May 16, 2020

North England Build opens its doors to leading Northern construction companies

construction
north england build
expo
industry
Admin
2 min
North England Build opens its doors to leading Northern construction companies
North England Build, the leading new construction show, is set to occur on the 27th and 28th of April. It focusses on construction projects and developm...

North England Build, the leading new construction show, is set to occur on the 27th and 28th of April. It focusses on construction projects and developments in Northern England, and is a great chance to create new business connections and network with industry professionals across the UK. The event will feature the major contractors, suppliers, architects, developers and many more construction industry professionals from across the region.

News over recent times has focused on the skills shortage within the industry which is putting the breaks on growth within the sector resulting in a number of companies having to turn down contracts. To address this, visitors will now also benefit from the go-to place to find the future of construction at the North England Build Skills Hub.

While the current skills shortage is an undeniable cause for concern, North England Build will be launching the skills hub. This zone will bring together some of the UK's leading universities, associations and talent procurement experts working within the construction industry, to provide an area for people to learn about the latest training and employment opportunities in the north of England. 

Opening the conference will be Dr. David Hancock, Head of Construction at the Cabinet Office, who will be examining the government's 2025 construction strategy outlined by the previous government and updated earlier this year.

Chris Chivers, CIOB President, who will also be chairing a panel discussion at the event, said: “North England Build is set to showcase why there is about to be a better balance between the rate of growth in the South East and the North in the near future. It is no coincidence that construction employers, educationalists and recruiters will be mixing together to discuss the employment opportunities that will come as a result. Chartered professionals like CIOB members will have a key role to play and we look forward to taking the message of professionalism into the Expo.”

 

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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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