一个关于材料力学例题的讨论
Discussions of an Example in Mechanics of Materials

现行的许多材料力学教材中列举过一个两端固定的静不定梁在横向集中力作用下的挠度和约束力的计算实例，然而，在该例的分析和计算当中，却忽略了固定端轴向约束力的影响。本文在计入固定端轴向约束力影响的基础上，分析计算了该梁中点的挠度以及梁两端的约束力，并与材料力学教材中所给出的未计入固定端轴向约束力影响的对应结果进行了比较，发现两者之间存在显著差异，进而说明：在两端固定的静不定梁的挠度和约束力的分析计算当中，计入固定端轴向约束力的影响是完全必要的。
There is an example of determining deflection and constraint forces of a statically indeterminate beam with two fixed ends subjected to transverse load in many textbooks on mechanics of materials. However, in this example, the influence of axial constraint forces at the fixed ends is not taken into consideration. In the present paper, taking into account the influence, the results of the deflection of the center point of the beam and constraint forces at the two fixed ends are determined. These results are found to be strikingly different from the corresponding results without accounting for the influence of axial constraint forces presented in textbooks on mechanics of materials. This indicates that the inclusion of the influence of axial constraint forces in determining deflection and constraint forces of statically indeterminate beams with two fixed ends subjected to transverse load is necessary.