主梁下挠变形的主要原因是受热引起的最大复合应力超过许用值，达到了屈服极限值，强度不满足要求。
The main reason of the main beam down deflection was that the most complex stress exceeded the admissible value and achieved the yield limit value.
主要结论：所选材料的许用应力大于通过该种方式计算得到的该防浪板的最大应力的3.5倍时，该防浪板是安全的。
Main conclusions: the wave-proof plate is safe when the permissible stress of the selected material is greater than the maximum calculated stress's 3.5 times of it.
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