New Breed Of Antennas

Researchers at NC State have developed shape-shifting antennas. These can overcome the limitations of traditional antennas by changing "... how far they can be bent – and how often – before they break completely."

From the article: "While the alloy makes an effective antenna that could be used in a variety of existing electronic devices, its durability and flexibility also open the door to a host of new applications. For example, an antenna in a flexible silicone shell could be used to monitor civil construction, such as bridges. As the bridge expands and contracts, it would stretch the antenna – changing the frequency of the antenna, and providing civil engineers information wirelessly about the condition of the bridge."

Click here to read more

Trump's tower (in Chicago) now 6th tallest building

From the Chicago Tribune:

"The Chicago-based Council on Tall Buildings and Urban Habitat, the global arbiter of height standards, has changed its criteria for measuring skyscrapers.

The old standard was that a skyscraper's height was determined by calculating the distance from the sidewalk outside the main entrance to the building's spire or structural top.

The new standard is that height is measured from "the lowest, significant, open-air, pedestrian entrance" to the top.

For the Trump tower, this means an extra 27 feet in height. Its bottom is now considered to be the entrance to the still-unoccupied shops along the along the Chicago riverwalk, not the main entrance on Wabash Ave."

Click here for the full article.

Falling Smoke Stack

This is a slow-motion video of the demolition of a smoke stack (probably from a power plant) on the campus of Drexel University. At the 0:35 second mark, once the stack impacts the ground, you can see a shock wave travel through the glass cladding on the building in the center of the video.



(It helps to view the video in a full screen mode)

Ryugyong Hotel

Infamously ugly and unfinished, the shell of the Ryugyong Hotel dominates North Korea's capital, Pyongyang. But work on the skyscraper began again last summer after a 16-year hiatus and, as the company behind it tells the BBC's Matthew Davis, an end may finally be in sight.

Read more at: http://news.bbc.co.uk/2/hi/asia-pacific/8306697.stm

Dynamic Soaring

From pbs.org:

...the concept of dynamic soaring dates back to the 1880s, when it was proposed by the physicist Lord Rayleigh. “He was watching the flight of birds and he figured out that birds could take advantage of gusts of wind,” explains Bowers. “He reasoned that as a stronger gust would hit a bird, the bird would see that as an increase in the amount of energy that it had and could convert that energy into an increase in altitude...”

Continue reading the article at pbs.org: Thermal vs. Dynamic Soaring

Changing Dynamics of Aerodynamics

The wind engineering community, like so many other science and engineering fields, are constantly exploring ways in which emerging and evolving technologies can be incorporated to enhance the current body of work.

This paper, entitled "The Changing Dynamics of Aerodynamics: New Frontiers," highlights some of the collaborative work being conducted between the NatHaz Lab and other partners. It will be presented at APCWE VII in Taipei, Taiwan.

Finding Order in Fluid Currents

"Over the past 10 years, scientists have made enormous strides in their ability to identify and make images of the underlying mechanics of flowing air and water, and to predict how objects move through these flows...."

... story continued at nytimes.com "Finding Order in the Apparent Chaos of Currents"

ICOSSAR 2009 Keynote

This video is of the first 10 minutes of Prof. Kareem's keynote address at ICOSSAR 2009.

Out of Step on the Bridge

(image from Wikipedia)

The Millennium Bridge in London, England, which opened in 2000, became famous for its "wobbly" motions after crowds of pedestrians moved across it. Different theories into the nature of the bridge motion were developed, one of which was highlighted in the May 2009 issue of ASCE's Civil Engineering Magazine in an article entitled "Bio-mechanics Research Yields Clues to Millennium Bridge Wobble." Dr. Kareem has provided some insightful follow-up comments to this article.

Making the most of storm damage

(image from Wikipedia)

In March of 2008, a tornado outbreak made its way through the city of Atlanta, GA. Roofs were damaged on low rise structures, trees were uprooted and glass damage was common to the high rise structures in the tornado's path. A year later, the city and building owners chose to make the best of the situation by rebuilding "Green".

Atlanta rebuilds "Green" after tornado. from the Atlanta Journal-Constitution (registration may be required)

ICOSSAR 2009 Keynote Lecture

The Audacity of Change: A Transition to Nonstationary and Nonlinear Era

by Dr. Ahsan Kareem

Travel through Dubai at 818 mph

Take a quick journey through the cityscape of Dubai from the vantage point of the metro at 818 mph.

224-story Skyscraper

From the Los Angeles Times...

"A Santa Monica architect known for his high-rise designs is working on what may be the ultimate "spec" building -- a 224-story skyscraper with green ambitions that would be the tallest structure in the world."

Click here for the full article

Embedded Documents

Leave it to Google to come up with very useful web features. With Google, it is possible to embed PDF and PowerPoint documents directly into the web page. No need for downloading or opening the document in another program, it can be viewed directly from the web page.

Trust and the Internet

The aim of the "TechnoCrowd" is to amass many different points of view and opinions into one space, giving readers/users the ability to parse that information for new concepts and ideas. However, with the freedom to express those opinions, it is the responsibility of the reader to decide what is true and what is false for themselves.

