一、这是一个多重复合句,其结构层次如下：
主句：Some of our projects have looked at … 有些设计着眼于…
宾语从句：what we call situational impairments,我们所称其为状况缺陷的东西
非限制性定语从句：which are challenges to accessibility 这种设计是对可达性的挑战
嵌套定语从句：that are caused more by the situation or context 一些由场合或者背景关系引起的挑战
第二层嵌套定语从句：that the computer user is in instead of maybe as we usually think of accessibility as having to do with someone's own physical or cognitive state.
其中——
主结构——that the computer user is in 电脑用户所处的场合或背景
复合介词 + 宾语从句——in instead of maybe as we usually think of accessibility 或许取代我们通常把这种情况（电脑用户所处的场合或背景）认为是可达性
状语——as having to do with someone's own physical or cognitive state （= as we have to do with someone's own physical or cognitive state）在我们不得不忍受一个人自己的身体或认知状况的时候,
二、问题释疑
问题1.
as we usually think of accessibility 中的 as 是关系代词,指代上文的 that the computer user is in （关系代词 that 指代 the situation or context）.其正常结构为——
think of + 宾语 + 名词补足语,意思是“把…考虑为…”（think of 表示“认为/考虑”）
其实就是：we usually think of that the computer user is in instead of accessibility.
由于多个词组成的宾语从句长于一个词的宾补,因此应该改为：
we usually think of it accessibility that the computer user is in instead of（其中的 it 是形式宾语）.
问题2.
1）accessibility 属于上个意群,应该把它从这个意群中划分出去.
2）as having to do with someone's own physical or cognitive state 其实是从句 as we have to do with someone's own physical or cognitive state 省略主语后把 have 改为分词的一种结构,在后面的嵌套定语从句作时间状语或原因状语,即“由于我们不得不忍受一个人自己的身体或认知状况”或者“当我们不得不忍受一个人自己的身体或认知状况的时候”.
大体意思是：有些设计（或者方案）着眼于我们所称其为状况缺陷的东西,这种设计是对可访问（或者存取）性的一些由电脑用户所处的场合或者背景关系导致的挑战,或许在我们不得不忍受一个人自己的身体或认知状况的时候我们通常不把这种情况认为是可访问性.
