Tag: construction

Cracks in pedestrian bridge possible root of failure

2:42 pm

Cracks found in a Florida pedestrian bridge prior to its collapse, killing six, might have indicated the upcoming failure.

A key concrete support truss in the doomed Florida International University pedestrian bridge developed worrisome cracks 10 days before the structure was lifted into place over the Tamiami Trail, photographs and an internal email unintentionally released by the school show.

The documents, released in response to public records requests from the Miami Herald, show that FIU’s construction and engineering team discovered potentially problematic cracks in the bridge earlier than officials have previously acknowledged.

Because of the ongoing investigation we do not yet how the engineering company building the bridge responded to the cracks. They might have analyzed them and dismissed them. Or the might have ignored them entirely.

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Construction by helicopter

6:01 pm

An evening pause: As noted on the youtube webpage, “The last two components of the Incity Tower spire were put in place by helicopter on Sunday 21 June [2015]. This metallic spire, which measures 50 metres and weighs 25.9 tonnes, took the building to its final height of 200 metres. This confirms its position as the highest tower in Lyon and the third highest in France. Three aerial beacons and a lightning rod will now be placed at the top.”

Hat tip Phill Oltmann.

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Under Seattle Bertha has stopped drilling because something is in the way.

9:27 pm

Under Seattle Bertha has stopped drilling because something is in the way.

Something unknown, engineers say — and all the more intriguing to many residents for being unknown — has blocked the progress of the biggest-diameter tunnel-boring machine in use on the planet, a high-tech, largely automated wonder called Bertha. At five stories high with a crew of 20, the cigar-shaped behemoth was grinding away underground on a two-mile-long, $3.1 billion highway tunnel under the city’s waterfront on Dec. 6 when it encountered something in its path that managers still simply refer to as “the object.”

The object’s composition and provenance remain unknown almost two weeks after first contact because in a state-of-the-art tunneling machine, as it turns out, you can’t exactly poke your head out the window and look.

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Scientists have finally discovered the forgotten formula for the concrete the Romans used.

8:48 am

Scientists have finally discovered the forgotten formula for the concrete the Romans used.

The secret to Roman concrete lies in its unique mineral formulation and production technique. As the researchers explain in a press release outlining their findings, “The Romans made concrete by mixing lime and volcanic rock. For underwater structures, lime and volcanic ash were mixed to form mortar, and this mortar and volcanic tuff were packed into wooden forms. The seawater instantly triggered a hot chemical reaction. The lime was hydrated—incorporating water molecules into its structure—and reacted with the ash to cement the whole mixture together.”

The Portland cement formula crucially lacks the lyme and volcanic ash mixture. As a result, it doesn’t bind quite as well when compared with the Roman concrete, researchers found. It is this inferior binding property that explains why structures made of Portland cement tend to weaken and crack after a few decades of use, Jackson says.

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Shifou Mountain Footpath Construction

6:01 pm

An evening pause: In China they are building a tourist footpath on the side of Shifou Mountain. For additional information as well as video of the work, go here.

A plank path along cliffs is taking shape in a scenic spot in Yuyang city, South China’s Hunan Province. The path zigzags several hundred meters long but is only one meter wide along cliffs, without guardrail. The path builders walk on it as if in an ordinary street.

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Traffic and more roads

8:12 am

Puncturing the myth that more roads mean more congestion Key quote:

Read enough of these studies and you get a sense that much of the induced-demand hubbub is really a sub rosa extension of the war on the suburbs: Stop highway expansion and you can make life miserable enough for the minivan-driving masses that they’ll move out of their gauche “urban-fringe developments” and back to high-density metropolitan cores, where they belong.

In reading the full essay, I was struck by how much the scientific campaign against road construction reminded me of climategate.

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