篮子手柄真正的拱形交叉构造|2021-02-10 |工程新闻记录

篮子手柄真拱门Crossing Takes Shape

Basket-handle true-arch bridge is the first of its kind over the Mississippi River.

图片由爱荷华州的点提供

2021年2月10日

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现在，一对篮子的双胞胎True-Arch桥现在正在伊利诺伊州和爱荷华州之间进行交通。根据爱荷华州运输部的说法，这座新的12亿美元的74河桥是在密西西比河上的第一个。

Weather conditions and the complexity of building the arches pushed initial opening of the westbound side from 2019 to 2020, but general contractor Lunda Construction met the modified deadline in November. Work is now underway on the Illinois-bound arch.

爱荷华州DOT项目经理Danielle Alvarez说，伊利诺伊州莫林（Moline）和爱荷华州贝滕多夫（Bettendorf）之间的独特地点条件使篮子手柄设计成为更典型的绑架拱桥上的首选。她说，该位置的河流水平低于河水的平均水平，基岩相对较浅，这使得真正的拱形设计成为可能。

新结构将取代一对悬架桥，该悬架桥是每天48,000辆车设计的。2016年，I-74桥的平均每日流量超过74,000，到2035年预计将增加到99,900。

爱荷华州的点和伊利诺斯州的交通部门一点点tled down options to four concepts—true arch, tied arch, cable-stayed and through truss. Public input indicated a preference for basket-handle true arch or cable-stayed, and the DOTs with the final design team of Alfred Benesch and Modjeski and Masters selected the former based on aesthetics, construction staging and redundancy.

“Compared to a cable-stayed bridge, the twin basket handle had the advantage of two separate structures,” says Ahmad Abu-Hawash, Iowa DOT chief structural engineer. “If we had to replace one, we can switch traffic to the other side.”

岩土技术范围从骨折和弱层的砂岩到整体石灰石地层。239基础竖井包括直径高达10英尺的码头脚，深50英尺。

每个篮子拱门的一部分有30个主要拱门部分，由两个中间和两个主要支撑连接。Keystone由两个由两个主要支撑杆连接的拱门段组成，该拱门安装为一件。

每个拱门细分市场可以重达约250,000磅。一个起重机将每个细分市场提升到位置，然后将其固定到位。与临时塔相关的留下电缆连接到四个拱门“腿”中的每个拱门的第三和第五拱门。这些停留时间用于支撑悬臂结构。

现在正在建造的伊利诺伊州结合的拱门“更复杂，因为它将支持多用途路径，因此它将需要有关拱门的位置和几何形状的其他考虑。由于新桥与旧桥梁之间存在，也存在一些站点的限制。” Alvarez说。其他挑战包括保护和重新定位受威胁的贻贝物种，并避免对附近下游大坝的影响。

Work is also ongoing on new approaches and improvements to roadways within a 7-mile corridor on both sides of the river, under separate contracts by Civil Constructors, Kraemer North America and Walsh Construction.

“今年，我们的重点是完成东行桥和道路。I-74木材环境和基础设施Solutions Inc.的I-74走廊经理乔治·瑞安（George Ryan）说，第18拱门的第18个拱门部分安装了。

“The eastbound span is being negotiated with the owners for an opening time between November and December of 2021,” said Tutor Perini, Lunda’s parent company, in a statement.

艾琳·乔, ENR's senior transportation editor, is a native of Los Angeles and recovering New Yorker. She studied English and theater at Occidental College, where a reporter teaching the one existing journalism course encouraged her to apply for the LA Times Minority Editing Training Program. Her journalism training led to her first stories about transportation, working as a cub reporter with the Greenwich Time. Her work has appeared in the Los Angeles Times and New York Times. Many of her experiences with engineers and contractors have inspired material for her alternative theater productions way, way off Broadway. For ENR, Aileen has traveled the world, clambering over bridges in China, touring an airport in Abu Dhabi and descending into dark subway tunnels in New York City. She is a regular at transportation conferences, where she finds that airport and mass transit engineers really know how to have fun. Aileen is always eager to hop on another flight because there are so many interesting projects and people, and she gets tired of throwing her cats off her computer in her home office in Long Beach, California. She is a very conflicted Mets/Dodgers fan.