation

The displacement stress staled in the piping design codes includes the stresses produced by thermal and support movement loads. However, in the pressure vessel design codes, the thermal stress is identified as the secondary stress. In this paper, by using a simple example, the calculation process and the characteristics of the stresses resulted from thermal and support movement loads were analyzed. It is indicated herein that the displacement stress can be identified as the secondary stress because it has the self- limiting characteristic. Then, the intensity limitations for the displacement stress and secondary stress used in the piping design codes and the pressure vessel design codes were discussed.