印度加尔各答立交桥倒塌

CNN新闻：
A flyover under construction in Kolkata, India, has collapsed killing at least 14 people.
在印度加尔各答，一座在建立交桥发生倒塌，造成至少14人死亡。
A 100-metre slab of metal and cement crashed onto moving traffic below, pinning down dozens of vehicles.
一块100米的金属和水泥板砸向下面穿行的车辆，数十辆汽车掩埋。
The death toll is expected to rise as up to 70 people are believed to be trapped in the debris, according to a disaster management official.
据一位灾害管理员称，死亡人数预计将上升，有70人被困在废墟中。
Locals and rescue workers alike could be seen trying to help those under the rubble.
当地和救援人员正在试图帮助那些掩埋在废墟下的人。
A senior police officer confirmed at least 15 critically injured people had been rescued.
一名高级警官证实至少有15名伤势严重者获救。
The bridge has missed several completion deadlines since construction began in 2009.
自2009年开建以来，这座桥已经错过了几次竣工最后期限。


印度时报：
Kolkata flyover collapse加尔各答立交桥坍塌
Live updates: 17 dead, dozens injured in Kolkata flyover collapse
加尔各答立交桥坍塌，17人死亡，数十人受伤
A part of the Vivekananda Road flyover, that was under construction, collapsed on Thursday in Kolkata leaving dozens trapped under the debris.
3月31日，加尔各答，正在施工的维韦卡南达路立交桥的一部分，坍塌，数十人被困在废墟下。
There was a sudden thundering noise” as the Vivekananda Flyover came crashing down, a witness said.He said he saw the flyover collapse over taxis, auto-rickshaws and other vehicles.
目击者称，他们先是听到一声突然传来的雷鸣般声音，然后就看到立交桥坍塌，出租车、人力车等车辆被压在下面。
Disaster management and trauma care teams joined the rescue and relief operations. So did hundreds of locals.
灾害管理和创伤护理团队也加入到救援行动中来。数百名当地人也加入其中（这座立交桥自2008年起开修建，已经好几次逾期未完工。印度交通部官员称，立交桥的建造事宜属于上一届政府）

呵呵，印度交通部官员称，立交桥的建造事宜属于上一届政府

从破坏的形式看，应该是失稳引起的坍塌

这种板梁组合桥，在施工阶段的荷载全部由钢截面承担，从图片看板梁间的横向联系似较弱。

太高又很薄的钢纵梁，局部稳定的问题

看来大家初步结论基本一致——即钢结构失稳！