New paper published: Review of Pedestrian Load Models for Vibration Serviceability Assessment of Floor Structures

Review of Pedestrian Load Models for Vibration Serviceability Assessment of Floor Structures is now published in the MDPI journal Vibration.

Innovative design and technological advancements in the construction industry have resulted in an increased use of large, slender and lightweight floors in contemporary office buildings. Compounded by an ever-increasing use of open-plan layouts with few internal partitions and thus lower damping, floor vibration is becoming a governing limit state in the modern structural design originating from dynamic footfall excitations.

This could cause annoyance and discomfort to building occupants as well as knock-on management and financial consequences for facility owners. This article presents a comprehensive review pertinent to walking-induced dynamic loading of low-frequency floor structures. It is intended to introduce and explain key walking parameters in the field as well as summarise the development of previous walking models and methods for vibration serviceability assessment.

Although a number of walking models and design procedures have been proposed, the literature survey highlights that further work is required in the following areas; (1) the development of a probabilistic multi-person loading model which accounts for inter- and intra-subject variabilities, (2) the identification of walking paths (routes accounting for the effect of occupancy patterns on office floors) coupled with spatial distribution of pedestrians and (3) the production of a statistical spatial response approach for vibration serviceability assessment.

A stochastic approach, capable of taking into account uncertainties in loading model and vibration responses, appears to be a more reliable way forward compared to the deterministic approaches of the past and there is a clear need for further research in this area.

Vibration Engineering Section ensures biosciences lab meets stringent vibration control requirements

VES collaborated with PCE Ltd to ensure the Capella biosciences laboratory for the University of Cambridge could be constructed off-site while still meeting stringent vibration control requirements.

PCE Ltd,  design and build specialist contractor of offsite engineered Hybrid structures, collaborated with Kier Construction on the laboratory and engaged VES to assist in the design process by ensuring vibration control requirements were met.

Capella 2

The original design was an on-site in situ concrete structure by Consultant Engineer Arup, but due to limited construction site space, PCE wanted to ensure their offsite construction philosophy would mean the finished structure complied with stringent vibration control requirements. This vibration control was essential due to the extremely vibration-sensitive laboratory equipment to be installed on completion of the facility.

While initial calculations by PCE inferred the specification could be achieved, they required specialist knowledge to assist with design concepts and prove by post-construction physical site testing that the design met vibration specification requirements. They therefore contacted Professor Paul Reynolds of VES to provide this assistance.

Capella 7

Developing the building design

VES worked with PCE, the main contractor and the client’s design team, to develop the initial PCE design concept of precast concrete prestressed solid floor units, supported on composite steel beams, with an in situ concrete topping that had a reduced floor thickness compared to the original client’s concept of an in situ concrete structure.

Full-scale testing

Following the construction of a floor level, VES conducted a full scale test to determine the actual vibration response. Test results showed the offsite engineered theoretical design approach met the requirements of the original specification.

The collaboration between PCE and VES demonstrated that offsite construction methods can be adopted for buildings that require stringent vibration control, in line with the growing trend and Governmental drive for more construction to be based on offsite construction methods.

Garry Langston, Pre-Construction Director for PCE, said: “Without the involvement of VES, it may not have been possible to provide the offsite construction solution that provided the client with a reduced construction programme, a significant reduction in the number of site operatives and vehicle deliveries required that was so advantageous for such a project on the busy and congested Addenbrookes Hospital campus.

“Engaging the specialist services of VES at an early stage of the design process to give certainty in the resolution of the low vibration specification reduced the design and approval process that might otherwise occurred, and ensured an offsite construction solution, whilst the post-construction testing gave the reassurance the client required.”

Concrete Magazine ran a piece in May 2018 entitled Hybrid techniques provide “shining example of modern concrete construction.”

 

Protecting our lighthouses for the safety of mariners – Stormlamp – full length film

STORMLAMP – STructural behaviour Of Rock Mounted Lighthouses At the Mercy of imPulsive waves – is an EPSRC funded collaborative research project between the Universities of Plymouth, Exeter and University College London and a number of industry partners. 

