Without warning the residents, construction crews began a string of night-time shifts to reinforce the bolted joints.

在没有警告居民的情况下，施工人员开始了一系列夜班以加固螺栓接头。

A change approved without his knowledge had replaced the exoskeleton's welded joints with cheaper and weaker bolted joints.

在他不知情的情况下批准了一项变更，用更便宜、更弱的螺栓接头取代了外骨骼的焊接接头。