May 16, 2020

Construction industry reports strong demand for new professionals

Birmingham NEC
2 min
Construction industry reports strong demand for new professionals
It's good news for engineering and construction professionals in the UK as more career opportunities are opening up across the country. British comp...

It's good news for engineering and construction professionals in the UK as more career opportunities are opening up across the country. British companies are reporting large demand for new specialist staff, with 53 percent of employers currently seeking new recruits according to an IET survey. 

Professionals searching for new job roles can discover hundreds of vacancies at the National Engineering and Construction Recruitment Exhibition, which takes place between the 22nd and 23rd of April at Birmingham's NEC. There is a vast range of career opportunities and advice available for skilled workers as well as graduates.

The event is free to enter, and those attending can meet face-to-face with industry-leading employers to discuss job openings. Major organisations are involved with the show, including HS2, British Antarctic Survey, Highways England, Ultra Electronics Sonar Systems, Carbibbean East Atlantic Company, QinetiQ, and GE. Many of these will host presentations and information about current projects, as well as discussing career opportunities. 

The first day of the show includes the Women in Engineering Forum - supported by the Women's Engineering Society - which offers women a platform to network and share their experiences.

John Hancock, MD of Venture Marketing Group which organises the event, commented: “This show has bred some real success stories with visitors meeting and then winning jobs with engineering and construction organisations. It has also played a major part in introducing visitors to roles they may not have previously considered. Meeting face to face with exhibitors delivers a real insight into what opportunities they have to offer and what they are looking for in an ideal applicant.” 


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Jun 17, 2021

Why engineers must always consider human-induced vibration

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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