The project characterises wave loading and structural performance of rock lighthouses, using combined field measurements, laboratory studies and analytical and numerical investigations, with the aim of supporting management of lighthouse structural conditions.

To find out more, check out the video below, created by Filmbright http://www.filmbright.com/

For more information about STORMLAMP, visit https://stormlamp.org.uk/

VSimulators – virtual reality facilities to support human factors research and innovation

Bridge with Users

Plans for a major new centre for research and development in the vibration engineering sector are in the final stages of development at the Universities of Exeter and Bath. In Exeter, a new, purpose built facility featuring a state-of-the-art VSimulator will, for the first-time, link structural movement and environmental conditions, with human perception monitoring, psychology and physiology, within a fully controllable virtual environment. At Bath, the VSimulator facility will focus on sensory perception of external environment and surroundings, and feature controls over room lighting colour and intensity, temperature, humidity, noise, air quality, and scent. The Bath facility will focus primarily aimed at exploring motion in tall buildings. The facilities will offer the opportunity to analyse the human factor impact of environments, whilst enabling full data capture.

VSimulators at the University of Exeter will be located on Exeter Science Park and will open in 2019. Meanwhile, the VSimulator at the University of Bath will be open from the end of 2018. The initial environments being studied in this EPSRC funded project include walking across bridges, working in high-rise office blocks and dancing in a crowded stadium. The VSimulators will recreate the impact of subtle motion in these spaces to enable a better understanding as to how this could affect the wellbeing of people, their work performance or behaviour.

Stadium With Users
The Exeter VSimulator scenes are being created by ‘Experience Designers’, Holovis, who specialise in multisensory training and simulated environments, with development of emerging technologies in these spaces. Virtual Reality will provide the ability to deeply immerse people into the desired scenarios, with up to nine people able to participate simultaneously.

The 4×4 metre space is on a custom designed Hexapod motion platform with freedom of movement in six directions. It was designed by E2M Technologies in Amsterdam, creating a fully instrumented floor capable of data capture and analysis. People can move freely around this space, seeing avatars of the other participants in the virtual world, tracked to their unique perspective. Alternatively, the space could recreate an existing environment, with physical objects placed where a virtual equivalent would be located. In these ways, the facilities are capable of being customised to fully explore the sensory immersion and human factor responses.

VR 2

Each person’s movements and reactions are captured via full body monitoring, and it is these metrics that will help the team to devise solutions to mitigate impact and assist designers, planners, architects and engineers in the future construction or refurbishment of buildings. However, there are uses beyond the construction and civil engineering field, with interest being expressed by the medical community, biomechanics specialists, the entertainment industry, sports scientists, psychologists, marine, autonomous vehicle, data science and virtual reality developers, amongst others.

Image of Exeter Science Park

Dave Elliott, Business Development Manager at Holovis comments:
“Increasingly, people are living and working in innovative environments where very little is known about the impact of the vibrations or their environment. The highly realistic nature of this multisensory environment will give them a true sense of immersion, making them believe they are in that location. Therefore they will subconsciously react to stimuli as they would in the real world. The flexibility of the VSimulators allows for an incredible range of conditions to be simulated, which will really help to advance the research and innovation in many sectors.”

Julie Lewis-Thompson, Commercial Manager for the VSimulators Project explains:
“There are extensive and diverse areas of commercial and academic interest for the VSimulators research facilities. We have identified 38 industry areas for exploration with interest from an expanding global based clients list, both within industry and academia..”

