New Opportunities for Construction SMEs
Recent announcements by the Homes & Communities Agency (HCA) have provided plenty of cause for optimism; 80 public land sites, coming in at over 600 acres, will be put up for sale to accelerate house building.
However, with the EU Threshold in place, a number of SMEs are struggling to compete in the tendering process due to restrictive financial controls. The House Builders Association (HBA) are working with the HCA to break this down by providing a catalogue of smaller sites with a simpler tendering process for smaller housebuilders, as well as facilitating access to finance.
Speaking on the behalf of the House Builders Association (HBA), Policy Advisor Rico Wojtulewicz said:
“Access to finance has improved but many developers have difficulty drawing it down due to a lack of planning permission. The Government has recognised this fact and as well as communicating with the HBA to find a solution the HCA is making a strong effort to identify small sites and support SMEs. This will surely help but the HBA remains staunch in its opinion that fixing planning and giving small sites and infill the same focus as large sites would not only improve the housing crisis but begin closing the gap between ‘affordable’ and realistically affordable.”
Alongside housebuilders, SMEs operating in the north of England stand to benefit substantially from government support, as the Northern Powerhouse plan begins to show more tangible benefits for smaller construction companies.
Supported by the Greater Manchester Chamber of Commerce, North England Build 2016 will be held at Manchester Central in April, and has positioned itself as a key platform for SMEs to discover opportunities within the housing sector as a result of the Northern Powerhouse initiative.
Chris Fletcher, Marketing & Policy Director at Greater Manchester Chamber of Commerce, said:
“We are really pleased to be able to support North England Build and it’s great that Manchester has been chosen as the venue for this event. There is a lot of discussion and talk around the Northern Powerhouse at present and also a lot of differing views over what business opportunities will come about as part of this. There’s no doubt that the construction sector will play a major part in the Powerhouse and events like this will help set the scene for many as to what the benefits will be.”
For more information and to register for a free ticket, visit www.northenglandbuildexpo.com.
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.