回复：只看了一张上海楼房倒塌照片，估计问题出在地基处理上。

You are right

The building is good and the foundation itself is fine.

Since most windows did not break, the collapse must be a soft landing (to soft soil surface) which means a slow failure.

Based on the appearances of those pile sections, the failure is not induced by lateral forces or shears.

A few issues may cause the final failure:

1. The weak soil support layer(s) under the foundation (may be partially)drags the build into dislocation

2. The dislocation produces large tensile forces and moments to break the piles in order.