“There are multiple opportunities for interdisciplinary research including architecture for wellbeing, computer science, data analytics, the built environment, construction design and human factor responses. These facilities will place the Universities of Exeter and Bath at the forefront of expertise in the use of virtual reality within industry focused research”

For VSimulators at University of Exeter and University of Bath please contact
Julie Lewis-Thompson, T: +44 (0)1392 722603, E: j.a.b.lewis-thompson@exeter.ac.uk

For the Vibration Engineering Section please contact Katy Manning, T: +44 (0)1392 725821, E: k.l.manning@exeter.ac.uk

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Students from all over the UK attend structural vibrations summer school run by Vibration Engineering Section

Participants from academia and industry from all over the UK attended a week long structural vibrations residential summer school run by the Vibration Engineering Section (VES) and partners from the University of Liverpool, at the University of Exeter.

Funded by the Engineering and Physical Sciences Research Council (EPSRC) BAYOMALAW grant the school attracted undergraduate and PHD students from University College London the Universities of Exeter, Oxford, Liverpool, Aberdeen and Warwick, as well as an industry visitor from WSP Parsons Brinckerhoff.

BAYOMA 1

The course covered structures with single and multi-degrees of freedom, stochastic process and stochastic structural dynamics, power spectral density estimation, vibration testing and experimental modal analysis.

SUMMER schoolBAYOMA ss photo 3BAYOMA ss photo 2

 

As well as theoretical sessions, students carried out experimental modal analysis in the state of the art structures lab at the University of Exeter, which prepared them for a modal test of Baker Bridge at Sandy Park.

Bridge test 2Bridge test 1Bridge test 3Bridge test 4

Emma Hudson, Senior Consultant at Full Scale Dynamics Ltd, gave an industry talk to the group, presenting examples on her experimental work on structures such as sports stadia and lighthouses, as well as her work with ground borne vibrations.

The summer school culminated in group work, which took place in the Structures Lab.
James Brownjohn, who ran the school alongside Ivan Au from the University of Liverpool, said:

“With the increasing use lighter weight, more flexible materials in structures leading to more vibrations, which could be problematic in terms of safety and human perception and comfort, the ability to test and control such vibrations is becoming all the more crucial a skill for the structural engineers of the future.

“We would like to thank the EPSRC, whose funding has enabled us to run this course, which will have given the participants both an important theoretical grounding, and some practical experience in how to carry out these important tests.”

Engineers of the future present their projects to industry experts

Engineering students at the University of Exeter presented on a range of innovative projects including drones, a self-propelled capsule, a knee brace and a shaking table to industry experts at a special event.

More than 100 Master of Engineering (MEng) students from across a range of disciplines showcased their group work as posters, displays and presentations, to representatives from Babcock, the Institution of Mechanical Engineers, the Royal Devon & Exeter Hospital, Exeter College, and BSW Consulting Engineers.

The day-long event, which took place at the University’s Streatham campus, was an opportunity for students to showcase their project work and to network with industry contacts.

Professor James Brownjohn, lead academic for the module, said: “This cohort of students have created some really impressive work, and this experience will have sharpened crucial skills required by industry, such as team working, problem solving and project management.

He added: “The poster day also provides an excellent opportunity for representatives from industry to meet and engage with the engineers of the future.”

Poster day photo.JPG
The Natural Ventilation team with their project and poster

 

Vibration Engineering Section experts to run CPD course in Vibration Serviceability in June 2018

Engineers interested in fundamental vibration theory can enrol on IStructE’s CPD course run in London by our experts. To find out more about the event on 13th June 2018, visit

There is a second day of the course, covering the applications of vibration engineering, on 14th June 2018 and a discount for booking on both days. To find out more, visit https://bit.ly/2q8js0M

Check out recent testimonials about the course below:

Very good course overall. Based on the courses I have attended over the years, the speakers are the key to making the course successful or not. The combination of lecturing professors that also practice on a commercial basis was a huge benefit.

 A big thanks to the 2 presenters. Very knowledgeable people. Good presentation skills.

 Fantastic speakers, well presented course, both very personable and helpful. Thank you.

To find out more about the expertise of the professors running the course, visit Alex Pavic’s page on the VES website here and Paul Reynolds’ page on the VES website here