Sites like Wikipedia are populated by anyone with a computer, while the task of verifying that information falls upon everyone else. To assist with fact checking, researchers at UC Santa Cruz are developing a system to parse common sites, like Wikipedia, and color code information in such a way to give a trustworthiness measure based on the reliability of the person posting and the information itself.

Article: "Adding Trust to Wikipedia, and Beyond"

Reflections on Alan Davenport

Dr. Ahsan Kareem, recipient of the Davenport Medal from the International Association for Wind Engineering, reflects on the impact that Prof. Davenport had, and continues to have, on his career and that of future researchers.

A Tribute to Avant Garde of Wind Engineering by Ahsan Kareem

Alan Davenport

For those of you who may not know, Prof. Davenport passed away last week. He was a prominent, defining figure in both the wind engineering community and the engineering community as a whole, and will certainly be missed.

The New York Times has a very good write-up of achievements, honors and contributions to the filed.

NYTimes: Alan G. Davenport, Noted Wind Engineer...

Time lapse video of a bridge

Here is a YouTube video of the Manhattan bridge, spanning several hours, showing it's structural performance.



The bridge was built in 1909 (wikipedia entry). The subway tracks are placed on the outside lanes of the lower level.

Sears Tower's glass ledge

The iconic Sears Tower, in Chicago, has a new feature. Jutting out from the 103rd floor is a new, enclosed glass ledge. It gives an unobstructed view to the ground from 1,353 ft. above. Given the discussion about glass damage, it's only fair to acknowledge some of the interesting uses of glass!

Sears Tower's new 'Ledge' offers visitors far-out views - Chicago Sun Times

11 ACWE

The NatHaz lab is attending the 11th Americas Conference on Wind Engineering in San Juan, Puerto Rico.

Some of the topics we will present include:

- Analysis of the surface pressure characteristics of prismatic models in gust front and downburst outflows

- Efficacy of damage detection measures for digital images

- Anatomy of damage to coastal construction: a multi-hazard perspective

- Consequences of urban aerodynamics and debris impact in extreme wind events

- A framework for Gust-Front Factor

- Load factors for dynamically sensitive structures

NY Times: study says U.S. winds are slowing

A June 15th, 2009 article in the New York Times (click here for the link) highlights a recent study that suggests wind speeds in the U.S. have been decreasing over the last 30 years.

A copy of the paper can be found here: S.C. Pryor et al., 2009 (Journal of Geophysical Research - Atmospheres)

Although there are issues pertaining to the data sets themselves, and the conditions of data collection (which are discussed in the paper), it does pose an interesting problem for U.S. Government mandates to harness more energy from wind to replace non-renewable sources. One of the authors did point out that most wind speed measurements are collected at airports, ~30 feet above the ground surface, which may differ from the wind speeds experienced by wind turbines at higher elevations.

The more interesting comment, however, was that a possible cause for the "slowing" winds might be the level of reforestation occurring in the U.S., the fourth fastest rate in the world between 2000 and 2005. Increasing forest cover my provide some much needed wind protection for many low rise structures that are currently reside in open exposures.

The Multi-Hazard Threat

(In addition to features about research in the NatHaz lab, we will periodically post news reports of interest which might spark interesting conversations)

As engineers, we typically like to focus on one problem at a time. However, multiple hazards occurring at the same time present an interesting puzzle for risk assessment and engineering design.

This report, Typhoons trigger earthquakes on Taiwan (click link for news report), highlights research which identifies sensor recordings of 20 "slow" earthquakes coinciding with 11 typhoons. The "slow" earthquake unfolds over a hours or days, rather than a few minutes or seconds. The researchers suggest that the low atmospheric pressure generated by the typhoon actually relieves pressure on one side of the converging plates. Interestingly, it is theorized that the stress relief caused by the typhoon may actually inhibit larger earthquakes from occurring, periodically releasing the stress build-up.

The question that remains is how do tall structures in Taiwan react to both the occurrence of "slow" earthquakes and wind action of the typhoon?

Saga of glass damage in hurricanes

Hurricane Ike impacted the Houston CBD at 2:30am on Sept. 13, 2008. Interesting damage patterns emerged, prompting engineers and researchers to examine the issue of urban aerodynamics related to glass damage.

The NatHaz Lab collected images of the damage, eyewitness accounts and utilized various techniques to assess the causes of glass/cladding damage to the JP Morgan Chase Tower (wikipedia link).

An earlier preliminary report of this investigation can be found on the NatHaz website. A direct link to the report is here (link to .pdf of report). Details of the findings since the earlier report, being presented at 11ACWE, can be viewed here (link to .pdf of full paper)

We invite you to post comments and your ideas about our findings, or the overall issue, in the "comments" section.

There is a lot to be learned!

Welcome to the NatHaz Blog

Welcome to the NatHaz Modeling Laboratory Blog. This will be a space to showcase some of the research being conducted in the lab, and to facilitate discussions about important topics using web-sourcing involving the "TechnoCrowd".

For more information about the NatHaz Lab, please view our laboratory website at the University of Notre Dame (NatHaz @ UND)