STORMLAMP - STructural behaviour Of Rock Mounted Lighthouses At the Mercy of imPulsive waves

Lead Research Organisation: University of Exeter
Department Name: Engineering Computer Science and Maths

Abstract

Historic rock-mounted lighthouses play a vital role in the safe navigation around perilous reefs. However their longevity is threatened by the battering of waves which may be set to increase with climate change. Virtual navigational aids such as GPS are fallible, and reliance on them can be disastrous. Mariners will therefore continue to need the physical visual aids of these strategic structures. The loss of any reef lighthouse will be incalculable in terms of safety, trade and heritage.

Plymouth University has trialled the use of recording instruments to capture limited information on the loading and response of Eddystone Lighthouse, with the support of the General Lighthouse Authorities (GLAs) having legal responsibility to safeguard aids to marine navigation around the British Isles. The study evaluated the extreme logistical constraints of lighthouse operations and the feasibility of using instrumentation to understand the response of the lighthouse to wave loads, with results strongly encouraging a comprehensive study of the load and response environment.

Hence a full-scale project is proposed whereby field, laboratory and mathematical/computer modelling methods, novel both individually and collectively, will be used to assess six of the most vulnerable rock lighthouses in the UK and Ireland. Depending on the findings the investigation will then focus on extended full-scale evaluation of one lighthouse for the following two winters.

The field instrumentation run by University of Exeter, and which will include modal testing and long term instrumentation will require novel procedures and technologies to be created to deal with the challenging environmental and logistical constraints e.g. of access, timing power.

The modal test data will be used to guide the creation, by UCL, of sophisticated multi-scale numerical simulations of lighthouses that can be used with the data to diagnose observed performance in the long-term monitoring.

The numerical structural model will also be linked with advanced physical modelling at Plymouth University's COAST Laboratory, and numerical (computational fluid dynamic) simulations.

Finally, based on the structural and wave loading models, the long term monitoring will be used to characterize the wave loading in-situ at full scale.

Outcomes of the project will be used to inform the comprehensive structural health monitoring of other lighthouses both in the British Isles and further afield through the International Association of Lighthouse Authorities. This will lead to the identification of structural distress and reduction in the risk of failure through preventative measures. Methods developed will also be of relevance to other masonry structures under wave loads so the project team includes a number of industrial partners: AECOM, Atkins, HR Wallingford and the Environment Agency who have interests in this area. As the UK has a large number of ageing coastal defences whose vulnerability to wave load was demonstrated in the winter 2013/14 storms, the applicability of the STORMLAMP findings to these structures is an important additional benefit of the project.

Publications

10 25 50
 
Description Forced vibration using a 'shaker' enables identification of at least the fundamental modes of vibration.

Where there is a helideck, there are up to 4 'fundamental' modes, in two directions and with different phase with respect to the masonry structure.
Helidecks modify the modal mass, a key parameter controlling the response to external horizontal loads.
For Wolf Rock, the identified modal parameters provide a means to estimate the breaking wave modal impulses.

Monitoring data for the 2017/2018 winter storm season corroborate wave tank data on extreme loads.

Fastnet's extreme wave climate shows no statistically significant effects of due to the climate change.
Lighthouses are not affected by direct breaking wave loadings but by broken wave impacts - intensity is reduced but duration is increased, compared to unbroken wave.
Wave load does not vary linearly with breaking distance - depends on whether the wave can regenerate after it first breaks, so depends on precise bathymetry.
Impulsive force is always larger than the quasi-static force.
Force laboratory data can be effectively analysed by means of seismic analysis techniques such as deconvolution and Duhamel integral.
Structural response of lighthouses due to waves is governed by uplift and rocking. DEM and FEM with contact interfaces between discontinuous blocks successfully used for modelling extreme wave impacts.
Limit analysis used for assessing failure using Python code used on 6 lighthouses - size, shape, density, and height above the sea level were found to be crucial.
The vulnerability of the lighthouses, in combination with extreme wave hazard can be used for prioritising the detailed analysis and structural assessment.
Exploitation Route There is an unrelated but parallel project on lighthouses being undertaken in France. We are exchanging findings with those investigators.
Sectors Construction,Digital/Communication/Information Technologies (including Software),Environment,Culture, Heritage, Museums and Collections,Transport

