Symbiosis is key for digitising surging cities
Roughly 3.5 billion people across the world live in cities, with the United Nations expecting this to almost double by 2050, stating that successful urban planning will be key to managing this influx. Transport, energy and utilities, and public services organisations will have to support this population growth, for which data analysis and collaboration with industry stakeholders will likely be the key to success.
Singapore is at the top of the list for preparing for this increase in urban dwellers. Winning the accolade for the smartest city in the world this year, it is in the process of creating a virtual representation of the city, deploying a vast number of sensors and cameras, to do things like helping monitor the cleanliness of its public spaces, storing the dimensions and construction materials of buildings, and assisting with traffic management. While Singapore is leading the way, we cannot ignore the steps that have already been taken in the UK.
If we look to Glasgow, smart street lights have been installed that can record air quality, noise and movement to save energy. While, Milton Keynes is using parking sensors to improve parking infrastructure and has also launched installations, such as an Open Energy Map, to empower local communities to better understand their fuel usage. Looking more broadly, the UK government has pledged for every home and business to have a smart meter by the end of 2020. The overall aim of this initiative is to achieve a low-carbon, efficient and reliable way of delivering gas and electricity, while also being a foundation for an eventual smart energy grid that aims to further green our processes and reduce wastage.
While there is no doubt that there is an insurmountable amount of data being collected from devices and sensors across the UK, this data is ineffective unless we analyse it effectively and turn it into valuable insight. Being able to collaborate and share data between different stakeholders involved, from local government, to construction companies, and energy and technology providers, will be key. For smart cities to truly work, we will need to create an eco-system whereby all services of a connected city are truly symbiotic.
Investing in infrastructure, integrating tools such as big data platforms and Internet of Things (IoT), and having appropriate storage requirements are a must. This means cities can analyse data on a big scale. Stakeholders also need to be upskilled with the knowledge of how to integrate big data analytics into the decision-making process before headway can be made. Eventually, they will be able to use analytics and algorithms to make precise predictions that will benefit everyone, such as foreseeing traffic congestion, knowing how infectious diseases may spread and responding to power outages faster.
UK cities are on the right path to solving these challenges and synchronising data - the 2020 smart metre pledge by the UK government and individual city initiatives show this. Just last year, we also saw the BIM Task Group unveil its ten-year plan for ‘Digital Built Britain’ which includes an open data policy and BIM Level 3 being used to support the growth of smart cities, services and grids. Now, we just need to create a collaborative environment in order to make truly smart, connected cities a reality.
Joe Campbell, Senior Director, Engineering Construction and Operations, Cognizant
Read the August 2016 issue of Construction Global magazine
Why engineers must always consider human-induced vibration
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.