structural hollow sections examples in practice.

框架梁端部开孔这么大，怎么没有补强？还未完工的原因？

This is cellular beam （蜂窝梁）which is very popular in Europeean countries because they do not need consider earthquake resistance.  
But in earthquake regions like China, it is not recommended.

应力集中的问题本身与洞口大小无关，主要是在洞口的四周存在；
这样，是否考虑地震设防好像也不是主要问题。
楼主能否讲讲，图上洞口很大，那么，上下翼缘如何考虑？

在梁端开这么大的洞没有见过
好像有些不可思议。
希望楼主给小弟详细介绍一下好么
谢谢

Design of composite and non-composite cellular beams -Presents design methods for simply supported steel and composite cellular beams (with circular openings) as used in buildings. The design methods, consistent with BS 5950: Part 1 and 3.1, are illustrated by a worked example

我记得蜂窝梁的第一个孔的孔边到支座边缘的距离不得少于250mm，看这个图我感觉好象不太够。国外的蜂窝梁也需要满足这个要求吧？