几何尺寸与公差论坛------致力于产品几何量公差标准GD&T (GDT:ASME)|New GPS(ISO)研究/CAD设计/CAM加工/CMM测量 - 查看单个帖子

1865 bridge photo
just a cool photo of a view down the chain bridge over the potomac at washington circa 1865.
cool photo! looks like it is being guarded by union troops.
daveatkins
looking at those yankees, i wonder how they won the war. guess by that time, our boys looked even worse.
here's a side view.
awesome pics!
looks like the designer couldn't decide on a truss bridge or an arch bridge, so he used both. i wonder how long a timber bridge like that lasted. looks like pine from virginia, not exactly a durable timber. the rods would have been cast iron, so would have outlasted the wood.
here's a website with some short history of this bridge (there were many at this site) this one apparently was destroyed in a flood.
hokie66 - it's actually called a burr bridge after theodore burr; a combination arch & truss.
if you're ever in the allentown pa vicinity, go to covered bridge state park. there are two well preserved burr bridges from the 1850's - and still open to traffic.
thanks bridgebuster, that's a new one for my vocabulary. will look him up. what materials were used in the allentown bridges?
they're timber bridges. a lot of covered timber bridges in southeast pa.
we just completed a bridge much like the one in the photo. ours was a 128' single span. all timber. hs20 loading. the only steel in it was the bolts and plates at the connections.
those were some fun shop drawings to check.

2009-09-06, 10:36 PM	#1
huangyhg 超级版主注册日期: 04-03 帖子: 18592 精华: 36 现金: 249466 标准币资产: 1080358888 标准币	1865 bridge photo 1865 bridge photo just a cool photo of a view down the chain bridge over the potomac at washington circa 1865. cool photo! looks like it is being guarded by union troops. daveatkins looking at those yankees, i wonder how they won the war. guess by that time, our boys looked even worse. here's a side view. awesome pics! looks like the designer couldn't decide on a truss bridge or an arch bridge, so he used both. i wonder how long a timber bridge like that lasted. looks like pine from virginia, not exactly a durable timber. the rods would have been cast iron, so would have outlasted the wood. here's a website with some short history of this bridge (there were many at this site) this one apparently was destroyed in a flood. hokie66 - it's actually called a burr bridge after theodore burr; a combination arch & truss. if you're ever in the allentown pa vicinity, go to covered bridge state park. there are two well preserved burr bridges from the 1850's - and still open to traffic. thanks bridgebuster, that's a new one for my vocabulary. will look him up. what materials were used in the allentown bridges? they're timber bridges. a lot of covered timber bridges in southeast pa. we just completed a bridge much like the one in the photo. ours was a 128' single span. all timber. hs20 loading. the only steel in it was the bolts and plates at the connections. those were some fun shop drawings to check. __________________ 借用达朗贝尔的名言：前进吧，你会得到信心! [url="http://www.dimcax.com"]几何尺寸与公差标准[/url]