请大家发表一下意见，怎样验算一个工程是否积水？

很多时候只能是靠经验估计吧。主要从形态上去判定。这本来就是一个定性的东西。

一般有要求排水坡度20%，主要在上、下荷载下的FORMFINDING里查有积水隐患的坐标。

The first thing can help a designer is a contour map of a DEFORMED SHAPE of a structure. Second is to understand your structure and make assessment for potential water ponding problem.
  
The original form is not the only shape you need to check for ponding, every load combination should be evaluated. By reviewing a contour map, it is possible to determine if there is a POCKET could collect water from its surrounding.
  
Sometimes contour map indicates water flows down and out of the membrane surface but your judgment may tell you otherwise. For example from the contour map there is a large area of water flowing to a corner which is surrounded by hard items such as cable and steel plate. Your judgment may tell you that before the large quantity of water can flow out, it will be stopped by the stiff objects and cause the fabric to deflecting downwards creating a pocket and more water will be accumulated to cause ponding.
  
If you have any doubt about certain area, you need to simulate the ponding situation as additional loading condition. This is not an exact science requires a lot of attention to avoid future problem.

如果你是用EASY软件，那么很容易看见其在荷载状态变形下的等高线分布。这样就可以看到是否积水了。

等高线的疏密程度判断还是一个经验活

个人认为，积水与否，软件里是可以看出，但要慎用。
如果你对载荷和材性很有把握，并经多个软件复核，可以相信。
如果不是，最好评估下，宁愿保守点。
精确与经验并重吧

可以根据膜的应力大小及外观形状来判别。

可以用等高线法判断一下

AutoCAD里写个等高线程序，等高怎么看就不必说了吧