May 16, 2020

AT&T to collaborate with Dublin City and IDA Ireland to explore smart cities development

Smart cities solutions
AT&T Smart cities solutions
IDA Ireland
Owen Keegan
Catherine Sturman
2 min
AT&T to collaborate with Dublin City and IDA Ireland to explore smart cities development
Smart cities solutions can offer citizens many benefits in sustainability, transportation, public safety, infrastructure and more. In fact, as part of A...

Smart cities solutions can offer citizens many benefits in sustainability, transportation, public safety, infrastructure and more. In fact, as part of AT&T’s smart cities initiative in the US., the company is currently working with several spotlight cities, including Atlanta, Chicago and Miami-Dade County on projects ranging from water conservation to intelligent lighting to citizen engagement. 

"IoT solutions are already generating a measurable value for businesses. And around the world, more cities are realizing the impact IoT solutions can have on making their communities more efficient, sustainable and enjoyable," said Mike Zeto, General Manager, AT&T Smart Cities. "As an IoT and smart cities leader, we're excited to lend our passion, expertise and insights to help Dublin create a more connected city that will have lasting benefits for current and future generations."

"IDA Ireland welcomes AT&T's choice of Ireland as the company's first international location for global Smart Cities collaboration," said Martin Shanahan, CEO, IDA Ireland. "The availability of world class talent, excellent infrastructure and openness from industry, academia and government to collaborate, enables companies to deliver outstanding IoT products and services. Companies are discovering that Ireland is small enough to trial, yet big enough to prove their Internet of Things technologies and solutions."

"Being smarter will be a defining characteristic of tomorrow's leading cities. Dublin has the key ingredients and is exploiting them to be at the forefront of smart city developments leveraging our unique cluster of global technology companies, thriving start-ups and research centres," said Owen Keegan, Chief Executive, Dublin City Council. "Dublin City Council is delighted to collaborate with AT&T, one of the world's leading technology companies, to explore future smart city innovations."

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Jun 17, 2021

Why engineers must always consider human-induced vibration

Vibrations
Engineering
design
Structuralintegrity
Dominic Ellis
3 min
Human-induced vibration can lead to a number of effects upon the structure and its users

Human induced vibration, or more accurately vibrations caused by human footfall, often conjures images of Millennium Bridge-style swaying or collapsing buildings.

But in reality, the ‘damage’ caused by human-induced vibrations is less likely to ruin a structure and more likely to cause discomfort in people. Though not as dramatic as a structural failure, any good engineer wants to make sure the people using their structures, be it bridges or buildings or anything in between, can do so safely and comfortably. This is why human-induced vibration must be considered within the design process.

Resonance v Impulse

There are two ways that human-induced vibrations affect structures: resonant, and impulse or transient response. Put simply, resonance occurs when Object A vibrates at the same natural frequency as Object B.

Object B resonates and begins to vibrate too. Think singing to break a wine glass! Although the person singing isn’t touching the glass, the vibrations of their voice are resonating with the glass’s natural frequency, causing this vibration to get stronger and stronger and eventually, break the glass. In the case of a structure, resonance occurs when the pedestrian’s feet land in time with the vibration.

On the other hand, impulse or transient vibration responses can be a problem on structures where its natural frequencies are too high for resonance to occur, such as where the structure is light or stiff. Here the discomfort is caused by the initial “bounce” of the structure caused by the footstep and is a concern on light or stiff structures.

Engineers must, of course, design to reduce the vibration effects caused by either impulse or resonance.

Potential impacts from human induced vibration

Human induced vibration can lead to a number of effects upon the structure and its users. These include:

  • Interfering with sensitive equipment Depending on the building’s purpose, what it houses can be affected by the vibrations of people using the building. Universities and laboratories, for example, may have sensitive equipment whose accuracy and performance could be damaged by vibrations. Even in ordinary offices the footfall vibration can wobble computer screens, upsetting the workers.
     
  • Swaying bridges One of the most famous examples of human-induced resonance impacting a structure occurred with the Millennium Bridge. As people walked across the bridge, the footsteps caused the bridge to sway, and everybody had to walk in time with the sway because it was difficult not to. Thankfully, this feedback can only occur with horizontal vibrations so building floors are safe from it, but footbridges need careful checking to prevent it.
     
  • Human discomfort According to research, vibrations in buildings and structures can cause depression and even motion sickness in inhabitants. Tall buildings sway in the wind and footsteps can be felt, even subconsciously by the occupants. It has been argued that modern efficient designs featuring thinner floor slabs and wider spacing in column design mean that these new builds are not as effective at dampening vibrations as older buildings are.
     
  • Jeopardising structural integrity The build-up of constant vibrations on a structure can, eventually, lead to structural integrity being compromised. A worse-case scenario would be the complete collapse of the structure and is the reason some bridges insist that marching troops break step before crossing. Crowds jumping in time to music or in response to a goal in a stadium are also dynamic loads that might damage an under-designed structure.

How to avoid it

As mentioned, modern designs that favour thinner slabs and wider column spacing are particularly susceptible to all forms of vibration, human-induced or otherwise, but short spans can also suffer due to their low mass. Using sophisticated structural engineering software is an effective method for engineers to test for and mitigate footfall and other vibrations at the design stage.

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