URL https://stormlamp.org.uk/blog
 
Description We are anticipating that the UK and Irish General Lighthouse Authorities (GLAs) will be changing their approach to the long-term assessment of their rock lighthouses. The final work package of the STORMLAMP project is the development of guidelines for the GLAs and we hope that details from this document will be incorporated into the International Association of Lighthouse Authorities updated Guideline on Extreme Environmental Conditions (Raby was contacted by the relevant IALA committee in February 2020 to see if She could provide information).
First Year Of Impact 2019
Sector Aerospace, Defence and Marine,Culture, Heritage, Museums and Collections,Transport
 
Description EPSRC magazine piece 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact The EPSRC's Pioneer magazine 19th edition featured the award winning aerial photograph of Fastnet lighthouse off the coast of Ireland which was captured by Vibration Engineering Section member James Bassitt while he was working off shore on the EPSRC funded STORMLAMP project.
Year(s) Of Engagement Activity 2018
 
Description Filmbright film 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Protecting our lighthouses for the safety of mariners - Stormlamp - full length film
Year(s) Of Engagement Activity 2018
 
Description Hong Kong lighthouse talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Dr Alison Raby at the University of Plymouth was invited to give a talk at the First International Lighthouse Symposium in Hong Kong
Year(s) Of Engagement Activity 2017
 
Description Lighthouses, Bridges and Breakwaters talk 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact On behalf of Dr Alison Raby at the University of Plymouth: The STORMLAMP project was invited to take part in the Institution of Civil Engineers 200th anniversary celebrations in conjunction with the Plymouth Museum. We gave a talk entitled 'Wave loading on heritage lighthouses in the British Isles'
Year(s) Of Engagement Activity 2018
 
Description Presentation at IOMAC conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact talk: Brownjohn JMW, Raby A, Au S-K, Zhu Z, Wang X, Antonini A, Bayesian operational modal analysis of offshore rock lighthouses: close modes, alignment, symmetry and uncertainty. IOMAC, Denmark, May 2019
Year(s) Of Engagement Activity 2019
 
Description Presentation at University of Cambridge 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Presentation about STORMLAMP to University of Cambridge
Year(s) Of Engagement Activity 2018
 
Description Refurb workshop and consortium meeting 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Third sector organisations
Results and Impact REFURB workshop (28th June) and REFURB consortium meeting (12th Sept)
Year(s) Of Engagement Activity 2018
 
Description STORMLAMP blog 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact EPSRC blog about STORMLAMP written by Alison Raby. We connected to this on the VES WordPress blog at https://veswordpresscom.wordpress.com/2019/01/24/check-out-the-epsrc-blog-about-stormlamp/
Year(s) Of Engagement Activity 2018
URL https://epsrc.ukri.org/blog/projectstormlamp/
 
Description STORMLAMP meetings 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Industry/Business
Results and Impact Meeting to discuss research outputs and industry collaborations
Year(s) Of Engagement Activity 2018
 
Description STORMLAMP promotion via blog, LinkedIn, Twitter 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Promotion of STORMLAMP via the Vibration Engineering Section blog (URL below), LinkedIn and Twitter @VibrationUoE
Year(s) Of Engagement Activity 2018
URL https://veswordpresscom.wordpress.com
 
Description STORMLAMP team deliver Royal Society journal themed special issue on environmental loading of heritage structures 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Media (as a channel to the public)
Results and Impact The special issue in Philosophical Transactions of the Royal Society A is about how heritage structures are impacted by environmental factors such as wind and waves. It was led by Prof. Alison Raby, University of Plymouth and joint edited by Prof. James Brownjohn (VES), Prof. Dina D'Ayala of University College London and Dr Alessandro Antonioni of TU Delft.
Year(s) Of Engagement Activity 2019
URL https://veswordpresscom.wordpress.com/2019/08/23/stormlamp-team-deliver-royal-society-journal-themed...
 
Description presentation at HEAMES conference 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Third sector organisations
Results and Impact talk: Brownjohn JMW, Raby A, Antonini A, Bassitt J, Condition assessment and monitoring of rock lighthouses around the British Isles. HEAMES, 23/24 May 2019 Glasgow
Year(s) Of Engagement Activity 2019