两起脚手架倒塌事件（ｉ）图１，图２１９９０年４月２５日，美国明尼苏达州、密西西比河上一顶大拱桥在浇捣桥面的混凝土工程时，桥跨中间部分脚手架倒塌，造成一人当场死亡，还有几个险些遭难，受了一点轻伤。桥梁是两个跨度为１６９ｍ的大拱桥，桥体为现浇钢筋混凝土箱... Two Collapses of Scaffolding (i) Figure 1, Figure 2 On April 25, 1990, when a large arch bridge over the Mississippi River in Minnesota and Minnesota was under concrete construction on a concrete bridge, the bridge collapsed across the middle part of the scaffold and killed one person on the spot. There were still a few hardships and minor injuries. The bridge is a large arch bridge with a span of 169m. The bridge is a cast-in-place reinforced concrete box...